BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Closed loop feedback control of an external cavity diode laser for laser cooling application DTSTART;VALUE=DATE-TIME:20180626T094000Z DTEND;VALUE=DATE-TIME:20180626T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-1@events.saip.org.za DESCRIPTION:Speakers: Victory Opeolu (Cape Peninsula University of Technol ogy)\nLaser cooling of neutral atoms is currently receiving a lot of atten tion worldwide due to the fact that cold atoms are promising candidates fo r implementation of quantum information processing elements. To cool neutr al atoms\, such as Rubidium and Caesium\, external cavity diode lasers (EC DL) are commonly used. The laser frequency is finely tuned by adjusting th e cavity length as well as the diode current. The ECDL is locked to the ap propriate transition\, of Rubidium in our case\, using a saturated absorpt ion setup in the feedback path together with a proportional-integral-deriv ative (PID) controller\, to control the cavity length and diode current. I n this presentation we report on the analysis and performance of the close d loop control system using theoretical and numerical analysis\, together with validation using experimental data. We present numerical and experime ntal results of the system’s response to various input stimuli and provi de regions of safe operation.\n\nhttps://events.saip.org.za/event/100/cont ributions/1/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Maximizing the Channel Capacity of a Space Division Multiplexing S ystem. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-2@events.saip.org.za DESCRIPTION:Speakers: Luthando Maqondo (University of the Witwatersrand)\n The communications systems be-it through free-space or optical fibers have a major potential\, the possibility of sending data through multiple chan nels at the same time\, this is called Multiplexing. The free space optica l link is studied in this project. We transmit light modes either Laguerre -Gaussian (LG) or Hermite-Gaussian (HG) in the presence of atmospheric noi se\, turbulence. The optimization process is carried out by choosing ortho gonal modes based on translational invariance and resilience from wavefron ts distortions. The results show a significant increase in channel capacit y of the system according to a choice of mode combinations.\n\nhttps://eve nts.saip.org.za/event/100/contributions/2/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Experimental thermal performance of a domestic latent heat medium temperature storage system during charging DTSTART;VALUE=DATE-TIME:20180627T102000Z DTEND;VALUE=DATE-TIME:20180627T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-3@events.saip.org.za DESCRIPTION:Speakers: Katlego Lentswe (NWU)\nThermal energy storage (TES) helps alleviate the mismatch between energy supply and demand by using the stored energy during peak demand periods when it is required. The two mos t appropriate types of TES systems for domestic applications are sensible heat and latent heat TES. Latent heat TES systems have larger thermal ener gy storage densities as compared to sensible heat TES systems thus reducin g the space requirements for TES. An experimental investigation for a dom estic latent TES system is presented in this paper. The latent heat TES sy stem consists of a packed bed of encapsulated adipic acid in spherical alu minium spheres. The TES system is charged electrically using Sunflower Oil as the heat transfer fluid (HTF). Charging experiments are done with thre e different flow-rates (4 ml/s\, 8 ml/s and 12 ml/s). Charging results are presented in terms of the HTF temperatures\, phase change material (PCM) temperatures\, charging energy rates and charging exergy rates. Results sh ow that increasing the flow-rate reduces the temperature difference betwee n the top and the bottom of the storage thus reducing the degree of therma l stratification. This reduction in thermal stratification results in the lowest peak charging energy and exergy rates with the highest flow-rate (1 2 ml/s). Energy and exergy rate profiles peak and drop for all flow-rates as the temperature difference between the top and bottom of the storage ta nk reduces as charging progresses. Charging with lowest flow-rate (4 ml/s) shows the best thermal performance and more pronounced phase change chara cteristics for adipic acid.\n\nhttps://events.saip.org.za/event/100/contri butions/3/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Physics and Humanity\, Humanity and Physics DTSTART;VALUE=DATE-TIME:20180629T070000Z DTEND;VALUE=DATE-TIME:20180629T080000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-4@events.saip.org.za DESCRIPTION:Speakers: Irvy (Igle) Gledhill (U. Witwatersrand)\n“The Prin ciple of Universality of Science advocates the free and responsible practi ce of science as fundamental to scientific advancement and human and envir onmental well-being. Such practice\, in all its aspects\, requires freedom of movement\, association\, expression and communication for scientists\, as well as equitable access to data\, information\, and other resources f or research.” In this context\, many questions arise. One might ask: wh y are there relatively few women in physics\, but more women in the life s ciences? Why does the fraction of women in physics decline with seniority\ , and vary across countries? How do scientists begin to engage with these questions\, without diluting the excellence of their own difficult researc h?\n\nThis talk will cover some introductory data\, including surveys of p hysicists. A few useful concepts\, including gender schemas\, cumulative a dvantage and disadvantage\, and professional schemas will be introduced. O bstacles and barriers are encountered by all physicists\, and some of thos e related to gender will be described.\n \nApproaches to overcoming the ba rriers are pieces of a jigsaw involving law and policy\, national and inte rnational initiatives\, incentives and rewards\, professional development \, and improving the workplace culture. A major source of barriers arises when gender schemas are confused with professional schemas\, leading to a consistent under-evaluation of women in a profession. The most fundamental remedies that can be applied are to move toward accurate and fair evaluat ion\, to challenge hypotheses\, and to make a safe\, welcoming and humane environment in which to work.\n\nhttps://events.saip.org.za/event/100/cont ributions/4/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Enhanced Photocatalytic Activity of TiO2 Nanoparticles by Copper a nd Silver Codoping DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-5@events.saip.org.za DESCRIPTION:Speakers: Olatunbosun Nubi Nubi (University of Limpopo)\nThe l arge band-gap of Titania\, and the high recombination of photogenerated ch arge carriers that limit its overall photocatalytic efficiency\, prompted the systematic investigation of copper and silver\, doped and codoped\, Ti O2 nanocatalysts. In the study\, four different TiO2 nanopowder species\, namely undoped\, Cu-doped\, Ag-doped and Cu+Ag-doped\, were fabricated via the sol-gel route for the activity assessment. After drying at 100oC\, t he powder samples were annealed for one hour at temperatures of 300oC\, 60 0oC\, 900oC and 1100oC. Analysis by XRD revealed that TiO2 was effectively doped\, and that the anatase – rutile mixed-phase occurred around 600oC . Brookite-bearing\, mixed‐phases (anatase – brookite\, brookite – r utile) appeared in the 300oC and 600oC of the codoped samples. UV-vis indi cated a shift of the absorption edge to a lower energy and a stronger abso rption in the visible light region for these two samples\, the highest qua ntum efficiency being induced by the former. Photoluminescence (PL) spectr oscopy suggests that these high activity photocatalysts produced lower PL spectra intensities. The visible emission observed were attributed to the enhancement of oxygen and Ti vacancies by the presence of the brookite pha se.\n\nhttps://events.saip.org.za/event/100/contributions/5/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Science at the Mahikeng Astronomical Observatory DTSTART;VALUE=DATE-TIME:20180626T102000Z DTEND;VALUE=DATE-TIME:20180626T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-308@events.saip.org.za DESCRIPTION:Speakers: Thebe Medupe (Department of Physics\, North West Uni versity\, Mafikeng)\nThe new observatory of the North West University (MAO ) houses a 40-cm MEADE LX200GPS ACF telescope with SBIG STT 8300M electron ically cooled camera. It was officially launched on the 21 April 2018. Thi s instrument is capable of detecting mili-magnitude changes in brightness of a star\, and is thus suitable for the study of pulsating stars and exop lanet research. In this paper we present light curves and Fourier spectra of the various Pulsating stars observed at the MAO. This demonstrates that MAO is capable of producing high precision photometry.\n\nhttps://events. saip.org.za/event/100/contributions/308/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/308/ END:VEVENT BEGIN:VEVENT SUMMARY:Generating high quality spatial modes of light at a high rate DTSTART;VALUE=DATE-TIME:20180627T104000Z DTEND;VALUE=DATE-TIME:20180627T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-6@events.saip.org.za DESCRIPTION:Speakers: Ravin Kara (University of the Witwatersrand)\nDigita l micro-mirror devices (DMDs) are composed of arrays of micro-mirrors that are able to reflect incident light in ways based on the binary operationa l state of each mirror. Traditionally used in digital light processing\, i ts importance in research aspects has increased. The operational states of the mirrors make the DMD an amplitude-only light modulating device at hig h speeds\, insensitive to polarisation states and significantly cheaper co mpared to traditional liquid crystal spatial light modulators. We have emp loyed a DMD to create and switch between different modes of light at a rat e of 400 Hz\, and as such demonstrated arbitrary control of the amplitude and phase of light. We show a high quality in the generated beams\, with c orrelation factors of more than 90\\%.\n\nhttps://events.saip.org.za/event /100/contributions/6/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Fluctuating Open Heavy Flavour Energy Loss in a Strongly Coupled P lasma DTSTART;VALUE=DATE-TIME:20180627T100000Z DTEND;VALUE=DATE-TIME:20180627T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-7@events.saip.org.za DESCRIPTION:Speakers: Blessed Ngwenya (University of Cape Town)\nHeavy ion collisions at RHIC and at the LHC produce an enormous amount of energy th at enables the nuclei and its constituent particles to melt\, thus releasi ng gluons\, quarks and antiquarks\, travelling in different directions wit h different momenta. Studies of these collisions have shown that low trans verse momentum observables describe a strongly coupled plasma (quark-gluon plasma)\, an almost perfect liquid that evolves hydrodynamically and flow s with almost no viscosity. Focusing on observables related to high mass a nd high momentum particles\, we numerically integrate the Langevin equatio n that describes the motion of unbound heavy quarks propagating in a stron gly-coupled quark-gluon plasma. We present predictions for the suppression of the heavy flavor mesons that these heavy quarks decay to\; we show tha t these predictions are in good agreement with experimental data. We outl ine future valuable measurements that will provide a vital consistency che ck for the assumed dynamics of the strongly-coupled quark-gluon plasma.\n\ nhttps://events.saip.org.za/event/100/contributions/7/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/7/ END:VEVENT BEGIN:VEVENT SUMMARY:Multi-wavelength variability and correlation studies of flaring Fe rmi-LAT blazars. DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-8@events.saip.org.za DESCRIPTION:Speakers: Tekano Mbonani (UFS)\nWe aim to place constraints on the size and location of the radiation production regions in flaring Ferm i-LAT blazars. Multi-wavelength data will be obtained from a selection of BL Lacs and FSRQ sources\, from available archival data and new observati ons. The Fermi-LAT gamma-ray data will be analysed using the Fermi Pass 8 data reduction\, which provides a significant improvement in terms of back ground rejection\, event reconstruction and photon acceptance. We aim to i nvestigate the time-domain relationship between several wavelength regimes . From high signal-to-noise light curves\, multi-wavelength cross-correlat ion studies will be performed in order to characterize and compare variabi lity and time-lags. By fitting exponential rise and decay functions to the light-curves\, variability times and time gaps between flaring events fro m different wavelengths will be extracted. The time scale of the variabili ty will be used to place constraints on the size of the emission.\n\nhttps ://events.saip.org.za/event/100/contributions/8/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Langmuir Probe diagnostics of the exhaust plume of a miniature DC- discharge plasma-thruster. DTSTART;VALUE=DATE-TIME:20180629T104000Z DTEND;VALUE=DATE-TIME:20180629T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-9@events.saip.org.za DESCRIPTION:Speakers: Mahlomola Cwele (Wits University)\nA U-Shaped plasma -propelled DC-discharge microthruster has been designed by the school of p hysics and its various properties are under examination. This study examin es the quasi-neutral plasma which constitutes the exhaust plume of the Arg on-propelled thruster by means of a mobile Langmuir Probe. The probe and i ts moving mechanism are designed\, constructed and controlled as part of t he study along with a computerized mechatronic and analytical system which forms part of the probe diagnostics. The study produces various propertie s of the plume\, which include the local ion and electron temperatures\, t he local plasma potential\, the local floating probe potential\, The local ion saturation current and the local electron saturation current. Each of these Properties is collected for complete region which constitutes the w ake of the thruster.\nThis study will inform future studies of which the p urpose will be to optimize the basic design of the microthrusters.\n\nhttp s://events.saip.org.za/event/100/contributions/9/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/9/ END:VEVENT BEGIN:VEVENT SUMMARY:Growth of zinc oxide nanostructures using block copolymer template s DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-10@events.saip.org.za DESCRIPTION:Speakers: Assane Talla (Nelson Mandela University)\nGrowth of zinc oxide nanostructures using block copolymer templates\n\nA.Talla\, S. R. Dobson\, Z. N. Urgessa and J. R. Botha\n\nDepartment of Physics\, Nels on Mandela University\, P O Box 77000\, Port Elizabeth\, 6031\, South Afr ica\ns217063969@Mandela.ac.za\n\nKeywords: nano template\, diblock copolym er\, wet etching\, zinc oxide nanorods\,\n\nAbstract\n\nThe growth of ZnO nanorods on a lattice mismatched substrate\, using solution methods\, typi cally results in a random orientation of the rods.. In this paper\, the us e of block copolymer films as a template for the oriented growth of ZnO na norods is presented. These rods can be used for solar cells or as template s for the growth of TiO2 nanotubes.\nPoly (styrene-block-methylmethacrylat e) (PS-b-PMMA) has been investigated as a potential nano-mask for semicond uctor growth. For this study\, diblock copolymer thin films were spun onto a zinc oxide seed layer-coated silicon substrate and on an aluminium dope d zinc oxide (AZO) substrate. Thermal annealing of PS-b-PMMA having an ap propriate thin film thickness led to vertically oriented cylinders of PMMA within a PS matrix. Samples were then processed by wet etching in acetic acid after ultraviolet (UV) exposure of the polymer film at a specific do se.. This resulted in the removal of the PMMA cylindrical nano-domains fro m the polymer films\,\, leaving an array of ordered nanoscopic pores in wh ich ZnO nanorods were subsequently grown. Samples were characterized using X-ray reflectometry to determine the thicknesses of the annealed PS-b-PMM A thin films. Scanning probe microscopy was used to view the phase morphol ogy and characterize the selective removal of the PMMA. Scanning electron microscopy was used to view the zinc oxide rods grown on the polymer templ ates produced on the two different substrates.\n\nhttps://events.saip.org. za/event/100/contributions/10/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/10/ END:VEVENT BEGIN:VEVENT SUMMARY:The first-excited 2+ state in 14C DTSTART;VALUE=DATE-TIME:20180627T084000Z DTEND;VALUE=DATE-TIME:20180627T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-21@events.saip.org.za DESCRIPTION:Speakers: Christiaan Brits (University of Stellenbosch)\nB(E2: 2+→0+) values of neutron-rich even-even carbon isotopes have been repor ted up to 20C and do not only provide important information on the evoluti on of the underlying structural mechanism towards the drip line but also p rovide critical constraints for theoretical models. The B(E2: 2+→0+) val ue in 14C can be indispensable to advance our understanding of the Carbon isotopic chain. However\, the experimentally determined B(E2: 2+→0+) val ue for 14C exhibits persistent inconsistencies with that obtained from the oretical models\, including the no-core shell model. The attempted safe Co ulomb excitation experiment of 14C at Florida State University took advant age of the unique beam capabilities and the availability of high-efficienc y large volume LaBr3 detectors and the S3 double sided silicon strip detec tor. The preliminary results from the experiment to attempt the Coulomb ex citation of 14C will be presented. \n\nThis work was supported by the Nati onal Research Foundation of South Africa under grant number 105205 and by the U.S. DOE by LLNL under Contract DE-AC52-07NA27344.\n\nhttps://events.s aip.org.za/event/100/contributions/21/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/21/ END:VEVENT BEGIN:VEVENT SUMMARY:Diffusion study of metal precursor layers for CZTS solar cell DTSTART;VALUE=DATE-TIME:20180627T130000Z DTEND;VALUE=DATE-TIME:20180627T132000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-11@events.saip.org.za DESCRIPTION:Speakers: Antonie Fourie (University of the Free State)\nThe c ore of a CZTS solar cell is the p-type absorber layer that gives this type of solar cell its name. It consists of copper\, tin\, zinc and sulfur in a single crystal structure: Cu2ZnSnS4. In this study two methods are inves tigated to deposit the copper\, zinc and tin as precursor layers for the f ormation of the Cu2ZnSnS4 layer\, namely electroplating and electron beam evaporation. One of the advantages of CZTS solar cells is that the constit uent elements are a lot more common and less toxic than what are usually u sed in other types of solar cells. The elements used in the solar cell its elf is only one half of the picture\, one also needs careful consideration of the methods and chemicals used during the manufacturing. This is why r eline\, an environmentally friendly deep eutectic solvent\, is used as the electrolyte during electroplating. The 3 metals were deposited in the cor rect stoichiometric ratio in different sequences on Mo coated glass\, and then annealed in vacuum.\nTo estimate annealing times and temperatures\, F ick’s diffusion equation was solved [1] for a finite diffusion region wi th finite diffusion source:\n\nC(x\,t) = ½ C 0 Σ ∞ n=-∞ erf ((h+2nL -x)/(2√Dt)) + erf ((h-2nL+x)/(2√Dt) ) ]\n\nFrom the calculated depth p rofiles the annealing times and temperatures were chosen 500 K\, 550 K\, 6 50 K and 725 K\, all for 1 hour. The annealed samples were characterised u sing Auger Electron Spectroscopy depth profiling\, and from these depth pr ofiles the inter-diffusions were calculated. .\n[1] J Crank\, The Mathemat ics of Diffusion\, 2nd edition\, (1975)\n\nhttps://events.saip.org.za/even t/100/contributions/11/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/11/ END:VEVENT BEGIN:VEVENT SUMMARY:Quantum mechanical ab initio calculations of the structural\, elec tronic\,vibrational\, mechanical and optical properties of bulk Silicon te llurides DTSTART;VALUE=DATE-TIME:20180626T082000Z DTEND;VALUE=DATE-TIME:20180626T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-13@events.saip.org.za DESCRIPTION:Speakers: George Manyali (Masinde Muliro University of Science and Technology)\nSilicon tellurides are being considered for next-generat ion non-volatile memory material. For the applications of these materials in electronic devices\, it is necessary to provide information on their th ermodynamic and mechanical stabilities\, structural\, electronic and optic al properties based on first-principles density-functional theory. The obt ained results are compared with experiment\nand with some available previo us calculations.\n\nhttps://events.saip.org.za/event/100/contributions/13/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/13/ END:VEVENT BEGIN:VEVENT SUMMARY:Flame retardants in City of Johannesburg EMS fire fighters bunker gear DTSTART;VALUE=DATE-TIME:20180627T100000Z DTEND;VALUE=DATE-TIME:20180627T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-14@events.saip.org.za DESCRIPTION:Speakers: Vincent Mokoana (Tshwane University of Technology)\n Fire fighting protective garment (bunker gear) is the main shield that fir e fighters use for protection against heat\, flame and other hazards durin g fires. The bunker gear’s thermal protection is enhanced by the additio n of flame retardants\, which resist ignition and or reduces the rate of f ire spread. Initial investigation of the bunker gear used by the City of J ohannesburg EMS fire fighter is found to contain brominated flame retardan ts\, that have been found to be harmful to human and the environment and h ave been banned or restricted in most parts of the world. Five (5) new and three (3) used bunker gears were investigated. X-ray fluorescence (XRF) scanning measurements showed that all the samples contained significant am ount of brominated flame retardants. Comparison of the old (used in fire f ighting events) and new samples showed no significant difference in bromin ated flame retardant content. The fire retardants effects of the samples w ere investigated using the Cone Calorimeter under 50 and 75 kW.m-2 externa l heat fluxes. Heat release rate\, smoke release rate and fire spread meas urements on the samples showed low values attributed to the retardants in the bunker gear. The average fire growth rate index (FIGRA) for the sample s were found to be 1.88  0.44 kW.s-1 (5 new bunker gear) and 2.63  0 .37 kW.s-1 (3 old/used bunker gear) for external irradiation flux of 50 kW .m-2. FIGRA values for external heat flux 75 kW.m-2 were 5.07  1.12 kW. s-1 and 6.17  0.99 kW.s-1 for new and old respectively. In the case of smoke growth rate (SMOGRA)\, values found were 3.12  0.34 and 4.96  0.59 m2.s-2\, respectively for new and used gears under 50 kW.m-2 irradiat ion and 13.26  3.63 and 14.60  2.37 m2.s-2under 75 kW.m-2 heat flux. \n\nhttps://events.saip.org.za/event/100/contributions/14/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/14/ END:VEVENT BEGIN:VEVENT SUMMARY:Charactarisation of the solar resource at the Fort Hare Institute of Technology DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-15@events.saip.org.za DESCRIPTION:Speakers: Carine Buma (University of Fort Hare)\nThe sun is th e primary source of energy on earth as almost all the sources of energy em anate either directly or indirectly from the sun. It is also at the center of the photovoltaic technology in which case\, sunlight is directly conve rted to electricity with the use of solar cells. An in-depth knowledge of the sun and the various factors that affect its intensity are very vital f or photovoltaic system manufacturers and operators. This will improve the efficiency of an already efficiency-limited photovoltaic energy technology . However\, solar characterization for locations in the Southern hemispher e are not common in literature. Attention is mostly paid to locations in t he Northern hemisphere. Here\, existing mathematical models were used to p erform a holistic solar characterization at the Fort Hare Institute of Tec hnology which is located in the southern hemisphere. The variation of sola r parameters such as solar declination\, elevation\, zenith and azimuth an gles as well as air mass ratio were examined. Also the variation of differ ent components of solar radiation such as\; direct beam\, diffuse and refl ected components were evaluated. These results were compared to the result s obtained from an onsite weather station. The comparison between the calc ulated and the on-site measured values yielded just a 1.1% difference. Thi s means in the absence of weather stations\, mathematical models can be us ed to evaluate various solar radiation parameters with a high degree of ce rtainty. Finally\, the results obtained from the computations and measurem ents were compared with data from nearby weather stations.\n\nhttps://even ts.saip.org.za/event/100/contributions/15/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/15/ END:VEVENT BEGIN:VEVENT SUMMARY:Elastic constants of as-deposited amorphous SiC thin films by Bril louin Spectroscopy DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-16@events.saip.org.za DESCRIPTION:Speakers: Hlosani Dube (Wits Masters Student)\nSilicon carbide (SiC) has proven to be the future of Micro-electromechanical systems. Pre vious research has dwelled on the properties of SiC thin films on Si or si licon-on-insulator substrates and it has been a success in realising the p otential of SiC (van Rijn\, 2013). However\, due to the difficult micromac hining process and high density of defects when dealing with the SiC subst rate \, the elastic properties of a-SiC thin film on 3C-SiC and glass subs trates remain a subject of tremendous scientific interest. In this study\, a complete set of elastic constants of amorphous SiC thin films were dete rmined by Surface Brillouin Scattering. The films were deposited by RF mag netron sputtering using a commercial SiC target. Subsequently the films we re characterized using scanning electron microscopy\, atomic force microsc opy\, and Raman spectroscopy to study the surface morphology and structura l properties. Raman showed a strong randomization of Si-Si (500 cm-1)\, Si -C (780-800 cm-1) and C-C (1400 cm-1) modes suggesting the films were amor phous. Velocity dispersion curves of surface acoustic waves in SiC films d eposited on glass\, were obtained\, from which the dispersive Rayleigh mod e was measured at 5120 m/s. Simulations of SBS spectra of SiC thin films o n silicon and glass substrates were carried out to inversely extract the e lastic constants of the films. The simulations were based on the elasto-dy namic Green's functions method that predicts the surface displacement ampl itudes of acoustic phonons. Sound velocities for both transverse and longi tudinal waves were determined along with the elastic constants C11\, C12\, C13\, C33 and C44.\n\nhttps://events.saip.org.za/event/100/contributions/ 16/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/16/ END:VEVENT BEGIN:VEVENT SUMMARY:Characterization of stirred calibration bath from -80 to 550 °C DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-17@events.saip.org.za DESCRIPTION:Speakers: Tshifhiwa Madiba (National Metrology Institute of So uth Africa)\nThis paper describes the methods of characterizing stirred li quid bath at the National Metrology Institute of South Africa (NMISA) in m aintenance and dissemination of the international temperature scale of 199 0 (ITS-90). In practice\, methods of characterizing stirred liquid baths v aries from institution to another as well as manufacturer. This results in either over estimation or under estimation of uncertainty in calibration of thermometers. Generally\, the criteria for choosing stirred calibration baths depends on the manufacturer stated stability of time and temperatur e gradients over the working volume of the bath. The methods used by manuf acturer in most specifications are not clearly defined or even stated. As a result\, most laboratories develop their own accredited procedures in es timation the effect of the stirred liquid baths in overall uncertainty of thermometer calibration\, which in turn differ amongst them. \n\nThrough a practical example\, the paper describes for three different methods in ch aracterizing stirred liquid baths from -80 °C to 550 °C. Axial or radial temperature gradients were observed as thermometers were placed in differ ent locations in the bath. Furthermore\, since the reading of the thermome ter(s) changes over time\, the methods used are independent of the variati on of the bath temperature over time. Hence the uncertainty due to the bat h is not over estimated or under estimated. Through these methods\, uncert ainty in calibration thermometers due to stirred calibration liquid baths were found to be in the range of sub mK to 100 mK from -80 °C to 550 °C . \n\n.\n\nhttps://events.saip.org.za/event/100/contributions/17/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/17/ END:VEVENT BEGIN:VEVENT SUMMARY:Temperature dependance of Pt\, Pd\, Ru and Ag on FeAl systems DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-18@events.saip.org.za DESCRIPTION:Speakers: Hasani Chauke (University of Limpopo)\nThe Fe-Al bas ed systems have recently attracted a lot of attention in various industrie s for future development of steels due to their excellent resistance to ox idation at high temperatures. These systems suffer from limited room tempe rature ductility and a sharp drop in strength above 600<0>00>\;C. The FeAl alloys are regarded as promising material for construction and steel coat ing especially for high temperature applications in aggressive and corrosi ve environment. They create wide prospects for applications such as in ind ustries\, aerospace\, automotive parts and steel-IT coating components. In our previous work\, attempts have been made on ternary alloying of FeAl s ystems\, and it was reported that Pt and Ru showed improvement on the stru ctural stability. The current study used a combination of ab-initio and m olecular dynamics employing virtual crystal approximation (VCA) and DMol t o investigate the influence of ternary addition of Pt\, Pd\, Ru and Ag and their temperature effect. Heats of formation\, density of states and elas tic constants were calculated to describe the structural\, thermodynamic a nd mechanical stability of these systems. It will also be shown that addi tion of Pt\, Ru\, Pd and Ag may significantly enhance the ductility of the FeAl-X ternary systems at high temperature.\n\nhttps://events.saip.org.za /event/100/contributions/18/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/18/ END:VEVENT BEGIN:VEVENT SUMMARY:High speed photometry of a pre-main sequence star HD 68695 using t he Mahikeng Astronomical Telescope (MAT) DTSTART;VALUE=DATE-TIME:20180626T100000Z DTEND;VALUE=DATE-TIME:20180626T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-19@events.saip.org.za DESCRIPTION:Speakers: Thapelo Mokgadi (Department of Physics\, North West University)\nHD 68695 is a well known pre-main sequence star with well est ablished infrared excess and emission in its hydrogen lines. In this paper we show for the first time that this star pulsates with periods around 23 minutes and the main amplitude of 3 mmag. We present the data collected u sing the new Mahikeng astronomical Observatory which confirms the frequenc ies that are found in the KELT data in Sutherland. We show that the MAT is capable of producing photometric data with noise levels of less than 2 mm ag. This makes the MAT not only an ideal instrument for performing photome try of pulsating stars\, but also a very useful tool in the search and stu dy transits of exoplanets.\n\nhttps://events.saip.org.za/event/100/contrib utions/19/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/19/ END:VEVENT BEGIN:VEVENT SUMMARY:Sol-gel combustion synthesis and stability of La2O 3:Bi3+ powder phosphor DTSTART;VALUE=DATE-TIME:20180627T120000Z DTEND;VALUE=DATE-TIME:20180627T122000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-20@events.saip.org.za DESCRIPTION:Speakers: Babiker Jaffar (ufs)\nBismuth (Bi) ions exhibit inte resting optical properties\, yet have been less intensively studied compar ed to rare earth ions. Bi doped lanthanum oxide (La2O3:Bi3+) phosphor was synthesized via the sol-gel combustion method at 250 °C using citric acid as the fuel. The product powder was annealed at different temperatures be tween 800 °C to 1400 °C in air for 2 h. X-ray diffraction (XRD) data con firmed that the La2O3 host as well as doped phosphor crystallized in a hex agonal lattice. For photoluminescence spectroscopy (PL) an excitation wave length of 308 nm\, the phosphor powder produced a blue emission band cente red at 462 nm. The maximum intensity was obtained for the sample doped wit h 0.2 mol% Bi which was annealed at 1200 °C. It was observed that the lum inescence from the samples decreased after storage of several weeks. XRD m easurements revealed that the La2O3 had changed to La(OH)3\, which does no t give luminescence when doped with Bi. It has been reported that La2O3 ca n absorb moisture from the air and transform to La(OH)3. This was observed to occur completely in about 6 days. The poorly emitting samples were re- annealed between 500 °C and 800 °C for 2 h. For the highest temperature it was found that the structure reverted completely to La2O3 and the blue PL emission was once again observed at about the same intensity as for fre shly prepared samples. Although La2O3:Bi3+ can be used as a blue emitting phosphor\, it is only suitable for applications where it will not be expos ed to moisture in the atmosphere. For samples stored in a vacuum desiccato r for one week\, no change for XRD and PL were observed. Therefore\, it ma y have an application as a moisture sensor\, because while the luminescenc e remains high it is evidence that it has not been exposed to the atmosphe re.\n\nhttps://events.saip.org.za/event/100/contributions/20/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/20/ END:VEVENT BEGIN:VEVENT SUMMARY:Crystal structure and thermodynamic properties of the non-centrosy mmetric PrRu4Sn6 caged compound DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-22@events.saip.org.za DESCRIPTION:Speakers: Michael Ogunbunmi (University of Johannesburg)\nPrRu 4Sn6 is a tetragonal\, non-centrosymmetric structure compound [1]. It is i sostructural to the extensively studied Kondo insulator CeRu4Sn6 [2\, 3\, 4] which crystallizes in the YRu4Sn6-type structure with space group I-42m . In this structure\, the Pr atom fills the void formed by the octahedral Ru4Sn6 units which results in a tetragonal body centered arrangement [1\, 5]. Here we present the physical and magnetic properties of PrRu4Sn6. The specific heat\, Cp(T)\, electrical resistivity\, &rho(T) and magnetic susc eptibility\, &chi(T) results collected between 300 K and 2 K do not show a ny phase transition in the temperature range. &chi(T) follows Curie-Weiss behavior above 100 K with effective magnetic moment\, &mueff = 3.34 &muB/P r which is close to the expected free ion value of 3.58 &muB/Pr and parama gnetic Weiss temperature\, &thetap = –19.47 K indicating a dominant anti ferromagnetic interaction. The magnetization\, M(H) at 2 K is quasi-linear in nature and attains a value of 0.86 &muB/Pr at 7 T which is well reduce d compared to the free ion saturation moment of 3.32 &muB/Pr possibly due to magnetocrystalline anisotropy in the polycrystalline sample. The low-te mperature analysis of Cp(T) gives a Sommerfeld coefficient\, &gamma = 38.6 0 mJ/(K2 mol). &rho(T) follows a typical metallic behavior down to low-tem peratures in contrast to the semi-metallic behavior observed in CeRu4Sn6. The thermal conductivity\, &kappa of PrRu4Sn6 shows a glassy behavior abov e 30 K possibly due to the interactions of the low-frequency “rattling ” vibrations of the guest atom with the acoustic phonons of the host lat tice resulting in heat dissipation.\n\nhttps://events.saip.org.za/event/10 0/contributions/22/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/22/ END:VEVENT BEGIN:VEVENT SUMMARY:Current Status of the Technology of Light Emitting Diodes from Sil icon Carbide: A Review. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-23@events.saip.org.za DESCRIPTION:Speakers: Kinnock Vundawaka Munthali (University of Namibia)\n Light-emitting diodes (LEDs) are semiconductor devices that emit light in a narrow-band spectrum with wavelengths ranging from the infrared to the u ltraviolet. This paper will look at current state of the art of the fabric ation techniques and characterisation of LEDs from silicon carbide (SiC). SiC has a wide band gap and high thermal conductivity. These unique proper ties make SiC an ideal candidate for fabricating high-temperature operatin g semiconductor devices. Most of the LED technology at present uses galliu m nitride (GaN) with phosphors. Phosphors have a short life-time and conta in rare-earths which are very expensive. In order to overcome these shortc omings\, the technology of producing highly efficient SiC-based LEDs has t o be explored so as to make them a viable alternative to GaN-based LEDs.\n \nhttps://events.saip.org.za/event/100/contributions/23/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/23/ END:VEVENT BEGIN:VEVENT SUMMARY:Angular correlation measurements with the iThemba LABS segmented c lover detector DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-24@events.saip.org.za DESCRIPTION:Speakers: OBED SHIRINDA (iThemba LABS/Stellenbosch University) \niThemba LABS has purchased a segmented clover detector\, a detector that uses the latest achievements in the Ge detectors technology. Contrary to the standard Ge detectors the new detector is segmented on the outer conta ct\, resulting in 8 segments per crystals\, or 32 segments for the whole d etector. The segments can be run as individual detectors\, allowing consid erably higher event rates to be handled successfully. In addition\, utilis ing segments allows improved accuracy for all direction-sensitive measurem ents\, such as Doppler correction\, angular distributions and correlations \, g-factor measurements based on recoil in vacuum technique\, linear pola rization\, lifetime measurements based on Doppler effects\, etc. The impac t of this improvements increases dramatically with the increase of the ope ning angle of the detector\, i.e. at small detector-to-target distances.\n \nIn close geometry the face of the detector covers a large opening angle\ , for instance at 4 cm from the radioactive target the detector subtends a solid angle of approximately 1/8 of 4π. Therefore\, it covers the whole range of angles needed for precise angular correlation measurements. Such full coverage in addition to the excellent position sensitivity of the det ector (due to its segmentation and its tracking ability) allows very preci se spin and parity measurements to be carried out. It should be noted that measurements with such precision cannot be performed at present with the current much larger AFRODITE array. In particular\, one would be able to m easure (i) high-order multipolarities such as E3\, M4\, E4\, M5\, E5\, etc \, (ii) mixing ratios of M1+E2\, M2+E3\, etc\, (iii) distinguish unstretch ed dipole from a stretched quadrupole transition\, etc. Furthermore\, due to the segmentation and the tracking capability\, the detector will produc e more precise linear polarization results too.\n\nWe collected data with several gamma-ray sources to evaluate the performance of the detector in c lose geometry for angular correlations measurements. A few targets were al so irradiated with neutrons in the neutron therapy vault to test the activ ity that can be produced and the performance of the detector. The data are being analysed\, but preliminary results look very promising. The results will be presented and discussed.\n\nhttps://events.saip.org.za/event/100/ contributions/24/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/24/ END:VEVENT BEGIN:VEVENT SUMMARY:Characterization of aluminium Schottky junction diode fabricated o n nickel oxide thin film synthesized through sol-gel method DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-25@events.saip.org.za DESCRIPTION:Speakers: Shadrach Akinkuade (University of Pretoria)\nNickel oxide (NiO) thin films were deposited on glass substrates through the sol- gel spin coating technique. Structural\, optical and electrical character istics of the films were studied using X-ray diffraction (XRD)\, scanning electron microscopy (SEM)\, atomic force microscopy (AFM)\, Uv-vis spectro photometery and linear four point probe resistivity measurement. The films were found to be polycrystalline\, uniform\, conducting and transparent. NiO film was also deposited on p-type silicon substrates and aluminium co ntacts of 0.6 mm diameter were deposited on the film to form an Al/NiO/p-S i structure. Indium-gallium was used as ohmic contact on the silicon and c urrent-voltage characteristics of the Al/NiO schottky junction were invest igated. The junction showed good rectification and the parameters of the j unction were determined.\n\nhttps://events.saip.org.za/event/100/contribut ions/25/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/25/ END:VEVENT BEGIN:VEVENT SUMMARY:Lifetime measurements in 44Sc excited states using LaBr 3 :(Ce) detectors coupled with the AFRODITE Array DTSTART;VALUE=DATE-TIME:20180628T092000Z DTEND;VALUE=DATE-TIME:20180628T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-26@events.saip.org.za DESCRIPTION:Speakers: Lumkile Msebi (iThemba Labs\, UWC)\nThe progressive development of the scintillator detectors has made it possible to do direc t electronic lifetime determination. The 2” x 2” LaBr3:(Ce) detectors provide a combination of excellent time resolution and good energy resolut ion. With these detectors it is possible to do direct lifetime measurement s of excited nuclear states up to a few hundred nanoseconds. Six 2” x 2 ” LaBr3:(Ce) detectors were coupled to the AFRODITE array as their first in-beam experiment. AFRODITE consisted of eight HPGe clover detetectors a s well two 3.5” x 8” LaBr3 (Ce) detectors. A particle telescope was us ed to select the desired reaction channel. The reaction of interest 45Sc(p \,d) 44Sc was carried out at a beam energy of 27MeV. Through this reaction \, excited states that have lifetimes which are apt for the characterizati on of the 2” x 2” LaBr3:(Ce) detectors were populated. One of the nucl ei of interest in this work\, 44Sc\, has states with a wide range of lifet imes at low to moderate energies.\n\nhttps://events.saip.org.za/event/100/ contributions/26/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/26/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigate ionizing radiation in the troposphere using ground-bas ed neutron monitor\, ACE/DSCVR satellite and RBSP satellite data for aviat ion radiation forecasting. DTSTART;VALUE=DATE-TIME:20180627T100000Z DTEND;VALUE=DATE-TIME:20180627T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-46@events.saip.org.za DESCRIPTION:Speakers: Golekamang Thaganyana (South Africa National Space A gency)\nThe aviation altitude is continuously bombarded with high-energy i onizing cosmic radiation. The two main sources of ionizing radiation at th e aviation altitude are the omnipresent background galactic cosmic rays wh ich originate from outside our solar system and the transient solar energe tic particle events which are associated with space weather events such as solar flares and coronal mass ejections. The passengers and aircraft crew are exposed to high-energy ionizing cosmic radiation during the flight. I n this work\, we will investigate the correlation between Neutron Monitor counts rates and solar wind speed and proton density from the Advanced Com position Explorer (ACE) satellite\, as well as Neutron Monitor count rates and radiation belt density from the Radiation Belt Storm Probes (RBSP) sa tellites\, during the coronal mass ejection (CME) events and quiet time. I f the correlation exists\, then it may be possible to use Neutron Monitor data in the future for the forecast the timing and level of ionizing radia tion in the troposphere.\n\nhttps://events.saip.org.za/event/100/contribut ions/46/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/46/ END:VEVENT BEGIN:VEVENT SUMMARY:First principles studies of Palladium nanoparticles on TiO2 surfaces for catalytic application DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-27@events.saip.org.za DESCRIPTION:Speakers: Andile Mazibuko (yes)\nPalladium-based catalyst are being developed as an alternative to the commonly used and high cost plati num catalyst because of their similar electronic configurations\, lattice constants and they are cheaper than platinum with a high methanol-toleranc e. In this study\, first principle density functional theory was used to s tudy the catalytic properties of Pd/TiO2\, in particular the interaction a nd electronic behaviour of palladium nano-clusters on a stable titanium di oxide surface using the plane-wave pseudo-potential method. Titanium dioxi de is used as a metal support to develop the palladium catalyst\, and is the most important transition metal oxide since its photo-catalytic activi ty was discovered. This transition metal oxide was used in many catalytic processes in the industries such as metal catalysts\, which include the pl atinum group metals such as Pd\, Pt\, and Rh. These metals are involved in processes such as fuel cells\, methane oxidation\, catalysis\, and in emi ssion control technology. Firstly\, the stability of titanium dioxide poly morphs was deduced from elastic properties and in good agreement with the experimental values to within 3%. The observation made was based on the sh ear modulus of rutile being higher and positive compared to that of the ot her polymorphs suggesting that rutile is more stable. The order of surface stabilities is given as (110)> (100)> (101)> (001)> (111)\, and in good a greement with previous work. Adsorption of water on the stable (110) surfa ce showed that the (110) surface was more preferred(exothermic). Secondly\ , the interaction of Palladium clusters with titanium dioxide surface show ed that Pd13 prefers the bridging adsorption site\, and as predicted it’ s the least negative D2E energy value. The findings of this work suggests that palladium-based catalysts may play a significant role in future devel opments and applications in emission control technologies.\n\nhttps://even ts.saip.org.za/event/100/contributions/27/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/27/ END:VEVENT BEGIN:VEVENT SUMMARY:Where does the problem start\, in as far as vectors are concerned? DTSTART;VALUE=DATE-TIME:20180626T084000Z DTEND;VALUE=DATE-TIME:20180626T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-28@events.saip.org.za DESCRIPTION:Speakers: Buyi Sondezi (University)\nThe challenge faced by le ctures of first year students at tertiary level is undermined. The percept ion is the thinking that the subject is a simple and manageable to student s. First year students enrolled for pure Bachelor of Science (BSc.) and Ba chelor of Engineering (BIng) are mostly expected to undertake some of thei r Physical Science modules with ease especially since they start with fami liar work. The first that the content of their first year Physics involved repetition of the high school work becomes a point of challenge for first year lecturers. This could be the case if assumptions are mostly made abo ut the students understanding those specific topics. An observation was ma de as an involvement with high school learners\, particularly grade 11. Th e curriculum of grade 11 included and covers vectors and forces extensivel y. Questions were raised as to where do we or where do our students miss i t\, especially when they have to undertake these topics at the university level. To try get to the bottom of this challenge\, first year level Physi cs papers which covered forces and vectors was given to grade 11 learners. This work presents the results of both groups (students and grade 11 lear ners)\, as we try to go deeper in finding out where the challenge starts.\ n\nhttps://events.saip.org.za/event/100/contributions/28/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/28/ END:VEVENT BEGIN:VEVENT SUMMARY:Measurement of fundamental ion beam – matter interaction paramet ers for heavy ion nuclear analytical techniques DTSTART;VALUE=DATE-TIME:20180628T080000Z DTEND;VALUE=DATE-TIME:20180628T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-30@events.saip.org.za DESCRIPTION:Speakers: Mandla Msimanga (Tshwane University of Technology)\n The use of heavy ion beams (Z>2) in ion beam materials analysis (IBA) tech niques has been shown to enhance the sensitivity of these techniques when compared to using light ions (H\, He). The development of theoretical mode ls to describe various ion beam-matter interaction phenomena for use in IB A analytical software is strongly dependent on the availability of experim ental data to test these models. One of the factors inhibiting widespread implementation of heavy ion IBA techniques is the scarcity of experimental data of basic parameters such as stopping force and X-ray production cros s sections. This contribution describes measurements carried out to determ ine heavy ion induced X-ray production cross sections and stopping force i n solid matter for applications in Heavy Ion ERDA and Heavy Ion PIXE. Stop ping force data is compared to predictions by the ab initio CasP code and the semi-empirical SRIM\, and X-ray production cross section measurement r esults are compared to the plane wave Born approximation (PWBA) and ECPSSR -UA calculations.\n\nhttps://events.saip.org.za/event/100/contributions/30 / LOCATION: URL:https://events.saip.org.za/event/100/contributions/30/ END:VEVENT BEGIN:VEVENT SUMMARY:First principle study of structural\, magnetic\, electronic and me chanical properties of A15 X3Ru alloys DTSTART;VALUE=DATE-TIME:20180627T142000Z DTEND;VALUE=DATE-TIME:20180627T144000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-32@events.saip.org.za DESCRIPTION:Speakers: BHILA OLIVER MNISI (University of South Africa\, Dep artment of Physics)\nRuthenium based alloys have excellent properties whic h makes them good candidates for high temperature applications. A large nu mber of equipment such as turbine and spacecraft engines operates at high temperatures in aggressive chemical environments. Therefore there is a nee d to search for materials that can withstand extreme thermal\, chemical an d mechanical conditions for these applications. This study aims to develop high temperature materials with good oxidation and corrosion resistance. We discuss trends in structural\, magnetic\, electronic and mechanical pro perties of 3d transition A15 X3Ru alloys (X = Sc\, Ti\, V\, Cr\, Mn\, Co\, Cu\, Ni\, Fe and Zn) observed using First principle density functional th eory calculations. The heats of formation predict an increase in stability in the following trend: Ti3Ru > V3Ru > Cr3Ru > Mn3Ru. We find that Ni3Ru\ , Fe3Ru\, Co3Ru and Mn3Ru compounds have magnetic moments of 1.0\, 1.6\, 1 .7 and 2.6 µB/atom. The density of states indicates that Sc3Ru\, Ti3Ru\, V3Ru and Cr3Ru systems are metallic due to valence-conduction overlap in t he Fermi energy level\, whilst X3Ru (Mn\, Fe\, Co and Ni) are half-metalli c with 100% spin polarization at the Fermi level. Furthermore\, the ratio of bulk to shear modulus indicates ductility in X3Ru (X = Sc\, Ti\, V\, Cu \, Ni\, Mn\, Cr and Zn) suggesting that these systems are mechanically sta ble. Doping the X3Ru (X = Sc\, Ti\, V\, Cr\, Mn\, Co\, Cu\, Ni\, Fe and Zn ) alloys with transition metals such as Nb\, Ta\, Pd or Pt improves their structural\, electronic and mechanical properties.\n\nhttps://events.saip. org.za/event/100/contributions/32/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/32/ END:VEVENT BEGIN:VEVENT SUMMARY:Characterization of dopant levels in a III-V molecular beam epitax ial system DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-33@events.saip.org.za DESCRIPTION:Speakers: Chris Theron (University of Pretoria)\nCommissioning of the III-V MBE system at the University of Pretoria has started. Doped GaAs layers have been grown and characterised electrically. The resulting carrier densities were used to determine the doping concentration versus c ell temperature parameters that are required for controlled growth.\n\nhtt ps://events.saip.org.za/event/100/contributions/33/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/33/ END:VEVENT BEGIN:VEVENT SUMMARY:An open quantum systems approach to the radical pair mechanism DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-34@events.saip.org.za DESCRIPTION:Speakers: Betony Adams (UKZN)\nThe development of the radical pair mechanism has allowed for theoretical explanation of the fact that ma gnetic fields are observed to have an effect on chemical reactions. The me chanism describes how an external magnetic field can alter chemical yields by interacting with the spin state of a pair of radicals. Since the incep tion of quantum biology\, there has been interest in the application of th is mechanism to biological systems\, in particular the avian compass. Howe ver\, one of the pitfalls of attempting to apply the tools of quantum theo ry to the messy and complex systems that typify living organisms is the ri sk of oversimplification. To this end\, the aim of the research outlined h ere is twofold. First to develop an open quantum systems approach to a mod el of the radical pair mechanism that allows for an investigation into the effects of different hyperfine configurations on radical pair dynamics wh ile maintaining the necessary complexity and flexibility of the biological context. This model would allow for the simulation of\, for instance\, th e case in which the electrons interact with a number of nuclei each at dif ferent distances from the radical and the distinction between weak or stro ng coupling with the nuclear environment. And second\, this research aims to investigate whether the radical pair model might be applied to other em erging topics of interest within the field of quantum biology.\n\nhttps:// events.saip.org.za/event/100/contributions/34/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/34/ END:VEVENT BEGIN:VEVENT SUMMARY:Defects in diamond created by NO+ ion implantation DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-36@events.saip.org.za DESCRIPTION:Speakers: Tresor MATINDI (University of the Witwatersrand)\nTh e formation of shallow n-type dopants in diamond is one of the major chall enges for the electronic application of diamond. n-type behavior in diamon d is observed for substitutional phosphorus and nitrogen\, with activation energies of ~0.62 and 1.7 eV respectively. It has been theoretically foun d that the substitution of N-O molecule into the diamond lattice induces a shallow defects below the conduction band edge which may lead to n-type c onductivity. \n\nIn this project we are exploring the possibility of achie ving n-type conductivity in diamond by conducting an experimental investig ation on the interaction between nitrogen and oxygen in the diamond as wel l as the related defects. This involves placing nitrogen and oxygen impuri ties close to each other into the diamond lattice by means of ion implanta tion\; which has the advantage to provide greater accuracy of depth and lo cation of ions in the host material. \n\nOptical spectroscopy and electric al characterization techniques are used to investigate the nature and beha vior of the defects induced by the implantation of N-O ions into type IIa CVD diamond samples. \n\nIn this presentation the experimental results of photoluminescence\, Raman spectroscopy and cathodoluminescence will be dis cussed.\n\nhttps://events.saip.org.za/event/100/contributions/36/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/36/ END:VEVENT BEGIN:VEVENT SUMMARY:Computational modelling studies of oxidation and hydration on NiS< sub>2 and NiAs2 surfaces DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-63@events.saip.org.za DESCRIPTION:Speakers: Bradley Nemutudi (UL)\nThe atmospheric oxidation of minerals either by weathering or aging involves physical and chemical adso rption of oxygen on the surfaces and this forms various peroxides and hydr oxides. In this study ab-initio computational method was employed to inves tigate the interaction of oxygen and water molecules at different adsorpti on sites on the most stable surfaces of NiS2 and NiAs2. Their calculated surface energies showed that the NiS2 (100) and NiAs2 (111) surfaces are m ore stable. We predicted the order of surface stability as: (100) > (111) > (210) > (110) for NiS2 and (111) > (110) > (100) > (210) for NiAs2. The adsorption of O2 was found to dissociate on mineral surfaces and different bonding mechanisms of the oxygen atoms were depicted. The O2 adsorption o n both NiS2 (100) and NiAs2 (111) surfaces was exothermic with adsorption energies of -3.19 eV and -4.83 eV\, respectively. The H2O adsorption on bo th NiS2 (100) and NiAs2 (111) mineral surfaces were found to relax deep in to the surface. The H2O adsorption on Ni-top site was more exothermic\, su ggesting preferential adsorption on Ni atoms than on S and As atoms on bot h NiS2 and NiAs2. These investigations suggests that the oxidation of NiS2 and NiAs2 prefer adsorbing on S and As atoms than on Ni\, while the hydra tion of NiS2 and NiAs2 prefer adsorbing on Ni atoms than S and As atoms. T hese investigations provide information on the bonding mechanism and chemi stry of oxygen and water molecules onto NiS2 (100) and NiAs2 (111) surface s that may be applicable to the atmospheric oxidation and during flotation process or mineral extraction.\n\nhttps://events.saip.org.za/event/100/co ntributions/63/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/63/ END:VEVENT BEGIN:VEVENT SUMMARY:Corrosive Sulphur in Transformers DTSTART;VALUE=DATE-TIME:20180627T092000Z DTEND;VALUE=DATE-TIME:20180627T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-38@events.saip.org.za DESCRIPTION:Speakers: Sharlene-Asia Naicker (University of KwaZulu-Natal)\ nThe failure of many power transformers have been linked to the presence o f an additive\, Dibenzyl disulphide (DBDS) in transformer oil. The additiv e degrades the insulation system of the transformer resulting in untimely breakdown. Most studies have focused on laboratory oil testing\, however\, the interaction between DBDS and the copper windings of the transformer a re still not fully understood. We present experimental results that were o btained from monitoring DBDS formation by varying the temperature of an ac tive oil-filled transformer. It was observed that at high temperatures\, t he DBDS concentration reached equilibrium. The activation energy for the D BDS reacting with copper and the formation of copper sulphide was determin ed. It was established that a significant amount of the initial concentrat ion of DBDS was needed in order to react with copper. The interaction of D BDS with the copper surface of the windings was also modelled using densit y functional theory (DFT). The most stable interaction configuration was d etermined by comparing different adsorption energies. This configuration w as the starting point for further DFT analysis. The respective interacting molecule/additive and surface was optimized to allow maximum interaction between the additive and the surface. These results are compared to our ex perimental results.\n\nhttps://events.saip.org.za/event/100/contributions/ 38/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/38/ END:VEVENT BEGIN:VEVENT SUMMARY:Spectral Resource Management based on VCSEL Wavelength Switching a nd Allocation DTSTART;VALUE=DATE-TIME:20180626T080000Z DTEND;VALUE=DATE-TIME:20180626T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-39@events.saip.org.za DESCRIPTION:Speakers: Phumla Dlamini (optical fibre research unit (nelson mandela metropolitan university))\nEmerging high bandwidth demanding appli cations such as cloud computing\, 5G wireless\, wearable devices for healt h monitoring and high definition video streaming has brought about a rapid growth of Internet traffic. This calls for upgrade of the traditional fix ed grid wavelength division multiplexing (WDM) system\, to improve capacit y\, reliability\, cost and simplicity in the network through spectrum flex ibility and cost effective sharing of fibre links\, transmitters and recei vers. Spectrum slicing into fine granular sub carriers and assigning a num ber of frequency slots to accommodate diverse traffic demands is a viable approach. This work experimentally presents a technique for bandwidth vari ability and wavelength selective switches in the nodes of a network\, capa ble of removing the fixed grid spacing. We present wavelength switching us ing a low cost\, high bandwidth and power efficient vertical cavity surfac e emitting laser (VCSEL) wavelength tenability property. In this study\, t he driving current of a 1550 nm VCSEL is varied from (2 mA to 8 mA)\, ther efore attaining different channel spacing 0.8 nm (100 GHz)\, 0.4 nm (50 GH z)\, 0.2 (25 GHz)\, 0.1 nm (12.5 GHz) and 0.05 nm (6.25 GHz) at over a con stant wavelength range of 5 nm. The majority of the spectrum was utilized at finer channel spacing\, wastage of the spectrum resource as caused by t he wavelength continuity constraint was reduced and bandwidth utilization was improved.\n\nhttps://events.saip.org.za/event/100/contributions/39/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/39/ END:VEVENT BEGIN:VEVENT SUMMARY:Analysis of Nd3+ concentration on the structure\, morphology and p hotoluminescence of sol-gel Sr3ZnAl2O7 nanophosphor DTSTART;VALUE=DATE-TIME:20180627T100000Z DTEND;VALUE=DATE-TIME:20180627T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-40@events.saip.org.za DESCRIPTION:Speakers: Motlalepula Rebecca Mhlongo (Sefako Makgatho Health Sciences University)\nNeodymium activated strontium zinc aluminate (Sr3ZnA l2O7:x%Nd3+) nanophosphor was synthesized using the sol-gel technique wher eby the Nd3+ concentration was varied in the range 0 ≤ x ≤ 2. The effe ct of Nd3+ concentration on the structure\, particle morphology and photol uminescence properties of Sr3ZnAl2O7 were investigated. The X-ray diffract ion (XRD) results revealed that all samples resembled the mixture of both ZnAl2O4 and Sr3Al2O6 cubic structures. Nd3+ doping influenced the crystall ite sizes of the prepared phosphor materials. The energy dispersive X-ray spectroscopy (EDS) results confirmed the presence of all expected elements in the composition. Scanning electron microscopy (SEM) revealed that as t he Nd3+ concentration increased the surface morphology changed to smooth m ountain like structures. The ultraviolet-visible (UV-Vis) diffuse reflecti on spectroscopy showed that the band gap of Sr3ZnAl2O7 can be tuned from 2 .74 to 2.95 eV by increasing the Nd3+ concentration. When the host is exci ted above the bandgap (374 nm)\, broad emission attributed to defects occu rs with the maximum near 585 nm. Doped samples excited in this manner do n ot exhibit additional luminescence due to the Nd3+ ions\, but in contrast there is a small dip in the defect emission band near 585 nm due to absorp tion attributed to Nd3+ ions. Characteristic infrared emissions of Nd3+ io ns at 885\, 1064 and 1340 nm were observed by directly exciting the Nd3+ i ons at 585 nm (4I9/2 → 5G5/2+2G7/2) and were attributed to 4F3/2 → 4I9 /2\, 4I11/2 and 4I13/2 transitions\, respectively. The Commission Internat ionale de l’Eclairage (CIE) coordinates results showed that the emission colour cannot be tuned by varying the Nd3+ concentration.\n\nhttps://even ts.saip.org.za/event/100/contributions/40/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/40/ END:VEVENT BEGIN:VEVENT SUMMARY:ZnO nanoparticles doped with cobalt and indium mechano-chemically for methane gas sensing application DTSTART;VALUE=DATE-TIME:20180627T080000Z DTEND;VALUE=DATE-TIME:20180627T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-64@events.saip.org.za DESCRIPTION:Speakers: Mahlatse Manamela (University of Limpopo)\nThe mecha no-chemical technique was employed to synthesise the undoped zinc oxide (Z nO)\, 5% cobalt (Co) and indium (In) single doped ZnO nanoparticles and Co -In double doped ZnO nanoparticles. The diffraction pattern for In-ZnO nan oparticles obtained from the X-ray diffraction (XRD) reveals an additional peak that is associated with the In+3 dopant. The scanning electron micro scope (SEM) images shows the spherical morphology of the nanoparticles for all the prepared samples. The gas sensing properties of ZnO nanoparticles were probed using the kenosistec station equipment. The response and sens itivity of ZnO nanoparticles to methane (CH4) gas were investigated at dif ferent temperatures and gas concentrations. The Co-In double doped ZnO and Co-ZnO nanoparticles show great sensitivity to CH4 gas at the concentrati on of 20 and 40 ppm\, respectively.The CH4 gas sensor seems to work better at lower temperatures and higher gas concentrations\, which is good for m onitoring the environment.\n\nhttps://events.saip.org.za/event/100/contrib utions/64/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/64/ END:VEVENT BEGIN:VEVENT SUMMARY:Probing colour reconnection and underlying event in top quark even ts at the LHC DTSTART;VALUE=DATE-TIME:20180629T092000Z DTEND;VALUE=DATE-TIME:20180629T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-41@events.saip.org.za DESCRIPTION:Speakers: Dimbiniaina Soanasolo Rafanoharana (University of th e Witwatersrand)\nImprovement in Monte Carlo (MC) event generators is crit ical for precise measurements in top quark events at the LHC. In fact\, mo delling of the color reconnection (CR)\, a mechanism that describes the in teractions between coloured particles during the hadronization\, and the underlying event (UE)\, defined as all particles produced from soft-hadron ic processes and partially radiation form the hard scattering process (HS) \, are the main sources of uncertainty in many measurements. Measurements of observables sensitive to them are thus required to constrained the para meters of these MC models to reduce the uncertainty in top quark simulatio n. Two different ttbar channels\, dileptonic and boosted all hadronic\, ar e used to study respectively the UE and the CR. \n\nWhile a top (or anti- top) quark with a large transverse momentum decays into a boosted Wb (or W bbar)\, jets initiated by partons\, produced from the decay of these boost ed objects\, and their radiative gluons are likely to cluster into a large -radius jet. We probe if one can define a geometric area in the neta-phi p lane inside these large-radius jets\, that are sensitive to color reconnec tion. The singlet color connected jets from the decay of the W boson can b e used as a benchmark. \n\nFor the measurement of the activity of the UE in dilepton ttbar\, we will study observables sensitive to the UE in th e transverse region in conjunction with event shape observables. Even thou gh this region is perpendicular\, by construction\, to the sum of the tra nsverse momentum of the decay product of particles interacting via HS\, it still receives some extra-jets from the HS. Thus we look for event topolo gy where the transverse region is less contaminated by these extra-jets.\n \nhttps://events.saip.org.za/event/100/contributions/41/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/41/ END:VEVENT BEGIN:VEVENT SUMMARY:Performance of missing transverse energy reconstruction in pp coll isions at 13 TeV in the diphoton channel with ATLAS DTSTART;VALUE=DATE-TIME:20180627T092000Z DTEND;VALUE=DATE-TIME:20180627T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-42@events.saip.org.za DESCRIPTION:Speakers: Shell-may Liao (University of the Witwatersrand\, Sc hool of Physics\, 1 Jan Smuts Avenue\, Braamfontein\, Johannesburg\, 2000\ , South Africa”)\nA good measurement of missing transverse energy (MET) is pre-eminent for many searches for new physics carried out by the ATLAS experiment at the LHC. The measurement of MET in the ATLAS detector makes use of the full event reconstruction and a calibration based on reconstruc ted physics objects. The performance of MET reconstruction is evaluated us ing data collected in proton-proton collisions at a centre-of-mass energy of 13 TeV in Run 2 of data taking in the diphoton channel. Regrettably\, t hese high luminosities achieved lead to undesirable backgrounds due to add itional proton-proton collisions occurring at the same bunch crossing as t he collision of interest (pile-up). As a result of this downside\, several methods have been implemented in an effort to alleviate the effects of pi le-up on the reconstruction and performance of MET. Some of these methods and the consequent performance of MET reconstruction at ATLAS in events wi th two photons are deliberated.\n\nhttps://events.saip.org.za/event/100/co ntributions/42/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/42/ END:VEVENT BEGIN:VEVENT SUMMARY:Storm-time TEC mapping over Africa and surrounding areas DTSTART;VALUE=DATE-TIME:20180628T102000Z DTEND;VALUE=DATE-TIME:20180628T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-43@events.saip.org.za DESCRIPTION:Speakers: John Bosco Habarulema (South African National Space Agency & Rhodes University)\nBased on storm-time ionospheric total electro n content (TEC) derived from Global Positioning Systems (GPS) measurements over the African sector and surrounding areas\, TEC maps will be develope d based on data assimilation technique. The region of interest extends fro m -40 to 40 and -20 to 60 latitude and longitude degrees\, respectively\, and the Kalman filtering technique with the International Reference Ionosp here (IRI) as a background model will be used during data assimilation pro cess. A statistical analysis of the results will also be presented.\n\nhtt ps://events.saip.org.za/event/100/contributions/43/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/43/ END:VEVENT BEGIN:VEVENT SUMMARY:Data extraction techniques for terahertz time-domain ellipsometry DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-44@events.saip.org.za DESCRIPTION:Speakers: Shane Smith (Student Member)\nTerahertz(THz) radiati on is a powerful tool for non-destructive spectroscopy and has the potenti al of being useful in analysing biological materials. Due to the strong ab sorption of THz radiation by water\, a reflection-based geometry is requir ed when investigating samples in an aqueous medium. Due to the relatively low alignment tolerance in THz time-domain spectroscopy it is preferable t o implement a technique that does not depend on the need for a reference m easurement when performing reflection-based measurements. Ellipsometry has been implemented to this end.\n\nThe construction of a THz ellipsometer h as been completed\, but to make use of the measured data\, analysis algori thms need to be implemented and tested.\n\nThe development of these algori thms\, which are model dependent and are applicable to specific cases\, wi ll be discussed. The cases investigated are bulk isotropic samples\, singl e-layer isotropic samples and two-layer isotropic systems where the second layer is a bulk isotropic layer.\n\nhttps://events.saip.org.za/event/100/ contributions/44/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/44/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthesis and characterization of Zn(1-x)S:Cux nanoparticle thin films by using spin-coating for enhancement of UV-LED s and Solar Cells DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-45@events.saip.org.za DESCRIPTION:Speakers: Molise Jan Mphuthi (University of the Free State)\nE fficient enhancement of solar cells has become more important due to the n eed for environmentally friendly renewable energy sources. Using thioglyce rol as the capping agent and concentrated HCl as the catalyst\, ZnS:Cu sol -gels with different Cu concentrations were successfully used to grow nano particle thin films on ultrasonically cleaned glass substrates. The as-dep osited films were spin-coated at room temperature for 30 s at different sp in speeds\, heat-treated at 275 °C for 10 minutes and annealed at differe nt temperatures in air. The x-ray diffraction studies revealed that both t he un-doped and Cu-doped ZnS films were amorphous when annealed at 300 °C and possess a hexagonal wurzite crystal structure with preferred orientat ions at higher temperatures. The films were optically characterized at roo m temperature using a Cary Eclipse spectrophotometer and UV-visible spectr oscopy. Photoluminescence (PL) spectra showed green and red emissions whic h may be due to excited electron transitions from both the shallow donor l evel and the deep donor level (sulphur vacancies) to the t2 level of Cu2+\ , respectively. The Zn0.05S:Cu0.05 film yielded the highest PL intensity w hen excited at 237nm and was used to study the effect of annealing tempera ture and spin speed. Optical absorbance and reflectance measurements revea led that changing both the Cu concentration\, annealing temperature and sp in speed tunes the band gap of the ZnS:Cu thin films. Copper doped zinc su lphide nanoparticle thin films with a hexagonal wutzite crystal structure were successfully synthesized using the spin coating method and can be use d for efficient enhancement of solar cells.\n\nhttps://events.saip.org.za/ event/100/contributions/45/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/45/ END:VEVENT BEGIN:VEVENT SUMMARY:South African Women in Physics- Progress DTSTART;VALUE=DATE-TIME:20180627T112000Z DTEND;VALUE=DATE-TIME:20180627T114000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-75@events.saip.org.za DESCRIPTION:Speakers: Mmantsae Diale (University of Pretoria)\nThe landsca pe of Women in Physics in South Africa has change dramatically since launc h of WIPISA in 2005. PhD graduates have increased with at least one female staff member in various institutions and research centres.Research groups led by female professors are visible but few. While there is such progre ss\, women are still found to occupy invisible positions in their institut ions and some get completely lost. This presentation will show the statist ical progress and possible solutions to visible issues.\n\nhttps://events. saip.org.za/event/100/contributions/75/ LOCATION: Scaena URL:https://events.saip.org.za/event/100/contributions/75/ END:VEVENT BEGIN:VEVENT SUMMARY:Sprites over South Africa DTSTART;VALUE=DATE-TIME:20180627T120000Z DTEND;VALUE=DATE-TIME:20180627T122000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-47@events.saip.org.za DESCRIPTION:Speakers: Dakalo Mashao (South Africa National Space Agency)\n Sprites observations were recorded in South Africa for the first time on t he 11th of January 2016 from Sutherland using a night-vision TV camera fro m SANSA's Optical Space Research laboratory. Sprites are middle atmosphere optical emissions produced by large positive cloud-to-ground lightning di scharges which have an average peak value of ~74 kA. Sprites appear in dif ferent forms\, such as carrot\, jellyfish\, column or disk-shaped\, typica lly in the height range ~40-90 km above the thunderstorm. Sprites also con tribute to the global electric circuit. Lightning strikes and sprites prod uce unique Very Low Frequency (VLF) and Extremely Low Frequency (ELF) radi o wave signatures that can be detected remotely on the ground by using ELF receiver. South Africa has large convective thunderstorms typically in Ja nuary and February of every year. Lightning strength\, time and position d ata is obtained from the SA Weather Service and may also be tracked in rea l time using the World Wide Lightning Locating Network (WWLLN). The aim of this research is to determine the maximum altitude of sprites\, and the a ltitude of maximum brightness\, as a function of the lightning magnitude. The cameras' spatial pointing geometry was calibrated using stars. The alg orithm for distance and height triangulation in spherical coordinates (lat itude\, longitude\, altitude) was developed. The data from 2016 Sprites ca mpaign was processed and we found that the average maximum altitude\, and altitude of maximum brightness\, of sprites is approximately 85 and 69 km\ , respectively. We also found the correlation between the sprites maximum altitude and charge moment change (CMC).\n\nhttps://events.saip.org.za/eve nt/100/contributions/47/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/47/ END:VEVENT BEGIN:VEVENT SUMMARY:Ab-Initio Study of Stability of Discharge Products in Li/Na-Air Ba tteries DTSTART;VALUE=DATE-TIME:20180626T092000Z DTEND;VALUE=DATE-TIME:20180626T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-48@events.saip.org.za DESCRIPTION:Speakers: Brian Ramogayana (UL)\nRechargeable metal-air batter ies have attracted a growing interest due to their significantly higher th eoretical energy density. It is well recognize that the performance of the battery is governed by the electrochemical reactions that occur at the ca thode which result in the formation of discharge products. Different disch arge products are produced\, through the Oxidation Reduction Reaction (ORR )\, and among those products some are unstable which might react with othe r components of the battery contribute to the capacity fading and aging. F irst principle density functional theory (DFT) was used to investigate the stability of discharge products. We found that LiO2 marcasite is stable a nd NaO2 is slightly stable due to the absence of soft mode along the Γ-di rection in the phonon dispersion curve. Ceder et al. previously investigat ed the nanoscale stabilization of sodium oxides and found NaO2 to be metas table at standard conditions and also found that LiO2 marcasite is stable. Our results are aimed to give an insight on the stability of major discha rge products and give research direction towards controlling the formation of desired Li/Na-O compounds in the batteries.\n\nhttps://events.saip.org .za/event/100/contributions/48/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/48/ END:VEVENT BEGIN:VEVENT SUMMARY:Lorentz Invariance Violation in high energy astrophysics DTSTART;VALUE=DATE-TIME:20180627T082000Z DTEND;VALUE=DATE-TIME:20180627T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-49@events.saip.org.za DESCRIPTION:Speakers: Hassan Abdalla (Centre for Space Research\, North-We st University\, Potchefstroom 2520\, South Africa)\nSeveral quantum-gravit y theories predict that familiar concepts such as Lorentz symmetry can be broken at energies approaching the Planck energy scale.\nSuch extreme ener gies are currently unreachable by experiments on Earth\, but for photons t raveling over cosmological distances the accumulated deviations from the L orentz symmetry may be measurable using the Cherenkov Telescope Array (CTA ). Considering the Lorentz Invariance Violation (LIV) effect\, we found th at the cosmic opacity for VHE gamma rays with energy more than 10 TeV can be strongly reduced. I will further discuss the impact of LIV on the Compt on scattering process\, and how future CTA observations may open an exciti ng window on studies of the fundamental physics.\n\nhttps://events.saip.or g.za/event/100/contributions/49/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/49/ END:VEVENT BEGIN:VEVENT SUMMARY:Cu nanoclusters embedded in a glass host: A tunable nonlinear opti cal response\, thermodynamic and dielectric behaviour DTSTART;VALUE=DATE-TIME:20180629T080000Z DTEND;VALUE=DATE-TIME:20180629T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-50@events.saip.org.za DESCRIPTION:Speakers: Kumar Promod (Department of Physics\, University of the Free state South Africa)\nCopper soda-lime glass nanocomposites were s ynthesized by an ion exchange method followed by thermal annealing in atmo sphere. Ultraviolet-visible absorption spectroscopy and transmission elec tron microscopy confirmed the presence of Cu nanoclusters embedded in the glass matrix. The size of the Cu nanoclusters has been found to increase w ith increasing the annealing temperature and time. The particles size calc ulated from Mie theory\, are in good agreement with the sizes measured fro m Transmission Electron Microscope (TEM). X-ray diffraction and high resol ution TEM (HRTEM) results were systematically studied to investigate and d etermine the microstructure of the Cu doped Soda-lime glass. The chemical state of copper was further analyzed by X-ray photoelectron spectroscopy. Time-of-Flight Secondary Ion Mass Spectrometry and Rutherford backscatteri ng spectrometry measurements were used to confirm the diffusion of Cu nano clusters in the glass matrix. Plasmonic and thermodynamic properties of th e embedded Cu clusters have explained the in situ thermal growth and effic ient distribution mechanism. An interdependence of entropy\, enthalpy and Gibbs free energy has been developed in relation to an activation energy o f 8.04 kJ/mol. The NLO properties of the embedded Cu nanoclusters were fur ther investigated with the Z-scan technique at 800 nm wavelength by execut ing both open and closed aperture methods to understand the behavior of th e nonlinear absorption and nonlinear refraction traces\, respectively. The frequency response of the dielectric constant\, ϵ^`\, and dielectric los s\, tan (δ)\, has also been studied. Dielectric constants with higher va lues on higher thermal treatments were obtained which may be a result of t he nanoclustering of Cu atoms. The above mentioned properties illustrate t he potential application of this glass in the field of nonlinear optics\, especially in optical limiting and contrast enhancement.\n\nhttps://events .saip.org.za/event/100/contributions/50/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/50/ END:VEVENT BEGIN:VEVENT SUMMARY:Modelling of the injection function of solar energetic particles ( SEPs). DTSTART;VALUE=DATE-TIME:20180629T100000Z DTEND;VALUE=DATE-TIME:20180629T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-51@events.saip.org.za DESCRIPTION:Speakers: Ruhann Steyn (Center for Space Research\, North-West University)\nSolar energetic particles are accelerated at the Sun during either short-lived\, impulsive events called solar flares or gradual event s called coronal mass ejections (CMEs). An injection function is used to m odel the injection of SEPs from a source region on the Sun. Previously\, i njection functions were modeled by using arbitrary functions\, but it has become increasingly important to base the injection function on more reali stic parameters and constrain it with available spacecraft data. This stud y investigates the particle intensities from transient events by varying p arameters of the injection function used in our model. The importance of t he onset\, decay-times and longitudinal extent are discussed while compari sons are drawn between single and multiple Gaussian injections from the sa me active region. Data from spacecraft is also used to constrain some of t hese parameters. In the near future\, the Parker Solar Probe and Solar Orb iter missions will provide us with new data to improve the injection funct ion even further. The future of this study includes using a multi-waveleng th approach from a multi-messenger perspective to quantify the injection f unction of SEPs to form the first steps toward a predictive space weather model.\n\nhttps://events.saip.org.za/event/100/contributions/51/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/51/ END:VEVENT BEGIN:VEVENT SUMMARY:Hardware optimization and open-source for learning and research DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-82@events.saip.org.za DESCRIPTION:Speakers: SENZO HLONGWANE (University Of KwaZulu-Natal)\nOpen hardware and software are intensively used in academia\, for research and teaching due to the affordable costs. Most famous open hardware devices li ke Arduino and RaspberryPi are fully accessorised with several shields abl e to perform general tasks. In this work we propose methods to optimise t he existing Open-source platforms with non-existing shields which are easy to explain to entry level students in applied physics subjects. These dev ices are designed to avoid the use of Surface Mounting Device (SMD) in ord er to be built by the students and anybody with scarce technical skills .\n\nhttps://events.saip.org.za/event/100/contributions/82/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/82/ END:VEVENT BEGIN:VEVENT SUMMARY:Radio observation of diffuse radio emission in Abell 773 galaxy cl uster DTSTART;VALUE=DATE-TIME:20180628T092000Z DTEND;VALUE=DATE-TIME:20180628T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-53@events.saip.org.za DESCRIPTION:Speakers: Gift Sichone (Rhodes University)\nA fraction of gala xy clusters host diffuse\,Mpc-scale\,low surface brightness emissions name d "radio halos"\,that spatially correlate with the diffuse X-ray emission. Current models indicate that radio halos are connected to the galaxy clus ter merger history: radio emission is due to particles that are re-acceler ated to relativistic energies via turbulence induced via cluster mergers.\ nHere we present radio observations of the A773 galaxy cluster taken with the Westerbork telescope aimed to study the physical properties(morphology \, size and spectral index\, polarization) of its radio halo and character ize their radio emissions at different frequencies.\n\nhttps://events.saip .org.za/event/100/contributions/53/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/53/ END:VEVENT BEGIN:VEVENT SUMMARY:INVESTIGATING SODIUM ALUMINIUM SILICATE CRYSTALS FOR LASER COOLING APPLICATION DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-54@events.saip.org.za DESCRIPTION:Speakers: KYALO Ngesu KITEME (UNISA)\nIn the search for a lase r cooling Nano-material a method to use in the laboratory to synthesize a suitable Nano-aluminium silicate is introduced.\nThe last decade has seen tremendous development in Nano- photonics and laser optical cooling\, thus interest in the synthesis and use of laser to cool certain materials has grown too.\nThe possibility for commercial use of laser in cooling materia ls in industry has further excited physicists and materials scientists to research into materials that cool when they are excited by tuned lasers be ams. \nIn this report we present one such special Nano – material in the form of Sodium aluminium silicate.\nSodium aluminium-silicate exhibits la ser photonic cooling characteristics at ambient condition.\nMaterials that exhibit such characteristics are mostly reactive or unstable at room temp erature and standard pressure. The challenge has been to synthesize a stab le Nano-material that has laser optical cooling characteristics that can b e investigated under normal laboratory conditions.\nA hydro thermal proces s was used to synthesize the purest possible crystals of Sodium aluminium silicate crystals\, the Crystals where then characterized using the follow ing methods.\n XRDP-X-Ray Diffraction Powders\,\n SEM- Scanning Electron M icroscope\, \nEDS-Energy Dispersion X-rays\,\n X-ray Photoelectron Spectro scopy and\nUV-Vs Ultraviolet-Visible Spectroscopy amongst others.\n In the characterization the morphology\, crystalline size\, chemical composition and thermal stability at room temperature where investigated.\nThe EDS an d XPS results were in agreement in the composition of the constituent comp ounds\, The XRDS gave us the approximate chemical structure of our alumini um silicate.\nInfra-red peaks in the near Infra-red\, visible region sugge sted a possibility of up-conversion with emission in the visible spectrum region.\n\nhttps://events.saip.org.za/event/100/contributions/54/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/54/ END:VEVENT BEGIN:VEVENT SUMMARY:Bose Einstein Condensation from a Gluon Transport Equation DTSTART;VALUE=DATE-TIME:20180627T092000Z DTEND;VALUE=DATE-TIME:20180627T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-55@events.saip.org.za DESCRIPTION:Speakers: Brent Harrison (University of Cape Town)\nWe present a novel numerical scheme to solve the QCD Boltzmann equation in the small -scattering angle approximation\, for the quenched limit of QCD. Using thi s we can investigate the evolution of spatially homogeneous systems of glu ons distributed isotropically in momentum space.\n\nWe numerically confirm results of Blaizot et al\, in particular that for certain “overpopulate d” initial conditions\, a transient Bose-Einstein condensate emerges dur ing equilibriation in a finite time. We further analyse the dynamics of th e formation of this condensate. \n\nThe scheme can be extended to systems with cylindrically symmetric momentum distributions\, in order to investig ate the effects of anisotropy. In particular we compare the rates at which isotropization and equilibriation occur. We also compare our results from the small-scattering angle scheme to the relaxation-time approximation.\n \nhttps://events.saip.org.za/event/100/contributions/55/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/55/ END:VEVENT BEGIN:VEVENT SUMMARY:QCD Boltzmann Equation: Beyond the Soft-Scattering Approximation DTSTART;VALUE=DATE-TIME:20180627T094000Z DTEND;VALUE=DATE-TIME:20180627T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-57@events.saip.org.za DESCRIPTION:Speakers: Nicole Moodley (University of Cape Town)\nUsing the case study of a spatially homogeneous many-gluon system\, distributed isot ropically in momentum space\, we will investigate more thoroughly than in the existing literature the evolution of a hot (quark-) gluon plasma from an initial state towards equilibrium. To that end we will investigate the QCD Boltzmann Equation beyond the popular soft-scattering approximation\, thereby shedding light on the applicability of previous results in the fie ld.\n\nhttps://events.saip.org.za/event/100/contributions/57/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/57/ END:VEVENT BEGIN:VEVENT SUMMARY:Use of machine learning techniques in high energy physics DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-225@events.saip.org.za DESCRIPTION:Speakers: Deepak Kar (University of Witwatersrand)\nThe large and complex dataset from Large Hadron Collider (LHC) at CERN has led to th e application of Machine Learning (ML) techniques in analysing the data. U p until now\, most of the methods used to extract useful information from the large datasets have been based on physics intuition built from existin g models. By applying advanced data science methodology\, we have develope d tools for determining achievable classification performance for a variet y of relevant physics processes. In this talk\, I will review the recent d evelopments\, focussing on optimising trigger\, object identification and reconstruction\, and tagging jets based on initiating particle using ML me thods. Applied to searches for new physics processes\, these show signific ant improvement in sensitivity. I will also summarise the challenges faced in implementing these algorithms in experiments.\n\nhttps://events.saip.o rg.za/event/100/contributions/225/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/225/ END:VEVENT BEGIN:VEVENT SUMMARY:Ion-Implanted Polyaniline thin films for radiation sensing applica tions DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-58@events.saip.org.za DESCRIPTION:Speakers: maloba matome (University of South Africa)\nPolymer based electronics is an emerging technology that is focused on developing electronic devices using semiconducting polymers that can potentially repl ace silicon based electronics. Polymer based electronics materials are rel atively cheaper to synthesize and are mechanically flexible compared to si licon. Metal-polymer nanocomposites\, for example\, have distinctive elect rical\, optical and morphological properties that can be useful for device applications. However\, fabrication-structure-property relationships of t hese materials are not yet fully understood\, and this warrants further in vestigative studies. In this work\, Polyaniline (PANI) was dissolved in di methyl sulfoxide and spun cast on an ITO/PET substrate to obtain PANI thin films. Prepared films were then implanted with 10 keV Ti+ ions to a fluen ce of 5x1015 ions/cm2 to form a Ti-PANI nanocomposite material. Rutherford Backscattering Spectrometry (RBS)\, X-ray Diffraction (XRD)\, Fourier Tra nsform Infrared Spectroscopy (FTIR)\, UV-Vis spectroscopy\, Current-Voltag e (I-V)and Capacitance-Voltage (C-V) measurements were used for structural \, optical and electrical characterization of the films before and after i on implantation. This presentation describes and explains the results of t he characterisation measurements\, with a view to modifying material prope rties of Ti-PANI nanocomposites for nuclear radiation sensor applications. \n\nhttps://events.saip.org.za/event/100/contributions/58/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/58/ END:VEVENT BEGIN:VEVENT SUMMARY:Observation of local entanglement oscillation in free space DTSTART;VALUE=DATE-TIME:20180627T102000Z DTEND;VALUE=DATE-TIME:20180627T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-59@events.saip.org.za DESCRIPTION:Speakers: Carmelo Rosales-Guzman (University of the Witwatersr and\, Johannesburg)\nIt is well known that the entanglement of a quantum s tate is invariant under local unitary transfor- mations. It dictates\, for example\, that the degree of entanglement of a photon pair in a Bell stat e remains maximally entangled during propagation in free-space. Here we ou tline a scenario where this paradigm does not hold. Using local Bell state s engineered from classical vector vortex beams with non-separable degrees of freedom\, so-called classically entangled states\, we demonstrate that the en- tanglement evolves during propagation\, oscillating between maxim ally entangled (purely vector) and product states (purely scalar). We outl ine the theory behind these novel propagation dynamics and confirm the res ults experimentally. Crucially\, our approach allows delivering a tunable degree of local entanglement to a distant receiver by simply altering a mo dal phase delay holographically\, or\, in essence\, a tractor beam for ent anglement. This demonstration highlights a hitherto unnoticed property of classi- cal entanglement and offers at the same time a device for on-deman d delivery of vector states to targets\, e.g.\, for dynamic laser material s processing as well as switchable resolution within STED systems.\n\nhttp s://events.saip.org.za/event/100/contributions/59/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/59/ END:VEVENT BEGIN:VEVENT SUMMARY:A photophysical investigation of bio-inspired molecular dyads by m eans of femtosecond transient absorption spectroscopy DTSTART;VALUE=DATE-TIME:20180629T092000Z DTEND;VALUE=DATE-TIME:20180629T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-60@events.saip.org.za DESCRIPTION:Speakers: Arthur Harrison (University of Pretoria)\nThe remark able efficiency and regulation of the initial\, photophysical events in ph otosynthesis are a great source of inspiration for solar technologies. To make a physical solar cell using bio-inspired processes requires a simple\ , practicable model that makes use of the same photophysical principles as natural light-harvesting systems but with reduced molecular size and comp lexity. The simplest form of an artificial light harvesting system is know n as a dyad and consists of a donor molecule and acceptor molecule\, coval ently bound to form a donor-acceptor dyad. We synthesized a photosensitive dyad consisting of fullerene C60\, a carbon nanoball serving as the elect ron acceptor\, bound to metal-porphyrin donor molecules. We developed a h igh-resolution ultrafast transient absorption spectroscopy setup to resolv e optical density changes of <10-4 in the visible region and supplemented the results with measurements in the near-infrared region\, to cover a ful l spectral window of 450 – 1250 nm. This enabled us to resolve the detai led charge transfer energy dynamics within the dyads and provided evidence of long-living electron-transfer states\, an attractive property of a sol ar cell.\n\nhttps://events.saip.org.za/event/100/contributions/60/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/60/ END:VEVENT BEGIN:VEVENT SUMMARY:Expansion of the Radar Link Budget Equation: Improving the number of estimated Lunar Laser Ranging returns for the HartRAO-LLR station DTSTART;VALUE=DATE-TIME:20180628T092000Z DTEND;VALUE=DATE-TIME:20180628T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-62@events.saip.org.za DESCRIPTION:Speakers: Sphumelele Ndlovu (HartRAO)\nThe Lunar Laser Ranger (LLR) system under development at HartRAO in South Africa will be used to measure the Earth-Moon distance through the use of laser pulses\, single p hoton detection system and other system components. The Earth-Moon distanc e measurements is achieved through accurate measurements of the round trip time-of-flight (TOF) of each returned laser signal\, which is weak. At Ha rtRAO\, laser pulses will be transmitted through a 1 metre aperture optica l telescope directed to hit one of five lunar reflector arrays (also known as retroreflectors) placed on the Moon between 1969 and 1973. The returne d signal is expected to be reflected from a targeted lunar array and thus received through the Earth “fixed” optical telescope. The existing rad ar link budget equation is normally used to estimate the number of returne d photons from a laser pulse aimed to hit a suitcase sized reflector array mounted on the Moon. In this work\, the existing radar link budget equati on is expanded to improve the estimations of the number of returned LLR ph otons: this has a direct relationship with the total LLR system efficiency . An improved LLR system reduces adverse effects such as beam divergence o n the transmitted laser beam that result from atmospheric thermal and dens ity fluctuations.\n\nhttps://events.saip.org.za/event/100/contributions/62 / LOCATION: URL:https://events.saip.org.za/event/100/contributions/62/ END:VEVENT BEGIN:VEVENT SUMMARY:Microstructural and Electrical Properties of Graphene-Oxide (GO) F unctionalized with Gold Nanoparticles (Au: NPs) DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-65@events.saip.org.za DESCRIPTION:Speakers: David Omoefe Idisi (Department of Physics\, College of Science\, Engineering and Technology\, University of South Africa)\nWe have synthesized Graphene-Oxide (GO) by the modified hummer’s process an d functionalized with gold-nanoparticles (Au-NPs) for the study of microst ructure and electrical properties. We have observed from the Raman spectro scopy that the intensity of D-peak (disorder) reduced with respect to G (g raphite-cluster) when GO is functionalizes with Au-NPs (r-GO: Au). Reducti on of D-peak (increase of G-peak) implies the reduction of ID/IG ratio tha t are obtained from the Raman spectra. The reduction of ID/IG ratio (GO: 1 .17 to rGO-Au: 0.95) clearly indicates that the sp2-cluster is reduced thr ough functionalization of GO with Au-NPs. The reduction of sp2-cluster and /or enhancement of sp3-cluster is due to replacement of sp2-cluster by the Au-NPs. The reduction of sp2-cluster in the film networks are also observ ed from the Fourier transform infrared (FTIR) spectroscopy and are consist ent with reduction of conductivity as we observe from the voltage (V) – Current (I) characteristics measurement curve. We believe that the reducti on of conductivity of r-GO:Au would be most suitable Ferro-electric materi als for memory storage device applications.\n\nhttps://events.saip.org.za/ event/100/contributions/65/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/65/ END:VEVENT BEGIN:VEVENT SUMMARY:Computational modelling of graphene mediated sodium air batteries DTSTART;VALUE=DATE-TIME:20180626T100000Z DTEND;VALUE=DATE-TIME:20180626T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-66@events.saip.org.za DESCRIPTION:Speakers: Mogahabo Morukuladi (UL)\nRechargeable metal–air b atteries are widely regarded as the next best generation of high energy de nsity electrochemical storage devices. The performance and rechargeability of these metal–air batteries is highly dependent on the stability and p erformance of the positive electrode materials\, where oxygen reduction an d evolution reactions occur. Due to the high cost and limited resources fo r lithium-ion batteries\, sodium air batteries are a promising alternative because of their high theoretical energy density and low cost to meet the rapidly increasing global energy demands. Graphene has shown a great pote ntial in electrochemical energy storage and conversion due to its remarkab le properties. In this work\, density functional theory (DFT) methodologie s are used to investigate the reaction mechanisms of sodium oxides being a dsorbed onto graphene surface. Generalized gradient approximation (GGA) as implemented in density functional theory was used to perform the calculat ions\, employing CASTEP code. The four discharge products namely\; Na2O2\, NaO2\, Na2O and NaO were adsorbed onto graphene layer. Our results show t hat Na2O is the most stable discharge product due to its lower adsorption energy.\n\nhttps://events.saip.org.za/event/100/contributions/66/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/66/ END:VEVENT BEGIN:VEVENT SUMMARY:Computerised Ionospheric Tomography (CIT) for supportive GNSS-deri ved ionospheric applications. DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-67@events.saip.org.za DESCRIPTION:Speakers: Kit Ng (University of Michigan)\nComputerised Ionosp heric Tomography (CIT) is a technique where multiple measurements from sig nals modulated when passing through an object\, are used as inputs to reco nstruct the three-dimensional structure of the object by employing mathema tical inversion techniques. In CIT the "object" is the spatial distributio n of the electron density composition of the Earth's Ionosphere\, i.e.\, t he ionised component of Earth's atmosphere extending from about 50-2000 km above Earth. SANSA's Matlab-based TEC imaging system utilizes GPS observa tions as available from the IGS network (http://www.igs.org/network). RINE X observations files from regional GPS receivers are processed to yield re gional 2D TEC maps. The objective of the project is to develop necessary a lgorithms and software to apply the MIDAS system for ionospheric tomograph y (developed by the University of Bath) to derive 2D TEC images using data from the African Equatorial region to support other ionospheric applicati ons such as TEC gradient studies for deriving scintillation proxies.\n\nht tps://events.saip.org.za/event/100/contributions/67/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/67/ END:VEVENT BEGIN:VEVENT SUMMARY:Computational Modelling of FeS2 Nanoparticles DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-68@events.saip.org.za DESCRIPTION:Speakers: Thabo Letsoalo (University of Limpopo)\nNanoparticle s have been the area of active research in the recent years due to their u nique material properties\, which distinguish them from the bulk materials due to the high surface atom ratio. Pyrite (FeS2) structures at a nanosca le are considered to be one of few materials for photovoltaics capable of bridging the cost and performance gap of solar batteries. It also holds pr omise for energy storage applications as the material for high-performance cathodes. Computational modelling technique\, molecular dynamics (MD) was performed to provide atomic or molecular level insights of the structural and dynamics of iron sulphide (FeS2) nanoparticles (NP’s). NP’s of di fferent sizes ranging from approximately 1 nm to 4.5 nm were considered. T he effect of temperature on different sizes of NP’s was determined via r adial distribution functions (RDF’s)\, energy as a function of temperatu re and structural changes. At low temperatures the RDF’s have many and s harp peaks (the structure is still compact)\, at higher temperature the pe aks are few and smooth which is an indicative of phase transition. Density Functional based Tight-Binding (DFTB+) code was utilized to study the ele ctronic properties of the different sizes of nanoparticles\, whereby the e ffect of temperature on the electronic properties. Band structures have in dicated at low temperature there is a low band gap but at high temperature the material become metallic. Our findings have demonstrated that nanotec hnology is the future for energy storage especially utilizing pyrite mater ials.\n\nhttps://events.saip.org.za/event/100/contributions/68/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/68/ END:VEVENT BEGIN:VEVENT SUMMARY:Climatology of thermospheric meridional winds derived from South A frican ionosonde network during extended solar minimum of 2007-2009. DTSTART;VALUE=DATE-TIME:20180628T094000Z DTEND;VALUE=DATE-TIME:20180628T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-69@events.saip.org.za DESCRIPTION:Speakers: Zama Thobeka Katamzi-Joseph (South African National Space Agency)\nThermospheric winds play an important role in the dynamics of the mean behaviour of the midlatitude ionosphere especially during quie t conditions\, which are dominant during low solar activity. This study wi ll present equivalent meridional winds derived from ionospheric F2 peak pa rameters using the servo and Liu et al. (2003) methods during the solar mi nimum period of 2007-2009. Midlatitude ionosonde data over Grahamstown (33 .3˚S\, 26.5˚E)\, Hermanus (34.4˚S\, 19.2˚E)\, and Madimbo (22.9˚S\, 3 0.9˚E) are used to derive the winds. For the first time\, local time and seasonal dependency of the derived winds over this region are explored and compared to global trends. The equivalent winds are compared to the winds predicted from the horizontal wind model 2014 (HWM14) and the coupled mid dle atmosphere thermosphere model (CMAT2) to test the validity of these me thods.\n\nhttps://events.saip.org.za/event/100/contributions/69/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/69/ END:VEVENT BEGIN:VEVENT SUMMARY:Search for a new boson by studying the Z(ll) + photon final state DTSTART;VALUE=DATE-TIME:20180629T094000Z DTEND;VALUE=DATE-TIME:20180629T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-226@events.saip.org.za DESCRIPTION:Speakers: Phuti Ntsoko Rapheeha (University of the Witwatersra nd)\nThe discovery of the Higgs boson opened up possibilities for searches Beyond the Standard Model. During the analysis of the run 1 data\, it was observed that there were a number of features in the data that can't expl ained by the Standard Model. \nOne of the models to explain the features i s a Heavy-Scalar model where a heavy scalar decays into a Higgs boson and missing transverse energy. The search uses a three body final state where the Higgs boson decays into a Z boson \, decaying into di-electron or di-m uons\, and a photon. In this study fake missing transverse energy is suppr essed using multivariate analysis.\n\nhttps://events.saip.org.za/event/100 /contributions/226/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/226/ END:VEVENT BEGIN:VEVENT SUMMARY:Physics in Industry: Overview DTSTART;VALUE=DATE-TIME:20180628T080000Z DTEND;VALUE=DATE-TIME:20180628T081000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-227@events.saip.org.za DESCRIPTION:Speakers: Brian Masara (SAIP)\nhttps://events.saip.org.za/even t/100/contributions/227/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/227/ END:VEVENT BEGIN:VEVENT SUMMARY:Physics in Industry: Nanotechnology DTSTART;VALUE=DATE-TIME:20180628T081000Z DTEND;VALUE=DATE-TIME:20180628T083500Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-228@events.saip.org.za DESCRIPTION:Speakers: Odireleng Ntwaeaborwa (University of the Witwatersra nd)\nhttps://events.saip.org.za/event/100/contributions/228/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/228/ END:VEVENT BEGIN:VEVENT SUMMARY:A virtual model of an Elekta Synergy linac for verification of pla nning system photon beams DTSTART;VALUE=DATE-TIME:20180629T084000Z DTEND;VALUE=DATE-TIME:20180629T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-70@events.saip.org.za DESCRIPTION:Speakers: Oluwaseyi M. Oderinde (Department of Medical Physics \, University of the Free State)\nThe purpose of this study is to investig ate the possibility of verifying the planning system photon beams using EG Snrc Monte Carlo (MC) code. The advantage of MC simulation over convention al measurement is that the linac output can be fine-tuned to eliminate unc ertainties with a clear understanding of dose distribution and it's conven ient to calculate dose distribution in complex geometries. A virtual model of an Elekta Synergy linac equipped Agility 160 multileaf collimator (MLC ) was simulated and validated. The simulated planning system beams were 6\ , 10 and 15 MV for 1 x 1 up to 30 x 30 cm2 square field sizes. This model was validated in the context of a homogeneous water phantom that included beam profiles\, depth dose\, and relative output factors. The MC calculati ons and physical measurements agreed to within 2.0% for percentage depth d oses (PDDs)\, profiles and output factors. The virtual linac model is accu rate up to 2%/2 mm. It has the potential to be used for dose verification in the advanced radiotherapy treatment planning system.\n\nhttps://events. saip.org.za/event/100/contributions/70/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/70/ END:VEVENT BEGIN:VEVENT SUMMARY:Probing Quantum Gravity through the Radio and Gamma Regimes DTSTART;VALUE=DATE-TIME:20180627T102000Z DTEND;VALUE=DATE-TIME:20180627T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-71@events.saip.org.za DESCRIPTION:Speakers: Geoff Beck (University of Witwatersrand)\nWhat is th e fate of a collapsing star? One possibility is that they evaporate due to Hawking radiation. The problem with this decay channel is that this pertu rbative phenomenon takes place on time scales far too large to be of astro physical concern. We consider the exciting and exotic proposal of Planck s tars put forth by Carlo Rovelli and others which posits new ways of probin g quantum gravity using radio and gamma astronomy. It also provides an alt ernative end point for black holes. A Planck star is the end result of a c ollapsing star that forms a black hole but does not ever reach the singula rity at r = 0. Instead the matter that had collapsed into the black hole i s released in an explosion as the black hole quantum tunnels to a white ho le. This tunneling process is similar to that which triggers nuclear decay . These Planck stars are modelled using primordial black holes\, at least those of interest to us\, since they will be exploding today. Larger black holes will only be exploding at times larger than the Hubble time. We stu dy two primordial black hole models and compare whether\, given certain as sumptions about the spectrum of an exploding black hole\, these models mig ht lead to reasonable observations in the radio and gamma regime. We then discuss whether the proposal by Rovelli\, that these signals may correspon d to fast radio and gamma ray bursts\, is plausible.\n\nhttps://events.sai p.org.za/event/100/contributions/71/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/71/ END:VEVENT BEGIN:VEVENT SUMMARY:The effect of temperature on electrical characteristics of Al/n-Ga Sb Schottky barrier diodes. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-72@events.saip.org.za DESCRIPTION:Speakers: Mpho Sithole (Sefako Makgatho Health Sciences Univer sity)\nSchottky barrier diodes (SBDs) are a basic structure for semiconduc tor characterization. Aluminium (Al) SBDs were fabricated on Te-doped n-ty pe Gallium Antimonide (GaSb) using electron beam deposition system. The el ectrical transport properties of Al/n-GaSb semiconductor material have bee n investigated. Current-voltage (I-V) and capacitance-voltage (C-V) charac teristics of Al/n-GaSb Schottky diodes have been measured over a temperatu re range of 100-380 K in 20 K steps. The Schottky diode showed a temperatu re dependence of ideality factor (n) from 1.07 to 1.28\, with a room tempe rature value of 1.22. The barrier height (ϕB) was found to decrease from 0.65 eV at 380 K to 0.35 eV at 100 K. It was found that room temperature b arrier heights were equal to 0.57 eV and 0.60 eV determined using I-V and C-V measurements\, respectively. It was observed that the leakage current at -1.0 V increased in the range of 3.82 × 10-7 to 5.41 × 10-4 A. The re sults showed a typical diode behavior of Al/n-GaSb Schottky diode. The bar rier height decreased while the ideality factor increased with a decrease in temperature.\n\nhttps://events.saip.org.za/event/100/contributions/72/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/72/ END:VEVENT BEGIN:VEVENT SUMMARY:Elemental analysis and Activation in Kimberlite using delayed gamm as after GDR photon induced activation. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-73@events.saip.org.za DESCRIPTION:Speakers: Thendo Emmanuel Nemakhavhani (University of Johannes burg)\nElement analysis as a nuclear activation analysis technique (gamma\ ,x) using photons above the Giant Dipole Resonance and the (gamma\,x) reac tions is a novel development. In these studies the excited nuclei decay by photon emission and these photons can be detected using time stamped even t-by-event data acquisition with multiple gamma detectors. In this way\, t he resulting spectra can be multi-dimensional as (energy\, time) or (energ y\, energy). The ambiguity in the identification of the decaying nuclide i s well resolved considering unique sequential decay chains or using the ex tracted lifetime for a given gamma energy. The data was acquired on a time scale of minutes to weeks following activation\, so that a wide range of activated nuclide lifetimes could be identified. The samples were various kinds of kimberlite rocks. A benchmark analysis using XRF was also perform ed. The elemental analysis technique is potentially of interest for non-de structive geochemical analysis. The study had a dual purpose in that it is also relevant to the study of nuclide activation that is of importance to the MinPET technique as elaborated in companion presentations. The experi ments were carried out at the electron injector microtron of the ASTRID st orage ring of the ISA\, Centre of Storage Ring Facilities at the Departmen t of Physics in Aarhus University\, Denmark.\n\nhttps://events.saip.org.za /event/100/contributions/73/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/73/ END:VEVENT BEGIN:VEVENT SUMMARY:Improved Photometric Identification Formula for Pulsating Stars DTSTART;VALUE=DATE-TIME:20180626T094000Z DTEND;VALUE=DATE-TIME:20180626T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-74@events.saip.org.za DESCRIPTION:Speakers: Getachew Mekonnen Mengistie (Northwest University)\n In this talk a detailed review of stellar pulsation and radiative transfer equations are presented. Starting from the radiative transfer equations a nd by considering appropriate physical conditions and mathematical formula tions\, we derived a formula that describes the effect of pulsations in th e light output of a star. We took into consideration the interaction of li ght with the different layers of the atmosphere. This is an improvement fr om previous studies where the atmosphere is treated as a single layer at τ = 2/3. In this talk\, we also investigated the depth dependence of eige nfunctions in the atmosphere of pulsating stars.\nOur results demonstrate that the displacement eigen function δr/r\, the temperature eigen functio n δT/T and the opacity eigenfunction show great variability in the atmosp here of the equilibrium models studied. Our formalism is based on non-grey approximation where the pulsation equation and opacity depends on depth a nd frequency of observation. We also showed that the observed luminosity\, for high overtone pulsators\, comes from all the layers above the photosp here and the upper layer\ncontributes the most. Moreover\, from the equili brium models considered in this study\, the plots of the temperature eigen function as a function of depth demonstrated that\, even with small T_eff \, the atmosphere of a pulsating star will not be considered as a solitary and distinct layer as depicted\nby Watson\, (1987) and Watson\, (1988). w e also show the depth dependence of eigenfunctions in the atmosphere of pu lsating stars.\n\nhttps://events.saip.org.za/event/100/contributions/74/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/74/ END:VEVENT BEGIN:VEVENT SUMMARY:Physics in Industry: Photonics DTSTART;VALUE=DATE-TIME:20180628T094500Z DTEND;VALUE=DATE-TIME:20180628T101000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-229@events.saip.org.za DESCRIPTION:Speakers: Darryl Naidoo (Council for Scientific and Industrial Research)\nhttps://events.saip.org.za/event/100/contributions/229/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/229/ END:VEVENT BEGIN:VEVENT SUMMARY:Physics in Industry: Photovoltaics DTSTART;VALUE=DATE-TIME:20180628T083500Z DTEND;VALUE=DATE-TIME:20180628T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-230@events.saip.org.za DESCRIPTION:Speakers: Ernest van Dyk (Mandela University)\nhttps://events. saip.org.za/event/100/contributions/230/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/230/ END:VEVENT BEGIN:VEVENT SUMMARY:Photonics Division Meeting DTSTART;VALUE=DATE-TIME:20180627T124000Z DTEND;VALUE=DATE-TIME:20180627T132000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-231@events.saip.org.za DESCRIPTION:Speakers: Andrew Forbes (U. Witwatersrand)\nhttps://events.sai p.org.za/event/100/contributions/231/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/231/ END:VEVENT BEGIN:VEVENT SUMMARY:Continuation of Photonics Division Meeting (if required) DTSTART;VALUE=DATE-TIME:20180627T134000Z DTEND;VALUE=DATE-TIME:20180627T140000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-232@events.saip.org.za DESCRIPTION:Speakers: Andrew Forbes (U. Witwatersrand)\nhttps://events.sai p.org.za/event/100/contributions/232/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/232/ END:VEVENT BEGIN:VEVENT SUMMARY:Crystal Growth and Agglomeration of Heterostructured Layered-Spine l Li-Mn-O Primary Particles DTSTART;VALUE=DATE-TIME:20180629T084000Z DTEND;VALUE=DATE-TIME:20180629T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-76@events.saip.org.za DESCRIPTION:Speakers: Raesibe Sylvia Ledwaba (University of Limpopo)\nLaye red-spinel Li-Mn-O nanostructured materials have ignited significant inter est as cathode materials in lithium-ion batteries due to their simultaneou sly great reversible capacity (302 mAh/g)\, amongst other exceptional prop erties. However\, their high electrode surface area has lead to side react ions with the electrolyte resulting in capacity fade. As such\, we employ molecular dynamics methods to simulate spontaneous growth\, crystallizatio n and aggregation of primary particles under the NVE\, NPT and NVT ensembl es\, prior to their surface modification. Characterization of the recrysta llized particles depicted the presence of heterostructured layered-spinel components and microstructural features such as microtwinning and intrinsi c defects\, which are essential for achieving high storage capacity. The v acancies and substitutions help facilitate faster mobility of Li through t he lattice and additional pathways. The primary nanoparticles were agglome rated with periodic neighbours to formulate secondary particles. Agglomera tion yielded different morphologies of particles with various simulation c ells\, such as spherical and rod-like structures. Efficient agglomeration of such primary particles will add valuable insights to the attainment of highly conformal coating strategies and subsequently\, the design of high- capacity batteries with enhanced storage capacity and performance.\n\nhttp s://events.saip.org.za/event/100/contributions/76/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/76/ END:VEVENT BEGIN:VEVENT SUMMARY:Towards an ab initio model for the radiation dose rate of cosmic r ays on and near various planetary surfaces is our solar system: solar cycl e-dependent modulation of galactic cosmic-ray intensities DTSTART;VALUE=DATE-TIME:20180627T094000Z DTEND;VALUE=DATE-TIME:20180627T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-77@events.saip.org.za DESCRIPTION:Speakers: KATLEGO MOLOTO (NORTH WEST UNIVERSITY)\nWith the adv ent of commercial space travel and the proposed colonization of Mars and o ther planets\, it has become even more important to study the cosmic ray r adiation environment on\, and near the surface of these bodies\, in order to plan for future manned missions. Galactic cosmic rays\, with a well-kno wn 11 year cycle pose the primary radiation risk. Solar energetic particle s that are frequent during solar maximum periods are sporadic and highly v ariable in terms of intensities\, are a secondary radiation risk. In this study we \nexplore an approach to model cosmic-ray radiation based on spac ecraft data inputs and existing models for galatic cosmic rays\, which wi ll have implications for the future modelling of solar energetic particle transport as well.\n\nhttps://events.saip.org.za/event/100/contributions/7 7/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/77/ END:VEVENT BEGIN:VEVENT SUMMARY:Employing Fast Neutron Radiography (FNR) to determine the Hydrauli c Conductivity (k) of sand via Darcy’s Law and Gardner’s Equation DTSTART;VALUE=DATE-TIME:20180629T100000Z DTEND;VALUE=DATE-TIME:20180629T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-78@events.saip.org.za DESCRIPTION:Speakers: Graham Daniels (Necsa)\nThis investigation highlight s the use of fast neutron radiography as a technique to determine the intr insic properties of sand with a primary focus being determination of the s ands hydraulic conductivity. The hydraulic conductivity is the ability of the sand to transmit water\, the knowledge of which is of importance when planning earth storage leakages and water control structures. The constant head method is applied\, using the PTB cyclotron as a fast neutron source and the TRION detection system to image the water absorption. The attenua tion of the fast neutrons by water\, shows the evolution of the water fron t with time and from the radiographs the parameters required to determine the hydraulic conductivity are obtained. These parameters are employed int o Darcy's law and Gardner's equation for the calculation of the sands hydr aulic conductivity. Fast neutron radiography is shown to yield unique info rmation of the live process of water absorption through sand and the hydra ulic conductivity (k) is determined.\n\nhttps://events.saip.org.za/event/1 00/contributions/78/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/78/ END:VEVENT BEGIN:VEVENT SUMMARY:A Practical Survey of Novel and Legacy Radio Interferometry Imagin g Algorithms and Packages DTSTART;VALUE=DATE-TIME:20180628T102000Z DTEND;VALUE=DATE-TIME:20180628T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-79@events.saip.org.za DESCRIPTION:Speakers: Athanaseus Ramaila (Rhodes University)\nRadio interf erometry software packages have grown sophisticated enough that we can now begin to address some of the imaging issues that are posed by the next ge neration of radio telescopes\, most notably the MeerKAT and Square Kilomet re Array (SKA). The main objective of this project is to develop a framewo rk that allows the evaluation of deconvolution algorithms and imaging tech niques using a platform independent pipelining tool. We use MeerKAT L-band simulated visibility data to perform the evaluation of the radio interfer ometric packages. Using the framework\, we compare the performance of imag ing tools such as CASA\, DDFacet\, LWImager and WSClean. Using these image s we recovered source flux density\, morphology\, angular position and spe ctral index. Therefore\, by comparing the model inputs and the recovered source properties with their corresponding measured uncertainties\, we can infer how well each imager performs the deconvolution process for a given set of observational parameters. It was found that at flux densities belo w 20σ\, there is a significant scatter in the measured properties as a re sult of the decrease in signal to noise ratios of the sources\, and at hig her source flux densities there is a clear correlation which was simply de scribed statistically.\n\nhttps://events.saip.org.za/event/100/contributio ns/79/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/79/ END:VEVENT BEGIN:VEVENT SUMMARY:Rust: The unusual candidate for hydrogen production DTSTART;VALUE=DATE-TIME:20180629T104000Z DTEND;VALUE=DATE-TIME:20180629T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-80@events.saip.org.za DESCRIPTION:Speakers: Mmantsae Diale (University of Pretoria)\nSustainable \, renewable and clean solar energy collection has seen rapid progress in research where different electrodes have been explored. Among these\, Hema tite\, a reddish-brown iron oxide has been found to possess remarkable cre dentials such as chemical stability\, low cost and abundance for use as ph otoanodes. In addition its bandgap of 2.2 eV is perfect for solar energy c ollection. In this paper\, recent progress focused on light absorption and charge transfer dynamics will be presented\, including the work done to s how how hematite obtained by a low cost synthesis can be refined by hydrot hermal treatment and further functionalized by coating with phycocyanin\, a light harvesting protein known for photosynthesis in blue-green algae\n\ nhttps://events.saip.org.za/event/100/contributions/80/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/80/ END:VEVENT BEGIN:VEVENT SUMMARY:The synthesis\, characterization and application of different morp hologies of ZnO in the photocatalytic degradation of Rhodamine B DTSTART;VALUE=DATE-TIME:20180627T140000Z DTEND;VALUE=DATE-TIME:20180627T142000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-81@events.saip.org.za DESCRIPTION:Speakers: Siyabonga Nkabinde (University of the Witwatersrand) \nColoured dye waste waters released by textile industry into the environm ent cause negative effects to living organisms due to their toxicity. A te chnique called advanced oxidation processes\, which employs semiconductor photocatalysts (e.g. ZnO) in conjunction with light\, has been developed t o effectively degrade dyes in aqueous solution through oxidative species. Advanced oxidation processes have received attention because the oxidative species (Hydroxyl radicals and electron-hole pairs) fully degrade the dye s into carbon dioxide and water as opposed to other traditional techniques . In this study\, rod\, spherical and bullet like ZnO nanoparticles are sy nthesized using microwave assisted digestion and their structural\, optica l and photocatalytic activity is investigated. The photocatalytic degradat ion of Rhodamine B was carried out by irradiating an aqueous solution of t he dye of known concentration (20 ppm) containing ZnO using a solar simula tor. The degradation process was followed by monitoring the change in the absorbance of the excitation peak of Rhodamine B at 553 nm spectrophotomet rically. Results indicated that the degradation efficiency of the model dy e (i.e. Rhodamine B) varied depending on the morphology of the ZnO nanopar ticles. The difference in photocatalytic efficiency between the three diff erent ZnO morphologies was attributed to surface area differences together with the proportion of polar exposed surfaces. The spherical ZnO nanopart icles were found to be the more photocatalytically active due to the fact that their high surface area allowed for large amount of dye molecules to be degraded quickly. Herein\, we demonstrated that varying the type of mor phology of ZnO nanoparticles can be used as a method of improving the rate at which organic dyes are degraded in water.\n\nhttps://events.saip.org.z a/event/100/contributions/81/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/81/ END:VEVENT BEGIN:VEVENT SUMMARY:Astrophysics and Space Science - joint meeting DTSTART;VALUE=DATE-TIME:20180627T134000Z DTEND;VALUE=DATE-TIME:20180627T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-233@events.saip.org.za DESCRIPTION:Speakers: Christo Venter (North-west University\, Potchefstroo m Campus)\, Du Toit Strauss (Centre for Space Research\, North-West Univer sity)\nhttps://events.saip.org.za/event/100/contributions/233/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/233/ END:VEVENT BEGIN:VEVENT SUMMARY:Modelling the polarisation signatures detected from the first whit e dwarf pulsar AR SCO. DTSTART;VALUE=DATE-TIME:20180627T122000Z DTEND;VALUE=DATE-TIME:20180627T124000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-83@events.saip.org.za DESCRIPTION:Speakers: Louis Du Plessis (NWU\, Potchefstroom\, Department o f Physics)\nMarsh et al. (2016) detected radio and optical pulsations from the binary system AR Scorpii(AR Sco). This system\, with a orbital period of 3.55h\, is composed of a cool\, low-mass companion star and a white dw arf with a spin period of 1.97min. Optical observations by Buckley et al. (2017) showed that the polarimetric emission from the white dwarf is stron gly linearly polarised (~ 40%) with periodically changing intensities. Thi s periodic emission is thought to be powered by the highly magnetised (5*1 08 G) white dwarf that is spinning down. The morphology of the polarisati on signal is similar to that seen in the Crab pulsar. All these observatio ns plus the lack of any obvious sign of accretion lead us to believe that this is the first observed white dwarf pulsar\, bringing a lot of exciteme nt to the field of pulsar physics.\n\nA next step is to investigate if kno wn neutron star pulsar models are applicable to describe the white dwarf p ulsar's polarimetric signatures. We applied the Rotating Vector Model (RVM \; Radhakrishnan and Cooke 1969) to model the polarisation swing of the wh ite dwarf pulsar. We also conducted a parameter study using a Markov chain Monte Carlo method\, making it possible to constrain the magnetic inclina tion angle &alpha and the impact angle &beta = &zeta - &alpha\, with &zeta the observer angle. Here\, we present first results of such constraints. In the future\, we will apply more detailed models to the polarisation swi ng data.\n\nhttps://events.saip.org.za/event/100/contributions/83/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/83/ END:VEVENT BEGIN:VEVENT SUMMARY:Potential Human Risk of Dissolved Heavy Metals in Gold Mine Waters of Gauteng Province\, South Africa DTSTART;VALUE=DATE-TIME:20180628T100000Z DTEND;VALUE=DATE-TIME:20180628T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-84@events.saip.org.za DESCRIPTION:Speakers: Caspah Kamunda (Rusangu University)\nThis paper eval uates the health risk caused by heavy metals in water around a gold mining area. In this study\, samples of water were collected around the mining area. After appropriate preparation\, all samples were analyzed for As\, P b\, Hg\, Cd\, Cr\, Cu\, Zn\, Co and Ni using Inductively Coupled Plasma-Ma ss Spectrometry (ICP-MS). Measured concentrations of the various heavy met als were then used to calculate the average daily intake (ADI) for the inh abitants of the area through ingestion and dermal contact. This ADI was th en used to calculate the hazard quotient (HQ) and hazard index (HI) leadin g to the determination of carcinogenic and non-carcinogenic effects of the se heavy metals. The average concentrations of heavy metals decreased in t he order of Ni>Cu> Zn>As> Cr>Co>Pb. In mg.L-1 the average concentrations were as follows: Ni (0.39)\; Cu(0.38)\; Zn (0.33)\; As (0.19)\; Cr (0.14)\ ; Co (0.08)\; Pb (0.01)\, respectively. Hg and Cd were not detectable. For the non-carcinogenic risk assessment\, calculated values of HQ showed an HI value of 3.38×10-1\, a value less than 1\, which is potentially safe a ccording to USEPA and South Africa guidelines. When the carcinogenic risk assessment was carried out\, the results showed that the total cancer risk due to the heavy metals was 2.94×10-6 mainly due to dermal contact. The US Environmental Protection Agency considers a cancer risk in the range of 1 × 10-6 to 1 × 10-4 acceptable for regulatory purposes. From the findi ngs presented\, it was concluded that dissolved heavy metal levels in mine water were within permissible limits in the mining area.\n\nhttps://event s.saip.org.za/event/100/contributions/84/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/84/ END:VEVENT BEGIN:VEVENT SUMMARY:Estimating the Modulated Inverse-Compton Flux Level from a Black W idow System DTSTART;VALUE=DATE-TIME:20180628T082000Z DTEND;VALUE=DATE-TIME:20180628T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-85@events.saip.org.za DESCRIPTION:Speakers: Christo Venter (North-west University\, Potchefstroo m Campus)\nThe Fermi Large Area Telescope has detected more than 200 gamma -ray pulsars. Many of them are in binary systems\, and a subset of these c omprise the "spider binary" class\, including black widows and redbacks. T he latter systems consists of energetic pulsars and companion stars that a re in tight binary orbits. The two stellar winds interact with each other\ , forming an intrabinary shock and leading to particle acceleration. Obser ved double-peaked X-ray light curves from these systems are attributed to Doppler-boosted synchrotron emission by relativistic particles flowing out along the shock. Additionally\, radio eclipses reflect the presence of th e shock enshrouding the companion in the black-widow case. Although energe tic arguments suggest that these systems may be detectable by ground-based Cherenkov telescopes\, detailed calculations remain to be done rigorously . Given the non-trivial geometry and particle dynamics\, we first attempt a simple approach to estimate the level of inverse Compton flux that shoul d result from nearby black-widow systems. We normalise the injected partic le spectrum to the pulsar current and spin-down luminosity and approximate ly take into account the processes of diffusion\, convection\, and radiati ve energy losses in an axially-symmetric\, steady-state approach. Future w ork will build on these first estimates and will include more detailed par ticle transport in a relativistic 2D approach.\n\nhttps://events.saip.org. za/event/100/contributions/85/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/85/ END:VEVENT BEGIN:VEVENT SUMMARY:Structural\, electronic and optical properties of CH3NH 3PbI3 DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-86@events.saip.org.za DESCRIPTION:Speakers: Aya Alsadig (Sudan University of Science and Technol ogy)\nOrganic-inorganic halide perovskites are promising candidates for lo w cost\, high-efficiency solar cells. We examined the structural\, electr onic\, and optical properties of the low temperature tetragonal phase of t he halide peroviskite CH3NH3PbI3 using Density Functional Theory (DFT). Our numerically predicted structure is in agreement with existing experime ntal data. DFT electronic structure calculations show that relativistic e ffects are important for the heavy lead atom and spin-orbit coupling has t o be included for accurate results. The experimental band gap of 1.63 to 1.66 eV is similar in magnitude to the DFT direct gap of 1.72 eV\, which s uggests that many-body and relativistic effects cancel in this compound. Our calculated fundamental gap\, at the G0W0 level of approximation\, is 2 .48 eV. Optical anisotropy of tetragonal CH3NH3PbI3 was investigated by including many-body effects at the time dependent Hartree Fock and the Bet he-Salpeter equation level of approximation\, with input data from a range separated Heyd-Scuseria-Ernzerhof DFT functional calculation. The optica l edge for radiation polarised parallel to the a- and b-axes differ by abo ut 0.15 eV and for polarisation parallel to the b- and c-axes the differen ce is about 0.05 eV.\n\nhttps://events.saip.org.za/event/100/contributions /86/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/86/ END:VEVENT BEGIN:VEVENT SUMMARY:Study the impact of pile-up jets in the MET reconstruction for the forward region at the ATLAS experiment DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-87@events.saip.org.za DESCRIPTION:Speakers: Esra Shrif (University of the Witwatersrand)\nIn 201 7 and 2018 data taking in the ATLAS detector at LHC\, the average bunch cr ossing per collision is much higher than before. Thus the pile-up effect i s much stronger\, which will\nsignificantly affect the MET reconstruction. In the MET reconstruction\, the forward jet\, which is hardly distinguish ed from the pile-up jet\, will cause a large MET resolution. This presenta tion will introduce the study that how the transverse momentum threshold a nd the jet vertex fraction tagger (JVT) can improve the MET resolution in the high pile-up situation.\n\nhttps://events.saip.org.za/event/100/contri butions/87/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/87/ END:VEVENT BEGIN:VEVENT SUMMARY:DPCMM Meeting DTSTART;VALUE=DATE-TIME:20180628T104000Z DTEND;VALUE=DATE-TIME:20180628T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-234@events.saip.org.za DESCRIPTION:Speakers: Rudolph Erasmus (University of the Witwatersrand)\nh ttps://events.saip.org.za/event/100/contributions/234/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/234/ END:VEVENT BEGIN:VEVENT SUMMARY:Physics in Industry: Nuclear DTSTART;VALUE=DATE-TIME:20180628T092000Z DTEND;VALUE=DATE-TIME:20180628T094500Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-235@events.saip.org.za DESCRIPTION:Speakers: M Mkhosi (Centre for Nuclear Safety and Security\, S outh African National Nuclear Regulator)\nhttps://events.saip.org.za/event /100/contributions/235/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/235/ END:VEVENT BEGIN:VEVENT SUMMARY:Physics in Industry: Discussion DTSTART;VALUE=DATE-TIME:20180628T103500Z DTEND;VALUE=DATE-TIME:20180628T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-236@events.saip.org.za DESCRIPTION:Speakers: Iyabo Usman (University of the Witwatersrand\, Johan nesburg.)\nhttps://events.saip.org.za/event/100/contributions/236/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/236/ END:VEVENT BEGIN:VEVENT SUMMARY:Solutions of Einstein-Klein-Gordon equations with logarithmic phan tom field DTSTART;VALUE=DATE-TIME:20180627T122000Z DTEND;VALUE=DATE-TIME:20180627T124000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-89@events.saip.org.za DESCRIPTION:Speakers: Vladimir Dzhunushaliev (KRSU)\nWe study Einstein-Kle in-Gordon equations with a phantom\, which is a scalar field with a negati ve sign in front of the kinetic energy term of its Lagrange density. Such equations can find applications in approximate cosmological models based o n a low-energy limit of the superfluid vacuum theory. We show that they ha ve spherically symmetric solutions\, and perform their stability analysis. \n\nhttps://events.saip.org.za/event/100/contributions/89/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/89/ END:VEVENT BEGIN:VEVENT SUMMARY:Did Dark Matter Kill the Dinosaurs? DTSTART;VALUE=DATE-TIME:20180627T094000Z DTEND;VALUE=DATE-TIME:20180627T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-90@events.saip.org.za DESCRIPTION:Speakers: Michael Sarkis (University of the Witwatersrand)\nPo tential links between astrophysical sources\, such as gamma ray bursts and supernovae\, and mass extinction events on Earth are of interest in the h istorical trajectory of life on our planet. There are strong arguments to suggest that these astrophysical sources can have several destructive effe cts\, including depletion of atmospheric ozone and an increase in the radi ation dose received by living organisms. Recently\, the possibility of gal actic Dark Matter (DM) clumps having an affect life on Earth has been of s ome interest in the literature. In this work\, it is shown that when the E arth passes through clumpy DM composed of WIMPs\, there is an equivalent d ose of ~15.9 μSv imparted to organic tissue when the WIMPs are treated as mutagenic radiation. There will also be an increase to the internal heat flow of the Earth of as much as ~3700 TW\, leading to increased flood-basa lt volcanism. It is also shown that when a clump of DM with ~1 M☉ passes through the solar system\, the annihilation and decay of WIMPs can produc e a gamma ray flux strong enough to deplete parts of the ozone layer. If W IMPs are found to be a major constituent of DM\, these effects (or a combi nation thereof) could provide an explanation for mass extinction events on Earth.\n\nhttps://events.saip.org.za/event/100/contributions/90/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/90/ END:VEVENT BEGIN:VEVENT SUMMARY:A comparative study of the high fluence neutron radiation effects on the structural and optical properties of plastic scintillator UPS 923A DTSTART;VALUE=DATE-TIME:20180629T082000Z DTEND;VALUE=DATE-TIME:20180629T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-91@events.saip.org.za DESCRIPTION:Speakers: Gaogalalwe Mokgatitswane (Botswana International Uni versity of Science and Technology)\nWe report on the optical and structura l properties of plastic scintillators irradiated with a neutron beam produ ced by the IBR-2 reactor of the Frank Laboratory of Neutron Physics in JIN R\, Dubna. Blue and green shifting Ukraine polystyrene-based scintillators UPS 923A were irradiated with neutron fluence ranging from 3 x 10^(13) to 1.7 x 10^(16) n/cm^2 and neutron energy E > 1 MeV. Discolouring in the pl astic scintillators was observed after irradiation. The effects of radiati on damage on the optical and structural properties of the samples were cha racterized by conducting light yield\, light transmission\, light fluoresc ence and Raman spectroscopy studies. According to the results obtained\, n eutron radiation does influence damage in the material. The disappearance of the Raman peak features in green emitters at 1165.8\, 1574.7 and 1651.2 cm^(-1) revealed significant structural alteration due to neutron bombard ment. We observed a loss in the fluoroscence intensity\, light yield and l ight transmission in the plastics.\n\nhttps://events.saip.org.za/event/100 /contributions/91/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/91/ END:VEVENT BEGIN:VEVENT SUMMARY:Wireless Mesh Data Communications and Reliability Analysis for Ant i-theft Application Deployment in Educational Institutions DTSTART;VALUE=DATE-TIME:20180627T094000Z DTEND;VALUE=DATE-TIME:20180627T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-92@events.saip.org.za DESCRIPTION:Speakers: Roger van Rensburg (Wits)\nThis research is a contin uation of a security application to protect portable computer devices agai nst theft in educational institutions of South Africa. The project is an i nitiative from the School of Physics with the goal of in-house development of a low-cost anti-theft system where devices require secure communicatio n to a wireless mesh network. Hundreds of thousands of packets were transm itted and logged between interconnected nodes to analyze the quality of th e network's service in harsh indoor building environments. Similar methodo logies in big data analysis as found in particle physics at the Large Hadr on Collider were adopted between multiple point data communications to an alyze the network's performance and reliability. Network development is fu rther extended consisting of hardware and software development for transce iving encrypted messages between interconnected nodes using the User Datag ram Protocol. Finally\, the anti-theft application will focus on proprieta ry firmware and Android application development to render the device inope rable using the encrypted messaging scheme as a medium for communication t o devices. Results thus far indicate reliable data transmissions in noisy indoor environments and between multiple asynchronous transmitting nodes i n the network. The distance vector routing algorithm adopted by the Thread networking protocol is simulated to determine hop routing distances betwe en source and destination routers. The results are compared with the netwo rk's multipoint data to determine coverage in large geographical areas.\n\ nhttps://events.saip.org.za/event/100/contributions/92/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/92/ END:VEVENT BEGIN:VEVENT SUMMARY:Quasi-normal modes and absorption probabilities of spin-3/2 fields in D-dimensional Reissner-Nordstrom black hole spacetimes DTSTART;VALUE=DATE-TIME:20180626T102000Z DTEND;VALUE=DATE-TIME:20180626T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-132@events.saip.org.za DESCRIPTION:Speakers: Alan Cornell (NITheP)\nIn this talk we consider spin -3/2 fields in a D-dimensional Reissner-Nordstrom black hole spacetime. As these spacetimes are not Ricci-flat\, it is necessary to modify the covar iant derivative to the supercovariant derivative\, by including terms rela ted to the background electromagnetic fields\, so as to maintain the gauge symmetry. Using this supercovariant derivative we arrive at the correspon ding Rarita-Schwinger equation in a charged black hole background. As in o ur previous works\, we exploit the spherically symmetry of the spacetime a nd use the eigenspinor-vectors on an N-sphere to derive the radial equatio ns for both non-transverse-traceless modes and tranverse-traceless modes. We then determine the quasi-normal mode and absorption probabilities of th e associated gauge-invariant variables using the WKB approximation and the asymptotic iteration method. We then concentrate on how these quantities change with the charge of the black hole\, especially when they reach the extremal limits.\n\nhttps://events.saip.org.za/event/100/contributions/132 / LOCATION: URL:https://events.saip.org.za/event/100/contributions/132/ END:VEVENT BEGIN:VEVENT SUMMARY:A numerical study of heterogeneous annealing in a finite one-dimen sional geometry DTSTART;VALUE=DATE-TIME:20180627T082000Z DTEND;VALUE=DATE-TIME:20180627T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-93@events.saip.org.za DESCRIPTION:Speakers: Jeremiah Lethoba (Department of Physics\, University of Pretoria)\nThe irradiation of a material with high-energy particles ca uses the formation of different types of defects in its crystalline lattic e. At any temperature above absolute zero\, the defects anneal spontaneous ly and the rate of annealing increases with temperature. The thermal energ y released in the process of annealing contributes to the temperature of t he material\, and creates a positive feedback effect referred to as the th ermal-concentration feedback. The non-homogeneous distribution of defects or of temperature in the material\, along with the thermal-concentration f eedback\, may lead to the appearance of a self-sustaining annealing wave. Conditions for the formation of the annealing wave are currently not well established. In this study numerical modelling of the heterogeneous anneal ing in a finite one-dimensional geometry was performed. To this end\, a fi nite difference solver was implemented\, verified and applied in our numer ical experiments. The self-sustaining annealing process was initialized by adding heat to a localized region near the material surface at the initia l moment. Evolution of temperature and defect distributions during the pro cess of annealing was obtained for different initiating heat distributions and initial defect concentrations. It was demonstrated that for large val ues of initiating energy\, the annealing process develops as a wave\, whic h propagates at a constant speed. For more moderate values of initiating e nergy\, the interplay of the heterogeneous initial heat distribution and t he spontaneous annealing leads to the appearance of the wave regime in the terminal part of the process.\n\nhttps://events.saip.org.za/event/100/con tributions/93/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/93/ END:VEVENT BEGIN:VEVENT SUMMARY:Studying the effects of pileup on the leptonic properties for the H-> ZZ -> 4l channel with the ATLAS detector at the LHC DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-94@events.saip.org.za DESCRIPTION:Speakers: Onesimo Mtintsilana (University of Witwatersrand)\nT he background composition and shapes are studied in spectral control regio ns which are constructed inverting selections or lepton identification req uirements. I will be looking at the effect of pileup for the H -> ZZ -> 4l channel with weighted histograms\, normalized to the expected luminosity. The background considered is the qq -> ZZ reducible background which is f rom a dominant quark-antiquark initial state. Comparisons between mc16a\, mc16d and mc16e samples for the pile effect and the expected yield will be studied for all channels. I will also look at studies on the high mass qq ->ZZ samples.\n\nhttps://events.saip.org.za/event/100/contributions/94/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/94/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigation of Pc5 pulsations during a TRINNI event DTSTART;VALUE=DATE-TIME:20180626T094000Z DTEND;VALUE=DATE-TIME:20180626T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-95@events.saip.org.za DESCRIPTION:Speakers: Bernad Mmame (UKZN)\nPc5 (1-5mHz) pulsations are glo bal magnetohydrodynamic (MHD) events in the magnetosphere. Identification of the causes of Pc5 ULF pulsations has been a challenging problem in the field of MHD physics because of the complex nature of the magnetosphere. S everal studies have shown that high speed ionospheric plasma flow in the n ight side which are mapped to the magnetospheric tail during magnetically quiet periods are associated with releasing of energy from quick reconfigu ration of tail magnetic field lines because of reconnection\, and these ev ents are referred to as a TRINNI\, which is an acronym for “Tail Reconne ction during IMF Northward\, Non-substorm Interval”. Numerous TRINNI eve nts have been reported using the SuperDARN (acronym for a network of HF ra dars) and magnetometer data. In this study\, we analyse a known TRINNI eve nt for the presence of associated Pc5 pulsations and investigate if TRINNI events could be their driving mechanism. SuperDARN cross-polar cap potent ial data were used as proxy for a TRINNI. We investigate the relationship between the TRINNI and Pc5 pulsations of this event by using sophisticated Fourier analysis techniques using complex demodulation on the SuperDARN c ross-polar cap potential and magnetometer data.\n\nhttps://events.saip.org .za/event/100/contributions/95/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/95/ END:VEVENT BEGIN:VEVENT SUMMARY:The relativistic length transformation: more than a Lorentz contra ction DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-96@events.saip.org.za DESCRIPTION:Speakers: R. E. Kroon (University of the Free State)\nA well k nown result of special relativity is that an object\, moving with constant speed away from an inertial observer\, has its proper length along the di rection of observation reduced due to the Lorentz contraction. Although so me might describe this effect as the relativistic length transformation\, a more appropriate use of this term could apply to how the observed length of the object changes as the observer goes from the original inertial fra me to a new one. Therefore the relativistic length transformation might yi eld an elongation or a contraction\, depending on the circumstances. The g eneral result for parallel velocities is derived. Although the result is n ot entirely new\, the concept of the length transformation does not seem t o be presented in this way in general texts. As an example of its applicat ion\, the result is used to substantially simplify the derivation given in a well-known electrodynamics textbook of the relativistic transformation of the electric field\, where the physical interpretation of the length tr ansformation is obscured by the mathematics.\n\nhttps://events.saip.org.za /event/100/contributions/96/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/96/ END:VEVENT BEGIN:VEVENT SUMMARY:Enhancement of signal to noise ratio through temporal pulse shapin g DTSTART;VALUE=DATE-TIME:20180627T084000Z DTEND;VALUE=DATE-TIME:20180627T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-97@events.saip.org.za DESCRIPTION:Speakers: George Okyere Dwapanyin (Stellenbosch University)\nT he quest to probe deeper into biological tissue has led to the development of many microscopic techniques ranging from the linear regime\, such as b right-field microscopy\, to higher order nonlinear optical microscopy (NLO M) techniques. These NLOM permit intrinsic 3D imaging with submicron spati al resolution\, decreased photodamage to tissue\, increased depth of penet ration\, as well as the ability to perform label-free imaging. This resear ch focuses on the enhancement of signal to noise ratio obtained in NLOM th rough temporal pulse shaping and phase manipulation of the excitation puls es. The application and effects of this pulse shaping and manipulation on contrast enhancement\, as applied to examples including nonlinear crystals and biological tissues\, will be discussed.\n\nhttps://events.saip.org.za /event/100/contributions/97/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/97/ END:VEVENT BEGIN:VEVENT SUMMARY:Measurements of phase distortions through pulse characterization DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-98@events.saip.org.za DESCRIPTION:Speakers: George Okyere Dwapanyin (Laser Research Institute\, Dept. of Physics\, Stellenbosch University)\nThe interaction of light with any material with refractive index\, n\, affects not only the amplitude o f the transmitted light but also its phase. Accurate determination of the spectral phase of a laser pulse is paramount in various spectroscopic appl ications. There are many phase measurement techniques such as direct inter ferometric approaches including Frequency Resolved Optical Gating (FROG) a nd Spectral Phase Interferometry for Direct Electric-field Reconstruction (SPIDER) as well as indirect techniques such as ptychography. This present ation discusses an alternative approach of measuring phase distortions thr ough the use of a Multiphoton Intrapulse Interference Phase Scan (MIIPS). The principle of the technique as well as the determination of the phase o f the generated signal will be looked at. Possible applications in phase c ontrast imaging will also be discussed.\n\nhttps://events.saip.org.za/even t/100/contributions/98/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/98/ END:VEVENT BEGIN:VEVENT SUMMARY:Elastic and Thermal Properties of Ge2Sb2Te5 by Surface Brillouin Scattering DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-99@events.saip.org.za DESCRIPTION:Speakers: Mmapula Baloi (University of the Witwatersrand)\nGe2 Sb2Te5 (GST225) is a chalcogenide phase change alloy widely used in optica l storage media and electronic memory devices. It has been studied in the past two decades due to its optical and electrical properties driven by fa st and reversible structural phase transformation. However\, its elastic p roperties have not been thoroughly investigated. Since thermal energy can be stored in vibrational modes\, surface Brillouin scattering (SBS) has be en used to determine the elastic properties and correlate them with therma l properties. RF-magnetron sputtering was used to deposit films of thickne ss varying from 50-500 nm on a Si/Si1O2 substrate. The crystalline (c) pha se was obtained by annealing the samples at a temperature of 150 ֯C for o ne hour. Since the transition between the amorphous (a) and crystalline ph ases is associated with a volume change\, we studied this by measuring the densities of the two phases using x-ray reflectivity. Rutherford Backscat tering was used to investigate the films chemical composition and atomic d ensity\, which was found to be n~3.05×〖10〗^22 and 3.01×〖10〗^22 a toms cm^(-3) for a-GST225 and c-GST-225. The elastic constants for the amo rphous (a) and crystalline (c) phases obtained are C11=37.9/37.0 GPa\, C12 =17.6/13.1 GPa and C44=10.2/12.0 GPa respectively. The corresponding longi tudinal and transverse velocities are vl=2558/2499 m/s and vt=1325/1421 m/ s. Lastly the calculated minimum lattice thermal conductivities of a- and c-GST225 were found as κmin=0.283 and 0.287 Wm^(-1) K^(-1). Such low ther mal conductivities are desirable for improving thermal management in memor y devices during programming.\n\nhttps://events.saip.org.za/event/100/cont ributions/99/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/99/ END:VEVENT BEGIN:VEVENT SUMMARY:Logarithmic nonlinearity in theory of quantum and classical liquid s DTSTART;VALUE=DATE-TIME:20180627T120000Z DTEND;VALUE=DATE-TIME:20180627T122000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-100@events.saip.org.za DESCRIPTION:Speakers: Konstantin Zloshchastiev (Durban University of Techn ology)\nWave equation with logarithmic nonlinearity find fruitful applicat ions in different branches of physics - from nuclear physics and condensed -matter theory to particle physics\, theory of quantum gravity and models of physical vacuum. In order to derive this nonlinearity from basic princi ples\, we apply statistical mechanics and Madelung hydrodynamical presenta tion for an effective description of strongly-interacting many-body system s\, such as Bose liquids or Korteweg-type materials. We show the relations hip between the “logarithmic” fluids and those described by polynomial ly nonlinear wave equations\, such as the Gross-Pitaevskii equation.\n\nht tps://events.saip.org.za/event/100/contributions/100/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/100/ END:VEVENT BEGIN:VEVENT SUMMARY:A preliminary study of the impact of metal-induced CT artifacts on Monte Carlo dose calculations in a pelvic prosthesis phantom DTSTART;VALUE=DATE-TIME:20180627T080000Z DTEND;VALUE=DATE-TIME:20180627T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-101@events.saip.org.za DESCRIPTION:Speakers: Nicholas Ade (University of the Free State)\nCompute d tomography (CT) images of patients undergoing radiation therapy form the basis of 3D radiotherapy treatment planning. But in the presence of metal lic implants\, metal streak artifacts are produced in CT images which coul d provide inaccurate electron density information (due to incorrect Hounsf ield units (HU) values) needed for accurate calculation of patient radiati on dose. In this study\, the dosimetric impact of metal-induced CT streak artifacts on Monte Carlo dose calculations in a pelvic phantom that contai ns unilateral hip Ti implant is evaluated. Correct HU values were assigned to known materials of the pelvic prosthesis phantom to create an artifact -free phantom model in contrary to HU values generated through the origina l artifact-induced CT images. DOSXYZnrc Monte Carlo dose calculations were then computed in the artifact-free phantom model created from the exact g eometry of the phantom with known materials and the phantom model made fro m the original CT images containing the metal artifacts. The dose calculat ions were benchmarked against Gafchromic EBT3 film measurements using 10 × 10 cm2 15 MeV electron and 10 MV photon beams. The average discrepancie s between film and MC dose data decreased from 4±2% to 2±1% and from 5± 3% to 3±2% in the two phantom models for the electron and photon fields\, respectively. The study shows that Monte Carlo calculated dose data in th e artefact-free phantom model were closer to film measurements compared to dose data computed in the original phantom model containing the metal-ind uced CT artifacts.\n\nhttps://events.saip.org.za/event/100/contributions/1 01/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/101/ END:VEVENT BEGIN:VEVENT SUMMARY:Effect of Li+ ion on the structural\, morphological and luminescen t properties of Y2O3:Tm3+ nanophosphor DTSTART;VALUE=DATE-TIME:20180626T082000Z DTEND;VALUE=DATE-TIME:20180626T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-102@events.saip.org.za DESCRIPTION:Speakers: Shivaramu N J (Department of Physics\, University of the Free State\, Bloemfontein\, ZA-9300\, South Africa)\nRare-earth ions doped nanocrystals are increasingly important as an active media for solid -state lasers which efficiently operate under diode pumping. Among them th e thulium (Tm3+) ion could be an attractive activator with suitable absorp tion for commercial diode pumping. In addition to this\, it shows long flu orescence life times and it is suitable for large energy storage devices. Tm3+ doped yttrium oxide (Y2O3) and lithium (Li+) co-doped Y2O3:Tm3+ were prepared by the solution combustion technique. The samples were annealed a t 900 °C to obtain crystalline phases. X-ray diffraction patterns confirm ed the cubic phase of Y2O3. The crystallite sizes were calculated by using the Scherrer formula and was found to be in the order of 20 nm. The parti cles were found to be spherical in nature and their sizes were estimated t o be 37 nm by the scanning electron microscope technique. A sharp andstron g photoluminescence (PL) emission peak at 453 nm was observed in the prist ine and in the Li+ co-doped Y2O3:Tm3+ sample. The emission peak at 453 nm was assigned to the 1G4→3H6 transition. It was found that the PL intensi ty increased with the Li ion concentration up to 4 mol% and then it decrea sed with a further increase of Li ion concentration. The 4 mol% Li+ co-dop ed material showed a strong blue emission. The 4 mol% Li+ co-doped materia l exhibited a long decay. Thermoluminescence (TL) glow curves were obtaine d for the samples exposed with a UV light at room temperature. These glow curves showed peaks at 323 K\, 356 K and 583 K and the intensities linearl y increased upto a Li+ concentration of 4 mol%. Whereas\, the pristine sam ple showed low intensity. The detailed TL kinetic parameters were evaluate d by a glow curve deconvoluted technique.\n\nhttps://events.saip.org.za/ev ent/100/contributions/102/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/102/ END:VEVENT BEGIN:VEVENT SUMMARY:Magnetic properties and magnetocaloric effect in NdPd2Al2 DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-124@events.saip.org.za DESCRIPTION:Speakers: Mbulunge Masevhe (University of the western cape)\nT he magnetic properties and magnetocaloric effect (MCE) of the tenary inter metallic NdPd2Al2 compound have been investigated by means of X-ray diffra ction (XRD)\, magnetic susceptibility χ(T)\, magnetization M(μ0H)\, isot hermal magnetization M(μ0H\,T) and MCE measurements. XRD studies indicate a tetragonal crystal structure with space group P4/nmm (No.: 129). The lo w temperature χ(T) data exhibits a maximum characteristic of antiferromag netic (AFM) phase transition at TN = 3.2 K. At high temperature\, the χ(T ) data follows the Curie – Weiss relation with effective magnetic moment μeff = 3.654(5) μB and a Weiss temperature θp = -3.3(4) K. The value o f μeff obtained is close to the value of 3.62 μB expected for the free N d3+ - ion. The magnetization data indicate metamagnetic transition at low magnetic field and a tendency toward saturation at high field. Arrot – p lots indicate a second – order phase transition. The MCE effect was esti mated from the isothermal magnetization to be 18 J/(kg.K) for a field chan ge of 7 T. The characteristic behaviour of the isothermal magnetic entropy change points to a second – order character of the AFM phase transition as observed from the Arrot - plots.\n\nhttps://events.saip.org.za/event/1 00/contributions/124/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/124/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthesis and thermoluminescence kinetic parameters of UV irradiat ed BaAl2O4:Nd nanocrystals DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-103@events.saip.org.za DESCRIPTION:Speakers: Divya Janardhana (Department of Physics\, University of the Free State\, Bloemfontein\, ZA-9300\, South Africa)\nBarium alumin ate (BaAl2O4) belongs to the spinel group of minerals. The BaAl2O4 exhibi ts high thermal\, chemical stability\, hydrophobic behavior\, low sinterin g temperature and high quantum yields. It is a wide-band gap semiconductor \, which occurs naturally as the mineral gahnite. Furthermore\, BaAl2O4:Nd phosphor material can be used as transparent conductor\, scintillators an d optical material. Nanocrystalline BaAl2O4 was prepared using the solutio n combustion synthesis. In this method\, urea was employed as a fuel. The crystallite size was found to be 27 nm with a hexagonal structure with the space group P63 as determined by the X-ray diffraction technique. The sca nning electron microscopy indicated towards the foamy and fluffy nature of the sample. The diffuse reflectance spectrum of the powder was also recor ded. The absorption bands centered at 269 nm was due to the band to band t ransitions of the host and the bands at 343\, 509\, 566\, 694\, 721 and 78 0 nm were due to the 4f–4f transitions from the Nd3+ ground states to a series of excited states. The corresponding bands were assigned to the tra nsition from 4I9/2 to 4D5/2+4D3/2+2P3/2\, 4G7/2\, 2G5/2+2G7/2\, 4F9/2\, 4F 7/2+4S3/2\, 4F5/2+2H9/2. Thermoluminescence (TL) studies of the BaAl2O4:Nd nanopowders irradiated with UV in the different interval of time0-360 min were recorded at room temperature. A well resolved and prominent TL glow curve with peaks at 332 K and 617 K and a weak peak at 453 K were observed . The TL peaks’ (332 K and 453 K) intensities increased with UV exposure up to 266 min and 236 min\, respectively and then decreased with a furthe r increase of UV exposure due to the creation of complex defects. The kine tic parameters were obtained from the computerized deconvoluted peaks usin g various glow curve shape methods.\n\nhttps://events.saip.org.za/event/10 0/contributions/103/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/103/ END:VEVENT BEGIN:VEVENT SUMMARY:Numerical investigation of solar energetic particle transport betw een the Sun\, Earth\, and Mars. DTSTART;VALUE=DATE-TIME:20180629T094000Z DTEND;VALUE=DATE-TIME:20180629T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-104@events.saip.org.za DESCRIPTION:Speakers: Phillip Heita (NWU (CSR))\nSolar energetic particles (SEPs)\, are particles (mostly electrons\, protons and alpha particles) t hat are generated in a solar flare or at a shock driven by a coronal mass ejection (CME)\, resulting in super-thermal particles with energies from a few keV up to several GeVs. These high energy particle increases pose a danger to astronauts in space\, can lead to the degradation of precious sa tellites and other Earth infrastructure\, and even closer to home\, they c an result in a radiation hazard for airline passengers. With computer adva ncements\, numerical methods such as finite-difference (FD) method have be come invaluable tools in approximating various properties of SEPs\, primar ily focusing at Earth position\, noting the accuracy to spacecraft observa tions. We shall seek to give a brief introduction to FD methods\, and thei r implementation into the development of a Python model that simulates SEP transport. Given the current NASA and SpaceX aspirations of a Mars resear ch base\, and eventual colony\, we shall provide initial model results at Mars\, and perform a comparative study of the initial model solutions to s pacecraft observations near both Earth and Mars\, noting the limited obser vational spacecraft data from the MAVEN mission at Mars.\n\nkeyword(s): So lar energetic particles\, Finite-difference methods\, Earth\, Mars.\n\nhtt ps://events.saip.org.za/event/100/contributions/104/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/104/ END:VEVENT BEGIN:VEVENT SUMMARY:Structural\, optical and photoluminescence investigations of Eu do ped ZnO spin coating films DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-105@events.saip.org.za DESCRIPTION:Speakers: Emad Hasabeldaim (University of the Free State)\nEu doped ZnO thin films were successfully prepared from sol-gel solution usin g the spin coating technique. X-ray diffraction confirmed that all the fil ms having a preferential c-axis orientation along the 002 plane\, and thei r degree of orientation decreased with an increasing Eu concentration. The crystallite size was found to be a minimum for the lower Eu content (0.4 mol%) while it first increased to a maximum at 0.6 mol% of Eu ions where a fter it decreased again at the higher Eu concentration of 0.8 and 1 mol%. The average values of the ratio between the root mean square roughness and the average roughness for the films were found very close to the value th at is predicted by the statistical theory of a Gaussian distribution asper ity for the applicable surface (1.25 is the theoretical value and 1.31 is the experimental results that is estimated by the theory). The band gap wa s found to decrease from 3.31 eV to 3.26 eV with an increase in the Eu con centration. The indirect excitation (excited at 325 nm He-Cd laser) of the undoped film revealed that the film emitted excitonic emission as well as deep level emission of ZnO\, while the Eu doped ZnO films showed small pe aks related to the Eu3+ emission around 614 nm on top of the deep level em ission. Selective excitation (at 464 nm) of the Eu doped films showed uniq ue Eu3+ emission features and their intensity increased with an increasing Eu content\, reaching to a maximum intensity at 0.6 mol% of Eu and then d ecreased.\n\nhttps://events.saip.org.za/event/100/contributions/105/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/105/ END:VEVENT BEGIN:VEVENT SUMMARY:Characterisation of Y2O3 co-doped Bi3+< /sup> and Yb3+ thin films synthesised using pulsed laser deposi tion and spin coating. DTSTART;VALUE=DATE-TIME:20180626T092000Z DTEND;VALUE=DATE-TIME:20180626T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-106@events.saip.org.za DESCRIPTION:Speakers: Edward Lee (University of the Free State)\nPhosphor materials doped with various rare-earth (RE) elements have been used by th e lighting industry in light emitting diodes and mercury free fluorescent tubes due to the wide range of possible luminescence ranging from ultravio let (UV) through to the near-infrared (NIR) regions. In recent years\, pho sphor materials have been used to alter the solar spectrum in order to red uce the spectral mismatch and improve the conversion efficiency of solar c ells. RE3+ - Yb3+ co-doped phosphors have shown potential for down-convert ing/shifting UV photons to NIR photons\, but due to the parity forbidden 4 f transition of RE3+\, they are generally inefficient at absorbing photons in the UV and blue regions resulting in a weak NIR Yb3+ emission. Metal d onor ions such as Bi3+ have shown to be an alternative to rare-earth ions for enhancing the NIR emission of Yb3+ ions. Y2O3:Bi3+\,Yb3+ thin films we re prepared using the pulsed laser deposition (PLD) and spin coating techn iques. For films prepared through spin coating we found that the molarity of the Y2O3:Bi3+\,Yb3+ solution plays an important role in the smoothness of the prepared films. Scanning electron microscopy analysis showed that f ilms prepared at concentrations greater than 0.4 M were rough and disperse d with large agglomerations in the order of 100 μm\, while films prepared at 0.2 M were significantly smoother and no agglomerations. Films synthes ised using PLD also showed a rough surface\, however the size of the agglo merated particles were approximately 1 μm. These small agglomerations wer e expected due to the laser ablation process which has an explosive-like c haracter. Finally\, under UV (325 nm) excitation the photoluminescence ana lysis for both the PLD and spin coating synthesised thin films yielded goo d luminescence properties in both the visible and more importantly in the NIR region. The result demonstrated that UV to NIR down-conversion/shiftin g is possible and may be used to modify the solar spectrum with the aim of improving the efficiency of solar cells.\n\nhttps://events.saip.org.za/ev ent/100/contributions/106/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/106/ END:VEVENT BEGIN:VEVENT SUMMARY:Vector vortex beams through amplifiers DTSTART;VALUE=DATE-TIME:20180627T094000Z DTEND;VALUE=DATE-TIME:20180627T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-237@events.saip.org.za DESCRIPTION:Speakers: Hend SROOR (University of The Witwatersrand)\nVector beams are spatial modes of light in which the polarization and spatial de gree of freedom are inseparable. Such beams have widely been used in appli cations ranging from optical tapping and tweezers to optical communication s. Yet\, these vector beams have been only generated in low power due to l imitation in the tools used to generate them. Here\, we show the amplifica tion of vector beams through birefringent amplifier. Since the beam purity is important key that determines the efficiency of the beam in specific a pplications. We measured the perturbation of the vector beam purity throug hout the amplification process. Our result shows that the purity of the ve ctor beams can be modified while increasing the power which is a significa nt step toward the high brightness lasers.\n\nhttps://events.saip.org.za/e vent/100/contributions/237/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/237/ END:VEVENT BEGIN:VEVENT SUMMARY:Electrically active induced energy levels and metastability of B a nd N vacancy-complexes in 4H-SiC DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-107@events.saip.org.za DESCRIPTION:Speakers: Emmanuel Igumbor (University of Pretoria)\nElectrica lly active induced energy levels in semiconductor devices could be benefic ial to the discovery of an enhanced p or n-type semiconductor. N implanted into 4H-SiC is a high energy process that produced high defect concentrat ions which could be removed during dopant activation annealing. On the oth er hand\, B substituted for silicon in SiC leads to a decrease in the die lectric properties and induced deep donor and shallow acceptor levels. Com plexes formed by the N\, such as the nitrogen-vacancy centre\, have been r eported to play a significant role in the application of quantum bits. The results of charge states thermodynamic transition level of the N and B va cancy-complexes in 4H-SiC are presented. The energies of formation of the N related vacancy-complexes shown the NCVC to be energetically stable clos e to the valence band maximum in its double positive charge state. The NCV Si is more energetically stable in the double negative charge state close to the conduction band minimum. The NSi VC on the other hand\, induced dou ble donor level and the NCVSi induced a double acceptor level. For B relat ed complexes\, the BCVC and BSiVC were energetically stable in their singl e positive charge state closed to the valence band maximum. As the Fermi e nergy is varied across the band gap\, the neutral and single negative char ge states of the BSiVC become more stable at different energy levels. B an d N related complexes exhibited charge state controlled metastability beha viour.\n\nhttps://events.saip.org.za/event/100/contributions/107/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/107/ END:VEVENT BEGIN:VEVENT SUMMARY:WPIT101 (Introduction to Wave-particle Interactions in Turbulence) : Micro-physics of Charged Particle Transport in Turbulent Magnetic Fields DTSTART;VALUE=DATE-TIME:20180629T092000Z DTEND;VALUE=DATE-TIME:20180629T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-108@events.saip.org.za DESCRIPTION:Speakers: Jabus van den Berg (North West University)\nTerms su ch as pitch-angle scattering and parallel or momentum diffusion are freque ntly used in plasma physics and transport theory when the propagation of c harged particles in turbulent magnetic fields are considered. Regardless o f the wide use of these terms\, their exact implications or physical descr iptions are often not well understood or misunderstood. Would you be able to draw a picture of perpendicular diffusion if asked to? This work attemp t to build a conceptual understanding of magnetic turbulence’s influence on the movement of charged particles. This is done by constructing toy sl ab\, 2D\, and composite slab-2D turbulence models and solving the Newton-L orentz equation numerically for particles propagating in these turbulence models. It is seen that the classical idea of particle scattering or hard- sphere collisions\, where particles physically collide or particles are de flected by some interaction potential between particles\, cannot and shoul d not be naively applied to charged particles interacting with turbulence. This is due to the physical interaction between charged particles and mag netic scattering centres being of an unique nature. It is shown that the m otion of the particle itself is smooth and continuous\, although it follow s a highly perturbed spiral path. It is only when the particle’s guiding centre is considered\, that the classical scattering idea can be applied as its motion is more irregular and display abrupt changes. The insights g ained in this work do not only allow a better conceptual understanding of the various terms\, but also to visualize the various processes described by these terms.\n\nhttps://events.saip.org.za/event/100/contributions/108/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/108/ END:VEVENT BEGIN:VEVENT SUMMARY:A Mechanism for (&epsilon\, &delta)-differential privacy using Stu dent's t distribution DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-109@events.saip.org.za DESCRIPTION:Speakers: Makhamisa Senekane (Department of Physics and Electr onics\, National University of Lesotho\, Roma\, Lesotho)\nThe proliferatio n of data and data analysis has resulted in a need to pay more attention t o the security of the the data being analyzed. Different options have been pursued to guarantee privacy of these statistical databases generated. Ho wever\, most of such options cannot offer guarantee of security of the sta tistical databases. On the other hand\, differential privacy is able to me et such a requirement of security definition. It guarantees privacy of an individual against an adversary with arbitrary auxiliary information. Diff erential privacy can be categorized as either &epsilon- or (&epsilon\, &de lta)-differential privacy. In this work\, we report a mechanism for (&epsi lon\, &delta)-differential privacy using Student's t probability distribut ion. Our results guarantee the privacy and the utility of the mechanism\, and this underlines the utility of this mechanism.\n\nhttps://events.saip. org.za/event/100/contributions/109/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/109/ END:VEVENT BEGIN:VEVENT SUMMARY:Computational study of ZIF with functional groups for CO2 adsorpti on. DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-110@events.saip.org.za DESCRIPTION:Speakers: Chih-Wei Tsai Tsai (University of the Free State)\nG reenhouse gases\, Carbon Dioxide in particular\, has been a main concern f or climate change. Zeolitic Imidazolate Framework (ZIF)\, a sub class of M etal Organic Framework (MOFs)\, is a 3-dimensional nanoparticle consisting of metal ion (Zn2+) and an organic linker (imidazole) with high chemical and thermal stability. The bond angle between the metal and imidazole has the same 145° angle found in zeolites. These cage like structure are poro us and have a high surface area (>1600 m2 g-1). The high surface area is a dvantageous in several applications such as gas storage\, gas separation\, chemical sensors etc. ZIFs with its organic imidazole counterpart can be easily modified to add or improve functionality of the materials. Addition al functional groups on the imidazole linker such as NO2 groups were foun d to greatly enhance the CO¬2 adsorption capabilities of ZIFs via a ligan d exchange process. In this study a series of functional groups on ZIFs we re computed with Grand Conical Monte Carlo (GCMC) simulations by Material Studio to determine whether NO2\, SH\, F\, Cl\, Br\, CH3\, OH\, NH2\, phen yl and H groups will benefit in improving CO2 adsorption. Our results show that ZIFs with electron withdrawing groups can greatly enhance CO2 adsorp tion and can easily predict which functional group to synthesis experiment ally.\n\nhttps://events.saip.org.za/event/100/contributions/110/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/110/ END:VEVENT BEGIN:VEVENT SUMMARY:Emergent Property Sets & Applications of Beta-Gallium Oxide DTSTART;VALUE=DATE-TIME:20180628T120000Z DTEND;VALUE=DATE-TIME:20180628T130000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-111@events.saip.org.za DESCRIPTION:Speakers: David Rogers (Nanovation)\nRecently\, there has been a surge in interest for the wide bandgap (Eg ~ 4.9 eV) semiconductor\ngal lium oxide (Ga2O3). A key driver for this boom is that single crystal wide area bulk β-Ga2O3\nsubstrates have become commercially available [1] and a variety of methods have been shown to\ngive high quality epitaxial grow th [2\,3].\nAlthough Ga2O3 has a number of polymorph forms (α-\, β-\, γ -\, δ- and ε) the more stable\nmonoclinic phase (β-Ga2O3) has attracted the most attention. Amongst a whole range of potential\napplications powe r electronics\, solar-blind photodetectors and UVC transparent electrodes offer\nexciting perspectives [3-5].\nIn this talk we give an overview of t hese applications illustrated with examples from the β-Ga2O3\ndevelopment work carried out at the French oxide epiwafer start-up\, Nanovation [4-7] .\n[1] http://www.tamura-ss.co.jp/en/products/gao/index.html\n[2] http://n anovation.com/en/products/\n[3] M. Razeghi\, D. J. Rogers et al. Proc. SPI E 15330 (2018) 15330 O R-1\n[4] D. J. Rogers et al. Proc. SPIE 15330 (2018 ) 15330 O R-1\n[5] A. Perez-Tomas\, D. J. Rogers et al. Proc. SPIE 15330 ( 2018) 15330 1 Q-1\n[6] F. H. Teherani\, D. J. Rogers et al. Proc. SPIE 101 05 (2017) 10105 1 P-1\n[7] E. Chikoidze et al. Materials Today Physics 3 ( 2017) 118\n\nhttps://events.saip.org.za/event/100/contributions/111/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/111/ END:VEVENT BEGIN:VEVENT SUMMARY:Simulation and analysis of spectral domain optical coherence tomog raphy. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-112@events.saip.org.za DESCRIPTION:Speakers: Wendall Coenraad (Stellenbosch University)\nHigh-res olution 2D profiles or 3D reconstructions of cellular structures are routi nely generated using an interferometric technique\, Optical Coherence Tomo graphy (OCT . The main advantages associated with OCT are its high resolut ion and depth of penetration\, which are in the micron and millimeter rang es respectively. The main purpose of this research is to investigate the p hysical mechanisms associated with Spectral Domain OCT (SD-OCT) imaging in order to identify the key parameters affecting imaging performance. This was achieved through system characterization\, modeling and simulation of the SD-OCT system currently under development at Stellenbosch University. The mathematical model\, developed in Mathematica®\, and the simulation\, developed in Matlab®\, allow us to observe the effect the critical param eters will have on the detected signal\, which provides us with the means to quickly test the limits of the SD-OCT technique. Specific samples were simulated and verified experimentally using our SD-OCT system. We found th at the model allows us to simulate a more general case due to the inclusio n of the more complex interactions\, which will provide the user with more information to aide in experimental work. In the future\, the model limit ations can be addressed\, namely moving from a discretized sample to a con tinuous non-homogenous sample and the inclusion of the effects of system o ptics such as objective lenses.\n\nhttps://events.saip.org.za/event/100/co ntributions/112/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/112/ END:VEVENT BEGIN:VEVENT SUMMARY:Contrast enhancement in spectral domain optical coherence tomograp hy. DTSTART;VALUE=DATE-TIME:20180627T080000Z DTEND;VALUE=DATE-TIME:20180627T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-113@events.saip.org.za DESCRIPTION:Speakers: Wendall Coenraad (Stellenbosch University)\nOptical Coherance Tomography (OCT) is an interferometric technique\, which allows for non-invasive in vivo diagnostic medical imaging. It is a powerful tool in ophthalmology since it is able to produce high-resolution 2D profiles or 3D reconstructions of ocular structures to aide in the early diagnosis of ocular diseases. The main advantages associated with OCT are its high r esolution and depth of penetration\, which are in the micron and millimete r ranges respectively. OCT typically makes use of a low coherence light so urce\, in order to obtain high depth resolution. Typical light sources fou nd in commercial systems include super luminescent diodes and super contin uum pulsed sources based on anomalous dispersion photonic crystal fibers. The phase instabilities associated with these sources contribute to noise and diminish the signal to noise ratio. The University of Stellenbosch are currently developing a multimodal laser microscopy setup\, which will mak e use of an All Normal Dispersion Photonic Crystal Fibre (ANDi-PCF) develo ped at the Laser Research Institute (LRI). This source does not suffer fro m the inherent phase instabilities found in conventional OCT sources\, whi ch makes it the ideal source for OCT applications.\n\nThe main purpose of this research is to observe the effects of the critical parameters\, ident ified using our SD-OCT system simulation\, has on the system resolution an d signal to noise ratio. In this presentation\, results from the setup usi ng the ANDi-PCF will be compared to those from conventional LED sources\, thereby highlighting the expected improvement in signal to noise obtained from using the ANDi-PCF.\n\nhttps://events.saip.org.za/event/100/contribut ions/113/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/113/ END:VEVENT BEGIN:VEVENT SUMMARY:Bio-based and Bio-inspired [nano]Technologies: The laboratory\, an d the field DTSTART;VALUE=DATE-TIME:20180626T120000Z DTEND;VALUE=DATE-TIME:20180626T130000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-114@events.saip.org.za DESCRIPTION:Speakers: Mun'delanji C Vestergaard (Kagoshima University)\nDe velopment and application of bio-based and bio-inspired technologies to (i ) screen for\, identify and quantify molecules of interest\; (ii) profile and characterize molecular activities/events\; and (iii) help elucidate p athophysiological mechanisms is a major field with applications in various sectors including biomedical\, environmental\, energy\, food and agricult ure. With students and researchers of Applied Physics in mind\, we will hi ghlight the fundamental chemical principles intrinsic in biological and bi ophysical interactions and their exploitation in development of the techno logies. Concrete examples with be discussed\, and relations to applied phy sics drawn. We will focus on the development and application of Biosensors \, a bio-based technology\; and biomimicry membranes\, a bio-inspired tech nology. These interactions are largely driven by natural affinities betwee n biological molecules such as substrate-enzyme\, antibody-antigen\, recep tor-ligand\, and Watson-Crick base-pairing. Advances in science and techno logy have allowed the inclusion of artificially synthesised molecules tha t mimic biomolecules of interest\, such as peptide nucleic acid (PNA). Bio mimicry membranes are cell-sized\, lipid vesicles that mimic the biologica l cell. Since the relative compositions of lipid mixtures used influence m olecular self-organization and vesicle properties\, preparation for tailor ed application is possible. Thus\, biomimetic membranes enable a researche r to manipulate a 'biological' micro-vesicle under a controlled environmen t. We will conclude by discussing the challenges in design\, development a nd application at point of use. The latter remains one of the biggest chal lenges in realizing the potential of bio-based and bio-inspired [nano]tech nologies.\n\nhttps://events.saip.org.za/event/100/contributions/114/ LOCATION: Auditorium URL:https://events.saip.org.za/event/100/contributions/114/ END:VEVENT BEGIN:VEVENT SUMMARY:The Search for High Efficiency Energy Conversion Nanocrystals: A P ersonal Account DTSTART;VALUE=DATE-TIME:20180626T070000Z DTEND;VALUE=DATE-TIME:20180626T080000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-115@events.saip.org.za DESCRIPTION:Speakers: Xiaogang Liu (Department of Chemistry\, National Uni versity of Singapore\, Singapore 117543 and Institute of Materials Resear ch and Engineering\, A*STAR\, Singapore 117602)\nLanthanide-doped nanopart icles exhibit unique luminescent properties\, including a\nlarge Stokes sh ift\, a sharp bandwidth of emission\, high resistance to optical blinking\ , and\nphotobleaching. Uniquely\, they can also convert long-wavelength st imulation into short-\nwavelength emission. These attributes offer the opp ortunity to develop alternative\nluminescent labels to organic fluorophore s and quantum dots. In recent years\, researchers\nhave taken advantage of spectral-conversion nanocrystals in many important biological\napplicatio ns\, such as highly sensitive molecular detection and autofluorescence-fre e cell\nimaging. With significant progress made over the past several year s\, we can now design and\nfabricate nanoparticles that display tailorable optical properties. In particular\, we can generate\na wealth of color ou tput under single-wavelength excitation by rational control of different\n combinations of dopants and dopant concentration. By incorporating a set o f lanthanide ions\nat defined concentrations into different layers of a co re-shell structure\, we have expanded the\nemission spectra of the particl es to cover almost the entire visible region\, a feat barely\naccessible b y conventional bulk phosphors. In this talk\, I will highlight recent adva nces in the\nbroad utility of upconversion nanocrystals for multimodal ima ging\, bio-detection\, display and\nphotonics.\n\nhttps://events.saip.org. za/event/100/contributions/115/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/115/ END:VEVENT BEGIN:VEVENT SUMMARY:Welcome to the Dome - Three surprising things a Robot Telescope ca n do DTSTART;VALUE=DATE-TIME:20180627T070000Z DTEND;VALUE=DATE-TIME:20180627T080000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-116@events.saip.org.za DESCRIPTION:Speakers: Lorraine Hanlon (University College Dublin)\nSmall r obot telescopes occupy a particular niche in the astronomy ecosystem by vi rtue of their autonomous scheduling capabilities\, rapid response times an d flexible operations. These characteristics offer a wealth of use cases\, three examples of which are explored in this talk.\n\nLocated at Boyden O bservatory\, Watcher is a robotic telescope owned by University College Du blin\, developed and operated in collaboration with University of the Free State. \n\nGamma-ray bursts are the most luminous electromagnetic events in the universe\, the signal of the collapse of distant massive stars\, or the mergers of two neutron stars. Gamma-ray bursts only last seconds to minutes\, producing rapidly fading visible light in some cases. The discov ery of a gamma-ray transient by the Fermi and INTEGRAL satellites\, coinci dent with the LIGO/VIRGO binary neutron star merger event of August 17th 2 017\, has revealed the connection between short gamma-ray bursts and the g ravitational wave universe in spectacular fashion. \n\nWatcher's main scie ntific goal is the rapid follow-up of newly discovered transient astrophys ical sources such as gamma-ray bursts. Upon receipt of a new trigger\, Wat cher can be on target within 30 seconds. Despite their vast distances\, th e incredible luminosities of gamma-ray bursts render them detectable even by a small telescope\, once it is fast enough.\n\nThe crude localisations of gravitational wave events provided by LIGO/VIRGO pose challenges to nar row field telescopes such as Watcher that must be addressed to ensure the continued relevance of such systems in this exciting new era of multi-mess enger astrophysics. \n\nWhen it is not chasing gamma-ray bursts\, Watcher conducts a diverse and rich observing programme that has impact beyond re search\, supporting learning in astronomy and astrophysics by providing be spoke data to students without requiring them to travel to the telescope. Beyond the traditional academic boundaries\, collaboration with an artist has led to Watcher data being used in work exploring the role of women in astronomy.\n\nhttps://events.saip.org.za/event/100/contributions/116/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/116/ END:VEVENT BEGIN:VEVENT SUMMARY:Decade of High Performance Computing in South Africa: Opportunitie s for Physics Community DTSTART;VALUE=DATE-TIME:20180626T084000Z DTEND;VALUE=DATE-TIME:20180626T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-117@events.saip.org.za DESCRIPTION:Speakers: Daniel Mojalefa Moeketsi (CSIR Meraka Institute (CHP C))\nThe Centre for High Performance Computing (CHPC) is part of the Natio nal Integrated Cyber-Infrastructure System of the government of South Afri ca. It was established in 2007 by Department of Science and Technology and is managed by the Council for Scientific and Industrial Research (CSIR). Its mandate is to provide world class computational resources to research community across different fields of Science and Engineering in the countr y\; and also to drive human capital development in field of high performan ce computing. Over the past 10 years\, the centre managed to significantly grow itself from a flagship project to a more sustainable institution. In this presentation\, I will share with you temporal evolution of the CHPC since it was established to date and how it can further benefit the Physic s community.\n\nhttps://events.saip.org.za/event/100/contributions/117/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/117/ END:VEVENT BEGIN:VEVENT SUMMARY:Experimental design and characterization of nano-photonic material s through classical and quantum calculations DTSTART;VALUE=DATE-TIME:20180625T131500Z DTEND;VALUE=DATE-TIME:20180625T140000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-118@events.saip.org.za DESCRIPTION:Speakers: Richard Harris (University of the Free State)\nhttps ://events.saip.org.za/event/100/contributions/118/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/118/ END:VEVENT BEGIN:VEVENT SUMMARY:Quantum Imaging Technologies Using Single Photon Detectors DTSTART;VALUE=DATE-TIME:20180628T070000Z DTEND;VALUE=DATE-TIME:20180628T080000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-119@events.saip.org.za DESCRIPTION:Speakers: Jonathan Leach (Heriot-Watt University)\nTechnology at the quantum limit promises significant advances in computing\, communic ation\, sensing and metrology\, and imaging. The UK and many other coun tries around the world have recently provided significant investment in th e development and realisation of such technologies. In this talk\, I will discuss the UK’s quantum technology landscape and highlight my group's activities in applied and fundamental quantum science\, specifically focus sing on advances in communication\, imaging\, and metrology. Much of our work relies on the detection of single photons via single-photon detector s\, either in single-point or array formats. Such detectors enable unprec edented sensitivity to light and allow precise detection of arrival times\ , down to picosecond timescales. This is the key enabling feature that al lows us to see around corners\, detect objects through scattering media\, and generate entanglement between photons that have never interacted. Our work highlights the progress in single-photon detection technologies and showcases a range of applied and fundamental applications of the science.\ n\nhttps://events.saip.org.za/event/100/contributions/119/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/119/ END:VEVENT BEGIN:VEVENT SUMMARY:NPRP Division Meeting DTSTART;VALUE=DATE-TIME:20180627T134000Z DTEND;VALUE=DATE-TIME:20180627T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-120@events.saip.org.za DESCRIPTION:Speakers: Simon Mullins (iThemba LABS (Gauteng))\nhttps://even ts.saip.org.za/event/100/contributions/120/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/120/ END:VEVENT BEGIN:VEVENT SUMMARY:Quantum Control by Self-fullfilling prophecy DTSTART;VALUE=DATE-TIME:20180626T100000Z DTEND;VALUE=DATE-TIME:20180626T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-121@events.saip.org.za DESCRIPTION:Speakers: Thomas Konrad (UKZN)\nWe describe a method based on a sequence of measurements combined with feedback that allows us to prepar e a quantum system in a target state or smooth target dynamics and protect it against noise. The convergence for arbitrary initial states is based o n the gradual increase of information about the post-measurement state in the course of the measurements\, which have to be weak in order to yield s mooth state trajectories. The mechanism is the same that enables the conti nuous monitoring of quantum states and is related to the monotonicity of f idelity between any two quantum states under selective (non-trace-preservi ng) operations\, as we will demonstrate.\n\nhttps://events.saip.org.za/eve nt/100/contributions/121/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/121/ END:VEVENT BEGIN:VEVENT SUMMARY:Spectroscopic follow up of TESS observations to study new Pulsatin g Pre-Main Sequence stars DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-122@events.saip.org.za DESCRIPTION:Speakers: Papi Lekwene (North West University)\nScientific rat ionale\n\nThe NASA KEPLER Mission sent a 1.0 m telescope into space to sea rch for planets around other stars. Tremendous amount of photometric data was produced and was used to study pulsating stars of the different types. Many of the observed pulsators had multiple frequencies which were used t o determined detailed physics of these stars. For example\, solar like osc illations were detected in highly evolved stars and used to determine thei r masses\, radii and even mass loss rates. Follow-up spectroscopic observa tions were used to provide further constraints in the properties of these Kepler stars. The only stars that were not found in the KEPLER data were t he pulsating Pre-main sequence stars (also called pulsating Herbig AeBe st ars). This is largely because the region of the sky that KEPLER telescope was pointing at is away from star forming regions where Herbig stars are u sually found. Herbig AeBe are very young stars (several million years old\ , compared to our Sun which is 5 billion years old for example). These sta rs derive most of their energy from gravitational contraction.\n\nFurtherm ore\, the region of interest for the KEPLER mission was in the northern sk y\, and thus was not suitable for follow-up observations with telescopes i n the Southern Hemisphere. In April 2018\, NASA is launching a new mission called TESS to search for earth-like planets around other stars. TESS wil l take photometric observations of stars and their exo-planets. It will si milarly produce tremendous amount of data of high precision. The main adva ntage of TESS is that it observe stars in both the Northern and Southern H emisphere\, and will thus be within reach of our telescopes in Sutherland. We will thus be able to perform follow-up spectroscopic observations of t he TESS targets. \n\nOur Phd proposal aims to observe Herbig pulsating Ae stars that have been observed by TESS with spectrograph attached to the 1. 9 metre telescope at Sutherland. The aim being to make detailed studies of the Herbig Ae stars in order to learn more about their internal physics f rom their pulsations and spectroscopy.\n\nThe light curves extracted from the TESS simulated data allows us to search and study to detail for Young Pre-main sequence stars.\n\nhttps://events.saip.org.za/event/100/contribut ions/122/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/122/ END:VEVENT BEGIN:VEVENT SUMMARY:Status of the ECR ionizer for polarized ion source at iThemba LABS DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-123@events.saip.org.za DESCRIPTION:Speakers: Ndumiso Mnikathi (student)\nThe polarized ion source at iThemba LABS has been in operation for over two decades using Electron Beam (EB) ionizer. The source has been used to deliver beam for nuclear p hysics research. Due to its disadvantages which are producing beam with la rge energy spread and having complicated extraction system\,the EB ionizer was replaced by Electron Cylotron Resonance (ECR) ionizer. The ECR ionize r has better plasma confinement due to its higher magnetic mirror fields a s well as low energy spread of which nuclear physics require. The use of E CR ionizer recently installed at iThemba LABS is under investigation.\n\nh ttps://events.saip.org.za/event/100/contributions/123/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/123/ END:VEVENT BEGIN:VEVENT SUMMARY:Hyperon-nucleon and hyperon-hyperon interactions constructed via M archenko inversion approach: Application to hypernuclear spectroscopy DTSTART;VALUE=DATE-TIME:20180627T124000Z DTEND;VALUE=DATE-TIME:20180627T130000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-125@events.saip.org.za DESCRIPTION:Speakers: Emile Meoto (Department of Physics\, University of S outh Africa)\nThe knowledge of the hyperon-nucleon (YN) and hyperon-hypero n (YY) interactions is vital toward our deeper understanding of the nature of the nucleon-nucleon interaction. However\, the direct study of the YN and YY interactions is practically impossible due to the limited or no dat a available. This is because the hyperon has a very short lifetime\, makin g experiments with hyperon beams extremely difficult. Currently the study of the nonzero strangeness hypernuclear spectroscopy proceeds via theoreti cally constructed models. For example\, the YN and YY interactions can be constructed ab initio via the Chiral Effective Field Theory (χEFT). This method has been extensively studied and is based on the chiral power count ing of Weinberg. That is\, starting with the field theoretical Lagrangian for the interacting particles\, one reduce the infinite dimensional equati on of motion to a finite and solvable one in the particles’ degrees of f reedom. That is the reduced or effective Schrodinger equation is the one t o solve. The process of power counting can be laborious and in general req uires large computer power. On the other hand\, one may employ the Marchen ko Inversion method to construct the interactions. In this work\, we const ructed the YN and YY potentials from the limited available YN experimental data and simulated YY data to study the structure and dynamics of selecte d hypernuclear systems within the three-particle model. We employ the diff erential Faddeev equations to construct the wave functions with the constr ucted YN and YY potentials as input and study the dynamics of the systems. \n\nhttps://events.saip.org.za/event/100/contributions/125/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/125/ END:VEVENT BEGIN:VEVENT SUMMARY:Search for W'->tb using the 2017 and 2018 in the hadronic final st ates with ATLAS DTSTART;VALUE=DATE-TIME:20180627T130000Z DTEND;VALUE=DATE-TIME:20180627T132000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-126@events.saip.org.za DESCRIPTION:Speakers: Fortune Mhlanga (Wits student)\nA previous search fo r W'->tb decays in the hadronic final state using collisions at sqrt(s) = 13 TeV with luminosity of 36.1 fb^-1 of the data collected by the ATLAS de tector in 2015 and 2016 at the Large Hadron Collider was conducted. At 1-5 TeV mass range the search was interpreted for both left-handed and right- handed chiral W' boson. It was observed that the top and bottom quark mass es were consistent with background prediction. The limits on the cross-sec tion were set at high $W'$-boson masses\, the W' boson with right left-han ded couplings of masses below 3 TeV\, 2 TeV are excluded respectively at 9 5% confidence level. \nSince this relies on identifying a large-radius jet from boosted top quarks\, jet substructure techniques are employed. The c urrent signal samples are generated using a Geant4 based full simulation\, which needs a significant amount of resources to produce. So in order to increase number of signal points probed\, a simpler fast simulation is bei ng investigated. The first step is to check the modelling of jet substruct ure observables relevant for this search between full simulation and fast simulation\, and derive appropriate correction factors if necessary.\n\nht tps://events.saip.org.za/event/100/contributions/126/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/126/ END:VEVENT BEGIN:VEVENT SUMMARY:The effect of different annealing period intervals on BaAl2O4:0.2% Ce3+ nano-phosphor’ structure\, morphology and luminescent properties s ynthesized by citrate sol-gel method. DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-127@events.saip.org.za DESCRIPTION:Speakers: Kgomotso Modisakeng (Sefako Makgatho Health Science University)\nCerium-doped Barium Aluminate (BaAl2O4:0.2%Ce3+) nano-powders were prepared by citrate sol-gel method to overcome the flickering lumine scence in signage and displays by offsetting dark duration with persistent luminescence. The effects of annealing period (AP) at a constant temperat ure of 900 ⁰C and dopant concentration of 0.2% Ce3+ on the structure\, p article morphology and photoluminescent properties of nano-powders were in vestigated. The X-ray powder diffraction (XRD) patterns showed that the 0. 2% Ce3+ dopant did not have a major influence on the crystalline structure of the host BaAl2O4. The crystalline quality and size of the nano-powders ware influenced by varying the AP. The scanning electron microscope (SEM) together with the energy dispersive spectra (EDS) images revealed the inc rease in AP affects the morphology of the prepared phosphor. There is a pr esence of hexagonal platelets with well-developed faces that dominate the morphology of the doped samples. The emission peaks at 427 nm\, 538 nm and 727 nm are attributed to band-gap defects in the host material at λex = 299 nm. The emission peaks at 481 nm\, 549 nm and 612 nm are attributed to the 5d⟶4f emission of Ce3+. The commision internationale de l’eclaira ge (CIE) results showed the there is a slight change in the emission color of 0.2% Ce3+ doped BaAl2O4 when varying the AP.\n\nhttps://events.saip.or g.za/event/100/contributions/127/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/127/ END:VEVENT BEGIN:VEVENT SUMMARY:Sampling of P91 base metal for in-situ neutron powder diffraction and dilatometer evaluation / characterisation DTSTART;VALUE=DATE-TIME:20180628T084000Z DTEND;VALUE=DATE-TIME:20180628T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-128@events.saip.org.za DESCRIPTION:Speakers: zeldah sentsho (necsa)\nASTM SA-335 Grade P91 / T91\ , a 9%Cr creep strength enhanced ferritic (CSEF) steel\, is commonly used in modern power industry for manufacturing critical pressure components an d vessels\, tubing\, piping and headers. The objective of the current stud y is to determine the temperatures at which transformation of BCC ferrite to FCC austenite starts and finishes on heating (the so-called Ac1 and Ac3 temperatures). In addition\, the transformation of austenite to delta fer rite (a BCC structure) at higher temperatures must be characterized. As re ported previously\, neutron powder diffraction and dilatometry were select ed to characterize these phase transformations. A small number of isotherm al heat treatments\, followed by water quenching was also done\, to verify neutron diffraction results at temperatures that could not be achieved us ing the dilatometer. The objective of the current paper is to describe cal ibration and sampling methods in P91 base metal for such phase transformat ion.Temperatures in the dilatometer and neutron furnace were verified by c omparing the experimentally measured phase transformation temperatures of pure iron rod with the theoretical temperatures.By using room temperature neutron powder diffraction\, the crystallographic preferred orientation in a tubular sample of P91 base metal was established along the longitudinal \, through-thickness and tangential direction by comparison of intensity r atios of the diffraction peaks with those of Fe powder. It was found that the tangential sample machined exhibited intensity ratios closer to those of Fe powder. The longitudinal sample presented severe preferred orientati on. Dilatometer results were insensitive to the orientation of the sample. The Ac1 and Ac3 temperatures in the different oriented samples were deter mined in the range 809-811°C and 875-811°C respectively in the dilatomet er. The quenching methods revealed that at 1150°C\, the onset of delta fe rrite in P91 base metal has already commenced\, which agrees with previous temperature range obtained by in-situ neutron diffraction (between 1140 a nd 1160°C). The calibration results indicate that the error in temperatur e (between published and experimentally determined temperatures\, and betw een neutron diffraction and dilatometry results) was less than 5°C\, and that the combination of neutron diffraction\, dilatometry and isothermal h eat treatments resulted in an assessment of the phase transformation behav ior over a wide range of temperatures\, not achievable using only one char acterization technique.\n\nhttps://events.saip.org.za/event/100/contributi ons/128/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/128/ END:VEVENT BEGIN:VEVENT SUMMARY:Constraining star formation history with Fermi-LAT observations of the gamma-ray opacity of the Universe DTSTART;VALUE=DATE-TIME:20180627T080000Z DTEND;VALUE=DATE-TIME:20180627T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-129@events.saip.org.za DESCRIPTION:Speakers: Ashlynn Le Ray (University of the Witwaterstrand)\nT he star formation history (SFH) of the Universe is of fundamental importan ce to cosmology\, not only to galaxy formation itself\, but also for ongoi ng efforts to determine cosmological parameters and matter content of the universe. Measurement of the extragalactic background light (EBL) as a fun ction of redshift can constrain models of the SFH\, including the initial mass function(IMF) and dust extinction. The gamma-ray spectra of AGN allo w us to study the extragalactic background light (EBL) through absorption of high-energy photons. In this work\, we present constraints on models of SFH using a sample of AGN observed by the Fermi-LAT instrument by investi gating the imprint of the EBL on the observed spectra of high-redshift Fer mi-LAT AGN above ~ 10 GeV.\n\nhttps://events.saip.org.za/event/100/contrib utions/129/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/129/ END:VEVENT BEGIN:VEVENT SUMMARY:Introduction to Luminescence DTSTART;VALUE=DATE-TIME:20180625T071000Z DTEND;VALUE=DATE-TIME:20180625T075500Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-130@events.saip.org.za DESCRIPTION:Speakers: Hendrik Swart (University of the Free State)\nhttps: //events.saip.org.za/event/100/contributions/130/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/130/ END:VEVENT BEGIN:VEVENT SUMMARY:Opening DTSTART;VALUE=DATE-TIME:20180625T070000Z DTEND;VALUE=DATE-TIME:20180625T071000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-131@events.saip.org.za DESCRIPTION:Speakers: Elizabeth Coetsee (University of the Free State)\nht tps://events.saip.org.za/event/100/contributions/131/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/131/ END:VEVENT BEGIN:VEVENT SUMMARY:Spectral and Morphological Fitting of Young Pulsar Wind Nebulae us ing a Markov-Chain-Monte-Carlo Procedure DTSTART;VALUE=DATE-TIME:20180627T120000Z DTEND;VALUE=DATE-TIME:20180627T122000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-133@events.saip.org.za DESCRIPTION:Speakers: Carlo van Rensburg (North West University Potchefstr oom)\nWe present results from a spatio-temporal leptonic emission code tha t models the spectral energy distribution (SED) from and the radiation spe ctrum at different positions in a pulsar wind nebula (PWN). The model incl udes a time- and spatially-dependent magnetic field\, spatially-dependent bulk particle speed implying convection and adiabatic losses\, diffusion\, as well as radiative losses and can predict the SED\, surface brightness vs. radius and thus the nebular size as function of energy. We apply the c ode to PWN G0.9+0.1 and a fit for both the SED and PWN size as a function of energy. We use a Markov-chain-Monte-Carlo (MCMC) method to find not onl y the best fit but also errors on these best-fit model parameters. We will investigate the error behaviour when only fitting the SED vs. concurrentl y fitting both the SED and energy-dependent size. Our model will contribut e to interpreting results by the future Cherenkov Telescope Array (CTA) th at will yield many more morphological details.\n\nhttps://events.saip.org. za/event/100/contributions/133/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/133/ END:VEVENT BEGIN:VEVENT SUMMARY:Thermoluminescence: Standards and contemporary developments DTSTART;VALUE=DATE-TIME:20180625T094500Z DTEND;VALUE=DATE-TIME:20180625T103000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-134@events.saip.org.za DESCRIPTION:Speakers: Makaiko Chithambo (Rhodes University)\nhttps://event s.saip.org.za/event/100/contributions/134/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/134/ END:VEVENT BEGIN:VEVENT SUMMARY:ZnO-based Photonics DTSTART;VALUE=DATE-TIME:20180625T090000Z DTEND;VALUE=DATE-TIME:20180625T094500Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-135@events.saip.org.za DESCRIPTION:Speakers: David Rogers (Nanovation)\nhttps://events.saip.org.z a/event/100/contributions/135/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/135/ END:VEVENT BEGIN:VEVENT SUMMARY:Closing and Thanks DTSTART;VALUE=DATE-TIME:20180625T140000Z DTEND;VALUE=DATE-TIME:20180625T140500Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-136@events.saip.org.za DESCRIPTION:Speakers: Elizabeth Coetsee (University of the Free State)\nht tps://events.saip.org.za/event/100/contributions/136/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/136/ END:VEVENT BEGIN:VEVENT SUMMARY:Light harvesting DTSTART;VALUE=DATE-TIME:20180625T075500Z DTEND;VALUE=DATE-TIME:20180625T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-137@events.saip.org.za DESCRIPTION:Speakers: Tjaart Krüger (University of Pretoria)\nhttps://eve nts.saip.org.za/event/100/contributions/137/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/137/ END:VEVENT BEGIN:VEVENT SUMMARY:Laser-induced differentiation of Adipose Stem Cells to neuron-like cells DTSTART;VALUE=DATE-TIME:20180629T104000Z DTEND;VALUE=DATE-TIME:20180629T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-138@events.saip.org.za DESCRIPTION:Speakers: Sajan George (University of Johannesburg)\nLaser-ind uced differentiation of Adipose Stem Cells to neuron-like cells\n\nSajan G eorge and Heidi Abrahamse*\nLaser Research Centre\, Faculty of Health Scie nces\, University of Johannesburg\, Doornfontein\, South Africa\n\nThe eff ect of lasers (light) on living cells and organs\, referred as photobiomod ulation (PBM) is capable of bringing morphological and functional changes to stem cells. However\, our understanding of transforming stem cells to a ny specific-lineages under the influence of photons (light) is very limite d. In many occasions light along with biological and chemical agents can i nduce\, lineage-specific differentiation of Adipose Stem Cells (ASCs) ofte n harvested from the body fats of adult humans. These stem cells possess b etter survivability and are capable of differentiation\, which makes them an ideal choice for replacement therapies in clinics. Particularly\, trans forming ASCs into neuron-like cells allow us finding solutions to maladies of Central Nervous System (CNS) for cell therapies based on patient’s o wn genetic background. This study was performed using ASCs isolated from h ealthy human subjects undertaking abdominoplasty in clinics. Harvested cel ls were maintained in culture medium supplemented with 10% fetal calf seru m and passaged repeatedly\, while been characterized based on their surfac e protein markers CD44/90/133/166. Cultured ASCs were proliferated and ind uced to differentiate into neuron-like cells using Fibroblast Growth Facto r\, basic (bFGF) and Forskolin in the presence of Near Infra-Red (NIR) las ers. Proportion of ASCs growing in the culture and capable of differentiat ion by induction was estimated as 6.3% based on the expression of CD90\, a key stem cell marker. Exposure to 15 J/cm2 of NIR and growth factors for 14 days resulted in the initiation of differentiation of 7.8% these ASCs e xpressing CD90 into neuron-like cells (as revealed by the expression of Ne stin\, an early neuronal marker). Subsequent analysis identified the prese nce of 6.25% of β-tubulin\, a late neuronal marker on the 21st day of ind uction. Current analysis identifies that Forskolin retained pluripotency o f ASCs for up to 10 J/cm2 of NIR. This study gives us an indication that l ight energy can alter the fate of stem cells in favour of differentiation. More such initiatives are essential for our understanding and standardiza tion of light in altering cellular phenotype and functionalities.\n\nhttps ://events.saip.org.za/event/100/contributions/138/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/138/ END:VEVENT BEGIN:VEVENT SUMMARY:Resonant Ionization Spectroscopy for laser isotope separation of z inc isotopes DTSTART;VALUE=DATE-TIME:20180629T084000Z DTEND;VALUE=DATE-TIME:20180629T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-139@events.saip.org.za DESCRIPTION:Speakers: Andre de Bruyn (Laser Research Institute\, Stellenbo sch University)\nResonant Ionisation Spectroscopy (RIS) refers to the sele ctive excitation of a particular atomic isotope to an excited state by mea ns of resonant light\, followed by photo-ionisation and ion detection. 68Z n and 67Zn are important stable nuclides in medicine and industry as used to produce Gallium isotopes (68Ga and 67Ga) that are used in medical imagi ng such as Positron Emission Tomography (PET) and SPECT (single-photon emi ssion computerised tomography) to detect inflammation\, infection or cance r. The main aim of this project is to investigate\, model and optimise RIS schemes for zinc (Zn) isotopes 68Zn and 67Zn that are suitable for laser- based separation of these isotopes from natural Zn. RIS will be used to ob tain spectroscopic data on the transition wavelengths\, hyperfine structur e\, and transition strengths of relevant energy levels. In this presentati on an overview is given of the progress towards a RIS system for Zn. Poten tial excitation schemes and ion collection techniques\, the sample tempera ture and laser bandwidth limitations have been identified by simulations. Experimental results from absorption\, fluorescence and optogalvanic spect roscopy will be discussed. The choice between the 3d¹⁰4s² ¹Sₒ - 3d ¹⁰4s4p ¹P₁ and the 3d¹⁰4s² ¹Sₒ - 3d¹⁰4s4p ¹P₃ transitio ns as first excitation step will be explained. The results generated thus far in this study will aid in the development of an optimised RIS system t hat may be applied in the commercial production of medical isotopes.\n\nht tps://events.saip.org.za/event/100/contributions/139/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/139/ END:VEVENT BEGIN:VEVENT SUMMARY:Luminescent gas sensors DTSTART;VALUE=DATE-TIME:20180625T121500Z DTEND;VALUE=DATE-TIME:20180625T130000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-140@events.saip.org.za DESCRIPTION:Speakers: Gugu Mhlongo (CSIR\, MSM\, Nano Centre)\nhttps://eve nts.saip.org.za/event/100/contributions/140/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/140/ END:VEVENT BEGIN:VEVENT SUMMARY:High Altitude Radiation Monitor (HARM) DTSTART;VALUE=DATE-TIME:20180627T102000Z DTEND;VALUE=DATE-TIME:20180627T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-141@events.saip.org.za DESCRIPTION:Speakers: Godfrey Moshe Mosotho (.)\nThe measurement of energy deposition in matter and tissue resulting from the exposure to ionizing r adiation can be classified as radiation dosimetry. Since our bodies are in capable of detecting ionizing radiation\, the energy deposited by radiatio n in our bodies could be harmful. Therefore\, it is important to measure a nd monitor the radiation exposure. Since radiation was classified as a hea lth hazard in the early 1960s\, one of the outstanding challenges for comm ercial airlines is to assess the radiation risks of passengers due to the complex radiation field at these flight altitudes. To improve our understa nding of this radiation field\, different factors have to be outlined and investigated.\n\nTo investigate the effects of radiation at flight altitud es\, a very small and lightweight active dosimeter known as HARM was built as a prototype for this project. This instrument use a silicon semiconduc tor sensor capable of measuring neutral and charged particles. The instrum ent is designed to measure the absorbed dose rate in silicon\, which is us ed to estimate how much energy have been directly deposited in tissue. Its measurements will address the biological effects when the ionizing radiat ion interacts with our bodies during a flight.\n\nIn this presentation\, I will talk about the current approaches to radiation risk estimation recom mended by the International Commission on Radiological Protection (ICRP). Then\, I will discuss HARM's prototype development and its working princip le\, as well as its performance and calibration tests.\n\nhttps://events.s aip.org.za/event/100/contributions/141/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/141/ END:VEVENT BEGIN:VEVENT SUMMARY:Fluence enhanced optical response of ion implanted stripper foil c arbon thin films DTSTART;VALUE=DATE-TIME:20180627T094000Z DTEND;VALUE=DATE-TIME:20180627T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-142@events.saip.org.za DESCRIPTION:Speakers: Abdulsalam Ismaila (WITS)\nSilver nanoparticles (NPs ) are known to exhibit a strong interaction with light because the conduct ion electrons on the metal surface undergo a collective oscillation once e xcited by light at specific wavelengths\; the so-called surface plasmon re sonance (SPR). However\, their incorporation into amorphous carbon is show n to greatly influence the overall optical response of the nanomaterial du e to aggregation of the NPs in the host amorphous carbon. In this paper\, we studied the optical response of silver irradiated amorphous carbon film s due to varying fluence of the NPs. Stripper foil amorphous carbon films were irradiated by 25kV Ag ions at different fluences ranging from 2.5 to 3.4 x 1016 ions/cm2. Optical absorption studies revealed that the SPR of A g NPs on quartz substrate occurs at wavelength ⁓410 nm but shows a blue shift (⁓60 nm) in the irradiated film with increasing ion fluence up to 3.4 x 1016 ions/cm2. Transmission electron microscopy (TEM) was used to in vestigate the particle size and aggregation. The blue shift response in pl asmonic wavelength is explained with respect to the increase in particulat e density due to increasing fluence of irradiation as confirmed by TEM.\n\ nhttps://events.saip.org.za/event/100/contributions/142/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/142/ END:VEVENT BEGIN:VEVENT SUMMARY:Electronic and Optical Properties of Lead-free Hybrid Perovskite C H3NH3SnI3 from first principles calculati ons DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-143@events.saip.org.za DESCRIPTION:Speakers: Ibrahim Omer Abdallah Ali (The National Institute fo r Theoretical Physics\, School of Physics and Mandelstam Institute for The oretical Physics\, University of the Witwatersrand\, Johannesburg\, Wits 2 050\, South Africa.)\nOrganic-inorganic halide perovskites have recently e merged as promising candidates for low cost\, high-efficiency solar cells. In this work\, the electronic and optical properties of the lead-free hyb rid halide perovskite CH3NH3SnI3 as a solar cell absorber has been investi gated using first-principles density functional theory calculations and ma ny body perturbation theory. Our calculated electronic band gaps are 0.77\ , 1.23 and 1.40 eV using the Perdew\, Burke and Ernzerhof\, the modified B ecke-Johnson and the hybrid functional HSE06\, respectively. CH3NH3SnI3 ha s been reported to have a band gap of 1.21 and 1.35 eV depending on the pr eparation method. Our calculated band gap using the modified Becke-Johnson and hybrid functional HSE06 agree well with experimental results. The inv estigated compound\n(CH3NH3SnI3) is found to be a direct band gap semicond uctor with fundamental band gap (1.44 eV). In order to obtain optical spec tra\, we carried out Bethe-Salpeter equation calculations on top of non-se lf-consistent G0W0 calculations. Our calculated band gap using Bethe-Salpe ter equation calculations is 1.22 eV\, within the experimentally reported range\, confirming that CH3NH3SnI3 has potential as a solar cell absorber. \n\nhttps://events.saip.org.za/event/100/contributions/143/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/143/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigation of traveling ionospheric disturbances (TIDs) using S ANAE SuperDARN radar DTSTART;VALUE=DATE-TIME:20180626T104000Z DTEND;VALUE=DATE-TIME:20180626T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-145@events.saip.org.za DESCRIPTION:Speakers: Tsige Atilaw (Rhodes University)\nTravelling Ionosph eric Disturbances (TIDs) are an ionospheric manifestation of Atmospheric G ravity Waves (AGWs) that occurs in the neutral atmosphere. They are genera ted by different sources\, such as solar terminators (sunrise and sunset)\ , magnetic storms and substorms\, tropospheric weather and mountain turbul ence. TIDs appear in power spectra of SuperDARN radars as spatially locali zed enhancements and as quasi-periodic fluctuations in Doppler velocities and reflection heights. SuperDARN is a network of HF radars designed to st udy plasma convection and plasma density irregularities in the E and F-reg ions of the ionosphere at high and mid-latitudes. The continues\, large sc ale nature of SuperDARN observations make them an ideal tool for TID study . Understanding the characteristics and source of mechanisms of TIDs has b een of interest since 1960’s. AGWs significantly affect global circulati on through their ability to transport energy and momentum vertically throu gh different layers of the atmosphere and horizontally across the globe. A lthough they have been different studies done on TIDs using ground and spa ce based instruments\, very few have used observations in the southern pol ar hemisphere\, in particular\, SANAE HF radar. This project aims to inves tigate TIDs events observed by SANAE SuperDARN radar in more details. This preliminary investigation includes determining possible source of mechani sms of the events. We have performed a survey of TIDs in the SANAE HF rada r data. When many events are identified\, we also survey other radar data which have common or conjugate field of view.\n\nhttps://events.saip.org.z a/event/100/contributions/145/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/145/ END:VEVENT BEGIN:VEVENT SUMMARY:OPTIMIZATION OF ELECTRON SPECTROMETER IN LENS-MODE OPERATION DTSTART;VALUE=DATE-TIME:20180626T104000Z DTEND;VALUE=DATE-TIME:20180626T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-156@events.saip.org.za DESCRIPTION:Speakers: Abraham Avaa (Wits\\iThemba)\nThe study of monopole transitions via excited 0+ states requires the measurement of internal con version electrons and internal pair formation using an electron spectromet er. Such a spectrometer\, consisting of a solenoid magnet transporter and a Si(Li) detector with an array of LaBr3\, is undergoing development at iT hemba LABS. Performance of the electron spectrometer has been investigated using radioactive sources produced at iThemba LABS. The spectrometer has been used in lens mode with the field swept under computer control. Transm ission and efficiency\, as well as the momentum resolution of the swept le ns\, are presented. Commissioning experiments are due to take place in Ju ly 2018 using an alpha beam at a maximum of Eα = 30 MeV with a beam curre nt of 10enA on isotopically enriched 70Ge which will provide an opportunit y to investigate E0 transitions in the target nucleus. This serves as a se nsitive probe for the study of shape coexistence in nuclei since the monop ole strength parameter is related to the change in mean square radius betw een the initial and final 0+ states.\n\nhttps://events.saip.org.za/event/1 00/contributions/156/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/156/ END:VEVENT BEGIN:VEVENT SUMMARY:Size and shape impact on thermal expansion coefficient of nanowire s DTSTART;VALUE=DATE-TIME:20180626T084000Z DTEND;VALUE=DATE-TIME:20180626T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-146@events.saip.org.za DESCRIPTION:Speakers: Madan Singh (National University of Lesotho)\nThe pr operties of bulk crystals depend upon their structure but in case of nanoc rysatal\, in addition to the structure\, size and shape are the significan t factor\, which affect their properties. The shape factor has been introd uced in the bond energy model. The basic idea is that the atomic cohesive energy decides the thermodynamical properties of the crystals. Also\, cohe sive energy changes with the atomic coordination background. The bond ener gy model justifies that how the surface dangling bonds depress the melting temperature of the nanomaterials and how the order disorder transition of the nanoparticles varies upon the particle size. The cohesive energy ass ociated with these surface atoms will be unlike from their bulk materials. The excess energy associated with these surface atoms is defined as the s urface free energy. On examining the surface effect\, a simple model is de bated to study the size and shape dependence of thermal expansion coeffici ent of Se and Si nanowires with different cross sectional shapes. It is pr ojected that the thermal expansion increases with decrease in particle siz e. Also\, it is recognized that the particle shape can impact the thermal expansion of nanoparticles and this effect on the thermal expansion become s more with decreasing of particle size. Our theoretical predictions appro ve fairly well with the existing experimental and simulation results for n anowires in different shapes. Due to the modesty and applicability\, this model can be stretched to the other nanomayterials and may be the recent a ttention of the researches engaged in the study of physical properties of nannomaterials.\n\nhttps://events.saip.org.za/event/100/contributions/146/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/146/ END:VEVENT BEGIN:VEVENT SUMMARY:The MinPET diamond discovery technique – an update DTSTART;VALUE=DATE-TIME:20180627T142000Z DTEND;VALUE=DATE-TIME:20180627T144000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-147@events.saip.org.za DESCRIPTION:Speakers: Thendo Emmanuel Nemakhavhani (University of Johannes burg)\nMinPET is a novel technology that provides the first ever high-thro ughput 3D quantitative imaging of locked diamonds within kimberlite rocks presented as a close packed run-of-mine stream. It is a patented technique that combines two existing technologies in a novel way. The ore is activa ted by an electron accelerator which produces a high-energy photon beam of some tens of MeV via bremsstrahlung. PET isotope production is the most significant source of photons for delay times of the order of 30 minutes. After this delay time\, scanners based on medical PET (Positron Emission T omography) technology image the activated rocks for diamond. Essentially a carbon density distribution map is created and analysed. This presentatio n will look at MinPET performance results based on a Full Dress Rehearsal of Activation\, Detection\, Analysis using experimental datasets with stat istics that would typically be collected in a run-of-mine scenario at 700 tons per hour of rock throughput. The data was collected using the PET det ectors optimized by the Research Group and Net Instruments and various spi ked kimberlite samples at the electron injector microtron of the ASTRID st orage ring of the ISA\, Centre of Storage Ring Facilities at the Departmen t of Physics in Aarhus University\, Denmark.\n\nhttps://events.saip.org.za /event/100/contributions/147/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/147/ END:VEVENT BEGIN:VEVENT SUMMARY:Plasmon-enhanced fluorescence from individual plant light-harvesti ng complexes DTSTART;VALUE=DATE-TIME:20180629T100000Z DTEND;VALUE=DATE-TIME:20180629T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-149@events.saip.org.za DESCRIPTION:Speakers: Farooq Kyeyune (University of Pretoria)\nLight-harve sting complex II (LHCII) is the main antenna complex in photosystem II (PS II) of plants and serves as a model for biological multichromophoric syste ms with great potential in biophotovoltaic applications. However\, in thes e applications\, the use of LHCII is limited by the relatively small porti on (less than 1%) of solar energy that can be absorbed by a single protein monolayer. The absorption and emission properties of LHCII can be strongl y enhanced when strategically positioned near metallic nanoparticles. Here \, we report on the plasmonic fluorescence intensity enhancement of indivi dual LHCII complexes coupled to single gold nanorods (AuNRs). The AuNR-LHC II hybrids were constructed via wet chemical synthesis combined with a spi n-assisted layer-by-layer technique and characterized using single molecul e spectroscopy. Strong plasmonic fluorescence enhancement of individual LH CII complexes of up to 670-fold was observed. In addition\, a significant reduction in fluorescence lifetime\, as revealed by time-resolved measurem ents\, and increased photostability of individual pigments were observed. These results serve as a platform for constructing inexpensive yet efficie nt hybrid light-harvesting devices.\n\nhttps://events.saip.org.za/event/10 0/contributions/149/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/149/ END:VEVENT BEGIN:VEVENT SUMMARY:Visualization and machine learning application for the sorting of diamondiferous rock from mined kimberlite DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-150@events.saip.org.za DESCRIPTION:Speakers: Thendo Emmanuel Nemakhavhani (University of Johannes burg)\nTraditional diamond mining methods require the use of vast amounts of water and energy to process mostly barren rock to recover diamonds. Th e crushing of rock can lead to diamond breakage reducing the profitability of a mine. PET sensor technology negates these undesirable effects by en abling the early detection of relatively unprocessed diamond bearing rocks which can be isolated and processed in an environmentally friendly manner that preserves diamond integrity. \n\nKey to automated diamond detection is the creation of PET images from raw sensor data and the identification of diamond features using AI methods. Raw gamma ray detector hits are us ed to construct lines-of-response which define 2D projections. These are then used to reconstruct 3D images using the Maximum Likelihood Expectatio n Maximization (MLEM) algorithm. Bright spots in the images are identifi ed along with their features. These are then used as inputs to various ma chine learning algorithms to train them for diamond identification.\n\nPre sented are MLEM reconstructed images for simulated 10cm kimberlite rocks c ontaining diamonds of various sizes. The training of various machine lear ning algorithms is also discussed. The results show the first ever applic ation of automated diamond detection using machine classifiers.\n\nhttps:/ /events.saip.org.za/event/100/contributions/150/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/150/ END:VEVENT BEGIN:VEVENT SUMMARY:Analyses of the Pore Structure Formation of Activated Carbon from Compactivation of Plant Biomass Waste for Electrochemical Device Electrode s DTSTART;VALUE=DATE-TIME:20180627T104000Z DTEND;VALUE=DATE-TIME:20180627T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-151@events.saip.org.za DESCRIPTION:Speakers: Tjatji Tjebane (Necsa/UP)\nThe formation mechanism o f the porous framework in nanostructured carbon materials is important in a wide variety of applications such as in supercapacitors\, gas storage\, adsorbents and catalyst supports etc. The accessibility to the pore sites by electrolyte ions and gases are highly determined by the precise synthes is techniques adopted for these materials. As such\, biomass waste materia ls are a good choice for synthesis as they are available in abundance and cheap\, while containing high carbon content and giving high specific surf ace area for electrochemical supercapacitor applications.\nIn this study\, activated carbon (AC) was synthesized from renewable plant biomass waste using a chemical vapour deposition (CVD) technique via a pre-hydrothermal conversion step and compactivation along with the fine-tuning of key growt h parameters\, such as activating agent and carrier gas. The textural\, st ructural and morphological features were investigated by the Brunauer-Emme tt-Teller (BET) technique\, X-ray diffraction (XRD)\, X-ray photoelectron spectroscopy (XPS)\, and Scanning/Transmission electron microscopy (SEM/TE M) characterization. The material tested in a three-electrode configuratio n exhibited electric double-layer capacitor (EDLC) behaviour in different electrolytes and working comfortably in KNO3 electrolyte in both negative and positive operating widow of 0.80 V. The results from this study provid e the pathway into designing hierarchically porous materials from cheap an d sustainable sources suitable in high power energy storage devices.\n\nht tps://events.saip.org.za/event/100/contributions/151/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/151/ END:VEVENT BEGIN:VEVENT SUMMARY:How do students use the knowledge of conservative and non-conserva tive forces when solving work and energy theorem problems? DTSTART;VALUE=DATE-TIME:20180626T100000Z DTEND;VALUE=DATE-TIME:20180626T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-154@events.saip.org.za DESCRIPTION:Speakers: Paul Molefe (University of Johannesburg)\nThe concep t of conservative force and non-conservative forces play a vital role in s olving problems related to the application of the principle of conservatio n of energy and momentum\, but they are generally ignored when solving qua ntitative problems. First year students usually assumed that the system is isolated even if isolated case has to be proven first before the equation is used. The study explores if students are using the knowledge of conser vative and non-conservative forces when approaching problems dealing with work and energy theorem.\n\nhttps://events.saip.org.za/event/100/contribut ions/154/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/154/ END:VEVENT BEGIN:VEVENT SUMMARY:UNDERSTANDING THE ELECTRONIC AND OPTICAL PROPERTIES OF TIO2 ANATAS E (100) AND (001) SURFACES DOPED AND CO-DOPED WITH SILVER AND CARBON FOR A PPLICATION IN DYE-SENSITIZED SOLAR CELL DTSTART;VALUE=DATE-TIME:20180629T084000Z DTEND;VALUE=DATE-TIME:20180629T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-155@events.saip.org.za DESCRIPTION:Speakers: Nnditshedzeni Eric Maluta (University of Venda)\nNat ure of adding some foreign atoms in titanium dioxide (TiO2) play a vital r ole in increasing its photocatalytic properties. As TiO2 has a large band gap and used in the dye sensitized solar cells\, the addition of different elements stabilizes the system and shifts its absorption to the visible s pectrum. Density functional theory (DFT) has been used to study a pair of dopants\, introduced to understand the electronic and optical properties o f Anatase TiO2 (100) and (001) surfaces doped and co-doped with Ag and C. The calculations employ the generalized gradient approximation (GGA). The model surfaces structures were constructed from an optimized Anatase bulk structure. Silver as transitional metals was doped in TiO2 surfaces with o ne Ti atom replaced by a silver and co-doping was performed with one oxyge n atom been replaced by carbon. The results indicate that both doping and co-doping narrows the band gap of TiO2\, leading to its improvement in the photo reactivity and simultaneously maintain strong redox potential. The theoretical calculations could provide meaningful guides of developing mor e activities of anatase TiO2 photocatalyst with visible light response.\n\ nhttps://events.saip.org.za/event/100/contributions/155/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/155/ END:VEVENT BEGIN:VEVENT SUMMARY:Real-time Vibration Sensing in Renewable Energy Wind Turbine Blade s Using a Polarization Based Optical Fibre Device DTSTART;VALUE=DATE-TIME:20180626T100000Z DTEND;VALUE=DATE-TIME:20180626T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-157@events.saip.org.za DESCRIPTION:Speakers: Shukree Wassin (NMMU)\nEnergy is essential for achie ving sustainable growth among developing countries within Africa. Wind is regarded as one of the most promising types of renewable energy source cap able of lowering the effects of greenhouse gases. Vibration monitoring and analysis is essential in the design of wind turbines due to the partially elastic structural property of the blades and because they are required t o function in harsh and unsteady environments. This work presents a novel technique for accurately measuring vibrational frequencies as well as moni toring the plane of vibrations in renewable energy wind turbine blades\, b ased on a polarimetric optical fibre sensor. The proposed technique furthe r involves an offline\, fast Fourier transform (FFT) digital signal proces sing (DSP) analysis. We successfully show operation for vibrations from 57 -117 Hz. A fibre sensing system capable of measuring vibrational frequenci es in one plane was first demonstrated. Frequencies of 56.7 Hz\, 84.8 Hz a nd 90.3 Hz were accurately measured within 99.2 % of the actual value. The reafter\, simultaneous sensing in two orthogonal planes at 99.4 Hz and 116 .5 Hz was experimentally achieved.\n\nhttps://events.saip.org.za/event/100 /contributions/157/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/157/ END:VEVENT BEGIN:VEVENT SUMMARY:Comparison of ionospheric scintillation to in situ electron densit y variations as measured by the Swarm satellites. DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-158@events.saip.org.za DESCRIPTION:Speakers: Pierre Cilliers (SANSA Space Science)\nIonospheric s cintillation is known to be caused by rapid variations in the electron den sity of the ionosphere. It manifests as rapid fluctuations in the amplitud e and phase of radio signals traversing the ionosphere. In the case of nav igation signals transmitted from satellites of the Global Navigation Satel lite System (GNSS) ionospheric scintillation can cause a decrease in the a ccuracy of position estimation. During extreme fluctuations\, a loss of lo ck on the satellites can occur\, which can result in data outages. The abi lity to estimate the likelihood of ionospheric scintillation is of great i mportance for precision navigation applications such as GNSS assisted airc raft landing systems.\n\nThe altitude at which the electron density irregu larities occur can be inferred from a comparison of the variations in elec tron density as measured by means of Langmuir probes on the Swarm LEO sate llites (Swarm A\, B and C) and the L-band scintillations on GPS signals de tected both by the scintillation monitors on the Swarm satellites and by d edicated GPS scintillation and total electron content monitors (GISTMs) on the ground. The aim of this research is to derive estimates of the altitu des where electron density irregularities occur and to estimate the spatia l extent of the irregularities which give rise to amplitude and phase scin tillations on the L-band signals from GNSS satellites. \n\nIn this paper w e present some preliminary results on the characterization of the electron density gradients that lead to ionospheric scintillation through a compar ison of conventional scintillation indices derived from GNSS signals recor ded by a GPS receiver installed at Pwani University (Geo. Lon: 39.78oE\, G eo. Lat: 3.24oS) in Kenya with in-situ measurements of L-band scintillatio n and electron density on the Swarm satellites during the equinox period M arch/April 2016.\n\nhttps://events.saip.org.za/event/100/contributions/158 / LOCATION: URL:https://events.saip.org.za/event/100/contributions/158/ END:VEVENT BEGIN:VEVENT SUMMARY:The ionospheric response to HILDCAA events over the African mid-la titude sector DTSTART;VALUE=DATE-TIME:20180628T104000Z DTEND;VALUE=DATE-TIME:20180628T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-159@events.saip.org.za DESCRIPTION:Speakers: Tshimangadzo Merline Matamba (SANSA Space Science)\n The response of the ionosphere to High-intensity\, long-duration\, continu ous AE activity (HILDCAA) events that occurred during the solar cycle 23 a nd 24 will be presented. HILDCAA are magnetospheric/ionospheric events tha t occur during high-speed solar wind streams. During solar minimum\, the corotating interaction regions (CIRs) are followed by lengthy (days to wee ks) periods of HILDCAA intervals characterised by low Disturbance storm ti me (Dst) index. The HILDCAA events were selected based on the high intensi ty\, long duration\, continuous Auroral electrojet (AE) activity where AE peak values exceed 1000 nT\, the duration were greater than 2 days and the AE values never drop to 200 nT for more than two hours at a time. The HIL DCAA must occur outside the main phases of the geomagnetic storms. The cri tical frequency of F2 layer (foF2) and Global Navigation Satellite System (GNSS) Total electron Content (TEC) over the African mid-latitude region w ill be used to analyse the ionospheric responses. Some physical processes responsible for the ionospheric responses will be discussed.\n\nhttps://ev ents.saip.org.za/event/100/contributions/159/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/159/ END:VEVENT BEGIN:VEVENT SUMMARY:Atomic and electronic structure investigation of germanene grown o n Al2O3(0001) DTSTART;VALUE=DATE-TIME:20180629T080000Z DTEND;VALUE=DATE-TIME:20180629T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-160@events.saip.org.za DESCRIPTION:Speakers: Ganga Babu Geetha (University of Johannesburg)\nGerm anene is considered as a potential alternative to graphene and has technol ogical potential owing to its unique electronic characteristics. The buckl ed structure of germanene\, combined with strong spin-orbit coupling\, is predicted to exhibit new topological phenomena such as the quantum spin Ha ll and anomalous Hall effects. Recent efforts have been directed to identi fy suitable substrates that allows the growth of ultra-thin layers\, while still preserving the desired 2D characteristics. So far\, germanene has b een successfully grown on metal substrates\, such as Pt(111)\, Au(111)\, A g(111) and Al(111). However\, mixing of germanium-substrate atoms often le ads to the formation of an ordered 2D surface alloy that prevents the expe rimental realization of the predicted characteristics. In this study\, we have chosen an insulating Al2O3(0001) substrate for growing germanene. We experimentally investigated the room temperature growth of monolayer to fe w layers of Ge on the Al2O3(0001) surface under ultra-high vacuum conditio ns. The atomic structure investigated using Low Energy Electron Diffractio n (LEED) shows that the as-grown germanene does not deviate from the 1 x 1 structure of Al2O3(0001). The measured Ge 2p and 3d core level spectra in dicate intermixing of Ge and O\, which is prominent at monolayer Ge thickn ess. Post-deposition annealing significantly influences the fraction of t he Ge-O interface component. Valence band spectra depict prominent changes with Ge deposition above one monolayer as electronic states within the ba nd gap of Al2O3(0001) are introduced. Our study paves the way to further u nderstand and realize the electronic structure of germanene on insulating substrates.\n\nhttps://events.saip.org.za/event/100/contributions/160/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/160/ END:VEVENT BEGIN:VEVENT SUMMARY:Collinear ptychographic pulse reconstruction of ultrashort laser p ulses DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-161@events.saip.org.za DESCRIPTION:Speakers: Ruan Viljoen (Stellenbosch University)\nReconstructi on of the phase and amplitude of ultrashort pulses are needed since no det ector is fast enough to measure these pulses directly. Many methods to do so exists each with its own set of advantages and disadvantages. The only pulse reconstruction methodology which allows one to reconstruct the elect ric field at the sample plane in the focus of a collinear pulsed laser sou rce\, is the multiphoton intrapulse interference phase scan (MIIPS). The t echnique requires rescanning a specific phase pattern for multiple steps a nd thereby allowing extraction of the phase from the measurement. The proc ess is repeated several times to improve the extracted phase until the dev iation from the previous extracted phase is small enough to stop. We have adapted the time-domain ptychographic reconstruction algorithm to take a M IIPS trace as an input and reconstruct the full electric field with the ad vantage that only a single scan needs to be taken where after the measure spectrogram is passed to the Ptycho-MIIPS reconstruction algorithm. Ptycho -MIIPS has the advantage that it returns not only the phase but also the a mplitude of the electric field\, unlike MIIPS which only returns the phase .\n\nhttps://events.saip.org.za/event/100/contributions/161/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/161/ END:VEVENT BEGIN:VEVENT SUMMARY:Controlling iron-oxide nanoparticle size with nanometer precision to synthesize monodispersed particles: a theoretical and experimental inve stigation. DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-162@events.saip.org.za DESCRIPTION:Speakers: Richard Harris (University of the Free State)\nNanos ized iron-based magnets have attracted a great deal of attention in life-s ciences and health-care research where they find use in tissue-specific dr ug delivery\, contrast enhancement agents in magnetic resonant imaging (MR I) and cell separation\, among others. To improve the efficiency of these nanoparticles (NPs)\, a very narrow size distribution centering on a smal l NP size is required\, since this directly affects the superparamagnetic behavior. Despite great progress in the synthesis of iron-oxide NPs using thermal decomposition methods\, production of NPs with a low polydispersit y index is still a challenge. To narrow down the size distribution\, size selective precipitation processes have to be performed. In this study we show that\, for the first time\, the production of monodisperse iron-oxid e NPs are indeed possible without employing any post synthesis size-select ive procedures. Surfactants oleic acid and oleylamine were used and an ex perimental and theoretical study on the role of the surfactant ratio to NP size-distribution was carried out. It was observed that at a very specif ic acid/amine ratio of 3/1\, different synthesis procedures may yield trul y monodisperse NPs with polydispersity of less than 7%. This acid/amine r atio of 3/1 allowed for the control of the NP size with nanometer precisio n by simply changing the reaction heating rate. We were able to predict t his specific ratio by performing molecular dynamic simulations in advance that revealed a maximization of binding energy at this ratio. HRTEM and X RD were used to confirm the narrow size distribution and hysteresis loops recorded at 300 K and 2 K confirmed the superparamagnetic character of the NPs.\n\nhttps://events.saip.org.za/event/100/contributions/162/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/162/ END:VEVENT BEGIN:VEVENT SUMMARY:Electrons inside jets in ATLAS: not an isolated problem DTSTART;VALUE=DATE-TIME:20180627T122000Z DTEND;VALUE=DATE-TIME:20180627T124000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-163@events.saip.org.za DESCRIPTION:Speakers: Lawrence Christopher (University of the Witwatersran d)\nThe standard electron and jet reconstruction processes in ATLAS happen independently\, as a result energy deposits from electrons in Electromagn etic calorimeter often end up reconstructed as a jet close to the electron . Also\, real jets can end up being reconstructed as a "fake" electron. Th erefore\, an overlap removal procedure is applied during analysis in ATLAS \, where a jet close to an electron is removed as a physics object\, and f urther if the electron has any more jets closer to it\, the electron is di scarded. This procedure results in using electrons which is isolated from nearby hadronic activity. In fact\, even during the reconstruction of the electron\, some isolation from hadronic activity is demanded.\n\nWhere for most of the scenarios\, this works as intended\, there are situations whe n this causes a problem. For example\, in top antitop pair production and semi-leptonic decay\, if the system is boosted and decay products overlap\ , then the electron can land up close to jet. Certain models of new physic s can also result in a similar situation\, for example in ATLAS heavy neut rino analysis\, for certain configurations\, the heavy neutrino can be rec onstructed as large-radius jet containing the electron inside where the el ectron is close to a real jet and we want to keep them both. Then the stan dard electron reconstruction and overlap removal procedure results in a la rge fraction of real signal events being discarded\, thereby severely hamp ering the search. \nAdditionally\, the events which are kept\, the perform ance of electron reconstruction is likely to adversely affected. Currently \, a larger systematic uncertainty is applied to account for this effect.\ n\nThis presentation proposes how we can deal with the reconstruction of s uch electrons that are close to the real jets. This work further aims at i dentifying such electrons in the midst of dense hadronic activity without removing either the electron or the jet which will highly benefit many ana lyses in ATLAS\n\nhttps://events.saip.org.za/event/100/contributions/163/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/163/ END:VEVENT BEGIN:VEVENT SUMMARY:Structure of 33 Si\, 35 S and 36 S nuclei and the N=20 shell gap DTSTART;VALUE=DATE-TIME:20180628T094000Z DTEND;VALUE=DATE-TIME:20180628T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-164@events.saip.org.za DESCRIPTION:Speakers: Sandile Jongile (Stellenbosch/ iThemba LABS)\nThe pr oject focuses on studying the evolution of the N=20 shell gap. The shell g aps have been previously investigated through studies of nuclear levels\, using various experimental approaches namely: Coulomb excitation\, knockou t reactions\, transfer reactions and g-factor measurements. In exotic nucl ei with an imbalanced number of neutrons and protons\, significant modific ations of the nuclear structure have been observed. A detailed study of th e evolution of the shell gaps will lead to a comprehensive understanding o f the structure of atomic nuclei. In order to investigate the evolving she ll structure it is necessary to determine single particle observables such as spectroscopic factors of the states involving the active\norbitals at these shells gaps. A knockout reaction is the first set of data for this p roject\, the experiment was performed at MSU/NSCL laboratory using the GRE TINA gamma-ray tracking array and S800 spectrometer. The knockout reaction was performed using inverse kinematics with a 36S secondary beam incident on a 9Be target. The nuclei of interest studied are 33Si\, 35S and 36S. V arious transitions in these nuclei have been identified from the analysis of add-back Doppler corrected spectra and a level scheme has been built fr om the resulting analysis. In addition parallel momentum distributions hav e been constructed to investigate the possible nature of the different sta tes.\n\nThis work is supported by the National Research Foundation of Sout h Africa .\n\nhttps://events.saip.org.za/event/100/contributions/164/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/164/ END:VEVENT BEGIN:VEVENT SUMMARY:Quantitative Predictions of Heavy Flavor Photon Bremsstrahlung in Heavy Ion Collisions from AdS/CFT DTSTART;VALUE=DATE-TIME:20180627T082000Z DTEND;VALUE=DATE-TIME:20180627T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-165@events.saip.org.za DESCRIPTION:Speakers: William Horowitz (University of Cape Town)\nWe prese nt quantitative predictions for the spectra of photon bremsstrahlung from heavy quarks propagating through a strongly-coupled quark-gluon plasma usi ng the techniques of AdS/CFT. The spectra are the result of including bot h drag and diffusion terms in the heavy flavor propagation in the plasma. The predictions show that future experimental upgrades and high-luminosit y runs at the Large Hadron Collider at CERN will allow for a quantitative comparison between data and our calculations\, providing novel insight int o the non-trivial\, emergent many-body dynamics of a non-Abelian gauge the ory.\n\nhttps://events.saip.org.za/event/100/contributions/165/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/165/ END:VEVENT BEGIN:VEVENT SUMMARY:La3+ doped ZnO nanofibers obtained through electrospinn ing: Influence of La3+ doping concentration on the structural\, optical and gas sensing properties DTSTART;VALUE=DATE-TIME:20180627T102000Z DTEND;VALUE=DATE-TIME:20180627T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-166@events.saip.org.za DESCRIPTION:Speakers: Katekani Shingange (CSIR/UFS)\nZnO has been used as a gas sensing material for different reducing and oxidizing gases\, howeve r\; poor sensitivity and slow response and recovery times are hindering it s commercial application. Doping of ZnO with different metallic ions such as rare earth and noble metals have proven to be one of the efficient ways of modifying its gas sensing performance. In this study\, ZnO nanofibers with different La3+ doping concentration (0\, 0ܧ\, 0ܩ and 0ܫ wt.%) were successfully obtained through electrospinning and subsequent annealing at 500 °C. The effect of La3+ concentration on the structural\, morphologic al\, surface area and optical properties were studied using X-ray diffract ion (XRD)\, scanning electron microscopy (SEM)\, Brunauer Emmett Teller (B ET) and Photoluminescence (PL) spectroscopy. XRD results revealed a single phase of hexagonal wurtzite ZnO that showed poor crystallinity\, shifted peaks to higher two theta and changes in lattice parameters with La3+ dopi ng\, confirming the substitution of Zn2+ by La3+ in the ZnO lattice. Morph ological studies revealed fibers structures that were made of tiny particl es of ̴20-40 nm adjoined together and no change in morphology was induced by the La3+ doping. BET indicated that the surface area of ZnO was improv ed by La3+ doping. The PL emissions quenched with increasing La3+ concentr ation. Gas sensing performance of these samples to different test gases wa s performed at different temperatures ranging from room temperature to 400 °C at different gas concentrations ranging from 5-100 ppm.\n\nhttps://ev ents.saip.org.za/event/100/contributions/166/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/166/ END:VEVENT BEGIN:VEVENT SUMMARY:LaAlO3 sheet-like nanostructures synthesized through mi crowave-assisted method and their gas sensing characteristics DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-167@events.saip.org.za DESCRIPTION:Speakers: Katekani Shingange (CSIR/UFS)\nLanthanum (La) based perovskite oxides such as LaFeO3\, LaCoO3 and LaAlO3 have stimulated great interest in the gas sensing technology world as promising candidates for gas sensing towards different gases. This is due to their unique electrica l and electrocatalytic properties\, providing good response with high sele ctivity and stability. Out of all the La based perovskite oxides\, LaAlO3 is a quite new perovskite that has mostly been used as an additive to othe r materials such as ZnO and SrTiO3 due to its good electron gas conductiv ity. However\, there are only a few reports on the application of LaAlO3 f or gas sensing. In this work\, LaAlO3 nanostructures have been synthesized using metal nitrate salts through the hydrothermal microwave-assisted met hod. Characterizations of the synthesized materials by means of X-ray diff raction\, scanning electron microscopy and nitrogen adsorption confirmed t he formation of high purity hexagonal 2D sheet-like structures LaAlO3 with high surface area. The sheet-like structures were assessed for gas sensin g towards several test gases namely CO\, CH3\, C2 H5 OH\, NH3 and NO2 at different working temperatures ranging from room temperature to 400 °C.\n \nhttps://events.saip.org.za/event/100/contributions/167/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/167/ END:VEVENT BEGIN:VEVENT SUMMARY:Quantification of Ag in Ag doped glass based metamaterials using X PS analysis. DTSTART;VALUE=DATE-TIME:20180627T084000Z DTEND;VALUE=DATE-TIME:20180627T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-168@events.saip.org.za DESCRIPTION:Speakers: Rethabile Makole (University of the Free State)\nQua ntification in XPS is not easy\, more especially if the concentrations of the substituents in the sample are not homogeneous on the sample surface o r with depth. In this study the Quases-Tougaard Software analyses approach was used to quantify Ag nano clusters in a Ag doped glass host. The speci mens were synthesized by a simple molten bath ion exchange method and then annealed at different temperatures. A XPS-spectrum of the Ag 3d peaks we re isolated from a survey spectrum of the specimen and compared to a spect rum generated from a pure Ag reference. The morphology was changed until t here was a good match between the two spectra. The results shows that the QUASES Software can be a vital tool in determining the morphology of eleme nts in a sample.These results are then compared with results from TEM data .\n\nhttps://events.saip.org.za/event/100/contributions/168/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/168/ END:VEVENT BEGIN:VEVENT SUMMARY:Production of electron sources at iThemba LABS DTSTART;VALUE=DATE-TIME:20180626T102000Z DTEND;VALUE=DATE-TIME:20180626T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-170@events.saip.org.za DESCRIPTION:Speakers: Bonginkosi Zikhali (University of wersten cape physi cs)\nAn electron spectrometer for the measurement of internal conversion e lectrons is undergoing development at iThemba LABS. The spectrometer will be used to study the nuclear configuration of multiple excited 0+ states around Z ≈50 region. The purpose of the project is to wider the stat e of knowledge for electron conversion sources of nuclei with proton numbe r near fifty (Z≈50). In order to accomplish this\, a set of different e lectron sources around this region will be produced (120Sn\, 109Cd & 170Yb ) 170Yb will be used to calibrate the spectrometer\, since this nu cleus has lot of discrete states. A proton beam ranging from 11 to 66 Me V will be used to produce sources using(p\,n) reaction. The cross sectio ns and activity yield for sources have been calculated\, 133Ba and 207Bi w ill be used to calibrate the spectrometer\, and hence their efficiency hav e been measured. This presentation will describe current progress on this project.\n\nhttps://events.saip.org.za/event/100/contributions/170/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/170/ END:VEVENT BEGIN:VEVENT SUMMARY:Photoblinking and photobleaching of single Rhodamine 6G molecules. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-171@events.saip.org.za DESCRIPTION:Speakers: Charmaine Sibanda (Laser Research Institute\,Physics Dept\,Stellenbosch University)\nSingle molecule resolved fluorescence mic roscopy used in this work relies on a combination of high detection sensit ivity and localization with nanometer precision. The detection of individu al molecules in single molecule experiments reveals rare events such as ph otoblinking and photobleaching\, which allows accessing of properties that are otherwise hidden in ensemble measurements [1].The photophysical prope rties of single rhodamine 6G molecules embedded in thin polymer films were studied\, from which the photoblinking and photobleaching behavior was id entified. Photoblinking is the reversible decrease of the emission of the fluorescent dye molecules whilst photobleaching is an irreversible process caused by light-induced chemical reactions which transform the fluorophor e into a molecule that does not fluoresce [2]. By analyzing the duration a nd distribution of the on and off times (photoblinking)\, the lifetime and population efficiency of the dark states of the rhodamine 6G molecules wa s obtained which provide specific information of the embedding medium.\n\n [1]. Dominik Woll et al\, “Polymers and single molecule fluorescence mic roscopy\,what can we learn?”\,Chem.Soc.Rev\,vol 38\,pp313-328\, 2009.\n[ 2]. T. Gensch et al\, "Single Molecule Blinking and Photobleaching Separat ed by Widefield Fluorescence Microscopy\," Journal of Physical Chemistry\, vol. 109\, no. 30\, pp. 6652-6658\, 2005.\n\nhttps://events.saip.org.za/e vent/100/contributions/171/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/171/ END:VEVENT BEGIN:VEVENT SUMMARY:Using the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) mo del to extract the thermal conductivity transport coefficient of hadron ga s. DTSTART;VALUE=DATE-TIME:20180627T084000Z DTEND;VALUE=DATE-TIME:20180627T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-172@events.saip.org.za DESCRIPTION:Speakers: Thendo Emmanuel Nemakhavhani (University of Johannes burg)\nThermal conductivity of hadron matter is studied using a microscopi c transport model\, which can support the newly Large Hadron Collider (LHC ) energy of up to √s = 14 TeV\, namely the Ultra-relativistic Quantum Mo lecular Dynamics (UrQMD). The molecular dynamics simulation is performed f or a system of light mesons species (pions\, rhos\, Kaons) in a box with p eriodic boundary conditions. Equilibrium state is investigated by studying chemical equilibrium and thermal equilibrium of the system. Particle mult iplicity equilibrates with time\, and the energy spectra of different ligh t mesons species have the same slopes and com- mon temperatures when therm al equilibrium is reached. Thermal conductivity transport coefficient is c alculated from the heat current - current correlations using the Green-Kub o relations.\n\nhttps://events.saip.org.za/event/100/contributions/172/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/172/ END:VEVENT BEGIN:VEVENT SUMMARY:Measurement of heavy ion induced X-ray production cross sections i n metallic targets at MeV energies. DTSTART;VALUE=DATE-TIME:20180628T082000Z DTEND;VALUE=DATE-TIME:20180628T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-173@events.saip.org.za DESCRIPTION:Speakers: Masedi Masekane (University of South Africa)\nExperi mental X-Ray production cross sections (i.e. probability of X-ray generati on in a target by an incoming MeV heavy ion beam) are useful not just for fundamental ion beam-matter interaction studies\,but also for the developm ent of new ion beam materials analysis techniques such as the Heavy Ion Pa rticle Induced X-Ray Emission (HI-PIXE) spectroscopy. Unfortunately\, whil e theoretical predictions of X-ray production cross sections due to light (Z <6) projectile ions are generally in good agreement with experiment\, t his is not the same for heavier projectiles. There is therefore need for substantial experimental data to improve theoretical models. This presenta tion describes measurements carried out to determine X-ray production cros s sections in zirconium (Zr)\, Tin (Sn) and Vanadium (V) metal oxide film s due to carbon and chlorine MeV ion beams. The measured cross sections a re compared to predictions by the modified Plane Wave Born Approximation ( PWBA) and the ECPSSR theory that takes into account the energy loss and co ulomb deflection of the projectile and the pertubed-stationary state and r elativistic nature of the target's inner shell. The observed agreements an d discrepancies between experiment and theory are discussed in terms of th e atomic ionization mechanisms for each projectile-target collision.\n\nht tps://events.saip.org.za/event/100/contributions/173/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/173/ END:VEVENT BEGIN:VEVENT SUMMARY:Single molecule fluorescence microscopy- An application in thin po lymer film dynamics. DTSTART;VALUE=DATE-TIME:20180627T144000Z DTEND;VALUE=DATE-TIME:20180627T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-174@events.saip.org.za DESCRIPTION:Speakers: charmaine sibanda (stellenbosch university)\nWith wo rldwide production of polymers pegged at over 300 million tonnes (2017)\, there’s need for sustainable options for production\, waste management a nd recycling of polymers [1]. This high demand of polymers has made them b ecome one of the most important materials in various industrial and biomed ical sectors. These materials have shown interesting and unique physical p roperties that change drastically such as conductivity\, viscosity and the rmal expansion below\, near and above the glass transition temperature whi ch originate from complicated relaxation processes of polymer chains [2]. However these unique properties have not yet been fully understood despite experimental and theoretical studies of the glass transition temperature of polymers over the past decades. Thus there has been a need in polymer r esearch to further understand the dynamics connecting the macroscopic and microscopic properties of polymers. Different experimental methods have be en used to try and understand the nano-environment of polymers. One of the se methods also used in this research is single molecule fluorescence micr oscopy. It is a powerful imaging tool that enables the direct observation of single fluorescent molecules in their nano-environment [3]. For this re search\, the diffusion of single fluorescent dye molecules embedded in thi n polystyrene and poly (isobutyl methacrylate) films was used to study and investigate the dynamics of the thin polymer films. In this presentation\ , dynamics of the thin polymer films below and near the glass transition t emperature as derived from the probe molecule diffusion will be discussed. \n\n[1]. Plastics Europe\, PEMRG\,2017.\n[2]. B. Flier\, et al. “Heterog eneous Diffusion in Thin Polymer-Films as observed by High-Temperature Sin gle Molecule Fluorescence Microscopy”\; J. Am. Chem. Soc.\,134\,480-488\ , 2012.\n[3]. Dominik Woll et al\, “Polymers and single molecule fluores cence microscopy\, what can we learn?”\,Chem.Soc.Rev\,vol 38\,pp313-328\ , 2009.\n\nhttps://events.saip.org.za/event/100/contributions/174/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/174/ END:VEVENT BEGIN:VEVENT SUMMARY:Directly Modulated 850 nm Multimode VCSEL Performance Analysis for Short Reach Optical Communications DTSTART;VALUE=DATE-TIME:20180626T102000Z DTEND;VALUE=DATE-TIME:20180626T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-175@events.saip.org.za DESCRIPTION:Speakers: George Isoe (Centre for Broadband Communication\,Nel son Mandela University)\nAbstract: \nShort reach optical interconnects mus t support higher data rates to manage the increasing needs of end users an d the commensurate increase in storage and computation within and between data centres. Multimode vertical cavity surface-emitting lasers (VCSELs) a nd multimode fibre (MMF) links provide a power efficient solution\, which is achieved in part by maximizing the data rate per transmission channel. We experimentally analyze the performance of a 10 Gbps 850 nm multimode VC SEL for adoption in high-speed VCSEL-MMF based short range optical interco nnects. Results show that an error-free operation at 10 Gbps is achieved a t back-to-back (B2B) configuration with less than 0 dBm of received optica l power. A successful transmission over OM3 optical fibre is achieved with a clearly open eye diagrams. Results from this work indicate that 850 nm multimode VCSELs have the potential for reliable operation over OM3 optica l fibres. They are therefore ideal candidate for bandwidth demanding shor- range applications. \n\nKeywords: VCSEL\, MMF\, OM3\, fibre\, optical inte rconnects\n\nhttps://events.saip.org.za/event/100/contributions/175/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/175/ END:VEVENT BEGIN:VEVENT SUMMARY:A predictive approach for vibration analysis in underground mining operation DTSTART;VALUE=DATE-TIME:20180626T084000Z DTEND;VALUE=DATE-TIME:20180626T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-176@events.saip.org.za DESCRIPTION:Speakers: Antoine Floribert Mulaba - Bafubiandi (University of Johannebsurg)\nMine fatalities\, accidents and incidents are often associ ated with ground\, roof\, stope or side instability. Attenuation of rock i ntegrity or the presence of (under)ground pockets of gases or ground water s lead to the collapse of the tunnel. Safety sensors and machine learning tools are placed in the underground mine tunnels to alert for emergencies and immediate evacuation. Numerous reported data are found on condition mo nitoring of mining machineries but scarce are on monitoring of an undergro und gallery roof\, floor or stope prior to the fatality or failure. Additi onally\, safe mining practices would include a proactive predictive approa ch instead of waiting for the occurrence of the unfortunate event. While t he magnitude of vibrations could be measured with accelerometers\, a progr amming model could assist with the prediction making used of curve fitting . This normally required knowledge of the pre-alarm and alarm standard lev el in order to assess the severity of the vibration. In this paper\, we ar e discussing a predictive approach for the monitoring and the analysis of the vibration in an underground mining tunnel roof. This approach has been illustrated using the software MATLAB. Ultimately\, an immediate action l eading to proactively preventing any damage to the structure constitutes t he main contribution of this work.\n\nhttps://events.saip.org.za/event/100 /contributions/176/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/176/ END:VEVENT BEGIN:VEVENT SUMMARY:Highly capable non-rare earth doped LiMgBO3 phosphor fo r light emitting diodes DTSTART;VALUE=DATE-TIME:20180626T082000Z DTEND;VALUE=DATE-TIME:20180626T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-177@events.saip.org.za DESCRIPTION:Speakers: Ankush Kumar Bedyal (Department of Physics\, Univers ity of Free State)\nNon- rare earth doped phosphor materials particularly Mn4+ activated nitrides and fluorides are emerging as an alternative to ra re earth doped red emitting phosphor materials for light emitting diodes\, as these materials are more cost effective. Still it remains a challenge to prepare high purity red light emitting and cost effective non-rare eart h doped red phosphors because of the broad emission and challenging synthe sis of nitrides and fluorides\, respectively. Herein we reported the red e mitting Mn4+ doped LiMgBO3 phosphor synthesized by solution combustion and solid state route. The photoluminescence spectrum had two broad bands fro m 260–410 nm and 420-545 nm\, due to the 4A2 → 4T1 and 4T2 transitio n of Mn4+\, respectively. Under UV and visible excitation the phosphor emi ts at 665 nm with CIE chromaticity coordinates of (0.706\, 0.292) and FWHM of 35 nm\, which revealed the high purity red light emission from the pho sphor. The concentration quenching of Mn4+ was observed at around 0.6 mol% . The predicted mechanism for concentration quenching to be a dipole–dip ole interaction among the Mn4+ ions. The results suggests that the phospho r with enough color purity ~62% and stable CIE coordinates could be an eve ntual choice as the red component for white light emitting diodes.\n\nhttp s://events.saip.org.za/event/100/contributions/177/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/177/ END:VEVENT BEGIN:VEVENT SUMMARY:A scheme to analyze the decay time of rare earth ions using a squa re wave technique DTSTART;VALUE=DATE-TIME:20180627T134000Z DTEND;VALUE=DATE-TIME:20180627T140000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-179@events.saip.org.za DESCRIPTION:Speakers: S P Tiwari (Department of Physics University of Free State)\nThree samples La2O3:Er3+/Yb3+ (LEY)\, La2O3:Ho3+/Yb3+ (LHY) and L a2O3:Er3+ (LE) were synthesized via the combustion method. Urea was used a s a fuel and reducing agent. The samples were annealed at 800 oC for 4 hou rs in order to get good crystallization. The phase confirmation of the sam ples was carried out by using X-ray diffraction analysis. Surface morpholo gy of the sample was done by field emission scanning electron microscopy a nalysis with spherical particles. Fourier transformed infra-red transmitt ance of the samples was done in order to investigate the impurities. The a nnealed samples (800 oC) were further used for optical measurements. Upcon version emission of all the samples were measured and three prominent band s were monitored at 522\, 548 and 662 nm corresponding to 2H11/2 → 4I15/ 2\, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2\, manifolds\, respectively. The decay time measurements were done using a monochromator coupled with a Cat hode ray oscilloscope (CRO). A continuous laser beam (976 nm) was chopped using a mechanical chopper (1000 Hz). Thus the data acquired by using the CRO was plotted as a square wave and this wave was further used to analyze the decay time with fixing different fitting parameters. This technique o f decay time measurements is very inexpensive and easy handled. Thus the c alculated decay time of the samples were found to be 252 ms\, 102 ms and 5 4 ms\, for LEY\, LHY and LE\, respectively.\n\nhttps://events.saip.org.za/ event/100/contributions/179/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/179/ END:VEVENT BEGIN:VEVENT SUMMARY:Bandgap tuned Co2+-doped ZnO for the photocatalysis of Methylene Blue and Rhodamine B DTSTART;VALUE=DATE-TIME:20180626T080000Z DTEND;VALUE=DATE-TIME:20180626T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-180@events.saip.org.za DESCRIPTION:Speakers: Samvit Menon (University of the Free State)\nWater p ollution and the insufficiency of proper clean energy sources have resulte d in the need for developing environmentally safe technologies and process es to combat this concern. One of the major constituents of wastewater are dyes\, that are carcinogenic and immune to conventional physical and chem ical remediation techniques. Thus\, suitable techniques need to be designe d to degrade these pollutants into harmless moieties before discharging th em into aquatic systems. In this study\, bandgap tuned Co2+-doped ZnO has been used as a UV/visible light photocatalyst on the degradation of methyl ene blue and rhodamine B\, a model organic dye. X-Ray diffraction patterns of the sample annealed at 500°C showed the formation of highly crystalli ne phase-pure ZnO with no impurities. The bandgap was calculated from diff use reflectance spectroscopy and the point of zero charge was evaluated us ing the pH drift method. The rate of degradation was investigated for diff erent pH values and a suitable pH was optimized for the most effective deg radation. The performance of this Co2+-doped ZnO photocatalyst under visib le light was superior compared to other known reports. The efficiency of d egradation was improved significantly by adding H2O2 and the amount of deg radation was quantified using a simple methanolic extraction technique. Zn O is an environmentally friendly mineral and this study demonstrates the u se of an effective and efficient\, eco-friendly technique for combating wa ter pollution.\n\nhttps://events.saip.org.za/event/100/contributions/180/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/180/ END:VEVENT BEGIN:VEVENT SUMMARY:Effects of annealing time on the structure and photoluminescence p roperties of Sr3Al2O6:1% Ce3+ nanophosphor synthesize via sol-gel method DTSTART;VALUE=DATE-TIME:20180626T104000Z DTEND;VALUE=DATE-TIME:20180626T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-181@events.saip.org.za DESCRIPTION:Speakers: Setumo Victor Motloung (SMU)\nSr3Al2O6:1% Ce3+ nano- powders have been successfully prepared via sol-gel technique. Citric acid was used as a chelating agent. All powder samples were annealed at 950 oC and the annealing time (AT) was varied from 0.5 - 20 hrs. X-ray diffracti on (XRD)\, scanning electron microscopy (SEM) coupled with an energy dispe rsive X-ray spectroscope (EDS)\, transmission electron microscopy (TEM) an d photoluminescence (PL) spectra were used to characterize the samples. Th e XRD data revealed that all the samples were single phase crystalline str uctures and the estimated average crystallites size were found to be 20 nm . EDS results confirmed the presence of the expected elementary compositio n. SEM image presented in Fig. 1 (a) illustrates that the crystals have ro ds-like morphology structures. The AT was found to influences the phosphor morphology. The TEM results confirmed that the prepared nano-powders are on the nano-scale. PL results showed that the excitation wavelength as a f unction of emission intensity has the Gaussian behaviour with the maximum at 263 nm. When the samples were excited at 263 nm\, four emission peaks a t 382\, 541\, 593 and 620 nm were observed (see Fig. 1 (b)). All of the em issions corresponds to the emissions observed on the un-doped (Sr3Al2O6)\, which suggest that all of the observed emissions are originating from the defects levels within the Sr3Al2O6 (host) [1\,2]. The optimum luminescenc e for 541 nm emission was found to be for the AT = 8 hrs sample.\n\nhttps: //events.saip.org.za/event/100/contributions/181/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/181/ END:VEVENT BEGIN:VEVENT SUMMARY:Aerosol and cloud studies using LIDAR\, satellite and model data i n South Africa DTSTART;VALUE=DATE-TIME:20180626T082000Z DTEND;VALUE=DATE-TIME:20180626T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-182@events.saip.org.za DESCRIPTION:Speakers: Lerato Shikwambana (SANSA)\nAtmospheric aerosols are minute particles suspended in the atmosphere. They interact both directly and indirectly with the Earth's radiation budget and climate. The aerosol optical depth (AOD) is the most important parameter used to quantify the impact of aerosols on radiative energy budget. In this study we report on the various aerosol and cloud measurements we have carried out this far. F irstly\, we report on the distribution and seasonal variation of various a erosols such as black carbon (BC)\, sulphate and dust AOD in South Africa using Modern-Era Retrospective analysis for Research and Applications\, Ve rsion 2 (MERRA-2) model data. BC aerosols were observed to be dominant in the north eastern parts of South Africa (SA) while sulphate aerosols were observed to be dominant in eastern parts of SA. Secondly\, we report on th e transport of volcanic aerosols over SA from the Calbuco volcano eruption in Chile that occurred on 21 April 2015. Volcanic aerosols were observed over SA from 28 April 2015 to 16 May 2015 as indicated by Cloud-Aerosol Li dar and Infrared Pathfinder Satellite Observation (CALIPSO) data. Lastly\, we report on the observation of clouds over Durban using the CSIR mobile Light Detection And Ranging (LIDAR) instrument. Low level cloud layers sho wed high extinction coefficients values ranging between 0.9 and 4.4 km −1\, whereas low extinction coefficients for high level clouds were obse rved at values ranging between 0.001 and 0.002 km−1.\n\nhttps://events .saip.org.za/event/100/contributions/182/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/182/ END:VEVENT BEGIN:VEVENT SUMMARY:Upconversion luminescence of NaGdF4 : Yb3+\, Ho3+ phosphors for po tential biomedical applications DTSTART;VALUE=DATE-TIME:20180627T140000Z DTEND;VALUE=DATE-TIME:20180627T142000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-183@events.saip.org.za DESCRIPTION:Speakers: ASHWINI SHARMA (UNIVERSITY OF THE FREE STATE)\nLanth anide ions (Ln3+) doped upconversion (UC) materials show great potential a pplications in optical and optoelectronic devices owing to their novel opt ical properties.Yb3+\, Ho3+ co-doped NaGdF4 materials were synthesized by a simple co-precipitation method. Powder X-ray diffraction and X-ray photo electron spectroscopy analysis demonstrated successful formation and incor poration of ions in NaGdF4: Yb3+\, Ho3+ materials. The UC luminescence pro perties of NaGdF4 materials co- doped with different Yb3+\, Ho3+ concentra tions were investigated\, and the related UC mechanisms of Yb3+\, Ho3+ co- doped NaGdF4 depending on pump power were studied in detail.The intense gr een UC emission bands at 540\, 549 nm\, red emission at 645 nm and 752 nm signals in the emission spectra could be assigned to the 5S2\, 5F4→5I8\, 5F5 →5I8 and 5F4→5I7 transitions of Ho3+ via 980 nm near infrared ex citation along with energy transfer from the Yb3+\, respectively. It was c onfirmed that the green UC emission was generated via a two-photon process from a quadratic dependence of the emission intensity on the pumping powe r. The chromaticity coordinate (0.276\, 0.708) of the optimized NaGdF4: 15 mol% Yb3+\, 2 mol% Ho3+ upconversion material was located in the green re gion and hardly changed due to the negligible red emission. The present Yb 3+\, Ho3+ co-doped NaGdF4 phosphor is an interesting UC material with a st able crystal structure\, good cytocompatibility and bioactivity possesses great potential for biomedical applications.\n\nhttps://events.saip.org.za /event/100/contributions/183/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/183/ END:VEVENT BEGIN:VEVENT SUMMARY:Effect of substrate temperature on photoluminescence properties of Eu3+ doped BaZrO3 thin films deposited by PLD DTSTART;VALUE=DATE-TIME:20180628T092000Z DTEND;VALUE=DATE-TIME:20180628T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-184@events.saip.org.za DESCRIPTION:Speakers: ARUP KUNTI (University of the Free State)\nPerovskit e type (A2+B4+O2-3)\nstructures are significantly important host for rare earth (RE) doping because they offer promising luminescence properties for light emitting diode\, field emission display and all solid compact laser devices. Eu(3+ doped BaZrO3 thin films with cubic structure were prepared on Si(100) substrates by using the pulse laser deposition (PLD) technique \, using an Eu3+ doped BaZrO3 target at 10 mTorr oxygen pressure. The subs trate temperature was varied from 400°C to 700℃. The thicknesses of the films were calculated from transmittance spectra. The thickness of all th e films were around 300 nm. The phase identification and structural proper ties of the films were characterized by X-ray diffractometry. Surface morp hology were studied by Scanning Electron Microscopy. Elemental analysis wa s performed using X-ray photoelectron spectroscopy (XPS). The oxidation st ates were also confirmed from XPS analysis. With the increase in substrate temperature\, the growth of the films changed. Intense red emission was o bserved by the excitation of UV light. Emission spectra showed peaks at 57 7\, 597 and 615 nm corresponding to the 5D0→7F0 \, 5D0→7F1 and 5D0 →7F2 transitions of Eu3+\, respectively. It was observed that the emissi on at 597 nm which was due to the magnetic dipole transition (5D0→7F1) w as the dominating emission. This confirms that Eu3+ ion occupied the centr o-symmetric Zr(4+ site. Emission properties and defects involved within t he films were investigated via photoluminescence. \n\nKeywords: PLD\, Thin film\, Photoluminescence\n\nhttps://events.saip.org.za/event/100/contribu tions/184/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/184/ END:VEVENT BEGIN:VEVENT SUMMARY:Efficiency calibration of the laboratory based gamma-ray detector for various sample geometries DTSTART;VALUE=DATE-TIME:20180626T082000Z DTEND;VALUE=DATE-TIME:20180626T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-185@events.saip.org.za DESCRIPTION:Speakers: Avuyile Sisanda Bulala (University of Cape Town / iT hemba LABS)\nRadioactivity has been present on earth since its formation a nd is part of the environment we live in. Humans are exposed every day to radioactivity through the radioactive elements that occur naturally in the environment. Radionuclides are found naturally in air\, water\, soil\, pl ants and inside our bodies. In this study\, radiometric measurements using various sample holders for environmental samples are performed. Available sample holders under study are Marinelli beaker (1l) and cylindrical pill bottle (100 ml). The gamma-ray spectrometry method is the tool used to an alyse samples. For absolute photo peak efficiency measurements IAEA refere nce material RGU-1\, RGTh-1 and potassium chloride powder were prepared fo r 100 ml pill bottles and the Marinelli beakers (1l) then each measured in HPGe detector for a day. Additionally\, certified reference point sources bought from NMISA were also measured. From the known activities of the po int sources and the prepared volume sources\, photopeak efficiency was cal culated and efficiency parameters for these geometries were obtained. Also Monte Carlo simulation was used to benchmark the parameters of the detect or used to determine the activity concentration of environmental samples. Later will compare the experimental data of reference samples with correct ion factors of the simulation data to match the experimental data. For thi s contribution\, the efficiency of the detector as function of gamma-ray e nergy in various measuring geometries will be known.\n\nhttps://events.sai p.org.za/event/100/contributions/185/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/185/ END:VEVENT BEGIN:VEVENT SUMMARY:Modelling Crosstalk and Propagation of LG Beams in Turbulence DTSTART;VALUE=DATE-TIME:20180627T120000Z DTEND;VALUE=DATE-TIME:20180627T122000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-186@events.saip.org.za DESCRIPTION:Speakers: Mitchell Cox (University of the Witwatersrand)\nThe use of higher order modes in optical communications is topical due to thei r versatility and in particular their ability to conveniently increase the number of degrees of freedom in a communications system. This enables mul tiplexing for higher bandwidth communications as well as diversity for imp roving the robustness of a link. One of the main reasons why we do not see commercial systems making use of Mode Division Multiplexing is because th e channel has not been accurately modelled and so it is impossible to engi neer a reliable system. Accurate models exist for flat and spherical wave- fronts\, but are not suitable for higher order modes and do not take into account crosstalk effects which is critical for multiplexing. Experimental measurements of the intensity fluctuations and crosstalk of Laguerre-Gaus s modes in various conditions was performed on a 150 m free space link at the CSIR in Pretoria. Statistical modes based on the data as well as some example mechanisms for how the models may be used in future will be presen ted.\n\nhttps://events.saip.org.za/event/100/contributions/186/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/186/ END:VEVENT BEGIN:VEVENT SUMMARY:Robust quantum key distribution with spatial modes DTSTART;VALUE=DATE-TIME:20180627T142000Z DTEND;VALUE=DATE-TIME:20180627T144000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-187@events.saip.org.za DESCRIPTION:Speakers: Bienvenu Ndagano (University of the Witwatersrand)\n Quantum key distribution (QKD) allows the secure sharing of information by exploiting the laws of physics. Traditionally demonstrated with polarisat ion\, there has been novel avenues of research whereby the spatial degree of freedom is employed to increase the bandwidth\; that is because spatial modes allow access to a larger state space beyond the qubit\, unlike pola risation. However\, unlike polarisation\, spatial modes are not resilient to atmospheric perturbations\; the random fluctuations in of refractive in dex cause wavefront aberrations that broadens the spectrum of a single mod e OAM state. In the context of quantum key distribution\, the broadening l eads to measurement errors that decrease or compromise the security of the QKD link. Here we present a study of the deleterious effects of atmospher ic turbulence on orbital angular momentum- based quantum key distribution protocols. We show that the impact of turbulence on the secret key rate ca n be mitigated by using spatial modes with high orbital angular momentum c ontent. We attribute the resilience of high OAM states (labelled with l) t o the separation in OAM space\; the further apart the modes are\, i.e.\, t he higher Δlℏ\, the lower the overlap for given turbulence conditions. Consequently\, the range of real-world quantum communication link that emp loy spatial modes can be significantly extended without compromise on secu rity.\n\nhttps://events.saip.org.za/event/100/contributions/187/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/187/ END:VEVENT BEGIN:VEVENT SUMMARY:Gadolinium doped and undoped silicon detectors for radiation sensi ng in high energy physics experiments DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-188@events.saip.org.za DESCRIPTION:Speakers: THOKOZANE MOSES SITHOLE (UNIVERSITY OF SOUTH AFRICA) \nSilicon radiation detectors are widely used in high energy and nuclear p hysics experiments hence they incur radiation damage. This leads to degrad ations in detector performance which include increases in leakage current\ , bulk resistivity and space charge concentration. The increase in space c harge concentration is particularly damaging since it significantly increa ses the sensor’s full depletion voltage\, causing either breakdown if op erated at high biases or charge collection loss if operated at lower biase s than full depletion. The detectors have also been found to be conductivi ty type inverted after the damage from n-type to apparent p-type. The dama ge is also responsible for a negative capacitance in forward bias and a lo w voltage peak in reverse bias of the detector.\n The results of these par ameters have not been fully understood and thus the effects of radiation o n silicon devices still need to further studied. \n The doping (defect eng ineering) of silicon with lifetime killers such as gold and platinum gener ates defects that are responsible for suppression of radiation effects. Th ey create “mid-gap defects” in the band-gap of silicon. The metals ar e however expensive and not easily available for research. \nGadolinium is a rare earth metal that is going to be used to generate defects in silico n. Gadolinium is very reactive and ferromagnetic with large net moment due to its half full f shell. Therefore it is important to study silicon dope d gadolinium to understand the diffusion mechanisms of the metal.\n \nKey words: Si detector\, radiation damage\, gadolinium doped silicon radiation detectors.\n\nhttps://events.saip.org.za/event/100/contributions/188/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/188/ END:VEVENT BEGIN:VEVENT SUMMARY:Attenuation correction for position resolved neutron powder diffra ction studies DTSTART;VALUE=DATE-TIME:20180629T094000Z DTEND;VALUE=DATE-TIME:20180629T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-189@events.saip.org.za DESCRIPTION:Speakers: Deon Marais (Necsa SOC Ltd)\nPhase quantification by means of neutron diffraction relies on the accurate measurement of Bragg peak intensities with respect to diffraction angle. When a neutron beam en ters a sample under investigation\, the beam is attenuated according to an exponential decay equation which is a function of the total distance that the beam has traversed the sample. As the total path length varies with r espect to diffraction angle\, gauge volume position and sample dimensions\ , the acquired diffraction pattern should be treated to account for the at tenuation effect. A new module was designed and integrated with the neutro n diffraction data reduction system ScanManipulator to perform this correc tion. Results show that sample shape and relative orientation can have a d etrimental effect on untreated data which can lead to incorrect phase quan tification. The correction technique can further be used to accurately det ermine diffraction patterns obtained form position resolved neutron diffra ction experiments.\n\nhttps://events.saip.org.za/event/100/contributions/1 89/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/189/ END:VEVENT BEGIN:VEVENT SUMMARY:Initial results and performance evaluation of a high speed OCT sys tem developed at the CSIR National Laser Centre DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-190@events.saip.org.za DESCRIPTION:Speakers: Ameeth Sharma (CSIR)\nSince first being reported in 1991 by Huang\, optical coherence tomography (OCT) has rapidly progressed into a powerful and widely used imaging technique\, more especially in bio medical application. This is due to its non-invasive and non-contact advan tages. Recent developments in laser technology and high speed electronics speeds have enable faster and more precise acquisition making it more comp etitive when compared to other techniques\, like ultrasound. As part of la rger DST funded project\, the CSIR developed a high speed swept source OCT system\, which to our knowledge is the first such system to be developed in South Africa.\nThe system is able to acquire 3D images 25 x 25 mm wide to a depth of 10 mm\, at a resolution of 512 x 512x 2048 pixels\, in appro ximately two seconds. Similar systems available commercially usually offer slower acquisition times or smaller scan areas. In this paper\, we presen t some initial results taken to evaluate the performance and specification s of optical and scanning sub-systems. Data was acquired and the FFT compu ted for both single and multiple reflectors. We will give an overview of t he system and elaborate on the analysis of the acquired data obtained to v alidate the performance of the laser and evaluate the depth resolution of the system compared against theoretical predications.\n\nhttps://events.sa ip.org.za/event/100/contributions/190/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/190/ END:VEVENT BEGIN:VEVENT SUMMARY:Magnetic and physical properties of new hexagonal PrPt4 X (X = Ag\, Au) compounds DTSTART;VALUE=DATE-TIME:20180627T144000Z DTEND;VALUE=DATE-TIME:20180627T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-191@events.saip.org.za DESCRIPTION:Speakers: Michael Ogunbunmi (University of Johannesburg)\nWe h ave synthesized PrPt4Ag and PrPt4Au compounds for the first time and repor t their crystal structure\, as well as magnetic and physical properties in the temperature range between 2 K and 300 K. Both compounds are derived f rom the substitution of Pt with Ag and Au respectively in the parent compo und PrPt5 which crystallizes in the hexagonal CaCu5-type structure [1\, 2] . Here\, we observed the preservation of the hexagonal CaCu5-type structur e under such substitutions which is in contrast to the observations in PrC u4Ag and PrCu4Au [3\, 4] adopting the cubic MgCu4Sn-type structure upon su bstitution on parent hexagonal PrCu5. The temperature dependence of specif ic heat\, Cp(T) and electrical resistivity\, &rho(T) of PrPt4Ag show an an omaly at 7.6 K but which is absent in the magnetic susceptibility\, &chi(T ) and thus suggesting a possible multipolar ordering of the Pr3+ magnetic moment. PrPt4Au on the other hand does not show any anomaly but an upturn in Cp(T)/T below about 10 K and reaching a value of 1.23 J/(K2mol) at 2 K. In addition\, &rho(T) ~ T and &chi(T) ~ T-1/3 for nearly a decade in temp erature. These observations in PrPt4Au are the hallmark of a non-Fermi liq uid (nFL) behavior and is characteristic of a system with a low lying orde r parameter. The analysis of the low temperature Cp(T) for PrPt4Ag and PrP t4Au give values of the Sommerfeld coefficient\, &gamma = 728.5 mJ/(K2mol) and 509.1 mJ/(K2mol) respectively indicating a significant enhancement of the quasiparticle mass in the two compounds.\n\nhttps://events.saip.org.z a/event/100/contributions/191/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/191/ END:VEVENT BEGIN:VEVENT SUMMARY:Quantum optical implementation of open quantum walks – a general ized approach DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-193@events.saip.org.za DESCRIPTION:Speakers: Ayanda Zungu (Sol Plaatje University / University of KwaZulu-Natal)\nOpen quantum walks (OQWs) are a new type of quantum walks \, where the “walker” is driven by dissipation [J. Stat. Phys. 147 (20 12) 832]. Recently\, a quantum optical scheme for the experimental realiza tion of OQWs was proposed [Int. J. Quant. Info. 12\, 1461010 (2014)]. In t he proposed quantum optical scheme\, a two level atom plays the role of th e “walker’’ and the Fock states of the cavity mode correspond to the lattice sites of the OQW. Using the small unitary rotations approach and rotating wave approximation the effective dynamics of the system is shown to be an OQW. The presence of spontaneous emission in the system was the k ey ingredient for obtaining an OQW. However\, the spontaneous emission lea ds to an uncompensated and continuous loss of energy by the system\, which is reflected in the relatively poor dynamics of the “walker’’. To o vercome this problem\, an external driving term of the cavity mode or two level systems was added to the system to pump in energy and drive the “w alker” in both directions.\n\nKeywords: Open quantum walks\; quantum opt ics\; quantum dynamics engineering.\n\nhttps://events.saip.org.za/event/10 0/contributions/193/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/193/ END:VEVENT BEGIN:VEVENT SUMMARY:Creation\, characterization and analysis of propagation invariant vector flat-top beams DTSTART;VALUE=DATE-TIME:20180627T122000Z DTEND;VALUE=DATE-TIME:20180627T124000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-194@events.saip.org.za DESCRIPTION:Speakers: NKOSIPHILE ANDILE BHEBHE (UNIVERSITY OF THE WITWATER SRAND)\nLaser beams structured to have a uniform peak intensity profile (f lat-top) have become ubiquitous and a topic of interest in many research f ields. However\, such beams alter their intensity profile as they propagat e in free space. This problem can be overcome by generating vector flat-t op beams. Here\, we present theoretical simulations and demonstrate experi mentally the creation of propagation invariant vector flat-top beams. By u tilizing the spatial light modulator’s polarization dependent efficiency \, we coaxially superimpose a Gaussian and donut beam with orthogonal pola rization states. We employ a classical and quantum toolkit to characterize and analyse the vector state of the resulting vector flat-top beam during propagation. As an example\, we demonstrate the adaptability of these be ams in an optical tweezer system however these beams can be of impact in a wide range of applications.\n\nhttps://events.saip.org.za/event/100/contr ibutions/194/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/194/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthesis and characterization of Halide Perovskite Materials for Photovoltaic Application DTSTART;VALUE=DATE-TIME:20180628T080000Z DTEND;VALUE=DATE-TIME:20180628T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-195@events.saip.org.za DESCRIPTION:Speakers: Akin Olaleru (University of venda\, South Africa)\nA mong all the components of perovskite solar cells (PSCs)\, the perovskite materials play a central role in light absorption and photoelectric conver sion. The optimization of the materials and structures is a key to enhanci ng the conversion efficiency. The perovskite materials for inclusion into solar cells were prepared by one and two-steps solution fabrication proces s to generate polycrystalline structures with diverse grain sizes. PbI2\, PbCl2 and MAI were used in the synthesis of organic-inorganic hybrid pero vskite \, as they facilitate the formation of well-organised perovskite la yer. In a quest to improve the performance of these devices\, the effect o f synthesis approach on the properties of the material have been investiga ted. Our fundamental objective therefore was to determine how synthesis in fluences the structure and the properties of perovskite material for the a pplication in photovoltaic cell. Samples were characterized by X-ray dif fraction (XRD)\, scanning electron microscope (SEM)\, UV-Vis spectrometry and thermogravic analysis (TGA). Subsequent to the characterization the l ight harvesting efficiencies of these materials have been investigated whi ch is significant for photovoltaic materials. \nKey words: Hybrid perovski te\, solar cells\, synthesis\, properties\, characterization\n\nhttps://ev ents.saip.org.za/event/100/contributions/195/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/195/ END:VEVENT BEGIN:VEVENT SUMMARY:Estimation of ionospheric vertical drifts based on magnetometer an d satellite data DTSTART;VALUE=DATE-TIME:20180628T100000Z DTEND;VALUE=DATE-TIME:20180628T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-196@events.saip.org.za DESCRIPTION:Speakers: John Bosco Habarulema (South African National Space Agency)\nThis work presents the development of a mathematical relationship between ground-based magnetometer and satellite data to estimate long-ter m values of ionospheric vertical drift during local daytime. The expressio n is developed based on a relatively long-term data set during 2008-2014 a nd validated with radar observations. The obtained correlation coefficient values computed using observed and derived vertical drift velocities are 0.78 and 0.83 for two different sets of radar measurements during 2008-201 4 when data was available. In this talk\, we will show that this approach is applicable during both quiet and disturbed conditions\; and forms a bas is for development of high resolution vertical drift models in equatorial latitudes.\n\nhttps://events.saip.org.za/event/100/contributions/196/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/196/ END:VEVENT BEGIN:VEVENT SUMMARY:Mesospheric Ozone Monitoring DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-198@events.saip.org.za DESCRIPTION:Speakers: Ed Lopez (University of Michigan)\nSANSA has built a low-cost (USD 100-) mesospheric ozone radiometer based on a BeagleBone mi cro-controller running Linux. This presentation describes the development of a real-time data viewer and algorithm that analyses the ozone spectrum to infer ozone density. A spectrum is generated roughly every 5 minutes\, and one data file per day. Results examining ozone density as a function o f day-of-year will be presented along with a description of the code devel opment.\n\nhttps://events.saip.org.za/event/100/contributions/198/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/198/ END:VEVENT BEGIN:VEVENT SUMMARY:Mitigating the effect of fake missing energy using Machine learnin g in the ATLAS experiment DTSTART;VALUE=DATE-TIME:20180627T094000Z DTEND;VALUE=DATE-TIME:20180627T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-223@events.saip.org.za DESCRIPTION:Speakers: Kehinde Tomiwa (University of the Witwatersrand)\nTh e missing transverse momentum in the ATLAS experiment is the momentum imba lance in the plane transverse to the beam axis. That is the resultant of t he negative vectorial sum of the momenta of all particles that are involve d in the proton-proton collision. A precise measurement of the missing tra nsverse energy is essential for many physics studies at the LHC\, such as Higgs boson measurements and dark matter search. The result presented in t his study are from the implementation of Boosted Decision tree (BDTs) base d on vertex variables and fake/real missing samples. The preliminary resul ts show the BDTs classifiers can improve signal purity to about 50% as com pared to the nominal selection.\n\nhttps://events.saip.org.za/event/100/co ntributions/223/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/223/ END:VEVENT BEGIN:VEVENT SUMMARY:Spectroscopy of trivalent neodymium ions (Nd3+) in zinc oxide (ZnO ) powders and thin films. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-199@events.saip.org.za DESCRIPTION:Speakers: Nyepudzai Charsline Gatsi (University of the Witswat ersrand\, African Materials Science and Engineering Network (A Carnegie-IA S Network))\nZinc oxide is a wide band-gap semiconductor that is considere d a good host for rare-earth ions. Nd3+ ions doped into ZnO cause variatio ns to the broad emission band that arises from the intrinsic vacancy\, ant isite and interstitial defects. The Nd3+ ions give rise to narrow and disc rete absorption and emission bands superposed on the broad band. Most of t he ZnO:Nd3+ emission reported in the literature was obtained using UV exci tations and with the sample at 300 K. The results presented here were obta ined from spectroscopic studies of ZnO:1mol%Nd:10mol%Li annealed powders ( in pellet form) and ZnO:3mol%Nd as-deposited films conducted at 10 K. Argo n ion laser lines in the 457 – 515 nm wavelength range were used for exc itation. Both the powders and the films yielded the broad emission band ch aracteristics of intrinsic ZnO defects as well as sharp emission transitio ns characteristic of Nd3+ ions. The Nd3+ emission occurs in the 895 to 905 nm wavelength range and is attributed to the 4F3/2 → 4I9/2 transitions. This near-infrared Nd3+ emission has found uses in bio-imaging and colore d-light emission while the re-absorption is used to block the yellow-flame glow on welding goggles. In addition\, several Nd3+ re-absorption bands w ere superposed on the broad emission for the powder samples. Doped pellets have potential use as cost-effective targets for thin-film deposition by the pulsed laser technique.\n\nhttps://events.saip.org.za/event/100/contri butions/199/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/199/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigating the relationship between Ground level enhancement ev ents and radiation enhancement at aviation altitude DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-200@events.saip.org.za DESCRIPTION:Speakers: Kyle Webster (University of Michigan)\nCosmic partic le flux is significantly higher on-board aircraft than at ground level. Th e radiation field at aviation altitude is very complex in terms of particl e composition and particle energies and as such\, the dose assessment is a very difficult task. The dose is usually estimated using numerical codes validated by experimental data. Ground‐level enhancements (GLEs) are sud den\, sharp\, and short‐lived increases in cosmic ray intensities regist ered by neutron monitors. These enhancements are known to take place durin g powerful solar eruptions such as solar flares\, coronal mass ejections ( CMEs)\, and solar energetic particle (SEP) fluxes. In this project\, the i dea is to analyze neutron monitor data during a solar storms that lead to a Forbush decrease and subsequently a GLE. The idea is to see how much the se series of events can influence or contribute to increasing dose at avia tion altitude. The Dose rate will be computed along certain chosen route b y using Model for Atmospheric Ionization Radiation Effects (MAIRE)\, the S ievert and EpCard online calculator\, to see if during an events there is a significant increase.\nThe neutron monitor data (from four neutron monit ors in Southern Africa: Hermanus (oldest in the world)\, Potchefstroom\, S anae (Antarctica)\, and Tsumeb (Namibia)) will also be utilized as this da ta gives the information about GLEs. The standard geomagnetic activity par ameters (Kp\, Bz the southward component\, Solar wind data and Dst) will b e used as an indicator to show the level of disturbance.\n\nhttps://events .saip.org.za/event/100/contributions/200/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/200/ END:VEVENT BEGIN:VEVENT SUMMARY:Global ionospheric vertical drift studies DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-201@events.saip.org.za DESCRIPTION:Speakers: Gabriel Lefebvre (University of Michigan)\nElectrody namic and dynamic processes mainly control low and equatorial latitude ion ospheric electron density changes. The transportation of plasma to high al titudes where recombination rate is lower over the equatorial regions resu lts in the formation of the equatorial ionization anomaly\ncharacterized b y enhancement of electron density at approximately 15 degrees latitude on both sides of the geomagnetic equator. Magnitudes of vertical ExB drifts i nfluence the extent of development of ionospheric irregularities and hence useful to understand for communication and navigation applications. Despi te the critical importance of vertical ExB drift (Lorenz force)\, long-ter m direct observations of low latitude electric field data remains scarce i n a number of longitude sectors. As a result\, a number of studies rely on Low Earth satellite data that are more appropriate for climatological stu dies. A useful complimentary data is daytime observations from ground-base d magnetometers. Ground-based magnetometer data have advantage of being co ntinuous with high temporal resolution and are available in a number of lo ngitude sectors\, thus increasing the probability of getting coincidental observations when the satellite is within the vicinity of the magnetometer location. It is established that the difference between horizontal compon ents of the Earth’s magnetic field observations (ΔH) from magnetometer locations at the equator and about 6- 9 degrees away from the equator is a proxy of EEJ\, which has a linear relationship with vertical ExB drift. T he framework of the current project involves performing climatological stu dies of vertical drifts observed by the Communications and Navigation Outa ge Forecasting System (C/NOFS) satellite and EEJ data with the ultimate ai m of developing a global model of low latitude vertical drifts.\n\nhttps:/ /events.saip.org.za/event/100/contributions/201/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/201/ END:VEVENT BEGIN:VEVENT SUMMARY:Statistical properties of 180\,181\,182Ta and their implications f or 180Ta nucleosynthesis DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-202@events.saip.org.za DESCRIPTION:Speakers: Kgashane Malatji (iThemba LABS / Stellenbosch Univer sity)\nMost stable and extremely low abundance proton-rich nuclei with A>1 10 are thought to be produced by the photodisintegration of s- and r- proc ess seed nuclei. However\, this so-called p-process is insufficient to exp lain the observed low abundance (0.012%) of the 180Ta isotope. Hence combi nations of several processes are considered to reproduce the observed abun dance of 180Ta in the cosmos\, provoking debates and making it a unique ca se study. Significant uncertainties in the predicted reaction rates in p-n uclei arise due to large uncertainties in nuclear properties such as the n uclear level densities (NLD) and gamma-ray strength functions (γSF) (S. G oriely et al.\, 2001)\, as well as the actual astrophysical environments. An experiment was performed in October 2014 to extract the NLD and γSF be low the neutron threshold (Sn) in 180\,181\,182Ta isotopes which provide i mportant input parameters for nuclear reaction models. In the present case study\, these parameters were measured using the 181Ta(3He\,3He’γ) and 181Ta(3He\,4Heγ) reactions with 34MeV beam\, 181Ta(d\,d'γ) and 181Ta(3H e\,tγ) reactions with 15 MeV beam \, and 181Ta(d\,d'γ) and 181Ta(d\,pγ) reactions with 12.5 MeV beam at the Oslo Cyclotron Laboratory (OCL). Usin g the SiRi array at backward angles (64 silicon particle telescopes) and t he CACTUS array (26 NaI(Tl) detectors)\, the NLD and γSF were simultaneou sly extracted below Sn from particle-γ coincidence matrices through itera tive procedures using the Oslo method (A. Schiller et al.\, 2000). The exp erimental results have been used to determine the corresponding neutron ca pture cross sections\, which in turn were utilized to extract Maxwellian a veraged cross sections. The latter were further used in astrophysical s- a nd p-process network calculations to investigate the galactic production m echanism of 180Ta. In this talk I will present final results on the statis tical properties of 180\,181\,182Ta and their implications for the nucleos ynthesis of 180Ta. \n\nThis work is based on the research supported in par t by the National Research Foundation of South Africa Grant Number 92600 a nd the IAEA under research grant number 20454.\n\nhttps://events.saip.org. za/event/100/contributions/202/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/202/ END:VEVENT BEGIN:VEVENT SUMMARY:Data Processing Procedure for the Time-of-Flight Spectrometer of H eavy Ions in the wide range of Energies. DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-204@events.saip.org.za DESCRIPTION:Speakers: Vusi Malaza (Stellenbosch University\, Faculty of Mi litary Science)\nAt the present moment it is well known that detecting fis sion fragments from a decay of heavy nuclei using silicon detectors comes with two experimental challenges\, namely Pulse Height Defect and Plasma d elay. The negative effect of the Pulse Height Defect (PHD) is observed whe n registering the energy of the fission fragment and the one of Plasma Del ay (PD) is observed when registering time of the fission fragments using t he silicon detectors. Finding a solution to these experimental challenges is critical to the investigation of the decay of low excited heavy nuclei called “Collinear Cluster Tri-partition” (CCT)[1].\n\nA precise but ra ther complicated procedure that takes into account the above mentioned exp erimental challenges (PHD and PD) has been successfully developed. This pr ocedure involves an iterative process where the correct masses of fission fragment are calculated taking into account both PHD and PD in the measure ment of energy and Time-Of-Flight (TOF) respectively. This procedure is di vided into 3 stages. The first stage is the first approximation where the energies of the fission fragment is calculated without taking into account the PHD and the PD. The second stage is the calculation of the PHD value using an empirical formula derived by Mulgin et al [2]. The last stage inv olves using a special equation suggested by Neidel and Henschel [3] to cal culate the PD. In this way\, the correct PD values are obtained and are th en used to calculate the correct TOF for fission fragments. \n\nA special code to perform the abovementioned procedures was first designed in Fotran 95 programming language. At the moment a newly improved and modern code i s currently being developed in C++ programming language. This modern code also includes a design of an easy to use graphical interface that runs the iteration used to find the parameters without compiling. In this paper we present both the description of this analysis procedure and a detailed ex planation of this modern code.\n\nReferences:\n1. Pyatkov Yu.V. et al.\,Eu r. Phys. J. A 48 (2010) p 94\n2. Mulgin S. et al.\, NIM A 388 (1997) p 254 -259.\n3. Neidel H\, Henschel H.\, Nucl. Instr. Meth. 178 (1980) p137 - 14 8\n\nhttps://events.saip.org.za/event/100/contributions/204/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/204/ END:VEVENT BEGIN:VEVENT SUMMARY:First principles studies of Palladium nanoparticles on TiO2 surfaces. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-205@events.saip.org.za DESCRIPTION:Speakers: Andile Mazibuko (yes)\nPrecious metal catalysts\, wh ich include the platinum group metals (PGMs)\, find their way into process es such as in emission control technology. Metal nanoparticles supported o n metal oxides are being considered as catalysts in the emission control t echnology\, with the most used catalysts being the Pt and Pt-based catalys ts. However\, Pd-based catalysts are being developed since they have simil ar electronic configurations and lattice constants as Pt but are cheaper a nd show other interesting properties which find them suitable for use in c atalytic converters. Here it is shown that the rutile (110) surface is sta ble and thus a suitable support material to be used in this type of cataly sis\, whereas previously anatase was suggested. The palladium clusters sho w that Pd13 is stable from its least negative second order difference (D2E ) energy value. Furthermore\, we found that the interactions of the Pd13/T iO2 gave the most favourable site to be the one where Pd13 adsorbs on the bridging oxygen. This suggests that adsorption is likely to be more effect ive when the catalyst and support material are configured in that order. O ur results demonstrate how the interaction of the stable components of Pd1 3/TiO2 will result in more carbon monoxide emissions being controlled when used in catalytic converters because of the high affinity to hydrogen tha t the Pd13-catalyst has which will subsequently result in the conversion o f carbon monoxide into carbon dioxide and water.\n\nhttps://events.saip.or g.za/event/100/contributions/205/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/205/ END:VEVENT BEGIN:VEVENT SUMMARY:Fast algorithm for the computation of the CMB polarization TE power spectrum using non-circular beam DTSTART;VALUE=DATE-TIME:20180627T100000Z DTEND;VALUE=DATE-TIME:20180627T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-206@events.saip.org.za DESCRIPTION:Speakers: Fidy Andriamanankasina Ramamonjisoa (University of t he Free State)\nA precise measurement of the Cosmic Microwave Background ( CMB) anisotropy has been one of the foremost concerns in modern cosmology as it provides a valuable information on the cosmology of the Universe. Th e estimation of the CMB power spectrum is complicated by different system atics. For the polarization experiments\, the signals are rather fainter i n comparison with the CMB total intensity\, which may lead to an important bias in the estimation of the angular power spectrum. One of the most imp ortant source of bias in CMB polarization experiment is the beam asymmetry . We present a semi-analytical framework using the pseudo-Cl estimator to compute the power spectrum TE of the temperature anisotropy and the E-comp onent of the polarization radiation field using non-circular beams. We ass ume that the beam is non-rotating. We adopt a model of beams obtained from a perturbative expansion of the beam around a circular (axisymmetric) bea m in harmonic space. We compute the resulting bias matrix which relates th e true power spectrum with the observed one by using an efficient algorith m for rapid computation. We show that for a multipole up to lmax=500\, th e bias matrix can be computed in less than one second with a single CPU pr ocessor at 2.53 GHz. We find that the systematic effect induced by the bea m asymmetry in the temperature and polarization power spectrum at the peak of the bias matrix for the WMAP and Planck experiments can be as large as a few 10 to 20%.\n\nhttps://events.saip.org.za/event/100/contributions/20 6/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/206/ END:VEVENT BEGIN:VEVENT SUMMARY:Signal and background ATLAS Monte Carlo Comparison studies in the H→ZZ→4l Channel. DTSTART;VALUE=DATE-TIME:20180627T104000Z DTEND;VALUE=DATE-TIME:20180627T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-224@events.saip.org.za DESCRIPTION:Speakers: Mzwandile Thabede (University of the Witwatersrand)\ nThe search for new heavy particles in the H→ZZ→4l decay channel repre sents one of the most promising searches in High Energy Physics. This stu dy focuses on the hadronic properties of this channel which leads to the f inal state consisting of four isolated leptons plus at least two light fla vor jets. gg→H signal and qq→ZZ background studies using High mass (m4 l > 140 GeV) ATLAS Monte Carlo samples with different pile-up conditions a re conducted. Comparisons of the shapes of the distributions are made betw een two sets of qq→ZZ background as well as two sets of gg→H (m4l = 20 0 GeV) signal Monte Carlo samples. Expected yields in each of the two sets of qq→ZZ background and signal efficiencies in each set of the gg→H s ignal Monte Carlo samples are also calculated and compared.\n\nhttps://eve nts.saip.org.za/event/100/contributions/224/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/224/ END:VEVENT BEGIN:VEVENT SUMMARY:Producing introductory videos for student preparation for physics practical work DTSTART;VALUE=DATE-TIME:20180626T092000Z DTEND;VALUE=DATE-TIME:20180626T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-207@events.saip.org.za DESCRIPTION:Speakers: Antonie Fourie (University of the Free State)\nExper imental work in the physics curriculum is vital to gain practical scientif ic skills as well as a better understanding of models and measurement. Due to increasing student numbers\, limited equipment and laboratory space\, students do not have unlimited time to perform experiments during practica l sessions. Therefore students need to be increasingly well prepared in or der to complete them successfully. Improved access to the internet has mad e it feasible to use introductory videos for preparation. The aim was not to reduce or replace written instructions or supervision\, but rather to a llow students to see the actual equipment and setup as well as measurement techniques in practice and hence allow the students to make better use of limited laboratory time. Producing the videos using professional help had significant time and cost implications\, so the challenge was set to prod uce these internally with filming equipment available in the department. T o pilot this project\, short introductory videos were produced on four exp eriments dealing with Lissajous figures\, Fourier synthesis\, standing wav es of a string\, and diffraction of light. The demonstrator assigned to ea ch experiment gained experience by acting as the presenter in the video to give an outline of the aim\, equipment\, method and measurement process. A single experiment took approximately 3 h of preparation and filming time \, which was done in short segments of a few sentences at a time. It was u seful to have two cameras so that an overview and close-up could be captur ed simultaneously. With the available filming equipment the quality video was excellent while the audio quality was merely sufficient. Editing of th e videos was done using free software. The running time and resolution wer e limited to keep the file size to a minimum for easier access on or off c ampus. Anonymous feedback on the videos was collected from students e.g. i nitial results showed that only 39% accessed the videos off-campus\, while 50% viewed them on campus and 11% not at all. It has been demonstrated th at it is possible to create educational videos at low cost and the experie nce gained will allow improvement of quality and saving of time for future endeavours. A later phase of this project will include assessment whether the videos improve student practical work performance.\n\nhttps://events. saip.org.za/event/100/contributions/207/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/207/ END:VEVENT BEGIN:VEVENT SUMMARY:A bond energy model to study the melting point and Debye temperatu re of nanomaterials DTSTART;VALUE=DATE-TIME:20180626T080000Z DTEND;VALUE=DATE-TIME:20180626T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-208@events.saip.org.za DESCRIPTION:Speakers: Madan Singh (National University of Lesotho)\nThe ph ysical properties of materials change when the size of the material approa ches from bulk to nanoscale. The size effect is taken by increasing the fr action of the surface atoms with lower coordination numbers\, therefore in creasing number of dangling bonds\, which results in causing the thermodyn amical properties as cohesive energy at nanoscale. The cohesive energy of nanoparticles decreases due to the dangling chemical bonds. On considerin g the surface effect\, using bond energy model\, a size dependent theory i s discussed to study the melting point and Debye temperature of nanoscale materials. The number of atoms on the surface to the total number of atoms in nanosolid is analysed in terms of shape factor and the size of nanomat erials. The variation of melting point and Debye temperature is reported f or spherical\, regular tetrahedral\, regular hexahedral and regular octahe dral nanomaterials. It is found that the melting temperature and Debye tem perature decrease as the particle size is reduced. The result reported is compared with the available experimental and simulation data. A good agree ment between the present calculated results and the results reported by ea rlier researcher confirms the validity of the existing theory. Due to the simplicity and applicability\, this model can be extended to the other nan omaterials and may be the recent consideration of the scholars engaged in the study of thermodynamical properties of nanosolids.\n\nhttps://events.s aip.org.za/event/100/contributions/208/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/208/ END:VEVENT BEGIN:VEVENT SUMMARY:The thermal quenching process of the La2O2S: Eu(III) phosphor material DTSTART;VALUE=DATE-TIME:20180626T102000Z DTEND;VALUE=DATE-TIME:20180626T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-209@events.saip.org.za DESCRIPTION:Speakers: Lucas Erasmus (University of the Free State)\nThis s tudy is concentrating on the measurement of the emission of commercially a vailable lanthanum oxysulphide doped with europium(III) (La2O2S:Eu(III)) p hosphor material at various temperatures. For the thermal quenching proces s\, the average activation energies for the emission from the 5D2\, 5D1 an d 5D0 excited states were determined as 0.49 eV\, 0.55 eV and 0.77 eV\, re spectively and the average pre-exponential constant was determined as 9.5 ×107 s-1. The optical band gap of La2O2S:Eu(III) was determined as 2.75 e V. It was also established that the sulphur(II) to europium(III) (Eu(III)) charge transfer band absorbs ultraviolet light and transfers the excited electrons to the excited states of the Eu(III) ions from where emission ca n take place. The lifetime of the luminescence results indicated that the higher excited states have a double exponential lifetime that results from the emission from both the conventional Eu(III) ions and Eu(III) ions tha t are in the vicinity of a defect or impurity group. It was determined tha t in the case of the La2O2S:Eu(III) phosphor material\, the presence of de fect or impurity groups is due to the hydroxide groups that forms when the material was exposed to water vapour in the atmosphere at room temperatur e. The average emission decay constants of the 5D2\, 5D1 and 5D0 excited s tates were determined as 10 ns\, 80 ns and 340 ns respectively. It was als o revealed that La2O2S:Eu(III) can be utilised as a temperature sensor by using the fluorescence intensity ratio of the emission from the 5D1 and 5D 0 excited states. This worked well for the temperature range from 80 °C t o 180 °C.\n\nhttps://events.saip.org.za/event/100/contributions/209/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/209/ END:VEVENT BEGIN:VEVENT SUMMARY:Phenomenology of 2HDM+S at the LHC DTSTART;VALUE=DATE-TIME:20180626T092000Z DTEND;VALUE=DATE-TIME:20180626T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-211@events.saip.org.za DESCRIPTION:Speakers: Mukesh Kumar (University of the Witwatersrand)\nEvid ences of new physics begins from the updated data sets at the ATLAS and CM S detectors based at the Large Hadron Collider. Among the noted deviations in multi-lepton final states which leads signatures of the heavy scalars beyond the Standard Model Higgs boson\, in this talk we discuss how these deviations can be explained by introducing two scalars of masses around 15 0 and 270 GeV in an effective filed theory approach and further in a model dependent two-Higgs doublet model with an additional singlet scalar (2HDM +S). Also we explain how the parameter space of this model constrained fro m the available relevant data sets. Further associated phenomenology of 2H DM+S is discussed.\n\nhttps://events.saip.org.za/event/100/contributions/2 11/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/211/ END:VEVENT BEGIN:VEVENT SUMMARY:The effect of photobiomodulation at 660 nm on the differentiation of diabetic wounded WS1 human fibroblasts into myofibroblasts DTSTART;VALUE=DATE-TIME:20180629T102000Z DTEND;VALUE=DATE-TIME:20180629T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-212@events.saip.org.za DESCRIPTION:Speakers: Dimakatso Mokoena (Laser Research Center\, Universit y of Johannesburg)\nDiabetes is associated with complicated wound healing and rapid wound progression which may be due to cells that fail to prolife rate and differentiate\, thus leading to ulcers and limb amputations. The administration of photobiomodulation (PBM) has been associated with increa sed cellular proliferation\, a decrease in wound repair duration and an in crease in wound flexibility. Most studies performed on PBM and myofibrobla sts dwell mostly on fibrosis\, and a minority of studies have investigated fibroblast differentiation for use in diabetic wound healing. This study aimed to determine the effect of PBM at 660nm with 5 J/cm2 on the differen tiation of diabetic wounded human fibroblasts at different time points. Th is was achieved by measuring the expression of the fibroblast surface mark er Thy-1 (CD90) by flow cytometry\, proto-myofibroblast marker EDA fibrone ctin (EDA-FN) by ELISA\, and the myofibroblast marker alpha smooth muscle actin (α-SMA) by flow cytometry. The measurement of the cellular markers was done at 24\, 48 and 72 h. Post-PBM\, there was a significant decrease in Thy-1 at 48 and 72 h\, an increase in EDA-FN at 48 h\, and an increase in α-SMA at 48 and 72 h. PBM at 660 nm with 5 J/cm2 stimulates cellular d ifferentiation of diabetic wounded fibroblast cells into myofibroblasts\, which contributes to the increased rate of wound healing observed in PBM.\ n\nhttps://events.saip.org.za/event/100/contributions/212/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/212/ END:VEVENT BEGIN:VEVENT SUMMARY:f(R) oscillating universes DTSTART;VALUE=DATE-TIME:20180626T104000Z DTEND;VALUE=DATE-TIME:20180626T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-213@events.saip.org.za DESCRIPTION:Speakers: Neo Namane (North West University)\nThe purpose of t his paper is to investigate the oscillatory behavior of the universe throu gh the Schrödinger equation and a modified gravitational background descr ibed by the theory of f(R) gravity. Motivation for this stems from the pro ven periodic structure of the universe when described within the scope of the general theory of relativity. A further analysis of different f(R) toy models and the equation of state associated with each epoch of interest r esults in different behaviors for the wave-function of the universe.\n\nht tps://events.saip.org.za/event/100/contributions/213/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/213/ END:VEVENT BEGIN:VEVENT SUMMARY:Computational modelling of binary titanium-based shape memory allo ys DTSTART;VALUE=DATE-TIME:20180626T104000Z DTEND;VALUE=DATE-TIME:20180626T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-214@events.saip.org.za DESCRIPTION:Speakers: Mphamela Enos Baloyi (UL)\nAb initio density functio nal theory approach was employed to investigate the structural properties\ , elastic constant and phonon dispersion of B2 binary TiPt\, TiCo\, TiNi a nd TiZr shape memory alloys. We employed the plane-wave pseudopotential me thod within generalized gradient approximation parameterized by Perdew\, B urke and Enzerhof using VASP code. These alloys have the ability to rememb er their shapes after deformation\, and this is due to their shape memory effect and super elasticity properties. We found that the lattice paramete rs are in good agreement with the experimental results within 2%. Furtherm ore\, the TiCo system is more stable B2 and displayed higher transformatio n temperature. The Pugh’s ratio clearly indicates that TiPt\, TiCo and T iNi binary alloys are ductile (B/G>1.75) while TiZr alloy are brittle (B/G <1.75). Phonon dispersion curves shows that TiCo is vibrational stable and there are acoustic modes observed at the gamma directions while TiPt and TiNi are not due to the existence of imaginary frequencies observed along M high symmetry direction\, in agreement with the literature.\n\nhttps://e vents.saip.org.za/event/100/contributions/214/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/214/ END:VEVENT BEGIN:VEVENT SUMMARY:Beyond Li-ion: Computational Modelling Studies on Stability of Li- S-Se System DTSTART;VALUE=DATE-TIME:20180626T080000Z DTEND;VALUE=DATE-TIME:20180626T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-215@events.saip.org.za DESCRIPTION:Speakers: Cliffton Masedi (UL)\nRecent rechargeable batteries are mainly based on conventional lithium intercalation chemistry\, using l ithium transition metal oxides as cathode material with typical capacities of 120-160 mA.h/g. The low energy density and/ or high cost of these cath ode materials have limited their large scale production and application in Li ion batteries. Exploration of new cathode materials is consequently ne cessary to realise more efficient energy storage systems. Lithium sulphur cells have a promise of providing 2-5 times the energy density of Li-ion c ells\, however\, they suffer poor cycling performance. Improvements that a re effected by using Li/SeS x system in different electrolytes have been r eported. \nIn the current study we employ computational modelling methods to explore stability\, structural and electronic properties of discharge p roducts formed in the Li/SeS x battery\, which has potential to offer high er theoretical specific energy and remedies the challenges that Li-S batte ry encounters. First principle methods were used to calculate thermodynami c properties of Li 2S and Li 2Se\, which agreed with available experimenta l results. A cluster expansion technique generated new stable phases of Li /SSe x system and Monte Carlo simulations determined concentration and tem perature ranges in which the systems mix. Interatomic Born Meyer potential models for Li2S and Li2Se were derived and validated and used to explore high temperature structural and transport properties of mixed systems. Our study demonstrated that a combination of different computational techniqu es could assist in generating new stable phases of materials for future hi gh energy density rechargeable batteries.\n\nhttps://events.saip.org.za/ev ent/100/contributions/215/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/215/ END:VEVENT BEGIN:VEVENT SUMMARY:Effects of annealing on luminescent properties of mixed lanthanum oxyorthosilicates co-doped Dy3+ and Pr3+ phosphors DTSTART;VALUE=DATE-TIME:20180629T082000Z DTEND;VALUE=DATE-TIME:20180629T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-216@events.saip.org.za DESCRIPTION:Speakers: Simon Nnalue Ogugua (University of the Free State)\n Effects of annealing on luminescent properties of mixed lanthanum oxyortho silicates co-doped Dy3+ and Pr3+ phosphors.\nSimon N. Ogugua1\, Hendrik C. Swart1\, Odireleng M. Ntwaeaborwa2\n1 Department of Physics\, University of the Free State\, Bloemfontein\, ZA9300\, South Africa.\n2School of Phys ics\, University of the Witwatersrand\, Private Bag 3\, Wits\, 2050\, Sout h Africa.\n\nFor the past three decades\, phosphors have made an impressiv e contribution to technological development for various applications inclu ding\, solid-state lighting\, solar cells\, theft prevention\, optical amp lifiers\, optical lasers\, medicine\, etc. We have investigated photolumin escent and cathodoluminescent properties of mixed lanthanum oxyorthosilica tes co-doped with dysprosium (Dy3+) and praseodymium (Pr3+). When co-doped with Dy3+\; Pr3+either act as a sensitizer or excitation energy absorber depending on the host material. Pr ions can exist in the trivalent (Pr3+) or tetravalent (Pr4+) state\, but only the Pr3+ ions are optically active\ , while the Pr4+ ions are luminescence quenchers. Hence\, it is important to reduce the amount of Pr4+ ions in any luminescence material to improve intensity of emitted light. We have prepared single and mixed host lanthan um yttrium oxyorthosilicates (La2-xYxSiO5\, x = 0\, 0.5\, 1\, 1.5 and 2) c o-doped Dy3+ and Pr3+ powder phosphors using solution combustion synthesis . The materials were annealed at 950 °C in air and 5% H2 (in Ar) gas to r educe the oxygen vacancies and excess Pr4+ to Pr3+\, respectively. The dif fuse reflectance data showed an absorption peak around 376 nm\, attributed to the O2-→Pr4+ charge transfer band. Both the band gap and luminescenc e properties of the samples were enhanced after annealing in 5% H2 (in Ar) . This suggests that the amount of Pr4+ in the samples decreased as confir med from the X-ray photoelectron spectroscopy results. The luminescence (P L and CL) showed evidence of energy transfer from Pr3+ to Dy3+ in some of the samples. The CIE coordinates of the samples (both PL and CL) showed tu nable colour that was influenced by annealing atmospheres and La to Y rati o.\n\nhttps://events.saip.org.za/event/100/contributions/216/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/216/ END:VEVENT BEGIN:VEVENT SUMMARY:Structural studies of YOF synthesized by hydrothermal and pyrolysi s of trifluoroacetate precursor methods DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-217@events.saip.org.za DESCRIPTION:Speakers: Nadir Saeed (University of the Free State)\nThe crys tal structure of yttrium oxyfluoride (YOF) samples were investigated for s olar cell applications [1]. The oxyfluorides show promising host potential since they combine the main advantages of oxides with fluorides\, such as low phonon energy and low probability of multiphoton quenching [2]. YOF s amples were synthesized by the hydrothermal and pyrolysis of trifluoroacet ate precursor methods. The x-ray diffraction patterns exhibit a crystallin e phase of stoichiometric rhombohedral YOF (space group: R3 ̅m (166)) aft er annealing for the hydrothermal and the pyrolysis methods respectively [ 3\, 4]. The as-prepared samples for the hydrothermal method first showed a n amorphous yttrium fluoride (YF3) structure that decomposed by annealing in air at 700 0C into a mixture of orthorhombic YF3 with appearance of pea ks of orthorhombic Y5O4F7 and at 900 0C into a YOF structure with small im purity peaks of cubic yttrium oxide. The as-prepared samples for the pyro lysis method exhibit amorphous yttrium trifluoroacetate that also decompos ed at 700 0C into orthorhombic YF3 with appearance of peaks of orthorhombi c Y5O4F7 and at 900 0C it decomposed into a pure YOF structure. Further in vestigations on the effect of annealing on the crystal structure\, the cry stallite sizes\, the morphology and photoluminescence will be done to comp are between the two synthesis techniques. \n\nReferences\n1. M. Ding\, C. Lu \, L. Cao\, Y. Ni\, Z. Xu\, Optical Materials\, 35 (2013) 1283 – 1287 .\n2. E. Martinez-Castro\, J. Garcia-Sevillano\, F. Cusso and M. Ocana\, J ournal of Alloys and Compounds\, 619 (2015) 44 – 51.\n3. G. Chai\, G. Do ng\, J. Qiu\, Q. Zhang and Z. Yang\, Scientific Reports\, (2013)\, DOI: 10 .1038/srep01598 \n4. Zhihua Lia\,b\, Longzhen Zhengb\, Luning Zhanga\, Ley an Xiongb\, Journal of Luminescence\, 126 (2007) 481 – 486.\n\nhttps://e vents.saip.org.za/event/100/contributions/217/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/217/ END:VEVENT BEGIN:VEVENT SUMMARY:Quantum efficiency of visible-light photochemical water splitting for hydrogen production by photocatalysis DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-218@events.saip.org.za DESCRIPTION:Speakers: Sibusiso Nqayi (ufs)\n: Hydrogen has been labeled as the cleanest energy carrier\, which can be used for fuel cells. However\, the use of clean and renewable energy has been largely hindered by the lo w efficiency of photocatalysts. An efficient and cheap photocatalyst is re quired to produce energy from hydrogen in large quantities to meet the eve r-increasing demand. Water splitting photocatalysts have attracted a lot o f interest because of the environmental friendliness of the technique\, ho wever\, most of these use only 4 % (UV-region) of the solar energy. In thi s study CdS\, nanoparticles for photocatalytic water splitting were synthe sized by using a chemical precipitation method. One of the aims of this i nvestigation was to see to what degree bandgap engineering over a large sp ectral range could be conducted through particle size manipulation. It is well known that the capping agent\, as well as the surfactant concentrati on\, largely contribute to the final nanoparticle size. As such\, in this study\, we investigated to what degree thioglycerol (TG) could be used as a capping agent (to this end). Structural and morphological properties o f the synthesized material were conducted with transmission electron micro scopy (TEM)\, scanning electron microscopy (SEM) as well as Scherrer analy sis of the x-ray diffraction patterns (XRD). We showed that the particle sizes and band gap energy could be successfully controlled with the TG cap ping agent and particle sizes were varied between 6.8 ±1 nm and 1.8 ±1 n m. The quantum-confinement effect was also visually observed in a change in the color of the CdS NP’s from dark yellow to light green with increa sing TG concentration was noted. Small sized particles have a high surfac e-to-volume ratio\, this shortens the distance the electrons travel during separation\, leading to a large number of electrons reaching the surface without recombination. An increase in the bandgap from 2.5 eV (500 nm) to 3.2 eV (384 nm) was observed with UV-vis spectroscopy. Furthermore\, ann ealing studies revealed that an enhancement in the crystallinity of the ma terial may lead to a reduction in the recombination rates of the electron- hole pair during photocatalytic water splitting. Photoluminescence (PL) st udies show a change in luminescence centers with increasing annealing temp erature and crystallinity.\n\nhttps://events.saip.org.za/event/100/contrib utions/218/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/218/ END:VEVENT BEGIN:VEVENT SUMMARY:Fabrication and characterization of Au and ZnO nanowires on silico n substrate spin coated with poly(methylmethacrylate) resist. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-219@events.saip.org.za DESCRIPTION:Speakers: Sekhants'o Lara (University of the Free State\, Depa rtment of Physics)\nOne of the goals of nanoscience and nanotechnology is to synthesize and manufacture nanodevices that are multifunctional\, excep tionally small and sensitive with low power consumption. In the past five decades\, numerous investigations resulted in novel nanodevices with appl ications such as resonators\, biosensors\, logic devices\, transistors\, o ptoelectronics and even in situ biomedical monitoring and detection. Real- time energy harvesting from the environment to power these nanosystems and devices is an essential requirement. As such solar-energy harvesting tec hnologies for nanoscale devices have been an emerging field of research. For example\, a singular silicon nanowire has been demonstrated to fabrica te a photovoltaic cell that is effective to drive a nanowire-based logic g ate or even pH sensor. As an added incentive\, these technologies may fur ther be scaled up to deliver more efficient green energy sources\, by mani pulating the current solar-energy harvesting technologies on the nanoscale to increase their efficiencies. In this study it is shown that metal (Au ) and semiconductor (ZnO) nanowires can be fabricated by a combination of pulsed laser deposition (PLD) and electron beam lithography (EBL). EBL wa s conducted using the electron beam from the auger electron spectroscopy ( AES) system to produce grooves trenched on poly (methyl methacrylate) (PMM A). This polymer was spin coated on oxidized silicon (110) substrates. PM MA thickness for each specimen was then measured using atomic force micros copy (AFM) and x-ray photoelectron spectroscopy (XPS) and the relationship of the thickness to spin speed and PMMA composition was established. The morphology of the fabricated nanowires was examined by utilization of scan ning electron microscope (SEM). The changes in optical and electrical prop erties with respect to nanowires dimensions were investigated through char acterization by photoluminescence (PL)\, UV absorption and solar simulatio n techniques.\n\nhttps://events.saip.org.za/event/100/contributions/219/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/219/ END:VEVENT BEGIN:VEVENT SUMMARY:The \\textbf{{\\textbf{ $H \\to h h\, S h\, S S\\to 4W\\to 4\\ell + 4\\nu$} analysis with the ATLAS detector: optimization and prospects for the full Run-2 data}} DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-222@events.saip.org.za DESCRIPTION:Speakers: Lehumo Mashishi (Wits)\nThe $H \\to h h\, S h\, S S\ \to 4W\\to 4\\ell + 4\\nu$ analysis using \\ensuremath{36.1 fb^{-1}} of $p p$ collision data at a center-of-mass energy of 13~TeV recorded with the A TLAS detector at the Large Hadron Collider is presented. The analysis intr oduces the new Higgs-like scalar\, $S$\, as well as the Standerd Model Hig gs boson\, $h$\, through the decay of the heavy scalar\, $H$. The search i s characterized by four lepton and missing transverse momentum carried out by the neutrinos in the final state. This is a very clean signature with low expected background. The analysis strategy relies on the invariant mas s of the four leptons and also uses dilepton kinematics to reject $ZZ$ bac kground. The paper discusses the published results with \\ensuremath{36.1 fb^{-1}} of the Run-2 data. The analysis optimization and also the prospec ts for the full Run-2 data are also presented.\n\nhttps://events.saip.org. za/event/100/contributions/222/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/222/ END:VEVENT BEGIN:VEVENT SUMMARY:4fN energy level schemes for the di-\, tri-\, and tetravalent lant hanides DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-238@events.saip.org.za DESCRIPTION:Speakers: Hendrik Swart (University of the Free State)\nSince the refinement of the famous Dieke diagram (DD) [1] to include all higher energy levels\, not much progress has been made in this field. It is now c lear\, though\, that the purely theoretical methods have still a long way to go to yield the 4fN (or 5fN) energy levels in any accuracy. This is bec ause the new applications\, e.g. up- and down-conversion\, require energy levels that are ever more accurate. In fact\, these processes are the most efficient when quasi-resonant condition is reached. The proven phenomenol ogical methods to calculate the energy level schemes (and wave functions r equired by many applications) are still the most reliable\, accurate and f astest way. Unfortunately\, some of the published data [2] are so inaccura te that they are of little or no use. In this work\, the energy level sche mes for the di-\, tri-\, and tetravalent lanthanides were calculated takin g into account the crystal field effects as well. The effect of the host w as synchronised for both the R2+ and R3+ series by the use of isomorphic c rystal structures (BaFCl and ROCl\, respectively) facilitating the compari son between them. Utmost care was taken to compare the calculated data wit h the experimental one which was easy for the R3+ but much more scarce for the R2+ series. For the RIV series\, experimental data is virtually inexi stent. The energy level schemes for the R3+ are the most useful ones whils t the 4fN levels of the R2+ series are often masked in practice by the low -energy 4fN-15d1 configuration. The 4fN levels of the RIV series are pract ically inaccessible because of the low-energy charge transfer transitions and the initial low-energy positions of the 4fN levels of RIV species.\nRe ferences\n[1] R.H.T. Wegh\, A. Meijerink\, R.-J. Lamminmäki\, J. Höls ä\, J. Lumin. 87-89 (2000) 1002.\n[2] C.-G. Ma\, M.G. Brik\, D.-X. Liu \, B. Feng\, Ya Tian\, A. Suchocki\, J. Lumin. 170 (2016) 369.\n\nhttps:// events.saip.org.za/event/100/contributions/238/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/238/ END:VEVENT BEGIN:VEVENT SUMMARY:Persistent luminescence excitation of BaAl2O4:Eu2+\,Dy3+ DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-239@events.saip.org.za DESCRIPTION:Speakers: Hendrik Swart (University of the Free State)\nBaAl2O 4:Eu2+\,Dy3+ is the heaviest but the least efficient persistent luminescen t material in the MAl2O4:Eu2+\,R3+ series. Low efficiency may be due to th e hygroscopic host material and/or polymorphic crystal structure [1]. Both may deteriorate the persistent excitation and emission through a change i n the trap structure thus shortening the persistent duration. Charging of BaAl2O4:Eu2+\,Dy3+ is rather slow\, a steady state was achieved only after 30 s. Deconvolution of the thermoluminescence (TL) curves yielded a singl e trap with a depth of 0.8 eV after UV irradiation. Results agree well wit h studies on BaAl2O4:Eu2+\,Dy3+ prepared with solid state and combustion m ethods [2]. 3D persistent excitation spectroscopy used in this study gives more detailed information than the simple TL measurements. The irradiatio n of BaAl2O4:Eu2+\,Dy3+ with 200 to 500 nm UV-vis radiation has no effect on the shape of the TL glow curves consisting of a single band at 57 °C. The excitation spectra show little fine structure: at least two bands at 2 80 and 330 nm (max) with a shoulder at 380 nm. This structure may be due t o the splitting of the 2D excited level of Eu2+. The use of free solar ene rgy for excitation is thus limited. The 3D TL emission spectra show only o ne broad band at 500 nm despite two Ba2+ sites. The BaAl2O4:Eu2+\,Dy3+ mat erials are interesting persistent phosphors though UV excitation is requir ed. The shallow trap at 0.8 eV yields weak and short persistent luminescen ce at room temperature\, as well. A stable crystal structure would be an a dvantage\, too.\nReferences\n[1] J. Hölsä\, H.C. Swart\, L.C.V. Rodri gues\, H.F. Brito\, M. Lahtinen\, M. Lastusaari\, ESTAC-11\, Aug. 17-21\, 2014\, Espoo\, Finland.\n[2] L.C.V. Rodrigues\, R. Stefani\, H.F. Brito \, M.C.F.C. Felinto\, J. Hölsä\, M. Lastusaari\, T. Laamanen\, M. Malkam äki\, J. Solid State Chem. 183 (2010) 2365.\n\nhttps://events.saip.org.za /event/100/contributions/239/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/239/ END:VEVENT BEGIN:VEVENT SUMMARY:Extensions of THERMUS and its Applications in High Energy Particle collisions DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-240@events.saip.org.za DESCRIPTION:Speakers: DAWIT WORKU (Cape Peninsula University of Technology )\nWe have analyzed and discussed the hadronic abundances measured in Au-A u\, p-p and Pb-Pb collisions at RHIC and LHC experiments using THERMUS. Th e results were obtained with two particle data tables\, and their differen ces were explained. In particular\, the data from the RHIC experiment for Au-Au collisions at 130 GeV and 200 GeV were discussed and analyzed. Simil arly\, using the preliminary particle yield results of p-p collisions at 0 .9 TeV and 7 TeV as well as Pb-Pb collision at 2.76 TeV particle yield cal culations were presented and the thermodynamic parameters were obtained fr om the fits.\n\nhttps://events.saip.org.za/event/100/contributions/240/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/240/ END:VEVENT BEGIN:VEVENT SUMMARY:Privacy amplification for a quantum key ditribution DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-241@events.saip.org.za DESCRIPTION:Speakers: Marie Louise Umuhire (University of Kwazulu Natal\, School of Chemistry and Physics\, Westville Campus\, Durban\, South Africa )\nQuantum key distribution (QKD) is a process of encoding information in quantum carrier such photons that is shared between legitimate users (usua lly referred to as Alice and Bob) in the presence of an eavesdropper (usua lly referred to as Eve) [1]. Alice (sender) and Bob (receiver) are connect ed via two channels namely a quantum channel and classical channel. A quan tum channel can be an optical fibre or free space\; it enables users to ex change quantum information (single photons). A classical channel can be a computer network or a telephone line\; it is used for the analysis of the transmitted information\, the evaluation of the efficiency of the system a nd elimination of any error committed during the communication [1].\nSince the introduction of QKD\, many protocols have been proposed which can ens ure the security of exchanging information [2-5]. The implementation of th ese protocols exploits the laws of Physics by using binary encoding based on phase\, polarisation or time-bin degrees of freedom and achieves a secr et key rate of at least one bit per photon [1\, 6]. \n\nThe implementation of a QKD system requires the execution of two major processes\, such as q uantum transmission and post-processing procedure. The second process is c omposed with 3 steps namely error estimation\, error reconciliation and pr ivacy amplification. This research project focuses on the privacy amplific ation where the size of the reconciled key is reduced in order to eliminat e any information an eavesdropper could have gained.\n\nReferences\n\n1. Gisin\, N.\, et al.\, Quantum cryptography. Reviews of modern physics\, 2002. 74(1): p. 145.\n2. Bennett\, C.H.\, Quantum cryptography using an y two nonorthogonal states. Physical review letters\, 1992. 68(21): p. 312 1.\n3. Ekert\, A.K.\, Quantum cryptography based on Bell’s theorem. P hysical review letters\, 1991. 67(6): p. 661.\n4. Scarani\, V.\, et al. \, Quantum cryptography protocols robust against photon number splitting a ttacks for weak laser pulse implementations. Physical review letters\, 200 4. 92(5): p. 057901.\n5. Gisin\, N.\, et al.\, Towards practical and fa st quantum cryptography. arXiv preprint quant-ph/0411022\, 2004.\n6. Sc arani\, V.\, et al.\, The security of practical quantum key distribution. Reviews of modern physics\, 2009. 81(3): p. 1301.\n\nhttps://events.saip.o rg.za/event/100/contributions/241/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/241/ END:VEVENT BEGIN:VEVENT SUMMARY:Non-specialist lecture: The new edition of the International Syste m of Units: Introducing the SI Redefined: Counting Atoms\, Single-Electron Tunnelling and Optical Atomic Clocks DTSTART;VALUE=DATE-TIME:20180629T092000Z DTEND;VALUE=DATE-TIME:20180629T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-242@events.saip.org.za DESCRIPTION:Speakers: Wynand Louw (NMISA)\nThe Metre Convention of 1875 es tablished the metric scale as the universal system of measurement.\nIn 196 0 the General Conference on Weights and Measures (CGPM)\, under the Metre Convention\,\nformally established the expanded metric scale as the Intern ational System of Units\, universally\nknown as the SI (from the French Sy stème international d’unités). It has subsequently been revised\nfrom time to time in response to the requirements of users and advances in scie nce and technology.\nThe most recent and perhaps most significant revision in the SI since its establishment is expected to\nbe approved in November 2018 by the 26th CGPM as documented in the draft 9th edition of the SI\nb rochure.\nThe definition of the SI units will be established in terms of a set of seven defining constants. From\nthe fixed values of these defining constants\, expressed in the units of the SI\, the complete system of\nun its can be derived. These seven defining constants are the most fundamenta l feature of the\ndefinition of the entire system of units. A variety of e xperimental methods generally described by\nthe Consultative Committees of the International Committee of Weights and Measures (CIPM) may\nbe used t o realise the definitions.\nThe presentation will outline the changes to t he current SI\, show what research have been\nconducted for the new realis ations and highlight the practical implications for the Southern African\n community.\n\nhttps://events.saip.org.za/event/100/contributions/242/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/242/ END:VEVENT BEGIN:VEVENT SUMMARY:Magnetic properties studies of Fe-substituted La0.67Sr0.33MnO3 DTSTART;VALUE=DATE-TIME:20180628T100000Z DTEND;VALUE=DATE-TIME:20180628T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-243@events.saip.org.za DESCRIPTION:Speakers: Itegbeyogene Ezekiel (University of KwaZulu-Natal)\n The magnetic phase transitions for pure ceramic La0.67Sr0.33FexMn1-xO3 (x = 0\, 0.05\, 0.1\, 0.2\, 0.3 and 0.5) perovskites are investigated. The un derstanding of the magnetic interactions that occur in these perovskites m anganite afford the opportunity to tune their properties for practical app lications. The double exchange interactions in Mn3+-O-Mn4+ was found to be suppressed by the superexchange interactions in Mn3+(4+)-O-Mn3+(4+) as th e Fe content x increases. The samples were found to be a mixed phase of fe rromagnetism FM and antiferromagnetism AFM with a paramagnetic component. The saturation magnetization decreased from 52 emu/g to 1 emu/g at 300 K a nd from 80 emu/g to 5 emu/g at 2 K due to antiferromagnetic interactions. Exchange bias effect was observed at low temperatures especially at 240 K and 260 K with maximum values of 190 Oe and 194 Oe respectively. 57Fe Mös sbauer spectroscopy measurements show a transition from a paramagnetic sta te to a mixed spectra of FM-AFM and paramagnetic components. The percentag e contributions of the magnetic phases and their hyperfine magnetic field values were estimated from the 57Fe Mössbauer results.\n\nhttps://events. saip.org.za/event/100/contributions/243/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/243/ END:VEVENT BEGIN:VEVENT SUMMARY:Study of structural damage in InGaN and InAlN thin films due to Cu + ion irradiation DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-245@events.saip.org.za DESCRIPTION:Speakers: Joshua Khoele (iThemba LABS)\nIn ion irradiation stu dies\, ion beam bombardment is known to cause the formation of defects in thin films. Efforts in ion implantation studies on III-nitride thin films include ion modification of structural properties of the materials in orde r to induce improvements within the materials. In this work\, InGaN and In AlN thin films\, 20 nm thick grown on sapphire with GaN buffer layer\, wer e irradiated with 130 keV 64Cu+ ions at various ion fluences ranging from 5 x 1015 to 5 x 1016 ions/cm2. The ion irradiated samples were analyzed us ing Rutherford backscattering Spectrometry (RBS)\, Scanning Electron Micro scopy (SEM)\, Raman Spectroscopy (RS) and X-ray diffraction (XRD). RBS ana lysis showed a reduction in the thicknesses of the InGaN and InAlN top lay ers after ion irradiation at high fluences. Peak shifts observed from Rama n spectra may suggest recrystallization in the top film due to ionization by the incoming ion beam as observed from previous studies.\n\nhttps://eve nts.saip.org.za/event/100/contributions/245/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/245/ END:VEVENT BEGIN:VEVENT SUMMARY:Structure and dynamics of noble gas temperature control on Ti meta l clusters DTSTART;VALUE=DATE-TIME:20180628T082000Z DTEND;VALUE=DATE-TIME:20180628T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-246@events.saip.org.za DESCRIPTION:Speakers: Tshegofatso Michael Phaahla (University of Limpopo)\ nTitanium clusters is one of the central theme in cluster science to inves tigate the evolution of the electronic\, structural and magnetic propertie s of the metal clusters as a function of cluster size. The atomic structur es and dynamics of nanoclusters have been of crucial importance in both ex perimental and theoretical studies owing to their useful physical and chem ical properties in various industrial applications. In particular\, the ti tanium metal clusters have been shown to strongly dependent on their inter nal clusters energy which dictate the geometrical arrangement and growth p atterns. In this study\, molecular dynamics simulation was used to investi gate the temperature effects on pure Ti metal nanoclusters in both vacuum and under pressure of Argon gas. The effect of gas phase environment on th e structural growth and dynamical properties was interrogated by subjectin g the nanoclusters to various temperatures in the range of 300K – 2000K. The radial distribution functions and diffusivity were examined to study the structural changes as a function of temperature. It was found that the gas phase and the vacuum structures melting point correspond well with th e experimental data. Furthermore\, the diffusivity of both the gas phase a nd vacuum increases as the temperature is increased. This observations is important in the production of titanium metal and development of titanium metal components for industrial and aerospace applications\n\nhttps://even ts.saip.org.za/event/100/contributions/246/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/246/ END:VEVENT BEGIN:VEVENT SUMMARY:Surface modified ZIF-67 and NH2-MIL(101)Fe Metal Organic Framework s for Photocatalysis and Supercapacitor Applications DTSTART;VALUE=DATE-TIME:20180629T100000Z DTEND;VALUE=DATE-TIME:20180629T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-247@events.saip.org.za DESCRIPTION:Speakers: Bertrand Sone (Chemistry Department\, University of the Free State\,Bloemfontein)\nMetal Organic Frameworks (MOFs) are highly ordered 3-dimensionally arranged crystalline hybrid materials containing b oth an inorganic and an organic component. Their base structure is compri sed of metal ions or clusters (inorganic) that are connected by electron-d onating “linker” groups (organic) to create a networked structure with periodically arranged rigid/semi-rigid pores. As a result of their porosi ty\, flexibility and ability to be functionalized they find use in applica tions such as gas storage\, separations\, sensing\, and catalysis. \nWe re port here an investigation on the impact of temperature on the growth of b ench-top synthesized Cobalt-based Zeolite Imidazolate Frameworks (ZIF-67). ZIF-67 annealed sequentially under inert atmosphere and air at 600°C and 350 °C\, was also prepared and a comparative photocatalytic profile for degradation of methylene blue is reported. Alongside these\, we report an environmentally friendly and energy-efficient method for preparing NH2-MIL (101) Fe MOFs. Traditional methods of synthesizing NH2-MIL (101) Fe invol ve solvothermal synthesis in N\,N-Dimethylformamide (DMF) at 150 °C\, for 1-2 days. The environmental trail left as a result of washing of DMF usin g methanol is usually huge. We report the use of a more environmentally fr iendly\, energy saving bench top synthesis of NH2-MIL (101) Fe using ethan ol at 60 °C. NH2-MIL (101) Fe doped with Cobalt alongside the pristine M OF\, were pyrolyzed at 500 °C\, 2h and employed for supercapacitor applic ations using cyclic voltammetry\, charge-discharge cycling and electrochem ical impedance spectroscopy. The impact of Co-impregnation on the capaciti ve properties of the pyrolyzed NH2-MIL (101) Fe MOF is discussed.\n\nhttps ://events.saip.org.za/event/100/contributions/247/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/247/ END:VEVENT BEGIN:VEVENT SUMMARY:Analysis of temperature dependent I-V characteristics of Pd/n-4H-S iC Schottky barrier diodes and the determination of the Richardson constan t in a wide temperature range DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-248@events.saip.org.za DESCRIPTION:Speakers: Valentine Gora (Mdlands State University)\nSchottky barrier diodes (SBDs) made on 4H-SiC have been commercially available for a considerable time but their properties and applications are still not th oroughly understood. Consistent control of metal contact properties is yet to be established so as to optimize reliability. As a result\, the inabil ity to physically reproduce the Schottky barrier height is a technological ly important concern which is continuously being researched. The current v oltage (I-V) characteristics of Pd/n-type 4H-SiC Schottky barrier diode in the 300-800 K temperature range have been analysed. Barrier height and id eality factor were found to be strongly temperature dependent. Barrier hei ght was observed to increase whilst ideality factor decreased with an incr ease in temperature and the conventional activation energy plot showed som e deviation from linearity. This was attributed to barrier inhomogeneities at the metal-semiconductor interface which resulted in a distribution of barrier heights at the interface. From the modified Richardson plot\, the Richardson constant\, A** was found to be 155 A cm-2K-2 and 87 A cm-2K-2 in the 300-525 K and the 550-800 K temperature ranges respectively.\n\nhtt ps://events.saip.org.za/event/100/contributions/248/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/248/ END:VEVENT BEGIN:VEVENT SUMMARY:Spontaneous Parametric Down-Conversion Beam Shaping DTSTART;VALUE=DATE-TIME:20180627T100000Z DTEND;VALUE=DATE-TIME:20180627T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-249@events.saip.org.za DESCRIPTION:Speakers: Jonathan Pinnell (University of the Witwatersrand)\n Spontaneous parametric down-conversion (SPDC) has been (and continues to b e) a very popular mechanism for generating entangled biphotons for applica tions in fields ranging from quantum key distribution and quantum computin g to quantum imaging. In a nutshell\, if ones impinges a crystal (characte rised by a nonlinear\, second-order susceptibility tensor) with a pump pho ton\, there is a small probability that the crystal will spontaneously dow n-convert the pump photon into 2 new photons (called signal and idler phot ons) subject to conservation of energy. There are other conserved quantiti es as well\, notably orbital angular momentum (OAM). It has been observed that the OAM of the signal and idler photons violate Bell's inequality and so SPDC can be used to generate entangled biphotons in the OAM degree of freedom. Typically\, one only observes entanglement in a 2-dimensional OAM subspace. We study whether it's possible to engineer arbitrary entangled qudit states by changing the spatial profile of the pump beam.\n\nhttps:// events.saip.org.za/event/100/contributions/249/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/249/ END:VEVENT BEGIN:VEVENT SUMMARY:Graphene/Transition metal oxides thin films using first principle approaches DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-250@events.saip.org.za DESCRIPTION:Speakers: Lutendo Phuthu (University of Venda)\nSince the effe ctively increase in the efficiency of dye sensitized solar cells (DSSCs) b y O’Regan and Gratzel in 1991\, the research in the string of DSSCs has grown rapidly. The preparation of the mesoporous oxide (typically\, titani um dioxide) film is a key factor in the optimization of DSSCs because of i ts enormous influence on the anchoring of dye molecules\, and the transfer and separation of charge carriers. However charge recombination is a main negative factor that limits DSSCs performance. It is predicted that impr oving the conduction from the location of the photo-generated carriers to the collecting electrode would considerably enhance the DSSC efficiency. O ne way to slow recombination is by use of composite semiconductor photoano de with different bandgaps.\n\nRecently\, carbonaceous nanomaterials such as carbon nanotubes and two-dimensional graphene sheet have attracted the attention of the scientific community in probe to improve energy conversio n and storage technologies. The graphene sheet is more preferred due to it s large specific area\, flexible structure\, high transparency and also ex cellent mobility of charge carriers and is expected to be able to slow the charge recombination. Graphene/Transition metal oxides nanocomposite stud y has become much of a wide interest recently with metal oxides like titan ium dioxide\, zinc oxide\, Chalcopyrite\, etc in search to improve the DSS Cs performance. The final composite embodies both the transport properties of the former and the semiconducting properties of the latter species. Th is talk gives preliminary results of electronic and optical properties of the final composite studied using the Density Functional Theory in applica tion to DSSCs.\n\nhttps://events.saip.org.za/event/100/contributions/250/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/250/ END:VEVENT BEGIN:VEVENT SUMMARY:Optimal Attacks on a High-Dimensional QKD System DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-252@events.saip.org.za DESCRIPTION:Speakers: Jonathan Pinnell (University of the Witwatersrand)\n Quantum Key Distribution (QKD) has received a lot of attention from the cr yptographic community since it's inception in the early 1970s\, owing to i t's ability to be provably secure. Unlike classical key distribution\, who se security relies on the inability of current computers to efficiently so lve certain difficult mathematical problems\, QKD's security is based on t he laws of quantum mechanics. With the looming advent of quantum computers (which are capable of solving these difficult math problems in polynomial time) there is raised awareness that we need to start thinking of more se cure cryptographic schemes to protect data from ever more powerful adversa ries. The study of quantum hacking\, which tries to undermine the security of\nQKD protocols\, is thus a necessary pursuit towards making QKD a prac tical tool for encryption in the future.\n\nHere\, we propose a novel atta ck on a high-dimensional entanglement-based QKD protocol which uses entang led modes of orbital angular momentum (OAM) as qubits. It is well known th at propagating OAM modes through turbulence has the effect of spreading th e modes into different OAM sub-spaces. We ask whether/how an adversary who has access to these untapped OAM sub-spaces is able to make educated gues ses to determine which qubits were sent between communication parties.\n\n https://events.saip.org.za/event/100/contributions/252/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/252/ END:VEVENT BEGIN:VEVENT SUMMARY:Radiological risk assessment of water sources from the Serule area of Botswana DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-253@events.saip.org.za DESCRIPTION:Speakers: Donovan Botlhole (Botswana International University of Science and Technology)\nAbstract. Environmental radioactivity studies involving water sources are essential for the monitoring of the quality of drinking water for public consumption. Natural water sources generally co ntain some level of concentration of alpha and beta emitters. Radiological examination of these sources becomes necessary to determine their contrib ution to internal radiation exposure by ingestion. Most villages in Botswa na use untreated natural water for human consumption. The recent discovery of uranium in the Serule village of Botswana has established the need for analysis of water samples from the area. Twenty water samples were collec ted from various sources such as boreholes\, wells\, rivers and local ditc hes in Serule. These will set a baseline that currently does not exist in Botswana with regard to radiological concentrations of both surface and gr ound water. Screening of water samples was carried out using a liquid scin tillation counter (Quantulus 1220) to determine the gross alpha and beta a ctivity of the water samples. A presentation will be made on the applicati on of the liquid scintillation counting method for measurement of gross al pha and beta activities in spiked water samples from Serule\, Botswana. Th is includes sample preparation\, radiation detection and analysis techniqu es.\n\nhttps://events.saip.org.za/event/100/contributions/253/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/253/ END:VEVENT BEGIN:VEVENT SUMMARY:Measurement of the cosmogenic isotope 10-Be at iThemba LABS and ap plications of cosmogenic isotopes in South Africa DTSTART;VALUE=DATE-TIME:20180628T084000Z DTEND;VALUE=DATE-TIME:20180628T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-254@events.saip.org.za DESCRIPTION:Speakers: Stephan Winkler (NRF/iThemba LABS)\n10Be is an impor tant isotope for accelerator mass spectrometry system of iThemba LABS in J ohannesburg\, because of local demand for cosmogenic radionuclide dating m ethods in the local earth science and paleosciences community. This demand also meets a very suitable basic AMS setup with its ion-source based on a version of the Cesium Sputter source of the Lawrence Livermore National L aboratories\, which delivers significantly higher output of BeO- than comm ercially available ion sources. The measurement of 10Be by accelerator mas s spectrometry requires the effective suppression of 10B before the detect or\, which is either done by using an gas absorber cell for full stopping of 10B\, or by differential energy loss of 10B versus 10Be in an absorber foil (post-stripping) followed by a high-resolution magnet or electrostati c analyser. The latter method has proven effective in that the 2+ charge s tate can be utilized\, which has in excess of 40% charge state transmissio n at 4MV terminal voltage\, but there are charge state losses from the abs orber foil. Using gas absorber cell employing havar windows usually requir es higher energies\, requiring the 3+ charge state and higher terminal vol tage\, resulting in additional interference from the 10B(p\,)7Li reaction that is not fully separated in the detector. Recently it has been shown th at low stress silicone nitride membranes can be used as absorber for full stopping with particle energies of 6MeV for 10-Be. This allows for the use of the 2+ charge state\, avoids the charge state losses of the post-strip ping method\, and – provided the chosen terminal voltage is low enough – it avoids incurring massive interference from the nuclear reaction. We implemented this method in lieu of the traditional gas absorber cell\, th us cashing in on the efficiency gain from using the 2+ charge state. Toget her with the efficiency benefits of our ion-source we have a high detectio n efficiency AMS system for 10Be. We applied the foilstack methods success fully in test runs and recently in first projects of our cosmogenic isotop e programme.\n\nhttps://events.saip.org.za/event/100/contributions/254/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/254/ END:VEVENT BEGIN:VEVENT SUMMARY:Computational investigation of vacancy ordering in gamma-Mn2< /sub>O3. DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-255@events.saip.org.za DESCRIPTION:Speakers: Khomotso Maenetja (University of Limpopo)\nA high en ergy demand as a result of a growth in living standards and population has stimulated the efforts to develop high energy density power sources which is\, metal air batteries. However\, the fundamental challenge that limits the use of metal air battery technology is the ability to find a catalyst that will catalyse Oxygen Reduction Reaction (ORR) and Oxygen Evolution R eaction (OER). Density Functional study was employed to investigate the or dered tetragonal structure using a supercell of the cubic structure Mn3O4. We obtain the spectrum of energies of all the ordered configurations whic h contribute to the partially disordered Mn2O3 structure. The degree of or dering in manganese vacancies in the octahedral sites appears to be more s table than the in tetrahedral manganese.\n\nhttps://events.saip.org.za/eve nt/100/contributions/255/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/255/ END:VEVENT BEGIN:VEVENT SUMMARY:AdS/CFT predictions for partonic and fragmented momentum\, azimuth al\, and rapidity correlations of heavy flavors in heavy ion collisions DTSTART;VALUE=DATE-TIME:20180629T100000Z DTEND;VALUE=DATE-TIME:20180629T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-260@events.saip.org.za DESCRIPTION:Speakers: Robert Hambrock (University of Cape Town)\nWe comput e the suppression\, angular\, and rapidity distribution of single open hea vy flavour and the momentum\, angular\, and rapidity correlations for pair s of open heavy flavour at RHIC and LHC from an AdS/CFT-based energy loss model. We quantitatively compare these strongly-coupled QGP predictions to the weakly-coupled QGP predictions of Nahrgang et al.\, PRC90 (2014) [arX iv:1305.3823]. In the strong-coupling energy loss model\, we include both the mean energy loss and thermal fluctuations\; in the weak-coupling energ y loss model\, one set of predictions corresponds to the inclusion of pure ly collisional processes while the other additionally incorporates radiati ve corrections.\n\nWhen restricted to leading order production processes\, we find that the strongly coupled correlations of high transverse momentu m pairs (>4GeV) are broadened less efficiently than the corresponding weak coupling based correlations\, while low transverse momentum pairs (1−4G eV) are broadened with similar efficiency\, but with an order of magnitude more particles ending up in this momentum class. The strong coupling mome ntum correlations we compute account for initial correlations and reveal t hat the particle pairs suppressed from initially high momenta to the low m omentum domain do not suffice to explain the stark difference to the weak coupling results in momentum correlations for 1−4GeV. From this\, we con clude that heavy quark pairs are more likely to stay correlated in momentu m when propagating through a strongly coupled plasma than a weakly coupled one.\n\nWhen initialised at next-to-leading order (aMC@NLO matched to Her wig++)\, we observe significant additional broadening of azimuthal correla tions\, with the angular correlations of low momentum pairs (1−4GeV) ess entially washed. However\, the momentum correlations remain even when NLO production mechanisms are included. Thus\, our conclusion for differences in momentum correlations with leading order production processes should ca rry over to next-to-leading order production processes once comparable pre dictions for a weakly-coupled QGP emerge.\n\nhttps://events.saip.org.za/ev ent/100/contributions/260/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/260/ END:VEVENT BEGIN:VEVENT SUMMARY:AES study of surface segregation in Ni-Cu alloy thin films DTSTART;VALUE=DATE-TIME:20180629T082000Z DTEND;VALUE=DATE-TIME:20180629T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-261@events.saip.org.za DESCRIPTION:Speakers: Xin Liang Yan (Shantou university\, China)\nSurface segregation in a thin film is different from that in a bulk system\, due t o the fact that the number of segregated atoms on the surface of the thin film is a significant fraction of the total number of atoms and resulted t hat the bulk concentration in the thin film is modified significantly upon segregation. In additional\, significant differences in the surface segre gation behavior\, as compared with that in the bulk material [1\,2]\, due to the lack of a reservoir of segregating atoms\, may occur.. Surface segr egations of Cu in the Ni-Cu alloy thin films was measured using Auger elec tron spectroscopy with the linear temperatures programmed heating method. The samples where heated at a constant rate of 0.03 K/s from 403 K to 823 K. It was found that the surface enrichment factor β of segregation for a thicker sample (52 nm) is higher than that for a thinner sample (26 nm). The measured segregation data was fitted with the modified Fick’s model and the bulk-to-surface diffusion parameters for Cu in the Ni-Cu alloy thi n films were extracted\, which compared well with those in the literature. \n\nReferences:\n[1] S. Swaminarayan\, D.J. Srolovitz\, Surface segregati on in thin films\, Acta Mater. 44 (1996) 2067-2072.\n[2] X. L. Yan\, J. Y. Wang\, Size effects on surface segregation in Ni–Cu alloy thin films\, Thin Solid Films 529 (2013) 483-487.\n\nhttps://events.saip.org.za/event/1 00/contributions/261/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/261/ END:VEVENT BEGIN:VEVENT SUMMARY:Probing the intergalactic magnetic field through observations of h igh energy gamma-rays produced by electromagnetic cascades. DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-262@events.saip.org.za DESCRIPTION:Speakers: Brandon Bisschoff (University of the Free state)\nCu rrently there is limited knowledge of the origin of the intergalactic magn etic fields (IGMF) that lie between galaxies\, galaxy clusters and cosmic voids. Understanding the origin of the IGMF is a crucial component in mode ls of galaxy and galaxy clusters formation. This magnetic field can be pro bed indirectly by its effect on electromagnetic cascades initiated by gamm a-gamma absorption of very high energy (VHE) gamma-rays\, produced in blaz ars\, due to its interaction with the extragalactic background light (EBL ). The electron-positron pairs produced via the gamma-gamma absorption int eract with the intergalactic magnetic field (IGMF) and can be deviated fro m their original trajectory path. These pairs can then Compton-scatter off the cosmic microwave background (CMB) to produce high energy gamma-rays t hat may be detected with Fermi-LAT. The strength of this signal strongly d epends on the IGMF strength (B) and the coherence length (L). This seconda ry gamma-ray emission would be superimposed on the blazar’s intrinsic ga mma-ray spectrum. A selection of bright blazars will be re-analysed using the upgraded Pass 8 analysis pipeline\, to search for this secondary compo nent. This will be used to place constraints on the IGMF strength. The ini tial results from this project will be presented.\n\nhttps://events.saip.o rg.za/event/100/contributions/262/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/262/ END:VEVENT BEGIN:VEVENT SUMMARY:Modelling the Spectral Energy Distribution and Polarisation of Bla zars DTSTART;VALUE=DATE-TIME:20180626T092000Z DTEND;VALUE=DATE-TIME:20180626T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-263@events.saip.org.za DESCRIPTION:Speakers: Hester M. Schutte (North-West University)\nThe optic al emission from most blazars is dominated by the polarised synchrotron ra diation of relativistic electrons in the jet\, but the thermal radiation f rom the accretion-disk and host galaxy also contributes towards the high a nd low frequency ends of the optical spectrum. As the accretion-disk and h ost galaxy emissions are expected to be unpolarised\, they reveal their pr esence in a decrease of the degree of polarisation towards the high- and l ow-frequency ends of the optical spectrum\, respectively. This motivates a target-of-opportunity programme of spectropolarimetry observations of ga mma-ray blazars with the Southern African Large Telescope (SALT). A model is constructed that combines modelling of the spectral energy distribution (SED) and of the degree of optical polarisation to constrain the accretio n disk contributions in the spectra of blazars.\n\nI will present the mode l fit to the Flat Spectrum Radio Quasar 4C+01.02 in its flare and quiescen t state in which degeneracies of parameters such as the electron spectrum energies\, accretion disk luminosity\, ordering of the magnetic field of t he jet and the mass of the black hole are constrained.\n\nPresentation key words: blazar\, active galactic nuclei\, spectropolarimetry\, spectral en ergy distribution\, optical polarisation\n\nhttps://events.saip.org.za/eve nt/100/contributions/263/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/263/ END:VEVENT BEGIN:VEVENT SUMMARY:The impact of phenomenography and variation theory on students’ understanding of the concept of acceleration. DTSTART;VALUE=DATE-TIME:20180626T082000Z DTEND;VALUE=DATE-TIME:20180626T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-264@events.saip.org.za DESCRIPTION:Speakers: Mphiriseni Khwanda (University of Johannesburg)\nCha llenges in the teaching and learning of physics existed as far as educatio n existed worldwide. During the period\, various approaches were continuou sly suggested and implemented but the learning gains were always disappoin ting\, and physics was labelled as a difficult subject for the chosen few and that idea encouraged instructors accept high failure rate in physics a s normal. Departing form that belief that physics is for the chosen few\, the current study explored how phenomenography and variation theories from social sciences can help students to understand the concept of accelerati on. Google form was initially used to collect data that informed the instr uctor about students’ prior understanding of the concept of acceleration . Later data gathered informed how activities should be designed guided by variation theory. The study reports about students’ prior understanding of the concept of acceleration\, the activities designed and lastly the i mpact of both phenomenography and variation theory on students’ understa nding of acceleration.\n\nhttps://events.saip.org.za/event/100/contributio ns/264/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/264/ END:VEVENT BEGIN:VEVENT SUMMARY:Including Variometers in Geomagnetic Field Interpolation DTSTART;VALUE=DATE-TIME:20180627T104000Z DTEND;VALUE=DATE-TIME:20180627T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-265@events.saip.org.za DESCRIPTION:Speakers: Michael Heyns (UCT/SANSA)\nOne of the best tools we have in geophysical modelling is the ability to interpolate the horizontal geomagnetic field at the surface of the Earth. This is especially useful in regions\, such as southern Africa\, where there is a sparse array of ab solute magnetometers available for geomagnetic field measurements. In term s of geomagnetic field interpolation\, the spherical elementary current sy stems (SECS) spatial interpolation scheme has shown to be very successful\ , and the planar approximation of this method adequate for modelling at mi d-latitudes. The SECS interpolation scheme is physics based\, making use o f the Biot-Savart law and equivalent ionospheric currents to interpolate m easured geomagnetic field data. As with most interpolation methods\, more data points result in lower error. Therefore\, we adapt the SECS method to work with variometers. These instruments measure variations in magnetic f ield and are more abundant in southern Africa. Merging the two resulting i nterpolated datasets\, the initial absolute geomagnetic field interpolatio n can be significantly improved. This improved interpolation scheme is inc redibly useful locally where a sparse magnetometer array is a challenge\, but can be applied just as effectively in other cases across the globe whe re there are numerous magnetometers and variometers available.\n\nhttps:// events.saip.org.za/event/100/contributions/265/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/265/ END:VEVENT BEGIN:VEVENT SUMMARY:Experimental and numerical study of a cavity and hot mirror receiv er of the parabolic trough collector DTSTART;VALUE=DATE-TIME:20180629T080000Z DTEND;VALUE=DATE-TIME:20180629T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-266@events.saip.org.za DESCRIPTION:Speakers: Khaled Mohamad (PhD students)\nThe solar parabolic t rough collectors (PTC) are the earliest and most widely accepted solar con centration style. It is the most mature technology\, has been intensively researched and its cost gradually reduced. In addition\, PTC has been put into commercial operations in many countries. The research in this technol ogy is moving towards increasing the efficiency of the system\, specifical ly raising the temperature of the working fluids by minimizing the energy losses. The efficiency of the whole system depends on the most complex par t of it\, which is the receiver unit. This work aims to design the receive r unit in a way that minimizes the energy losses and raises the temperatur e of the working fluid. The receiver unit incorporates the application of different optically active layers in tandem with the application of a cavi ty absorber. The cavity geometry with the hot mirror coating application w ill enable efficient capturing of incoming concentrated solar radiation vi a multiple internal reflections. This study entails numerical heat analysi s\, which is used to simulate the temperature profile of the receiver unit and study the optical properties of different designs. In addition\, this idea has been examined in the laboratory and the experimental data will b e presented.\n\nhttps://events.saip.org.za/event/100/contributions/266/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/266/ END:VEVENT BEGIN:VEVENT SUMMARY:Influence of citric acid on LiMn2O4 nanostructures prepared by mod ified chemical bath method DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-267@events.saip.org.za DESCRIPTION:Speakers: Lehlohonolo Koao (UFS (Qwa Qwa Campus))\nLiMn2O4 pow ders were prepared by modified chemical bath method using citric acid solu tion (CA) a catalyst. The volume ratio (VR) of Li and Mn on LiMn2O4 was ke pt constant and the volumes of CA were varied. The effect of CA on structu re\, morphology and optical properties of LiMn2O4 nanostructures were inve stigated. The VR’s of CA were varied from 1 mL≤ VR ≤120 mL. The X-ra y diffraction (XRD) patterns of the LiMn2O4 nanostructures correspond to t he various planes of a spinel LiMn2O4 phase. The diffraction peaks increas e in intensity up to 40 mL of CA. The estimated average crystallite sizes calculated using the XRD spectra were found to be in the order of 63 ± 1 nm. It was observed that the estimated average crystallite sizes increases with an increase in CA up to 40 mL. The surface morphology study revealed the polygon shape. By varying CA solution morphology changed from polygon to irregular shape. The UV-Vis spectra showed a red shift with an increas e in the amount of CA. The band gap energy of LiMn2O4 was also found to de crease. The best VR of CA on LiMn2O4 nanopowders were obtained at Li:Mn:CA ratio of 1:1:4. Lithium ion batteries are widely used in portable equipme nt\, such as mobile phone\, notebook computer\, electron instrument\, and so on.\n\nhttps://events.saip.org.za/event/100/contributions/267/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/267/ END:VEVENT BEGIN:VEVENT SUMMARY:Regulation of star formation in X-ray rich galaxy groups (stellar populations in brightest group galaxies) DTSTART;VALUE=DATE-TIME:20180626T082000Z DTEND;VALUE=DATE-TIME:20180626T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-269@events.saip.org.za DESCRIPTION:Speakers: Okkert Havenga (North-West University)\nAn important component of galaxy formation and evolution studies\, is to accurately co nstrain their star formation histories (SFHs). While the SFHs of most mass ive early-type galaxies can be described using a single passively-evolving stellar component (Single Stellar Population [SSP])\, there is a fraction of massive early-type galaxies in the centres of galaxy groups and galaxy clusters where recent star formation is observed and are better described by two or more stellar components (Composite Stellar Population [CSP]). I n this project we identify and constrain possible recent star formation ep isodes in a sample of 23 BGGs (Brightest Group Galaxies)\, of which most a re in the centres of X-ray rich groups and all are closer than 80Mpc\, and a sub-sample of the Complete Local-Volume Groups Sample (CLoGS). We use archival spatially-resolved long-slit spectroscopy from the Hobby-Eberly T elescope (HET) at the McDonald Observatory\, and determine whether the BGG s are better described by a SSP or a CSP using ULySS. We compare the resul ts with existing X-ray observations of some of the BGGs\, obtained by Chan dra/XMM-Newton\, and the X-ray determined physical properties of the host groups\, e.g. cooling time and central entropy. The results of these BGGs can then be compared to a comparable sample of 32 Brightest Cluster Galaxi es (BCGs) in rich galaxy clusters at a redshift (z) between 0.05 and 0.3.\ n\nhttps://events.saip.org.za/event/100/contributions/269/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/269/ END:VEVENT BEGIN:VEVENT SUMMARY:Modeling of a Resonant Tunneling Transistor under Uniaxial Strain DTSTART;VALUE=DATE-TIME:20180627T122000Z DTEND;VALUE=DATE-TIME:20180627T124000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-270@events.saip.org.za DESCRIPTION:Speakers: Mahmood Akbari (University of Cape Town)\nGraphene i s an atomically thin two-dimensional (2-D) crystal with unique thermal\, m echanical\, and electronic transport properties such as the high mobility of carriers\, perfect 2-D confinement\, and linear dispersion\, etc.\, has been attracted many interests as a promising candidate for nano-scale dev ices over the past decades. Multilayer stacks of graphene and other stable \, atomically thin\, 2-D materials offer the prospect of creating a new cl ass of heterostructure materials. Hexagonal boron- nitride (hBN)\, is a gr eat candidate to be stacked with graphene due to an atomically 2-D layered structure with a lattice constant very similar to graphene (1.8% mismatch )\, large electrical band gap (∼ 4.7eV )\, and excellent thermal and che mical stability. The graphene/hBN based tunneling transistors show the res onant tunneling and strong negative differential resistance (NDR). These d evices which have the potential for future high-frequency and logic applic ations such as high-speed IC circuits\, signal generators\, data storage\, etc.\, has been studied both theoretically and experimentally recently.\n \nThe aim of this paper has been to study the effect of the uniaxial strai n on the graphene nanoribbon resonant tunneling transistors (RTTs). The un iaxial strain may be induced either by an external stress applied to the g raphene in a particular direction or by a substrate due to deposition of g raphene on top of the other materials. The strain modifies distances betwe en carbon atoms which leading to different hopping amplitudes among neighb oring sites.\n\nA resonant tunneling transistor consisting of armchair gra phene nanoribbon (AGNR) electrodes with three layers of hBN tunnel barrier between them has been considered. By using the nearest-neighbor tight-bin d (TB) method and the nonequilibrium Green function (NEGF) formalism\, the electronic transport characteristics of RTT is calculated. In this work\, we focus on how the strain affects the current-voltage characteristics of AGNR/hBN RTT.\n\nThe results demonstrated that the strain decreased the a mount of the current in both cases\; however\, the quantitative behavior o f the I-V plot turned out to be different for the strain in different dire ctions. The current collapsed more rapidly when the strain was applied in the armchair direction.\n\nhttps://events.saip.org.za/event/100/contributi ons/270/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/270/ END:VEVENT BEGIN:VEVENT SUMMARY:Properties of Cubic Boron Nitride Particles formed by Ion Implanta tion. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-271@events.saip.org.za DESCRIPTION:Speakers: Trevor Derry (University of the Witwatersrand)\nHard ness measurements of poly-crystalline hexagonal boron nitride (h-BN) ion i mplanted samples were carried out using the FM-700 (Vickers) micro-hardnes s tester. Previously\, it has been shown that the implantation of h-BN wit h different ions structurally deforms the irradiated surface layer to cubi c-BN nano-particles as revealed by Raman spectroscopy\, X-ray diffraction and electron microscopy\, and the measured hardness increases with ion flu ence. In the present study\, the h-BN samples were implanted with 150 keV helium (He+)\, lithium (Li+)\, boron (B+) and neon (Ne+) ions at different ion fluences from 1 x 1014 to 5 x 1016 ions/cm2\, while varying the sampl e temperature from room temperature to 300oC. The stress\, strain and Youn g's modulus of the formed cubic-BN nanoparticles were determined from micr o-indentation measurements. The results show that maximum stress on the sa mples was induced at an ion dose of 5 x 1015 ions/cm2 and the calculated Y oung's modulus at that fluence was 0\,3 GPa for all ions.\n\nhttps://event s.saip.org.za/event/100/contributions/271/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/271/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthesis and Characterization of spinel type Zinc Ferrite for pos sible application in gas sensing DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-272@events.saip.org.za DESCRIPTION:Speakers: Nemufulwi Murendeni (University of free state)\nSpin el ferrite nanomaterials have attracted a lot of attention in chemical gas sensing due to their tuneable electronic and magnetic properties through the variation of cation distribution. Cation distribution\, structural mor phologies and particle size has become of great interest in gas sensing as they enhance the sensing properties of spinel ferrites. Morphological con trol heavily depends on the synthesis parameters of different synthesis me thods. In this study\, we prepared ZnFe2O4 nanoparticles through electrosp inning and microwave-assisted hydrothermal methods using metal nitrates as starting precursors\, PVP and CTAB as a capping agents\, distilled water and ethanol as solvents. X-ray diffraction (XRD) revealed spinel type phas e purity. The particle size was estimated using the Scherrer’s equation and lattice parameter calculated using reciprocal lattice metric tensor eq uations. Scanning electron microscopy (SEM) images showed the formed nanof ibers and mesoporous nanoparticles with a good surface area identified by BET. Characterization results show good possibilities of gas sensing appli cation and various parameters can be tuned for optimum sensing properties. \n\nhttps://events.saip.org.za/event/100/contributions/272/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/272/ END:VEVENT BEGIN:VEVENT SUMMARY:Shear-free Dust Cosmological Models in Gravitational Scalar-Tensor Theories DTSTART;VALUE=DATE-TIME:20180627T104000Z DTEND;VALUE=DATE-TIME:20180627T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-273@events.saip.org.za DESCRIPTION:Speakers: Heba Abdulrahman (North-West University)\nTheoretica l physics in general and cosmology in particular have faced some challenge s due to the recent observations in cosmology and astronomy\, such as the discovery of the accelerated cosmic expansion and the existence of dark ma tter and dark energy. Einstein’s theory of General Relativity (GR) toget her with the standard model of cosmology fall short of giving any explanat ions for these\nproblems. Higher-order gravitational theories such as f(R) and scalar-tensor theories of gravity have been suggested to provide an a nswer to these shortcomings. In this work\, we investigate the cosmologica l implications of such theories such as the background expansion history a s well as the evolution of cosmological density perturbations. We present the equivalence between f(R) and\nscalar-tensor theories of gravity. Altho ugh GR is a generalization of Newtonian gravity in the presence of strong gravitational fields\, there is no properly defined Newtonian limit of GR on cosmological scales.\nRecently\, general relativistic quasi-Newtonian c osmologies have been studied in the context of large-scale structure forma tion and nonlinear gravitational collapse in the late-time universe. This despite the general covariant inconsistency of these cosmological models e xcept in some special cases such as the spatially homogeneous and isotropi c\, spherically symmetric\, expanding FLRW spacetimes. f(R) models have be en shown to exhibit more shared properties with Newtonian gravitation than \ndoes GR. We investigate the existence and integrability conditions of qu asi-Newtonian cosmological spacetimes of classes of shear-free cosmologica l dust models with irrotational fluid flows in the context of scalar-tenso r theories of gravity. We also derive the covariant density and velocity p ropagation equations of such models and analyse the corresponding solution s to these perturbation equations.\n\nhttps://events.saip.org.za/event/100 /contributions/273/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/273/ END:VEVENT BEGIN:VEVENT SUMMARY:Cryogenic ion implantation of polyethylene terephthalate (PET) thi n films: structural and electrical properties DTSTART;VALUE=DATE-TIME:20180627T124000Z DTEND;VALUE=DATE-TIME:20180627T130000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-274@events.saip.org.za DESCRIPTION:Speakers: Gaopalelwe Motaung (University of South Africa)\nOrg anic polymer based electronics have attracted attention in the semiconduct or industry for many different applications which include solar cells\, li ghting\, display\, and so on. Since polymers are naturally insulating mate rials\, enhancing their electrical properties through modification of thei r conductance using ion implantation is a focal research area in the semic onductor industry. Previous research shows that structural\, optical and e lectrical properties of Polyethylene Terephthalate (PET) can be modified t hrough ion implantation. However\, most of the PET implantations reported in the literature are under room temperature conditions\; not much has bee n done to investigate the effects of temperature on the target material du ring implantation. In this study\, ITO coated PET is implanted with 80keV metal (Ti+) and non-metal (Ar+) ions at three different ion fluences (5 x 10^14\, 5 x 10^15 and 5 x 10^16 ions/cm^2)\, at both room and cryogenic (l iquid nitrogen) temperatures. Implanted samples are characterized using th e Elastic Recoil Detection Analysis (ERDA) technique to determine the dept h profiles of implanted species. Additionally\, SEM\, FTIR and UV-Vis are carried out to determine the morphology\, chemical and molecular structure \, and the electronic band gap respectively. The electrical properties of the implanted PET are investigated through current-voltage (I-V) and capac itance-voltage (C-V) measurements. This presentation describes and explain s results of the characterization measurements with a view to establishing structure-property relationships of the cryogenically implanted PET.\n\nh ttps://events.saip.org.za/event/100/contributions/274/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/274/ END:VEVENT BEGIN:VEVENT SUMMARY:Precursor Kibble (Watt) balance for the revision of the kilogram f or South Africa DTSTART;VALUE=DATE-TIME:20180629T102000Z DTEND;VALUE=DATE-TIME:20180629T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-275@events.saip.org.za DESCRIPTION:Speakers: Thapelo Mametja (University of Capetown and National Metrology Institute of South Africa)\nAccording to International Bureau o f Weights and Measures (BIPM)\, the International System of Units (SI) wil l undergo a major change in November 2018. The base units will then be bas ed on fundamental physical constants. Currently\, the kilogram is the only base unit that is still based on an artefact\, a Platinum-Iridium Alloy c ylinder known as the International Prototype Kilogram (IPK). All mass meas urements are traceable to the IPK. There is a drift between the IPK and na tional prototypes (IPK copies) at an average rate of 50µg per century\, w hich indicates that the primary mass reference standard is unstable. The I PK will be replaced by a Kibble (Watt) balance. Kibble balance is an elect romechanical weight measuring instrument that measures the mass of a test object through the strength of an electric current and voltage. The Kibble balance method has been proposed to overcome the drifting challenge since it can provide a link between the macroscopic mass m and Plank’s consta nt h as the fundamental physical constant and realize the kilogram within a few parts in 108. The National Metrology Institute of South Africa (NMIS A) and University of Cape Town (UCT) Physics department\, have embarked on a joint project to construct the first Kibble balance in South Africa and most probably on the African continent. Prototypes have been developed fr om Lego blocks\, 3D printing and using an old equal-arm mass balance. Expe rimental results from the Kibble balance (comparing calibrated mass pieces with the measurement results) indicate that the system may be feasible. A ny measurement performed and expressed as a number without been accompanie d by any statement of uncertainty\, is incomplete. All uncertainty measure ments evaluations and expressions should be according to the ISO-recommend ed framework\, the so-called “Guide to the Expression of Uncertainty in Measurement”\, or ISO-GUM. An ISO-GUM method has been applied to give a full uncertainty assessment on all the major sources of uncertainty incorp orated within the prototype Kibble balance contributing to less than 1% re lative uncertainty achieved from gram-level mass measurements of the balan ce. This paper discusses the results from all the prototypes\, major measu rement uncertainty contributors and improvements/ future for the real syst em.\n\nhttps://events.saip.org.za/event/100/contributions/275/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/275/ END:VEVENT BEGIN:VEVENT SUMMARY:DFT STUDY OF SELECTED NEAR INFRARED (NIR) FREE METAL DYE MOLECULES FOR APPLICATION IN DYE SENSITIZED SOLAR CELLS DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-276@events.saip.org.za DESCRIPTION:Speakers: Tshifhiwa Steven Ranwaha (University of Venda)\nDye ‐sensitized solar cells (DSSCs) have attracted considerable attention in recent years as they offer the possibility of low‐cost conversion of ph otovoltaic energy. DSSCs use the dye molecules adsorbed on the TiO2 semico nductor in nano architecture with the role of absorbing photon from the su n. The electronic structure and excitation properties of dye sensitizer de termine the efficiency of the DSSCs. The dye molecule is sensitizer that a bsorbs the photon from the sun and inject an excited electron on the TiO2 semiconductor. The study focuses on the understanding of different propert ies (electronic optical properties) of NIR-dye molecules employing density functional theory (DFT) calculations. The calculations are based on the d eterminations of Absorption spectrum\, UV-Vis spectrum and Light Harvestin g Efficiency of the dye molecules. The results obtained shows that NIR-dye molecules can improve the efficiency of DSSCs as there is a shift of abso rption to the near infrared\, which increase the absorption range from vis ible on the solar spectrum.\n\nKeywords: Dye Sensitized Solar Cells\, Dye\ ,Efficiency\n\nhttps://events.saip.org.za/event/100/contributions/276/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/276/ END:VEVENT BEGIN:VEVENT SUMMARY:Computational and experimental studies on heats of adsorption of h eterocyclic collectors onto pyrite mineral surface DTSTART;VALUE=DATE-TIME:20180629T092000Z DTEND;VALUE=DATE-TIME:20180629T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-277@events.saip.org.za DESCRIPTION:Speakers: Peace Mkhonto (University of Limpopo)\nDuring flotat ion liberated particles are rendered hydrophobic by addition of organic co llectors that will facilitate their attachment to air bubbles. This study employed both computational density functional theory and experimental mic rocalorimetry to investigate the heats of adsorption of 2-mercaptobenzothi azole (MBT)\, 2-mercaptobenzoxazole (MBO) and 2-mercaptobenzimidazole (MBI ) onto pyrite mineral surfaces. The (100) surface was used to investigate the structural\, density of states (DOS) and atomic charges to understand the reactivity of heterocyclic collectors. The selectivity of collectors t o recover minerals with high grade is still a challenge and requires detai led fundamentals knowledge from both experiments and computational approac hes. The heterocyclic collectors’ offers hope due to their high selectiv ity and being able to function at neutral pH. The order or reactivity of t hese compounds were deduced from the predicted HOMO and LUMO energies and appears to favour MBO. We observed that the MBT adsorbed through the exocy clic sulphur atom\, while MBO and MBI adsorbed through the exocyclic sulph ur and N atoms onto the Fe atoms. The computed heat of adsorption energies indicated that the MBO has the strongest adsorption\, and the order of re activity decreased as: MBO > MBI > MBT for both computational and microcal orimetry. The DOS and atomic charges of the collectors indicated that the collectors S atoms behaved as electron donor\, while the Fe atoms accepted charges. Computational modelling effectively predicted the reactivity of molecules and showed a great correlation with the experimental approach.\n \nhttps://events.saip.org.za/event/100/contributions/277/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/277/ END:VEVENT BEGIN:VEVENT SUMMARY:A review of nuclear clustering formulation DTSTART;VALUE=DATE-TIME:20180627T080000Z DTEND;VALUE=DATE-TIME:20180627T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-365@events.saip.org.za DESCRIPTION:Speakers: Timothy Gary Carolus (Stellenbosch University)\nNucl ear cluster models are a means to describe complex many body systems\, spe cifically to predict nuclear structure properties within strongly correlat ed subsystem of nucleons. The binary cluster model has shown some success in predicting the alpha decay and spontaneous fission half-lives. A relati vistic description of the Binary Cluster Model using the Dirac formulation treats spin correlations in a more natural way. \n\nThe objective of this study is to develop a fully microscopic description of the nuclear cluste ring based on a relativistic mean field theory. So doing\, extending the a pplication of the model to a greater range of observables\, testing it in scattering phenomena and Colinear Cluster Tri-Partition (CCT). This presen tation which gives an overview of binary clustering model and the formalis m used identify the core-cluster partition and corresponding nuclear clust er observables. A comparison with existing phenomenological and non-relati vistic Brueckner G-Matrix model predictions will be done.\n\nhttps://event s.saip.org.za/event/100/contributions/365/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/365/ END:VEVENT BEGIN:VEVENT SUMMARY:Cross section measurements of light ion production using (p\,xp) r eactions DTSTART;VALUE=DATE-TIME:20180626T100000Z DTEND;VALUE=DATE-TIME:20180626T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-278@events.saip.org.za DESCRIPTION:Speakers: Doris Carole Kenfack Jiotsa (Stellenbosch University / iThemba LABS)\nNeutron-rich beams are being developed at iThemba LABS to study nuclear structure away from stability. This is also the opportunity of deepening our understanding of astrophysical origin of elements. The i nterest of using (p\,xp) reactions in the production of exotic nuclei\, li es in the fact that proton beams have a large penetrating power and can be produced with high intensity. Some measurements have been performed at iT hemba LABS using\, 7Li\, 9Be and natB targets with proton projectiles of e nergy 50 MeV and 66 MeV. The detection setup included two electron spectro meters composed of a 5mm thick plastic scintillator\, for energy loss meas urement\, and a thin window Germanium detector (LEPS) for residual energy measurement. The E- ∆E technique with this combination of detectors allo ws particle identification and high-resolution measurement simultaneously. Lanthanum Bromide detectors where also used to measure gamma particles. S ome preliminary results will be presented. Beryllium and Boron are chosen here because they can be used in oxide\, carbide or nitride form that can sustain large temperature amplitudes and therefore can be used in place as Uranium carbide in the current design of the ISOL source of iThemba LABS. This is important as there is no significant cost or resources implicatio ns. In addition\, light targets produce a lot less species which makes deb ugging easier. The results of this investigation will be used to evaluate the feasibility of light neutron rich beams at iThemba LABS.\n\nhttps://ev ents.saip.org.za/event/100/contributions/278/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/278/ END:VEVENT BEGIN:VEVENT SUMMARY:Commutative/Non-Commutative Dualities DTSTART;VALUE=DATE-TIME:20180626T094000Z DTEND;VALUE=DATE-TIME:20180626T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-279@events.saip.org.za DESCRIPTION:Speakers: Paul Henry Williams (Stellenbosch University)\nWe sh ow that it is in principle possible to construct dualities between commuta tive and noncommutative theories in a systematic way. This construction ex ploits a generalization of the exact renormalization group equation (ERG). This link can also be understood as a blocking (coarse graining) transfor mation of the degrees of freedom. We apply this to the simple case of the Landau problem and then generalize it to the free and interacting non-cano nical scalar field theory. In non-canonical quantum field theories\, the c anonical equal time commutation relations between fields are modified in a similar way to non-commutative quantum mechanics. This differs from usual non-commutative field theories where the space-time labels are non-commut ative. This constructive approach offers the advantage of tracking the imp lementation of the Lorentz symmetry in the non-commutative dual theory. We briefly demonstrate this for the free scalar theory. In principle\, we ca n construct completely consistent non-commutative and non-local theories w here the Lorentz symmetry and unitarity are still respected but may be imp lemented in a highly non-trivial and non-local manner.\n\nhttps://events.s aip.org.za/event/100/contributions/279/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/279/ END:VEVENT BEGIN:VEVENT SUMMARY:ATLAS Monte Carlo studies for the search of heavy resonances in th e H->ZZ->4l decay channel. DTSTART;VALUE=DATE-TIME:20180627T120000Z DTEND;VALUE=DATE-TIME:20180627T122000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-280@events.saip.org.za DESCRIPTION:Speakers: Mampionona Ralaimiaramanana RAJAOFERASON (Wits-Unive rsity of Witwatersrand)\nThe search of a heavy resonance denoted H\, decay ing into four-leptonic final states through a pair of Z bosons is discusse d. This study mainly focuses on the high mass region of the H->ZZ->4l deca y channel with the ATLAS detector. Two different sets of signal Monte Carl o (MC) samples produced with different pileup conditions were studied for the gluon-gluon fusion production mode. For the MC comparisons\, signal ef ficiency studies are presented at selected mass points. Also\, shape compa risons of selected mass and kinematic (H\, Z\, leptons) variables were per formed at the same time.\n\nhttps://events.saip.org.za/event/100/contribut ions/280/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/280/ END:VEVENT BEGIN:VEVENT SUMMARY:Multi-spectral observations of sprites: N2(1PG) and N2+(2PG) Emiss ions DTSTART;VALUE=DATE-TIME:20180627T122000Z DTEND;VALUE=DATE-TIME:20180627T124000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-281@events.saip.org.za DESCRIPTION:Speakers: Stanislaus Nnadih (SpaceLab\, Electrical Engineering Department\,University of Cape Town)\nWe present a series of simultaneous ground-based observations of sprite events over convective thunderstorms in southern Africa. These observations were made at the South African Astr onomical Observatory in Sutherland during the austral summer of 2016/17 an d 2017/18\, using multiple cameras to record unfiltered images in white li ght and filtered images at 426-438 nm and 640 – 675 nm\, which correspon d to the N2+ and N2 emission spectra of sprites. The orientation of the ca mera (azimuth and elevation angle) was determined during the analysis by i dentifying the stars recorded in the image\, which was done to single-pixe l accuracy. The sprite locations were compared with the lightning location s derived from the lightning detection network operated by the South Afric an Weather Service (SAWS). Low-Frequency radio waveforms associated the ob served events were inferred from Extremely Low-Frequency electric field me asurements recorded at Sutherland simultaneously with the optical measurem ents. The results are presented and discussed.\n\nhttps://events.saip.org. za/event/100/contributions/281/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/281/ END:VEVENT BEGIN:VEVENT SUMMARY:ATOMISTIC SIMULATION STUDY OF SODIUM INTERCALATION IN TITANIUM DIO XIDE NANOSTRUCTURES DTSTART;VALUE=DATE-TIME:20180626T102000Z DTEND;VALUE=DATE-TIME:20180626T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-282@events.saip.org.za DESCRIPTION:Speakers: Tshidi Malibe (UL)\nSodium-ion batteries (NIBs) have emerged as a promising candidate for application in large scale energy de vices. These batteries have the same battery configuration as lithium–io n batteries (LIBs)\, however the huge difference in the ionic size\, makes it impossible for graphite (anode material in LIBs) to intercalate sodium ions. Therefore it is crucial to develop high-performance anode materials for NIBs. We investigate the potential of titanium dioxide (TiO2) nanosph ere as an anode material for NIBs since TiO2 is highly stable with most or ganic electrolytes\, has small structural changes during intercalation\, i t is nontoxic and inexpensive.TiO2 nanosphere was sodiated with a total of 300 atoms and investigated the structure from amorphous to crystalline ph ase while varying temperature. Recrystallization was achieved by using mol ecular dynamics (MD) simulation with the DL_POLY code this was confirmed b y the configurational energy plots. The structural rearrangement during co oling to 0K were analysed by radial distribution functions (RDFs) and the microstructures thereof shows the presence of sodium vacancies\, rutile an d brookite polymorphs\, these polymorphs were also observed on the XRDs. O ur study shows that sodium ions can be intercalated in Na0.06TiO2 nanosphe re\, thus TiO2 nanosphere can serve as suitable anode material for sodium ion batteries.\n\nhttps://events.saip.org.za/event/100/contributions/282/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/282/ END:VEVENT BEGIN:VEVENT SUMMARY:Colloidal Synthesis of Molybdenum Diselenide Nanomaterials for Sup ercapacitor Applications DTSTART;VALUE=DATE-TIME:20180627T104000Z DTEND;VALUE=DATE-TIME:20180627T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-307@events.saip.org.za DESCRIPTION:Speakers: Zakhele Ndala (Wits university)\nMolybdenum diseleni de(MoSe2) is a layered material that has attracted a lot of interest in th e scientific community\; the 2D nanomaterials derived from the bulk crysta ls of these materials have been found to have exceptional electronic and o ptical properties. These properties include a high surface to volume ratio \, high carrier mobility\, relatively high stability and a band-gap in the visible region of the electromagnetic spectrum. One possible application for these materials is as electrode materials in supercapacitors. Supercap acitors are energy storage devices that have high power densities\, high c ycle stability\, large operational temperature range and a higher energy d ensity than conventional capacitors. Unfortunately\, these devices suffer from low energy densities compared to batteries. To circumvent this major drawback nanomaterials are being explored as alternatives to activated car bon for use as electrode materials in supercapacitors. In this work a nove l colloidal synthetic method has been developed to synthesize 2H hexagonal phase MoSe 2 nanomaterials with a nanosheets and nanoflower morphology fo r supercapacitor applications. The electrochemical performance of the two morphologies were compared to determine the best suitable MoSe2 nanomateri als morphology for the application. The MoSe2 nanomaterials displayed elec tric double capacitance. The specific capacitance of the MoSe2 nanosheets and nanoflowers was determined to be 30 Fg-1 and 81 Fg-1 respectively. The impedance MoSe2 nanosheets and nanoflowers was determined to be 57.1 Ω a nd 34.0 Ω respectively. The nanoflowers morphology has superior electroch emical performance because the 3D interconnected nature of the nanoflowers gives them higher surface area and pore volume.\n\nhttps://events.saip.or g.za/event/100/contributions/307/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/307/ END:VEVENT BEGIN:VEVENT SUMMARY:Design\, development and characterization of a magneto-optical tra p for laser cooling of Rubidium atoms: a project at the Cape Peninsula Uni versity of Technology DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-283@events.saip.org.za DESCRIPTION:Speakers: Kessie Govender (Cape Peninsula University of Techno logy)\nLaser cooling of neutral atoms have opened up a new area of researc h into ultra-low temperature physics of quantum systems. These systems hav e shown potential in many areas of quantum information processing\, such a s single photon sources\, entangled photon generation\, quantum simulation s using cold atoms in optical lattices etc. We describe in this presentati on the theory of laser cooling and the development and characterization of a device to cool and trap neutral Rubidium atoms.\n\nThe system consists of an octagonal vacuum chamber having a number of view ports\, vacuum pump s\, piping\, vacuum gauge and valves. Three stages of pumping (i.e. rotary \, turbo and ion pumping\,) are used to reduce the pressure from atmospher ic down to ~ 10^(-10) mbar. Rubidium atoms stored in a getter material are released into the vacuum chamber by means of electrical heating. Three pa irs of counter propagating laser beams\, each pair positioned on opposite sides of the chamber along three orthogonal axes are used for cooling of t he atoms in the chamber. The lasers are frequency locked\, using a saturat ed absorption setup and incorporating a PID controller\, to the 5S1/2(F=2) to 5P3/2(F=3) transition of Rb87. Because the atoms eventually move out o f the cooling transition cycle a re-pumping laser is also incorporated and tuned to 5S1/2(F=1) to 5P3/2(F=2) transition.\n\nThe cooled atoms will be trapped using a pair of anti-Helmholtz magnetic coils positioned on eithe r side of the vacuum chamber. Measurements will be conducted using optical sensors such as CCD cameras and avalanche photo detectors for measuring t he light emitted by the trapped atoms. By measuring the fluorescence of th e cooled atoms\, the number density\, size of the atomic cloud\, and tempe rature can be inferred. We provide preliminary measurements of these\, in addition to details of the performance of the saturated absorption setup a nd of the laser control for Doppler cooling.\n\nhttps://events.saip.org.za /event/100/contributions/283/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/283/ END:VEVENT BEGIN:VEVENT SUMMARY:Data Analysis and Security Development of a Wireless Mesh Network DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-285@events.saip.org.za DESCRIPTION:Speakers: Rorisang Sitoboli (University of the Witwatersrand)\ nA multiple router\, low-power mesh wireless network with multi-hopping ne tworking capabilities was developed at the Physics building ground floor. Multi-point data between routers was collected over an extended period of time. This study contributes to the analysis of the data for an anti-theft application\, based on the future work of the research 'System Control Ap plications of Low-power Radio Frequency Devices' (S.A.I.P 2017). Data pack ets were sent between multiple mesh routers and quantitative experimental data was collected consisting of latency delays and packet losses. The net work performance\, based on statistical analysis\, has indicated reliable interconnected node communications even in the presence of physical obstac les in the environment. To extend the study\, an algorithm is proposed for implementation on an Android application of the device and application la yer of the routers. This is to ensure secure communications within the mes h components. Secure communications between the device and the network wil l result in normal device operation while device locations outside the cov erage perimeter may render the device inoperable. The added security featu re allows secure communications of devices connected to the network and pr events unauthorized connections such as black-hat hacking.\n\nhttps://even ts.saip.org.za/event/100/contributions/285/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/285/ END:VEVENT BEGIN:VEVENT SUMMARY:Statistical Properties of highly-deformed Samarium isotopes DTSTART;VALUE=DATE-TIME:20180628T102000Z DTEND;VALUE=DATE-TIME:20180628T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-286@events.saip.org.za DESCRIPTION:Speakers: Kgashane Malatji (iThemba LABS / Stellenbosch Univer sity)\nThe rare-earth isotopic chain of Samarium provides an excellent opp ortunity to systematically investigate the evolution of nuclear structure effects from the near spherical (β2=0.09) 144Sm isotope to the highly-def ormed system 154Sm (β2=0.34). As the nuclear shape changes\, statistical properties such as the nuclear level density (NLD) and γ-strength functio n (γSF) are expected to be affected. In particular resonance modes\, such as the Pygmy Dipole (PDR)\, Scissors Resonances (SR) and the recently dis covered Low-Energy Enhancement (LEE) in rare-earth region may reveal inter esting features when their evolution is investigated across several nuclei in an isotopic chain. Most reliable knowledge can be obtained when result s from several different experiments are compared. An experiment was perfo rmed in September 2016 at Oslo Cyclotron Laboratory (OCL) where the NaI(Tl ) γ-ray array\, silicon particle telescopes and 6 high-efficiency LaBr3: Ce detectors were utilized to measure particle-γ coincidence events from which the NLDs and γSFs will be extracted below the neutron separation en ergy threshold\, Sn\, using the Oslo Method (A. Schiller et al. 2000). The deuteron beam with 13 and 15 MeV energies was used to populate excited st ates in 154\,155Sm through the inelastic scattering (d\,d’γ) and the tr ansfer reaction (d\,p). Based on the results from these measurements\, the extracted NLDs and γSFs will be used to investigate the evolution of nuc lear structure effects in 154\,155Sm and provide complementary information to the 154Sm(p\,p’)154Sm and 154Sm(α\,α’γ)154Sm data on resonance features that lie on the low-energy tail of the GDR. In addition\, the res ults will further provide a near-complete picture on the evolution of the PDR\, SR and/or the LEE as the isotopic chain transitions from near spheri cal to very deformed. In this talk I will present preliminary results of t his investigation of statistical properties for 154\,155Sm in comparison t o the previous and recent measurements of 148\,149Sm and 151\,153Sm isotop es\, respectively\, and ongoing measurements of 152\,153Sm at OCL.\n\nThis work is based on the research supported in part by the National Research Foundation of South Africa\, the IAEA under research grant number: 20454 a nd by the DFG under contract SFB 1245.\n\nhttps://events.saip.org.za/event /100/contributions/286/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/286/ END:VEVENT BEGIN:VEVENT SUMMARY:Radio Intereformetric Calibration using a Complex Student-t distri bution and Wirtinger derivatives DTSTART;VALUE=DATE-TIME:20180628T094000Z DTEND;VALUE=DATE-TIME:20180628T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-305@events.saip.org.za DESCRIPTION:Speakers: Mbou Sob Ulrich Armel (Rhodes University)\nCalibrati on in radio astronomy is the step during which all systematic errors and i onospheric curruptions\, are estimated and removed from the observed data. This consists of solving for all propagation effects\, i.e.~Jones matrice s\, which minimizes the difference between the measured and the model data using a mathematical framework known as the Radio Interferometric Measure ment Equation (RIME). The model data is constructed based on our existing knowledge of the observed field using a Gaussian likelihood function. Ho wever various outliers in the data and errors in the model cause deviation s from the assumed likelihood function. This leads to “poor”' calibrat ion solutions and formation of various artefacts in the calibrated images. These include generation of spurious sources\, suppression in the flux of real structures and an increase in images' rms that reduces the detection probability of faint sources. Recently some authors (Kazemi and Yatawatta (2013)\; Ollier\, Virginie\, et al.~2016) have proposed using a different statistical noise model that better fits the noise as well\, as unmodelle d data and errors\, in order to improve calibration. Kazemi and Yatawatta (2013) used a Student-t likelihood in place of a Gaussian likelihood and o btained considerable improvement in flux’ suppression of the faint unmod elled sources. The algorithm implemented by Kazemi and Yatawatta (2013) re quires us to separate the complex visibilities data in to real and imagina ry parts\, and independently solve for the real and imaginary parts of the gains. We derive and implement an analogue algorithm using a complex stud ent-t distribution\, which evicts the need of separating the data in their real and imaginary parts. This is achieve by exploiting the recent develo pments in optimization theory and particularly the Wirtinger calculus as e xplained by Smirnov and Tasse (2015) for gain calibration. We show result s from simulations and the improvements obtained using the latter approach .\n\nhttps://events.saip.org.za/event/100/contributions/305/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/305/ END:VEVENT BEGIN:VEVENT SUMMARY:Mechanical properties of three stage heat treated Austempered duct ile iron DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-287@events.saip.org.za DESCRIPTION:Speakers: Delphine Mulaba-Kapinga (University of Johannesburg) \nWith engineering properties comparable to those of steel\, austempered d uctile iron (ADI)\, commonly used on mines and in structural applications\ , has high tensile strength\, moderate elongation\, acceptable wear and co rrosion resistances. Its microstructure is made of ausferrite retained aus tenite and martensite. This could be a result of either a heat treatment p rocess or of micro-alloying. In the view of developing the materials for i mproved properties\, multi stages heat treatment process has been suggeste d. This paper aims at understanding the effect of the microstructural cons tituents present in the ADI material on a further heat treatment - ageing at 260 C\, conducted with ferritic and pearlitic spheroidal graphitic (SG) cast iron. Each sample was austenitized at 900 C for 30 minutes\, austemp ered at 370 C for various durations ( ie 30 minutes\, 60 minutes and 90 mi nutes) then aged at 260 C also for different durations (ie for 1 hour\, 2 hours\, 3 hours and 4 hours). Metallographic examination of the two stage heat treated ADI\, at 500x magnification and the X-Ray Diffraction (XRD) w ere conducted to determine the types and the quantity of phases present in the heat treated samples. It was observed that prolonging the aging time (from 1 hour to 4 hours) led to a decrease in the hardness values in the f erritic SG cast iron for all the austempered durations\, hence leading to an increase in the impact toughness. With the pearlitic SG cast iron\, aus tempering for 30 minutes and 90 minutes showed a similar trend in the decr ease of the hardness values from 1 to 2 hours and again from 3 to 4 hours\ , thus showed an increase in the impact toughness from 1 to 2 hours and ag ain from 3 to 4 hours. It is concluded that the two stage further heat tre atment affected the hardness and the toughness of the ADI.\n\nhttps://even ts.saip.org.za/event/100/contributions/287/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/287/ END:VEVENT BEGIN:VEVENT SUMMARY:Effect of domain transformation on the magnetic properties of NixC o1-xFe2O4 DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-288@events.saip.org.za DESCRIPTION:Speakers: Amos Nhlapo (University of KwaZulu-Natal)\nIn this s tudy\, nanoparticles of NixCo1-xFe2O4 (x = 0\, 0.1\, 0.2\, 0.3\, 0.8 and 1 .0) were produced by glycol thermal process and characterized by several t echniques such as XRD\, TEM\, SEM\, FTIR\, Mössbauer spectroscopy and mag netization measurements. The as-prepared fine powders show transformation from single- to multi-domain behaviour at a critical particle size depende nt on sample chemical composition. The effect of domain transformation on the magnetic properties has been investigated. 57Fe Mössbauer spectral st udies and magnetization data show significant differences between single- and multi-domain particles. The results are explained on the basis of crys tallite size and constituent atoms. The variation of the magnetic paramete rs such coercive fields and saturation magnetization revealed by hysteresi s loop measurements in the temperature range 4 – 300 K is also reported. \n\nhttps://events.saip.org.za/event/100/contributions/288/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/288/ END:VEVENT BEGIN:VEVENT SUMMARY:Are Bessel beams resilient to aberrations and turbulence? DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-289@events.saip.org.za DESCRIPTION:Speakers: Nokwazi Purity Mphuthi (Hartebeesthoek Radio Astrono my Observatory: Space Geodesy)\nIt is understood from the conical wave pic ture that Bessel beams may self-heal after certain opaque obstructions\, b ut the extrapolation to transparent phase screens is not self-evident. We demonstrate that self-healing is not guaranteed when the Bessel beam is pr opagated through transparent obstacles with aberrations but is rather depe ndent on the strength of the aberrations. Finally we combine aberrations t o simulate the Bessel beam passing through turbulence and debunk the myth that Bessel beams are resilient to such perturbations.\n\nhttps://events.s aip.org.za/event/100/contributions/289/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/289/ END:VEVENT BEGIN:VEVENT SUMMARY:Single photon emission from NV defects in diamond DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-290@events.saip.org.za DESCRIPTION:Speakers: Nyiku Mahonisi (University of the Witwatersrand)\nSo lid-state based single photon systems are at the heart of the second quant um revolution. Particularly NV⁻ defects in diamond\, due to their emissi on properties and that they can easily be integrated to current and scalab le optical networks. The fluorescence from the excitation of NV defects in diamond has been studied extensively. It has been shown that the excitati on of these quantum systems generates non-classical states applicable in a variety of fields. This has enhanced the ambition of building quantum-bas ed technological devices. In this study\, we engineer NV defects in well-d efined isolated regions within a pure type IIa diamond sample via ion impl antation. We then characterize the fluorescence and photon distribution fr om the NV defects. Ultimately\, this will allow us to fabricate isolated N V defects at desired regions for easy access for applications.\n\nhttps:// events.saip.org.za/event/100/contributions/290/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/290/ END:VEVENT BEGIN:VEVENT SUMMARY:Effects of Ion Implantantion on Energy Storage Properties of Bulk Molybdenum Disulphide DTSTART;VALUE=DATE-TIME:20180627T130000Z DTEND;VALUE=DATE-TIME:20180627T132000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-291@events.saip.org.za DESCRIPTION:Speakers: Patrick Mwonga (University of the Witwatersrand)\nWe report the effects of implanted molybdenum and tungsten ions on the capac itance of electrodes made from bulk molybdenum disulphide (MoS2). Six samp les of crystalline MoS2\, were modified by ion implanted. Three samples wi th Mo ions and three with W ions\, at varying fluences and an acceleration voltage of 10 keV. The ion implantation process first simulated using the Stopping and Range for Ions in Matter (SRIM) software. This provided us w ith the simulated defect density in terms of vacancies and ion penetration depth. Raman Spectroscopy (RS) and Photoluminescence (PL) Spectroscopy ha ve been used to give some insight into vibrational and optical properties respectively\, before and after the ion implantation. Pseudocapacitance pr operties\, specific capacities\, performance and stability of the electrod es were measured using Electrochemistry techniques. Coulombic efficiencies \, retention capabilities as well as the knee frequencies are measured as well. All our modified electrodes showed remarkable improvement on perform ance\, especially in terms of specific capacity and % capacitance retentio n after 1000 cycles of charge and discharge\, with reference to the pristi ne (as received) MoS2 electrodes.\n\nhttps://events.saip.org.za/event/100/ contributions/291/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/291/ END:VEVENT BEGIN:VEVENT SUMMARY:Full phase space simulation of the relativistic Boltzmann equation in the context of heavy-ion collisions DTSTART;VALUE=DATE-TIME:20180627T080000Z DTEND;VALUE=DATE-TIME:20180627T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-292@events.saip.org.za DESCRIPTION:Speakers: Ernst Grunow (University of Cape Town)\nRelativistic hydrodynamics has been the tool of choice to simulate the dynamics of the quark-gluon plasma produced in heavy-ion collisions.\nDespite the success of hydrodynamics\, it has several shortcomings stemming from the fact tha t it assumes a system close to equilibrium.\nAn alternative to hydrodynami cs is solving the Boltzmann equation\, which describes the evolution of th e full distribution function of the system without the close to equilibriu m requirement.\nThe Boltzmann equation\, however\, has hitherto proved com putationally intractable.\nBy using a novel algorithm\, and leveraging the computational power\, we numerically integrate the Boltzmann equation in the relaxation time approximation.\n\nhttps://events.saip.org.za/event/100 /contributions/292/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/292/ END:VEVENT BEGIN:VEVENT SUMMARY:Microwave induced electron losses from an ECR Ion Source DTSTART;VALUE=DATE-TIME:20180628T104000Z DTEND;VALUE=DATE-TIME:20180628T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-293@events.saip.org.za DESCRIPTION:Speakers: Muneer Sakildien (iThemba LABS)\nTo enhance high cha rge state ion beam production it is imperative to maximize the electron co nfinement time of the heated electron populations of an Electron Cyclotron Resonance Ion Source (ECRIS). A key loss mechanism for heated electrons a re induced by the injected microwaves which heats the plasma electrons of an ECRIS. This electron loss mechanism is thought to limit ultimate source performance. With this investigation a number of plasma diagnostics were combined to study this plasma process. Here we will report on the results of preliminary measurements on the JYFL 14 GHz ECRIS.\n\nhttps://events.sa ip.org.za/event/100/contributions/293/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/293/ END:VEVENT BEGIN:VEVENT SUMMARY:DFT study of Modifications of Pt-doped TiO2 using N\, for applicat ion in DSSCs DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-295@events.saip.org.za DESCRIPTION:Speakers: Ratshilumela Steve Dima (University of venda)\nDopin g has found to be one of the most promising method to in increasing photoc atalytic activity of various materials. The location and nature of the dop ing elements strongly affect the structural\, electronic and optical prope rties of TiO2. To tailor the band structure and modify the photocatalytic activity of TiO2 brookite (210) surface\, a pair of dopants is selected. P latinum and Nitrogen atoms are inserted in the TiO2 network as substitutio nal and N was also doped through absorption on the surface. The main objec tive behind the different locations and methods of the dopant elements are to banish the isolated unoccupied states from the forbidden region that n ormally annihilates the photogenerated carriers. Pt replaced Ti\, N replac ed O and N was also absorbed and bond with 2 coordinated O in the TiO2 bro okite (210) surface network. N absorbed Pt\n TiO2 provided a suitable conf iguration of dopant atoms in terms of geometry and band structure. Moreove r\, the optical properties showed a notable shift to the visible regime. I ndividual dopants either introduced isolated unoccupied states in the band gap or disturbed the Fermi level and structural properties. Furthermore\, the other co-doped configurations showed no remarkable band shift\, as we ll as exhibiting a suitable band structure. Resultantly\, comparing the ba nd structure and optical properties\, it is argued that Pt (at Ti) and N a bsorbed (at O) doped would strongly improve the photocatalytic activity of TiO2 brookite (210) surface.\n\nhttps://events.saip.org.za/event/100/cont ributions/295/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/295/ END:VEVENT BEGIN:VEVENT SUMMARY:Optical structural properties of Y2SiO5:Ce thin films prepared by spin coating. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-296@events.saip.org.za DESCRIPTION:Speakers: Alfred Odirile Mashalane (UFS)\nOptical and structur al properties of Y2SiO5:Ce thin films prepared by spin coating.\nA Mashala ne\, HC Swart and MM Duvenhage\n\nY2SiO5:Ce is a blue emitting phosphor th at is used in field emission displays (FED). In this study thin films of Y 2SiO5:Ce was prepared by spin coating and their luminescent and structural properties were compared to that of commercially available Y2SiO5:Ce powd er.\nThin films of Y2SiO5:Ce were prepared by spin coating on soda lime gl ass substrates. The concentration of the solution was kept constant while the spinning speed was varied between 500\, 1000 and 2000 RPM. X ray diffr action (XRD) was performed on the samples to determine the crystal structu re and particle size of the films. Diffuse reflectance measurements were p erformed to determine the optical bandgap of the films. Photoluminescence (PL) studies were done to determine the excitation and emission wavelength of the various films.\nThe XRD confirmed the monoclinic crystal phase of Y2SiO5:Ce powder with the two major peaks at -402 and 103 present. The fil ms showed lower intensity of the XRD peaks. The PL showed broad blue emis sion between 400 and 500 nm.\n\nhttps://events.saip.org.za/event/100/contr ibutions/296/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/296/ END:VEVENT BEGIN:VEVENT SUMMARY:Growth and Characterization of Metallic Film Precursors for the Sy nthesis of CZTS Thin Films for Photovoltaic Applications DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-297@events.saip.org.za DESCRIPTION:Speakers: Tshegofatso Moipolai (University of South Africa)\nC opper Zinc Tin Sulphide (CZTS) thin films are materials of interest for lo w cost solar cells due to their suitable direct band gap of between 1.4 an d 1.5eV\, large absorption coefficient of over 104 cm-1\, abundance and lo w toxicity of the elements in the CZTS compound compared to the currently used compounds\, such as copper indium selenide (CIS)\, copper indium gall ium selenide (CIGS) and cadmium telluride (CdTe)\, which are rare and toxi c. However\, the suitability of CZTS materials under different radiation e nvironments has not yet been tested. In this work\, i.e.\, the first phase of CZTS synthesis\, Cu-Zn-Sn film precursors\, were deposited on glass su bstrate using electron beam deposition. The crystal structure of the synth esised film precursors were characterised by X- ray Diffraction (XRD) and elemental identification performed using Rutherford Backscattering Spectro metry (RBS). Moreover\, ion beam energies and fluences to be used to study the radiation hardness capability of the grown CZTS thin films were simul ated using the Transport of Ions in Matter (TRIM) code. The synthesis resu lts obtained are in agreement with those presented in the literature indic ating that the metallic CZT film precursors were successfully synthesised. \n\nhttps://events.saip.org.za/event/100/contributions/297/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/297/ END:VEVENT BEGIN:VEVENT SUMMARY:A Planned Calibration Facility For In-Situ Gamma-Ray Detectors DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-298@events.saip.org.za DESCRIPTION:Speakers: Alfred Mogotsi Sehone (Military Academy)\nIn-situ me asurements are affected by changes in the geometry of the landscape. Due t o these challenges\, a dedicated calibration facility is required. The cal ibration facility is best optimized by making use of a combination of Mont e Carlo simulations and a dedicated measurement setup\, MEDUSA system. Wit h the simulation\, one can optimize the dimensions of the calibration faci lity\, the type of material to be used and the geometry. The use of Monte Carlo simulations is used in instances\, where measurements would require too much time\, expensive or are even impractical to consider and moreover to account for the differences between the calibration and other geometri es.\n\nVarious types of samples of bricks were acquired\, crushed and meas ured using the hyper-pure germanium (HPGe) detector\, a laboratory-based s etup used to count low-level radiation samples. The results of the HPGe de tector system was used to calculate the activity concentrations of 40K\, 2 32Th and 238U decay series. In addition\, the type of the brick to be sele cted will depend amongst others on the homogeneity of the sample. \n\nThe brick castle is constructed at iThemba LABS\, Cape Town\, Western Cape\, S outh Africa. The brick castle has dimensions of 121 cm height\, 119 cm wi dth and 134 cm depth with a 10 cm PVC tube\, facing upwards\, for insertin g a detector for measurements. Initially\, the brick castle is designed to house an 8 cm diameter detector (MEDUSA). It has a wall thickness of 55 c m (width) and 63 cm (depth) to reduce the background radiation from reachi ng the detector. On completion of the brick castle\, activity measurements were taken in order to create spectra of the natural-occurring radionucli des (40K and radionuclides from the 232Th and 238U-series). These spectra were converted to create what we call standard spectra for the castle geom etry.\n\nhttps://events.saip.org.za/event/100/contributions/298/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/298/ END:VEVENT BEGIN:VEVENT SUMMARY:Temperature-dependent gas sensing study of chemically prepared CeO 2-CuO nanoparticles DTSTART;VALUE=DATE-TIME:20180627T144000Z DTEND;VALUE=DATE-TIME:20180627T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-300@events.saip.org.za DESCRIPTION:Speakers: Dina N. Oosthuizen (CSIR and University of the Free State)\nThe combination of nanosized cerium dioxide (CeO2) with transition metal oxides\, like copper oxide (CuO)\, containing Ce1-xCuxO2-y\, have r eceived significant attention for their catalytic application due to their economic\, environmental\, and catalytically favourable properties.[1] Th ese systems proved efficient for selective CO oxidation the water-gas shif t (WGS) reactions and the hydrogen combustion reactions.[2] Even though th e surface and catalytic properties of the Ce1-xCuxO2-y systems can be tran slated to the field of gas sensors\, the gas sensing performance of these systems have not yet been investigated. \n\nTherefore\, herein\, we report for the first time\, the gas sensing performance of Ce1-xCuxO2-y systems towards various gases such as CO\, H2S\, H2\, CH4\, NH3\, ethanol\, NO2 an d toluene at various operating temperatures and relative humidity. The inf luence of the crystallize size\, point defects and adsorbed surface oxygen species on the response\, selectivity and sensitivity of Ce1-xCuxO2-y nan oparticles was investigated using X-ray diffraction\, transmission electro n microscopy attached with electron energy loss spectroscopy\, X-ray photo -electron spectroscopy and photoluminescence spectroscopy. The underlying gas sensing mechanism was also examined and discussed.\n\n[1] (a) Putla\, S.\, M.H. Amin\, B.M. Reddy\, A. Nafady\, K.A. Al Farhan\, and S.K. Bharga va\, ACS Applied Materials & Interfaces\, 7\, 16525-16535 (2015)\; DOI: 10 .1021/acsami.5b03988\; (b) Qin\, J.\, J. Lu\, M. Cao\, and C. Hu\, Nanosca le\, 2\, 2739-2743 (2010)\; DOI: 10.1039/c0nr00446d\n[2] (a) Bernardi\, M. I.B.\, A. Mesquita\, F. Beron\, K.R. Pirota\, A.O. de Zevallos\, A.C. Dori guetto\, and H.B. de Carvalho\, Physical Chemistry Chemical Physics\, 17\, 3072-3080 (2015)\; DOI: 10.1039/c4cp04879b\; (b) Elias\, J.S.\, N. Artrit h\, M. Bugnet\, L. Giordano\, G.A. Botton\, A.M. Kolpak\, and Y. Shao-Horn \, 6\, 1675-1679 (2016)\; DOI: 10.1021/acscatal.5b02666\n\nhttps://events. saip.org.za/event/100/contributions/300/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/300/ END:VEVENT BEGIN:VEVENT SUMMARY:Radiation from relativistic particles accelerated at shear layers in relativistic jets. DTSTART;VALUE=DATE-TIME:20180627T084000Z DTEND;VALUE=DATE-TIME:20180627T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-301@events.saip.org.za DESCRIPTION:Speakers: Tej Chand (Center for Space Research\, North-West Un iversity Potchefstroom South Africa)\nThe supermassive black holes in the centers of some active galaxies (AGN) eject powerful relativistic jets whi ch propagate over kpc scales\, showing no significant momentum loss. Both observational evidence as well as theoretical considerations from MHD simu lations of jets suggest that they are radially stratified\, with a fast in ner spine surrounded by a slower-moving outer sheath. The resulting relati vistic shear layers are a prime candidate for the site of relativistic par ticle acceleration in the jets of AGN and gamma-ray bursts (GRBs). In this talk\, we will present results of particle-in-cell simulations of magneti c-field generation and particle acceleration in the relativistic shear bou ndary layers of jets in AGN and GRBs. We outline future plans to include s elf-consistent calculation of radiation produced by the particles accelera ted at these shear boundary layers.\n\nhttps://events.saip.org.za/event/10 0/contributions/301/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/301/ END:VEVENT BEGIN:VEVENT SUMMARY:Enhanced photocatalytic degradation of methyl violet on TiO2/N-MWC NTs DTSTART;VALUE=DATE-TIME:20180626T092000Z DTEND;VALUE=DATE-TIME:20180626T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-302@events.saip.org.za DESCRIPTION:Speakers: Xiluva Mathebula (University Of The Witwatersrand)\n Textile industries are amongst the top environs of water polluters. They r elease complex organic pollutants (such as organic dyes) that are resistan t to conventional water purification methods. Lately\, TiO2-based photoca talytic degradation method has been successfully used to ravage the organi c dye pollutants in aqueous medium at a low cost. However\, the efficiency and turnover number of TiO2 is limited due to its low surface area\, sint ering\, and the electron-hole recombination. Thus\, multiwalled carbon nan otubes (MWCNTs) can be used to enhance the photocatalytic activity of TiO2 by increasing the catalyst surface area and also acting as photo-generate d electron capturers. Moreover\, the MWCNTs can be modified with nitrogen dopants to create more defects on the carbon lattice and a net positive ch arge to strengthen the TiO2-C interaction. We herein report on the compete nce of CVD-synthesized nitrogen doped MWCNTs (N-MWCNTs) in the enhancement of TiO2 photocatalytic activity for the degradation of methyl violet. Our results showed that N-MWCNTs supported TiO2 photocatalyst exhibit a large surface area\, good TiO2-C interaction\, and a reduction in the electron- hole recombination. Consequently\, the photocatalytic activity of raw TiO2 was drastically increased after the inclusion of N-MWCNTs. Furthermore\, the N-MWCNTs showed a great potential of improving the photocatalytic stab ility of TiO2 and its reusability.\n\nhttps://events.saip.org.za/event/100 /contributions/302/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/302/ END:VEVENT BEGIN:VEVENT SUMMARY:Computational Modelling of Platinum Arsenide (PtAs) DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-303@events.saip.org.za DESCRIPTION:Speakers: Kgwajana Barnard Molala (UL)\nCompound such as coope rate\, braggite\, sperrylite and platarsite are important sources of plati num (Pt) and palladium (Pd) in many of the world’s largest deposits of p latinum group minerals (PGM). South Africa is major producer of platinum g roup elements (PGE)\, therefore research in understanding the surface chem istry and surface reactivity of this platinum group mineral is central to major mining industrial process. Sperrylite (PtAs2>) is an important and v ery rare ore of mineral of platinum\, but still by far the best known comp ound containing platinum. Industrial mineralogical studies have found plat inum group minerals\, such as Sperrylite (PtAs2>) to be poorly recovered d uring flotation. Research on the flotation behaviour of Sperrylite mineral is very limited\, due to their small size (<10μm)\, and also the scarcit y of individual grains contribute to the complexity of studying fundamenta l interactions. We have performed density functional theory calculations w ithin the generalized gradient approximation (GGA) to study bulk\, electro nic and surface properties of PtAs2> using CASTEP code. The theoretical ca lculated lattice constant and bulk modulus compare very well with the avai lable experiment and theoretical calculations. The convergence test of sl ab thickness and vacuum width for low index surfaces (100)\, (110) and (11 1) were carried out and the results are discussed.\n\nhttps://events.saip. org.za/event/100/contributions/303/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/303/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigating the candidate 5-alpha cluster state in 20Ne at Ex = 22.5 MeV with the 22Ne(p\, t)20Ne reaction. DTSTART;VALUE=DATE-TIME:20180627T082000Z DTEND;VALUE=DATE-TIME:20180627T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-304@events.saip.org.za DESCRIPTION:Speakers: Lerato Baloyi (University of the Witwatersrand)\nThe study of alpha-cluster in light nuclei have been well documented with exp erimental evidences. Meanwhile\, in the recent experiments performed at iT hemba LABS using (p\,t) reaction on 22Ne with the K600 magnetic spectromet er\, a 22.5 MeV state was found\, which accounts for 5-alpha cluster situa ted at 3.3 MeV above the 5-alpha break-up threshold. However\, this state could not be accounted for by theoretical shell-model calculations and ang ular distribution data taken at forward angles including zero degrees. In the present project\, (p\, t) reaction on 22Ne will be carried out at zero degrees\, to ascertain whether this state exist or not. A proton beam wi th an energy of Elab= 80 MeV from the Separated Sector Cyclotron (SSC) fac ility impinged on a 22Ne gas target at lab angles of Θlab= 00 was conside red. Preliminary results of these experiments will be discussed.\n\nhttps: //events.saip.org.za/event/100/contributions/304/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/304/ END:VEVENT BEGIN:VEVENT SUMMARY:Interpreting features of the LHC data with a second complex double t and a singlet DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-306@events.saip.org.za DESCRIPTION:Speakers: Elie Danien RAJAOBELINA IARILALA (Wits University)\n Based on a number of features of the LHC data in Run I\, that have re-emer ged in Run II\, the HEP group at Wits formulated a hypothesis. This hypoth esis entails the existence of a heavy boson with a mass around twice the m ass of the SM Higgs boson and a single scalar with a mass around 150 GeV. Data reported recently displays discrepancies with the SM that are consist ent with the decay of a boson of a mass around 600 GeV that decays into th e above mentioned bosons. We interpret these effects in the context of a s econd scalar complex doublet and a singlet. The parameters of the model th at fit the data are extracted.\n\nhttps://events.saip.org.za/event/100/con tributions/306/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/306/ END:VEVENT BEGIN:VEVENT SUMMARY:Using Monte Carlo Simulations and Experiments to Investigate the A ctivation of Heavy Metals Using 14.1 MeV Neutrons DTSTART;VALUE=DATE-TIME:20180626T080000Z DTEND;VALUE=DATE-TIME:20180626T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-309@events.saip.org.za DESCRIPTION:Speakers: Sizwe Mhlongo (University of the Western Cape)\nThe area of Richards Bay is one of the industrialized areas in South Africa an d\, as a result\, it is prone to industrial pollution. Two studies were re cently conducted in the area\, one of the studies focused on the chemical contamination and radiological risk of water sources in the area and it wa s found that heavy metals such as As\, Mn and Cd were the main contaminant s\, with Mn being above the target water quality range (TWQR). In this stu dy the aim was to investigate the feasibility of employing the Neutron Act ivation Analysis (NAA) technique to measure the levels of heavy metals and other trace elements in Richards Bay water and sediments. The technique i s known to be sensitive to about 78 elements in the periodic table when em ploying thermal neutrons\, since it decreases with an increase in neutron energy\, a Monte Carlo-based code was used to simulate the activation of c opper\, a matrix consisting of the elements under study and a standard ref erence sample. Gamma energies identified in the\nCu spectrum were 1718 keV \, 2097 keV and 2301 keV. The simulations showed that elements are most li kely to be activated by 14.1 MeV neutrons if present in higher quantities\ , due to typically low fast neutron cross-sections in most elements. The s imulation results for the matrix of elements were poor due to saturation\, and also due to some activation products such as Mg-27\, Fe-53 and Al-28 having a half life shorter than the preferred irradiation time.\n\nhttps:/ /events.saip.org.za/event/100/contributions/309/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/309/ END:VEVENT BEGIN:VEVENT SUMMARY:Search for a heavier Higgs like boson and a dark force boson using ATLAS experiment results DTSTART;VALUE=DATE-TIME:20180627T124000Z DTEND;VALUE=DATE-TIME:20180627T130000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-310@events.saip.org.za DESCRIPTION:Speakers: Xolani Mapekula (University of Johannesburg)\nA sear ch is described for a new boson that lies beyond the standard model is con ducted where the progenitor 125 GeV Higgs Boson decays ultimately to four leptons (electrons or muons). The Higgs boson provides a portal into the h idden sector\, which contains dark particles. The processes under consider ation include H → ZX→ 4l and H → XX → 4l where X is the dark vecto r boson Zd or the pseudoscalar boson a\, which are part of the two benchma rk models used in the analysis. The mass range under consideration for the dark vector boson or the pseudoscalar boson are 1 < X < 60 GeV. The data under analysis is collected from p-p collisions at the LHC from the ATLAS detector using a centre of mass energy of √s=14 TeV with an integrated l uminosity of 36-1 fb. Upper limits at the 95% confidence level are imposed on the fiducial cross sections for the processes under consideration. Th e subsequent work considers relaxing the Higgs Boson mass constraint upwar ds\, introducing improved filtering and also improvements in the backgroun d estimation.\n\nhttps://events.saip.org.za/event/100/contributions/310/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/310/ END:VEVENT BEGIN:VEVENT SUMMARY:The effect of varying Cu2+ concentration on the structure and opti cal property of BaAl2O4: x%Cu2+ (0 ≤ x ≤ 1) nano-phosphors prepared us ing the citrate sol-gel method. DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-311@events.saip.org.za DESCRIPTION:Speakers: Vusani Muswa Maphiri (Sefako Makgatho Health Science University)\nBarium aluminates (BaAl2O4) are an important class of materi als of the alkaline earth aluminates. BaAl2O4 phosphors are known for thei r high emission intensity and long afterglow. In this study\, the emission from the BaAl2O4 is being further optimized by introducing Cu2+ ions with in the host matrix. Hear it is shown that BaAl2O4 has an optimum emission\ , when doped with 0.075% Cu2+ and excited by the 282 nm. BaAl2O4:Cu2+ syst em has never been reported on literature. BaAl2O4 is known to emit a blue colour. When BaAl2O4 is doped with rare earth metal such as trivalent eur opium (Eu3+) it is known to emit a red colour. In this study\, the CIE als o confirmed that the un-doped (host) emits a blue colour. When varying the excitation wavelength for the x = 0.075% or varying the dopant concentrat ion the emission colour shifts from navy blue to the light blue. Our resul ts show the appropriate excitation wavelength to get the highest emission. These results also show the excitation wavelength and dopant concentratio n together with they are corresponding expected emission colour.\n\nhttps: //events.saip.org.za/event/100/contributions/311/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/311/ END:VEVENT BEGIN:VEVENT SUMMARY:An evaluation of the Newton-Raphson iteration method in the predic tion of leaf temperature DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-312@events.saip.org.za DESCRIPTION:Speakers: Martin Kudinha (CPUT)\nA knowledge of the temperatur e of leaves is of enormous significance particularly from a plant physiolo gical point of view. A study was conducted under field conditions to evalu ate Newton-Raphson iterative method as an alternative approach in the indi rect determination of leaf temperature from meteorological data. Three fie ld experiments were performed at two different sites at Cape Peninsula Uni versity of Technology (CPUT)\, Bellville Campus in Cape Town\, using three different plants. Leaf temperatures predicted from the iteration method w ere compared with field measurements of leaf temperatures obtained from a local tree\, potted Strelitzia Nicolai flower plant and Agapanthus Praecox \, another flower growing at CPUT nursery complex. The strongest relation\ , characterized by reasonable precision (R2 = 0.89)\, high accuracy (D = 0 .96) and a fairly high value of the confidence index (C = 0.91) was obtain ed when Agapanthus Praecox was used\, whilst Strelitzia Nicolai yielded a poorer relationship (R2 = 0.71\; D = 0.77\; C = 0.64). The tree had the wo rst correlation. Leaf temperature computed by the iteration process showed a tendency of underestimation in all the field experiments.\n\nhttps://ev ents.saip.org.za/event/100/contributions/312/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/312/ END:VEVENT BEGIN:VEVENT SUMMARY:Physics of microwave processing of geological materials and their interactions DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-313@events.saip.org.za DESCRIPTION:Speakers: Antoine-Floribert MULABA-BAFUBIANDI (School of Minin g\, Metallurgy and Chemical Engineering\, University of Johannesburg)\nApa rt their usages in telecommunication Microwaves have been used in minerals and materials processing. The materials in-outer ward heating mechanism i s exploited to improve the reaction mechanism as well as the thermodynamic s and process efficiency. This paper discusses findings obtained when soil materials were processed with microwaves either in a pre-treatment stage or in a final process stage. Sandtones and slates have been cracked using microwaves. This process was exploited in the artisanal mining of the abov e mentioned two commodities. Clayey soils have been processed with microw aves. Bacteria strains populations were reduced through microwave irradia tion of geophagic clays. Sulphide and oxide ores have been Microwave treat ed. Partial and full roasting of sulphide ores were observed while oxidati on-reduction of metals in their oxide minerals were studied. The physics o f the interactions between the microwaves and the mineral phonons will be discussed through their macroscopic evolution and impact.\n\nhttps://event s.saip.org.za/event/100/contributions/313/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/313/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthesis and characterization of ZnS prepared by Co-precipitation method DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-314@events.saip.org.za DESCRIPTION:Speakers: Tshegofatso Modungwe (University of Free State)\nZin c Sulphide is an important optoelectronic device material with a wide band gap and it is used for violet to blue light applications. Zinc Sulphide ( ZnS) nanoparticles doped with Manganese and Copper have been synthesized w ith the chemical co-precipitation method using Polyvinylpyrrolidone (PVP) as a capping agent to control the particle growth. The crystal structure a nd particle size were studied utilising X-ray diffraction and it was found that the un-doped ZnS\, the Mn-doped ZnS and the Cu-doped ZnS powders all have the cubic zinc blende crystal structure with a (111) preferred orie ntation. The crystallite sizes were in the order of 4 nm. UV-visible spect roscopy was used to characterize the powders at room temperature and refle ctance measurements were performed on all samples. From these measurements the band gap of the un-doped ZnS\, the Mn-doped ZnS and the Cu doped ZnS powders was found to be 3.3 eV\, 3.2 eV and 3.1 eV\, respectively. Photolu minescence (PL) measurements were performed on all samples with a Cary Ecl ipse spectrophotometer. From the PL measurements it was found that the un- doped ZnS had a broad emission peak at 480 nm (blue). Both doped samples h ad the same broad emission peak at 480 nm (blue) with a stronger second em ission peak at 605 nm (orange) for Mn-doped ZnS while for the Cu-doped ZnS the second emission peak was at 580 nm (yellow). The broad blue emission is attributed to Zinc or Sulphur vacancies while the orange and yellow emi ssion can be attributed to the Mn and Cu dopants respectively.\n\nhttps:// events.saip.org.za/event/100/contributions/314/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/314/ END:VEVENT BEGIN:VEVENT SUMMARY:Preference of Co and Sn additions on Zr-xNb alloy DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-315@events.saip.org.za DESCRIPTION:Speakers: Hasani Chauke (University of Limpopo)\nZr-based allo ys are aimed for the more severe operating conditions\, such as higher bur n-up and increased operation temperature\, this is due to their good resis tance to corrosion and high melting point. Most of these Zr alloys contain s Nb as the major alloying element\, which is recommended for developing n ew fuel cladding materials since it is an effective strengthening element. This study uses ab initio method to investigate the effect of Co and Sn a ddition on Zr-Nb alloy\, their thermodynamic and mechanical properties wer e calculated to understand the effect of alloying. In the quest to enhance the resistance to corrosion of the advanced future cladding nuclear mater ial\, we have investigated the Zr-Nxb alloys which allow to introduce smal l Co and Sn contents at less computational costs. The Zr-xNb alloys with a higher percentage of Nb ( x> 5) causes the deterioration of corrosion pro perties. We have noted significance of alloying Zr-Nxb at small concentrat ions. It was found that the Co and Sn addition on the Zr-Nxb alloy at smal l concentrations are more preferred for thermodynamic and mechanical stabi lity of the alloy system. Their elastic stability was also evaluated at hi gh temperature and revealed that the Sn addition is more preferred and may be applicable in the development of future cladding nuclear materials.\n\ nhttps://events.saip.org.za/event/100/contributions/315/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/315/ END:VEVENT BEGIN:VEVENT SUMMARY:High-resolution confocal Raman microscopy analysis of the transpar ent hematite films prepared on fluorine-doped tin oxide coated glass subst rates by spray pyrolysis DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-316@events.saip.org.za DESCRIPTION:Speakers: Sipho Congolo (University of Pretoria)\nHematite (Fe 2O3) is a promising material that is being studied immensely for its appli cation in solar water splitting. It has attractive properties such as a na rrow bandgap that allows for absorption of visible light\, earth-abundant and is an easily processable photocatalytic material. In this study\, we r eport hematite thin films prepared by spray pyrolysis on fluorine-doped ti n oxide (FTO) coated glass substrates\; it has been shown in literature th at films prepared by ultrasonic spray pyrolysis allow for better light har vesting than those prepared by conventional spray pyrolysis. Amongst other characterization techniques\, Raman micro-spectroscopy is a preferred met hod for hematite analysis since it is non-destructive. This work demonstra tes the characterization of the as-prepared hematite thin films using the confocal Raman technique (with three different laser sources\, i.e. 488\, 532 and 633 nm) combined with an integrated atomic force microscopy (AFM) and force-distance curves measurements. Raman imaging/spectroscopy confirm ed the characteristic Raman spectrum of the hematite. In addition\, the le ss rough surface of the films seen from the Raman optical microscope image s as well as AFM 3D surface images confirmed the uniform and conformal cov erage across the substrate with surface roughness in the order of <10 nm. The force-distance curves (approach and retract) have shown an average adh esion force of about 10.4 nN for hematite on FTO substrates. Moreover\, fr om Raman depth profiles the thicknesses of the films were estimated.\n\nht tps://events.saip.org.za/event/100/contributions/316/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/316/ END:VEVENT BEGIN:VEVENT SUMMARY:Temporal Effect on Optical Pulse-per-second Clock Stability DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-318@events.saip.org.za DESCRIPTION:Speakers: KAGISO J LEBURU (NELSON MANDELA UNIVERSITY)\nTelesco pe array networks rely on highly stable clock tones distributed over optic al fibre to each antenna for driving the digitizers\, data time stamping a nd other monitoring and control functions. However\, optical clock tones s uffer from time deviation from their true periodicity\, known as jitter. J itter is contributed by noise\, thermal effects and aging of clocks. In th e case of buried and aerial optical fibres\, a complex interplay between n umbers of factors adversely affects the stability in the light-wave clock tone as it propagates within an optical fibre\, key among them being tempo ral effect. In this paper\, we experimentally demonstrate temporal effect on pulse-per-second (PPS) clock stability. A PPS clock signal is transmitt ed over a 3.21 km of optical fibre at 5 °C. A jitter measurement of 50.55 ps is experimentally attained. However\, as the fibre temperature is incr eased to 25 °C\, a jitter stability of 59.13 ps is measured. This is due to the fact that a typical fibre has thermal coefficient of expansion of 7 ppm/°C. Temperature changes results in expansion and contraction of opti cal fibre\, therefore altering the flight time and jitter of PPS signals. The mastery of these factors allows for jitter correction mechanisms to ef fectively compensate for the jittery in such systems.\n\nhttps://events.sa ip.org.za/event/100/contributions/318/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/318/ END:VEVENT BEGIN:VEVENT SUMMARY:Using reference radiation source to test Monte Carlo simulations DTSTART;VALUE=DATE-TIME:20180626T084000Z DTEND;VALUE=DATE-TIME:20180626T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-319@events.saip.org.za DESCRIPTION:Speakers: Mistura Bolaji Ajani (University of the Witwatersran d/iThemba LABS)\nThe environments that surround us contains some amount of radioactive (unstable) materials or radionuclides that are derived from p rimordial and cosmogenic sources. In addition to naturally occurring radio active materials (NORMs)\, there are technologically enhanced naturally oc curring radioactive material (TENORMs) and man-made radionuclides that hav e been introduced into ecosystems due to proliferation of different nuclea r applications in industry\, medicine and research. The main aim of this s tudy is to assess level of concentration of natural and man-made radionucl ides in environmental samples. To achieve this goal\, we seek to use Monte Carlo simulations and gamma-ray spectroscopy method. For this conference we will be presenting the test result obtained from GEANT4. The trial runs aimed at environmental gamma-ray spectrometry analysis of 60Co and 22Na p oint source samples on Hyper Pure Germanium detector and are verified usin g a Monte Carlo simulation code (GEANT4). Preliminary comparison results w ill be discussed.\n\nhttps://events.saip.org.za/event/100/contributions/31 9/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/319/ END:VEVENT BEGIN:VEVENT SUMMARY:Optimization of X-ray radiography DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-320@events.saip.org.za DESCRIPTION:Speakers: Robert Nshimirimana (NECSA)\nX-ray radiography is a 2-D projection imaging technique that is extensively used for non-destruct ive investigation of objects. The investigation is performed on the radiog raphic image produced by a radiography scanning system of which parameters such as degree of collimation\, spectrum tailoring and relative distances between source\, object and detector can be adjusted. The aim is to arran ge parameters in such a way that a radiograph is produced that optimises t he qualities of a radiograph. This can be done experimentally by changing parameters until a desired image quality (such as say contrast or sharpnes s) is achieved. However this is a time consuming\, labour intensive proces s and it is prone to human error. An X-ray radiography scan optimizer soft ware was designed and implemented to provide Pareto optimal scanning param eters. The optimizer is based on ray tracing and particle swarm optimizati on techniques. The optimizer uses a computer model of an X-ray radiography system to automatically search for the best scanning parameters. The opti mizer was successfully tested and benchmarked against experimental results . The test results showed that the optimizer software was able to provide a set of Pareto optimal solutions within which scanning parameters can be retrieved to optimize an X-ray radiography scan.\n\nhttps://events.saip.or g.za/event/100/contributions/320/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/320/ END:VEVENT BEGIN:VEVENT SUMMARY:Magnetic and Mössbauer studies of Ca_xZn_{1-x }Fe_2O_4 nanoferrit es DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-322@events.saip.org.za DESCRIPTION:Speakers: Kemi Adewale (School of Chemistry and Physics\, Univ ersity of KwaZulu-Natal\, Durban\, South Africa)\nA one-step synthesis of Ca_xZn_{1-x }Fe_2O_4 (x=0\, 0.5 and 1) nanoferrites and nanocomposites by the glycol-thermal method is reported. The structural\, morphological and magnetic properties were studied using XRD\, HRTEM/SEM\, VSM and Mössbau er spectroscopy. The XRD patterns show a single phase cubic spinel structu re of ZnFe_2O_4 at x=0. A composite phase of a spinel and hematite struc ture of Ca_{0.5}Zn_{0.5}Fe_2O_4/Fe_2O_3 was observed for x=0.5 and CaFe_2 O_4/Fe_2O_3 for x=1. The addition of Ca2+ increased the particle size due to large ionic radius of Ca2+ ions. This was also evident from the HRTEM/S EM images. The images show that the particles are almost spherical in shap e. The Mössbauer results showed a higher percentage of the α-Fe_2O_3 pha se for x=1 and only the presence of Fe3+ ions was detected in all the sam ples. The small coercivity and high magnetization of the samples reveal th e superparamagnetic nature of the samples and the saturation magnetization decreases as the percentage of the α-Fe_2O_3 phase increases.\n\nhttps:/ /events.saip.org.za/event/100/contributions/322/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/322/ END:VEVENT BEGIN:VEVENT SUMMARY:Low Pressure Focal Plane Detectors for the K600 :A design study DTSTART;VALUE=DATE-TIME:20180626T094000Z DTEND;VALUE=DATE-TIME:20180626T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-323@events.saip.org.za DESCRIPTION:Speakers: Thuthukile Khumalo (University of Zululand & iThemba LABS)\nMagnetic spectrometers have proven to be very useful in the world of experimental nuclear and astrophysics. The focal plane detection system instrumenting these spectrometers is instrumental in their success. A new focal plane detection system is envisaged for the K600 QDD magnetic spec trometer at iThemba LABS in Cape Town\, South Africa. The existing focal p lane detection system\, consisting of two multi-wire drift chambers (MWD Cs) and plastic scintillators\, is designed to detect light ions (H and He isotopes) at medium energies (50-200 MeV). To be detected these particles go through a lot of material before reaching the scintillators and an ev ent is registered. This affects the low energy threshold for operation of the K600. This study will quantify the low energy limitations as well as i nvestigate the material budget for a new low energy detector. A conceptual design for a new focal plane detection system will be explored.\n\nThis work is supported by the National Research Foundation South Africa\n\nhttp s://events.saip.org.za/event/100/contributions/323/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/323/ END:VEVENT BEGIN:VEVENT SUMMARY:Development and characterization of a micro-controller based two p hoton correlation interferometer DTSTART;VALUE=DATE-TIME:20180626T104000Z DTEND;VALUE=DATE-TIME:20180626T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-324@events.saip.org.za DESCRIPTION:Speakers: Kessie Govender (Cape Peninsula University of Techno logy)\nQuantum properties of light are usually characterized by the measur ement of the first and second order correlation functions. These correlati on functions are estimated from measurements of difference in arrival time s of photons striking two single photon detectors. In this presentation\, we describe the design\, implementation and results of such a correlation interferometer. The device is capable of measuring time difference between the arrival of photons with a resolution of 110ps or smaller. The two pho ton correlator discussed here was built using two 16 bit micro-controllers \, each having an analogue charge-time-measurement unit. The charge-time-m easurement unit is an analogue circuitry within the micro-controller that charges a capacitor for a time period. A pulse from one photon detector st arts the capacitor charging while a pulse from the other detector stops th e charging. The voltage on the capacitor then is proportional to the charg ing time\, in this case the time between arrival of the start and stop pul ses. Our system provides the following features: (1) performs a measureme nt of time differences via the charge-time-measurement unit and produces a histogram of time differences\, (2) counts the number of individual photo ns detected by each single photon detector\, (3) detects coincidence event s\, i.e. photons arriving at the detectors simultaneously\, using addition al logic gates and (4) provides an interface between the micro-controllers and a user PC running a dedicated software. The system was tested in a la b using fabricated signals simulating classical chaotic light\, single pho tons and light from a coherent source. The system was also tested using ph otons from a live quantum entanglement experiment where our system was com pared to a commercial product. Measurements of the histograms of differenc e in photon arrival times are presented for both cases. From these histogr ams the first and second order correlation functions are extracted. Also p resented are measurements of coincidence rates.\n\nhttps://events.saip.org .za/event/100/contributions/324/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/324/ END:VEVENT BEGIN:VEVENT SUMMARY:Can exemption from practical(s) help students to pass physics modu les? DTSTART;VALUE=DATE-TIME:20180626T094000Z DTEND;VALUE=DATE-TIME:20180626T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-325@events.saip.org.za DESCRIPTION:Speakers: Buyi Sondezi (University of Johannesburg)\nPure BSc major and engineering students at University of Johannesburg undertake a s tandard calculus-based physics course as an introduction to their degree m ajor. Each module in a semester consists of both theory and a practical co mponent that need to be passed if credit has to be given. Failure to attai n 50% pass mark in practical component makes it impossible for a student t o sit for a final exam and this renders the students ineligible for promot ion. Most of repeating students take the option of exemption from practica ls\, as a result some fail the module for the second time. This paper pres ents observations that reflect advantage of passing a module if good pract ical marks are attained\, and the possibility of failing the module for th e second time if exemption from practical sessions was chosen.\n\nhttps:// events.saip.org.za/event/100/contributions/325/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/325/ END:VEVENT BEGIN:VEVENT SUMMARY:Measuring the mesoscale neutral wind variability near auroral arcs using Fabry-Perot Interferometer (FPI). DTSTART;VALUE=DATE-TIME:20180626T102000Z DTEND;VALUE=DATE-TIME:20180626T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-326@events.saip.org.za DESCRIPTION:Speakers: Ntlakanipho Ngwane (SANSA/UKZN)\nFabry-Perot Interfe rometers (FPIs) measure the Doppler shift and broadening of the green-line emission from which neutral velocities and temperatures can be derived re spectively. The Scanning Doppler Imager (SDI) which is an all sky version of the FPI measures the neutral winds. SDIs are currently located in Alask a\, Antarctica and Svalbard Island. This study investigates the E region n eutral wind response to the driving force caused by the enhanced electric field upon the occurrence of an aurora. Subsequently\, it is intended to s tudy the ion-neutral coupling in the E layer focussing on energy dissipati on in the form of Joule heating. Other scientific goals that can be achiev ed from knowing thermospheric neutral wind velocity include studying the g eomagnetic effects on the neutral wind and temperature\, direct observatio n of gravity waves originating in the thermosphere and comparing ion drift measurements. The main scientific thrust is to expand our knowledge on th e interaction of neutral thermospheric winds and temperatures with auroral arcs from an initial single publication [Kosch et al.\, 2010] using exist ing SDI data from McMurdo and South Pole (projects 1 and 2). The Super Dua l Auroral Radar Network (SuperDARN) data set is used as a source of ion ve locities to estimate the electric field.\n\nhttps://events.saip.org.za/eve nt/100/contributions/326/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/326/ END:VEVENT BEGIN:VEVENT SUMMARY:First principles investigation of structural\, dynamic\, electroni c and optical properties of Barium seleno-germanate Ba2GeSe4 DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-327@events.saip.org.za DESCRIPTION:Speakers: Abdu Barde (The National Institute for Theoretical P hysics\, School of Physics and Mandelstam Institute for Theoretical Physic s\, University of the Witwatersrand\, Johannesburg\, Wits 2050\, South Afr ica.)\nTernary and quaternary chalco-germanates and stannates have a rich structural chemistry. Experimental studies of their nonlinear optical prop erties have been reported\, but there are few published computational stud ies on their structural\, dynamic\, electronic and optical properties. In this work\, we investigate the structural\, dynamic\, electronic and optic al\nproperties of Ba2GeSe4 using Density Functional Theory (DFT) and post- DFT many body perturbation theory. The ground state energy and properties\ , including equilibrium lattice parameters\, bulk modulus\, band gap and p honon dispersion were calculated at the DFT level of approximation. The fu ndamental gap was determined at the post DFT G0W0 level of approximation w hile optical absorption was determined within the Bether-Salpeter Equation approximation. The ground state energy\, mechanical and phonon dispersion results show that Ba2GeSe4 is a stable compound while the calculated opti cal absorption results show that it is a wide band gap material that is we ll-situated for photon absorption in visible range.\n\nhttps://events.saip .org.za/event/100/contributions/327/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/327/ END:VEVENT BEGIN:VEVENT SUMMARY:Searching for Majorana Zero Modes Using Model-free Reinforcement L earning DTSTART;VALUE=DATE-TIME:20180628T094000Z DTEND;VALUE=DATE-TIME:20180628T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-328@events.saip.org.za DESCRIPTION:Speakers: Makhamisa Senekane (Department of Physics and Electr onics\, National University of Lesotho\, Roma\, Lesotho)\nMajorana fermion s are particles which are their own antiparticles\; hence they have zero c harge. They are governed by non-Abelian statistics. For a Majorana fermion ic operator &gamma\, and the Hamiltonian of a system H\, Majorana fermions satisfy fermionic anti-commutation relation (that is\, for a pair of Majo rana operators &gammai\, &gammaj\; {&gammai\, &gammaj} = 2&deltaij) and a Majorana fermion squares to 1 (that is\, &gamma2 = 1). If\, in addition to this\, the fermionic operator commutes with the Hamiltonian of the system (that is\, [H\,&gamma] = 0)\, then such an operator is a Majorana zero mo de (MZM). Majorana zero modes are Majorana fermions bound to zero energy. MZMs have applications in both topological quantum computation and spintro nics. However\, Majorana zero modes are yet to be conclusively demonstrate d experimentally. In this work\, we report the algorithm that searches for MZMs using reinforcement learning. Reinforcement learning is a machine le arning paradigm where the learner is a decision-maker (agent) that takes a ction in an environment and receives rewards or penalties for the actions taken. Results obtained from this work demonstrate the significance of usi ng reinforcement learning in the quest for Majorana zero modes.\n\nhttps:/ /events.saip.org.za/event/100/contributions/328/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/328/ END:VEVENT BEGIN:VEVENT SUMMARY:Migration behavior of selenium implanted into polycrystalline SiC DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-395@events.saip.org.za DESCRIPTION:Speakers: Zaki Abdalla (Postgradiuate student)\nMigration beha vior of selenium (Se) in polycrystalline SiC was investigated using Ruther ford backscattering spectrometry (RBS)\, scanning electron microscopy (SEM ) and Raman spectroscopy. Se ions of 200 keV were implanted into polycrys talline SiC samples to a fluence of 1×10^16 cm-2 at room temperature. Som e of the implanted samples were annealed in temperature ranging from 1000 to 1500 oC in steps of 100 oC for 10 hours. Implantation of Se amorphized SiC. Annealing at 1000 oC already resulted in the recrystallization of amo rphous SiC. Diffusion of Se began after annealing at 1100 oC and become mo re pronounced with increasing temperature. At 1300 oC it was accompanied b y 10% loss of Se while at above 1300 oC it was accompanied by loss and pea k shift towards the surface. From the peaks broadening the diffusion were estimated in the temperature range from 1300 to 1500 oC.\n\nhttps://event s.saip.org.za/event/100/contributions/395/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/395/ END:VEVENT BEGIN:VEVENT SUMMARY:Effects of pore size on the electrochemical properties of Li-Mn-O nanoporous cathode material DTSTART;VALUE=DATE-TIME:20180626T100000Z DTEND;VALUE=DATE-TIME:20180626T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-329@events.saip.org.za DESCRIPTION:Speakers: Beauty Shibiri (University of Limpopo)\nNanoporous s pinel materials have ignited interest as cathode materials for lithium ion batteries owing to their superior rate capability at ambient temperature\ , improved electrochemical performance and mechanical stability\, compared to the bulk material. However\, nanospherical layered-spinel lithium mang anese oxides (LMOs) cathodes have demonstrated spontaneously great reversi ble capacity (302 mAh/g) and superior rate capability due to their composi te nature. In this study we simulated the synthesis and investigate the ho st capability of various Li-Mn-O nanoporous composite materials. The predi ction of electrochemical behaviour of these layered-spinel composite catho des\, during the discharge process of a lithium ion battery\, is carried o ut by employing the amorphization and recrystallization technique\, using the DL_POLY code. The radial distribution functions (RDFs)\, X-ray diffrac tion patterns (XRDs) and structural snapshots of various microstructures f or the Li-Mn-O composites showed efficient spontaneous recrystallization ( exothermic) and co-existence of spinel and layered components in the nanop orous materials with different pore sizes. Increment of the Li content res ulted in more polycrystallization structures and increment of the layered content in the nanostructures.\n\nhttps://events.saip.org.za/event/100/con tributions/329/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/329/ END:VEVENT BEGIN:VEVENT SUMMARY:An investigation of the presence of Pc5 oscillations during a TRIN NI event DTSTART;VALUE=DATE-TIME:20180626T100000Z DTEND;VALUE=DATE-TIME:20180626T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-330@events.saip.org.za DESCRIPTION:Speakers: Njabulo Mbanjwa (UKZN)\nPc5 ULF pulsations are magne tohydrodynamic (MHD) events in the magnetosphere. To identify the causes o f Pc5 ULF pulsations has been a challenging matter in the field of MHD thr ough the complexity of the nature of the magnetosphere. Flow bursts in th e magnetotail are known as TRINNIs short for ”tail reconnection during I MF northward\, non-substorm intervals. In this study we used the SuperDARN to observe the convection maps with the cross polar cap potential (CPCP) and the Greenland magnetometer stations to investigate the presence of Pc5 pulsations during a TRINNI event which occurred on 20 March 2002 (01:00-1 2:00 UT). These two instruments measure the resonance from the cavities wi thin the magnetosphere during quiet time magnetosphere. We employed the Fa st Fourier Transform (FFT) method to compute the power spectrum . The spec tral analysis has shown that there are possible pulsations associated with this TRINNI event. We present results in a graphical form and discuss the m in relation to magnetic reconnection in the magnetotail and in the conte xt of magnetohydrodynamic (MHD) theory of magnetic pulsations.\n\nhttps:// events.saip.org.za/event/100/contributions/330/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/330/ END:VEVENT BEGIN:VEVENT SUMMARY:Thermoelectric properties of CdGa2O4 spinel DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-331@events.saip.org.za DESCRIPTION:Speakers: Elkana Rugut (Elkana Rugut University of the Witwate rsrand\, Johannesburg.)\nThermoelectric materials can convert heat into el ectricity and thermoelectric devices can play an important role in the eff icient use of energy. In this study\, we investigate the thermoelectric pr operties of hard glassy spinel mineral CdGa2O4. The potential of a materi al to be a candidate as the active component of a thermoelectric device is captured in the figure of merit\, ZT\, which includes information on the lattice and electronic transport properties. Given the difficulties of dir ectly measuring ZT experimentally\, we computed its value within density f unctional theory using linearised Boltzmann transport equations in a relax ation time approximation. We find that CdGa2O4 is promising as a high temp erature thermoelectric material.\n\nhttps://events.saip.org.za/event/100/c ontributions/331/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/331/ END:VEVENT BEGIN:VEVENT SUMMARY:Cation distribution and mixing thermodynamics in Li(Mn1-xNix)O4 spinel via tuning of the Ni concentration DTSTART;VALUE=DATE-TIME:20180627T092000Z DTEND;VALUE=DATE-TIME:20180627T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-332@events.saip.org.za DESCRIPTION:Speakers: kemeridge Tumelo Malatji (University of Limpopo)\nSp inel LiMn2O4 is a promising cathode material for secondary lithium-ion bat teries which\, despite its high average voltage of lithium intercalation\, suffers crystal symmetry lowering due to the Jahn-Teller active six-fold Mn3+ cations. LiMn2 O4 is a low-cost\, environmentally friendly\, and high ly abundant material used as a cathode in Li-ion batteries. Although Ni ha s been proposed as a suitable substitutional dopant to improve the structu ral and mechanical stability of LiMn2O4 and enhance the average lithium in tercalation voltage\, the thermodynamics of the Ni incorporation and its e ffect on the electrochemical properties of spinel LiMn2O4 is not known yet . In this paper we have implemented two approaches\; the cluster expansion which determined stable multi-component crystal structures and ranks meta stable structures by the enthalpy of formation\, while maintaining the acc uracy of first-principles density functional methods. In the second approa ch we employed density functional theory calculations with a Hubbard Hamil tonian (DFT+U) to investigate the thermodynamics of mixing of the Li(Mn1-x Nix)O4 solid solution. The results suggest that LiMn1.5Ni0.5 O4 is the mos t stable composition at temperatures ranging from room temperature to 1000 K. The configurational entropy is much lower at low temperatures. It was also found that the mechanical properties of Ni-doped LiMn2O4 are stable a t 0K. The calculated maximum average lithium intercalation voltage was fou nd to be 4.8 V for LiMn1.5Ni0.5O4 composition and is in agreement with the experimental value of 4.7 V. The temperature was found to have a negligib le effect on the Li intercalation voltage of the most stable composition.\ n\nhttps://events.saip.org.za/event/100/contributions/332/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/332/ END:VEVENT BEGIN:VEVENT SUMMARY:Photodynamic Therapy using Sulfonated Aluminum Phthalocyanine Mix for the eradication of Cervical Cancer\, An in vitro Study DTSTART;VALUE=DATE-TIME:20180627T082000Z DTEND;VALUE=DATE-TIME:20180627T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-333@events.saip.org.za DESCRIPTION:Speakers: Elvin Chizenga (Laser Research Center\, University o f Johannesburg)\nThe use of phthalocyanines in Photodynamic Therapy (PDT) has greatly altered the difficulties associated with the treatment of canc er. PDT is a treatment modality that uses photo-physical properties of a p hotosensitizer (PS)\, in the presence of light and molecular oxygen to era dicate cancer cells. The correct choice of PS used maximizes its therapeu tic potential and efficacy. This study\, therefore\, investigates the effe ctiveness of Sulfonated Aluminum phthalocyanine Mix (AlPcSmix) in PDT for the treatment of cervical cancer\, which in developing countries\, South A frica included\, is a common type of cancer among women\, and the leading cause of cancer-related deaths. A working solution of AlPcSmix was prepare d in Dimethyl Sulfoxide. Cervical cancer HeLa cells (ATCC® CCL2™) were cultured in liquid medium\, Dulbecco’s Minimum Eagle’s Medium suppleme nted with 10% Foetal Bovine Serum and incubated at 37 °C\, 5% CO2 and 85% humidity. The cells were treated with varying concentrations of AlPcSmix. The treated cells were then irradiated using 673 nm diode laser at fluenc es of 5\, 10 and 15 J/cm2. Cellular responses were evaluated 24h post-irra diation using Trypan blue viability assay\, Adenosine Triphosphate assay f or proliferation\, Lactate Dehydrogenase cytotoxicity assay for membrane i ntegrity\, and fluorescent microscopy for cellular localization. Results i ndicated that AlPcSmix localized in the mitochondria and lysosomes\, and c ellular responses showed dose-dependent structural changes\, with increasi ng cytotoxicity and decreased cell viability and proliferation. Results ob tained indicate AlPcSmix as an excellent choice of PS for use in PDT and t he eradication of cervical cancer cells in vitro.\n\nhttps://events.saip.o rg.za/event/100/contributions/333/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/333/ END:VEVENT BEGIN:VEVENT SUMMARY:Surface chemical characterization of ZnO-Eu3+/Yb3+ thin films on S i (100) substrates using TOF‐SIMS DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-334@events.saip.org.za DESCRIPTION:Speakers: Balakrishna Avula (University of The Free State)\nMi xed Nitrates of Zn\, Eu and Yb were deposited on Si (100) substrates using the sol-gel spin coating method under optimized deposition conditions usi ng monoethanolamine as stabilizing component. This paper reports on the morphology and topographical images of ZnO:Eu3+\,Yb3+(7%) thin films. The surface composition of the annealed ZnO films were investigated by using Field emission Scanning Electron Microscopy (FE-SEM) and Time-of-Flight S econdary Ion Mass Spectroscopy (TOF-SIMS). The presence of various types o f particles on the surface of the spin coating thin films as well as the d ifferences in the film structure\, played an important role to induce arti ficial topographical effects on the ZnO:Eu3+\,Yb3+ thin films. The presenc e of H on the surface and throughout the entire thickness of the thin film s was confirmed by TOF-SIMS. Furthermore\, it was found that the near surf ace region of the as-grown thin films was Zn-rich\, and annealing at highe r temperatures (1000 °C) removed the H-related defects from the surface o f the thin films and affect the balance of the Zn and O concentrations. Bo th the positive and negative ion depth profiles of the ZnO:Eu3+\,Yb3+(7%) thin films were measured. The two and three-dimensional (2D and 3D) images have also been recorded in the positive and negative ion mode. Analysis o f the 3D images showed big agglomerated particles on the surface of the Si substrate that appears to be embedded in the substrate and the substrate appears to be on the same level as the particles. This phenomenon was due to the artificial topographic effects which are attributed to the experime ntal setup of the TOF-SIMS system. The details of these features will be d iscussed.\nKey words: Spin coating\, Tof-SIMS\, 2D and 3D images.\n\nhttps ://events.saip.org.za/event/100/contributions/334/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/334/ END:VEVENT BEGIN:VEVENT SUMMARY:Lattice thermal conductivity of bulk PtSe2 and PtTe2 DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-335@events.saip.org.za DESCRIPTION:Speakers: Hamza Mohammed (University of Witwatersrand)\nThermo electric devices can play a role in efficiently using available energy by converting heat produced by a wide range of devices into electricity. Low lattice thermal conductivity is a requirement for efficient thermoelectric devices and layered materials offer potential in reducing the lattice the rmal conductivity perpendicular to the layers. We present\ndensity functio nal theory calculations of the structural and thermal properties of layere d platinum dichalcogenides PtSe2 and PtTe2 compounds in the CdI2 structure \, space group P3̄m1. Phonon and elastic constants calculations confirm t hat the compounds are dynamically and mechanically stable. Lattice thermal conductivities were calculated within the single-mode relaxation-time app roximation of the linearised phonon Boltzmann equation. We found that at t he room temperature\, the in-plane lattice thermal conductivities for PtSe 2 and PtTe2 are 9.33 and 6.54 Wm-1 K-1 \, while perpendicular to the plane they are 2.06 and 1.8 Wm-1 K-1\, respectively. The out-of-plane thermal c onductivities confirm that further investigation of PtSe2 and PtTe2 as the rmoelectric materials is necessary.\n\nhttps://events.saip.org.za/event/10 0/contributions/335/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/335/ END:VEVENT BEGIN:VEVENT SUMMARY:Computational modelling study of hydrated nickel-rich pentlandite (110) surface DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-336@events.saip.org.za DESCRIPTION:Speakers: Peace Mkhonto (University of Limpopo)\nThe hydration of minerals is one of the main processes that occur during mineral proces sing. These include wet grinding of the ore and during flotation of libera ted particles. In this study we employed ab-initio density functional theo ry to investigate the adsorption of water molecules onto nickel-rich pentl andite (110) surface. We considered three adsorption aspects: Fe-top\, Ni- top and complete surface coverage adsorptions and explored the bonding geo metry\, density of states (DOS) and Bader charges which are directly relat ed to the reactivity of the water molecules. The hydrophobicity and hydrop hilicity of minerals during mineral processing require detailed understand ing in the mineral-water interaction that could give valuable insight duri ng flotation. We found that the adsorption of water molecules on pentlandi te (110) surface showed exothermic reaction. The water adsorption energie s were more exothermic on Fe-top than Ni-top. This indicates that the wate r molecule interacts strongly with Fe than Ni atoms. The complete surface coverage revealed a physisorption process on (110) surface. Furthermore\, DOS showed orbital shift to lower energy level and their energy states are lowered near EF. This indicates that there are electron/charge transfers from the surface metals to the water molecule. The charge density differen ce indicated that some charges are localised at the internuclear region. D ue to the 1b1-3d orbital mixing\, some charges are depleted from the 3d-or bitals to the lower lying manifold 3d-orbitals. These observations gave va luable insights on how the metals (Fe and Ni) react with water during mine ral extraction using the flotation process.\n\nhttps://events.saip.org.za/ event/100/contributions/336/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/336/ END:VEVENT BEGIN:VEVENT SUMMARY:Ultra-diffuse galaxies in Stripe 82 Clusters DTSTART;VALUE=DATE-TIME:20180626T080000Z DTEND;VALUE=DATE-TIME:20180626T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-337@events.saip.org.za DESCRIPTION:Speakers: Nazir-Ahmed Makda (University of Cape Town)\nUltra-D iffuse Galaxies(UDGs) are low surface brightness galaxies with a very low stellar mass component but their sizes are comparable to the Milky Way. To survive in the cluster environments where they have been observed these g alaxies must contain significant amounts of dark matter as the strong tida l fields would normally tear diffuse low-mass galaxies apart. UDGs are har d to detect and classify as they are very faint and have the appearance of nearby dwarf galaxies. We are developing a pipeline to identify and analy ze UDGs within galaxy clusters within the deep Stripe 82 region of the Slo an Digital Sky Survey. Preliminary results show a significant number of UD Gs in all 16 clusters in our sample\, at redshifts below 0.15. The abundan ce of these galaxies in clusters has only recently been recognized\, there fore identifying and measuring their properties is key in understanding ho w they are formed and continue to exist. The resulting UDG sample will all ow us to constrain how common UDGs are as a function of halo mass and reds hift\, and to determine their properties and distribution within the host clusters.\n\nhttps://events.saip.org.za/event/100/contributions/337/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/337/ END:VEVENT BEGIN:VEVENT SUMMARY:Event Selection and Signal Optimization of Three-Lepton and $b$-je ts Search in ATLAS DTSTART;VALUE=DATE-TIME:20180627T100000Z DTEND;VALUE=DATE-TIME:20180627T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-339@events.saip.org.za DESCRIPTION:Speakers: Lebohang Mokoena (University of the Witwatersrand)\n A study is performed to investigate the phenomenological signatures of add itional scalar bosons at the LHC. This talk summarizes an overview of the ATLAS detector results for events observing excesses in multi-lepton event s with three-leptons and at least two b-jets and number of jets\, two and three. The channel investigated is that of $A \\rightarrow ZH[250] \\right arrow Z(\\rightarrow\\ell^{\\pm}\\ell^{\\mp}) + hh\, SS\, Sh(\\rightarrow b\\bar{b}\, VV)$\, The final state is a very clean signature with low expe cted background processes. In the CMS measurement of the cross section for top quark pair production in association with a $W$ or $Z$ boson in proto n-proton collisions at 13~TeV\, the production in three-lepton channels f or the expected and the observed significances is found to be in excess of 5 standard deviations. This further enforces the high interest in perform ing multi-lepton with $b$-jet searches. The strategy of the event selectio n is described in this talk and leads to the signal optimization strategy. \n\nhttps://events.saip.org.za/event/100/contributions/339/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/339/ END:VEVENT BEGIN:VEVENT SUMMARY:Background estimation for multilepton and $b$-jets analysis at ATL AS at the LHC DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-340@events.saip.org.za DESCRIPTION:Speakers: Jeremiah Monnakgotla (University of the Witwatersran d)\nBackground estimation is one of the most important aspects for all the analysis at the Large Hadron Collider. This proceeding presents the backg round estimation for the $A\\rightarrow ZH$ search with the heavy scalar\, $H$\, decaying into a pair of Higgs\, or Madala\, $S$\, bosons. The final state for this search is formed by 3 leptons\, $\\geq$~2 $b$-jets and low jet multiplicity. The $t\\bar{t}Z$ process is the dominant background con tribution for this analysis. The second important background is the $WZ$ f or which a control region is defined to check the modeling and the normali zation of this process. Finally\, processes with fake leptons are expected to have a small contribution\, estimated using a data-driven techniques.\ n\nhttps://events.saip.org.za/event/100/contributions/340/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/340/ END:VEVENT BEGIN:VEVENT SUMMARY:Effect of Hf and Cu on the cubic B2 TiPt shape memory alloys DTSTART;VALUE=DATE-TIME:20180628T102000Z DTEND;VALUE=DATE-TIME:20180628T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-341@events.saip.org.za DESCRIPTION:Speakers: Rosinah Modiba (CSIR)\nComputational modelling appro ach has been used to investigate the effect of hafnium and copper on the B 2 TiPt shape memory alloys. The calculations were performed using the CAST EP code embedded in materials studio. Cubic B2 TiPt is known to be thermod ynamically unstable at 0 K as compared to the B19 orthorhombic phase with it having the highest heats of formations and soft modes in the lowest fre quency. Moreover\, the C´ of the structure was previously found to be ne gative as compared to the commercialised B2 NiTi which is positive. With t he recent increasing demand on shape memory alloys that can be used at hig h temperatures in aerospace and automobiles\, TiPt is found to be one of t he promising alloys with the transformation temperature of 1300 K. These a lloys are known to remember their original shape when a certain temperatur e or pressure is exerted on them upon cooling. In order to enhance the ela stic properties of the B2 TiPt alloy\, Hf and Cu elements are substituted in the TiPt to form ternary and quaternary alloys. The stability of these structures are investigated with respect to their heats of formation\, ela stic constants and density of states. Interestingly\, the addition of thes e elements increases the C´ of the structures with all the elastic const ants being positive for the hafnium addition.\n\nhttps://events.saip.org.z a/event/100/contributions/341/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/341/ END:VEVENT BEGIN:VEVENT SUMMARY:A Heat Pipe Setup for Resonant Ionisation Spectroscopy of Zinc DTSTART;VALUE=DATE-TIME:20180627T082000Z DTEND;VALUE=DATE-TIME:20180627T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-342@events.saip.org.za DESCRIPTION:Speakers: Brandon Hattingh (University of Stellenbosch)\nReson ant Ionisation Spectroscopy (RIS) is a technique to selectively ionise a p articular element or even isotope. It has applications in the production a nd quality assurance of isotopes for medical applications. It is also appl ied for the production and study of beams of exotic nuclei in large nuclea r physics facilities such as CERN. We report on the development of a heat pipe based setup for atomic spectroscopy that will be used to investigate and optimise resonant ionisation schemes for Zinc (Zn). RIS is a multi-ste p process of which the first 1 or 2 photons are resonant\, and the last ph oton ionises the atom. We apply a novel setup for atomic absorption spectr oscopy using multiple laser beams and time-delayed pulses to investigate a nd characterise the different steps in the RIS scheme. A python program wa s created to analyse the data that will be obtained. The design and develo pment of the setup and preliminary results are presented. The results are relevant to inform the design of an optimised resonant ionisation scheme t hat could be applied in industry within the limitations posed by a product ion environment.\n\nhttps://events.saip.org.za/event/100/contributions/342 / LOCATION: URL:https://events.saip.org.za/event/100/contributions/342/ END:VEVENT BEGIN:VEVENT SUMMARY:The compatibility of the LHC data with new bosons DTSTART;VALUE=DATE-TIME:20180629T102000Z DTEND;VALUE=DATE-TIME:20180629T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-343@events.saip.org.za DESCRIPTION:Speakers: Bruce Mellado (University of the Witwatersrand)\nWit h the discovery of a Higgs boson at the Large Hadron Collider (LHC) new\n window of exploration of fundamental interactions is now available. The st udy of the couplings of this Higgs boson to other particles and the search for new bosons have become a focus. Based on features of the data collect ed by experiments at the LHC during Run 1 the hypothesis of a new boson wa s formulated and the compatibility with the data was estimated. In this hy pothesis the new boson would have a mass around 270 GeV and would decay in to the Higgs boson and another scalar\, referred to as S\, among other de cays. This results in a number of predictions that will be summarized. The compatibility of the hypothesis with new data reported by the experiments will also be discussed.\n\nhttps://events.saip.org.za/event/100/contribut ions/343/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/343/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthesis\, structural and magnetic properties of Ni0.5Ti0.5Fe2O4 DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-344@events.saip.org.za DESCRIPTION:Speakers: Sanele Dlamini (UKZN)\nNickel base ferrites of the s pinel structure have been reported to have interesting properties such as low coercivity\, high saturation magnetization\, chemical and thermal stab ility. These qualities allow the materials to be used in applications such as gas sensors\, magnetic fluids\, magnetic storage systems. The properti es of NiFe2O4 can be tuned by doping in the A or B sites of the spinel str ucture. Furthermore\, the synthesis technique used has great influence on the resulting properties. Hence\, we have successfully synthesized a polyc rystalline Ni0.5Ti0.5Fe2O4 compound by high energy ball milling. To our su rprise the phase quickly takes form as early as 0.25 hours. The sample was milled for 10 hours. Prolonged milling destroyed the phase. From the stru ctural analysis it is evidence that starting precursors for a chemical rea ction are of vital importance as they have great influence on the reaction product. The mean particle size was obtained to be 45.2±9.4 nm. Particle size reduces with milling time whilst the strain increases. The density i s inversely proportional to the lattice parameters. Intriguingly\, The coe rcivity and saturation magnetization followed Stoner Wohlfarth model with two distinct regions at high temperature (300-100) and low temperature (50 -10) with approximately equal anisotropy. Saturation magnetization was ob tained to be between 38.73 to 38.84 ± 0.03 emu/g and the coercivity is be tween 820 to 407 ± 32 Oe. Room temperature Mossbauer revealed hyperfine fields of 446 ± 1 kOe and 480 ± 1 kOe for A and B sites respectively. Is omer shift values revealed co-existence of both F3+ and Fe2+. The interest ing and intriguing properties displayed by the material serves as great po tential and open room for further investigation.\n\nhttps://events.saip.or g.za/event/100/contributions/344/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/344/ END:VEVENT BEGIN:VEVENT SUMMARY:Systematic uncertainties in the search for a high mass scalar deca ying to 4 leptons in the ATLAS detector at the LHC DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-345@events.saip.org.za DESCRIPTION:Speakers: Stefan von Buddenbrock (University of the Witwatersr and)\nSearches for heavy scalars beyond the Standard Model are ongoing end eavours at the LHC. One particularly interesting method of doing this is t hrough the hypothetical decay of the heavy scalar to two Z bosons\, which subsequently decay to four leptons. In this work\, the ATLAS high mass fou r lepton search is discussed with emphasis on its experimental systematic uncertainties. The background statistical framework is explained and appli ed to the Run 2 ATLAS data. Prospects and implications are discussed in th e context of searches for new heavy bosons at the LHC.\n\nhttps://events.s aip.org.za/event/100/contributions/345/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/345/ END:VEVENT BEGIN:VEVENT SUMMARY:Stopbands of fast ion-acoustic solitons in non-thermal plasmas wit h two-temperature adiabatic ions DTSTART;VALUE=DATE-TIME:20180629T102000Z DTEND;VALUE=DATE-TIME:20180629T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-346@events.saip.org.za DESCRIPTION:Speakers: Shimul Kumar Maharaj (South African National Space A gency (Space Science))\nThe existence of a stopband in soliton speeds asso ciated with the fast ion-acoustic wave was reported for the very first tim e by Nsengiyumva et al. (Physics of Plasmas 21\, 102301\, 2014) in a model which is composed of cold ions\, adiabatic ions (both positive) and Boltz mann electrons. The stopband\, which\, is an intermediate range of speeds for which solitons cannot propagate\, arises when the limiting value of th e potential beyond which the adiabatic ion density becomes complex valued\ , yields two solutions for the speed. The lower (higher) valued solution i s the lower (upper) boundary of the stopband. The model of Nsengiyumva et al. was extended by Maharaj and Bharuthram (Physics of Plasmas 24\, 022305 \, 2017) by considering non-thermal effects of the electrons on the stopba nds through adopting Cairns and kappa distributions for the electrons. The two earlier studied models are extended in this paper to consider finite temperature effects of the cool ions on the stopbands. Transitions from th e existence of the stopband to the disappearance of the stopband are studi ed for increasing temperature of the cooler ions and increasing non-therma l effects of the electrons\, considering both a Cairns and kappa velocity distribution of the electrons. This study will endeavour to provide deeper insights into what may be the driving mechanisms for the existence of a s topband.\n\nhttps://events.saip.org.za/event/100/contributions/346/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/346/ END:VEVENT BEGIN:VEVENT SUMMARY:Theoretical and Computational Physics Division Meeting DTSTART;VALUE=DATE-TIME:20180627T102000Z DTEND;VALUE=DATE-TIME:20180627T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-347@events.saip.org.za DESCRIPTION:Speakers: Alan Cornell (NITheP)\nhttps://events.saip.org.za/ev ent/100/contributions/347/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/347/ END:VEVENT BEGIN:VEVENT SUMMARY:Applied Physics Division Meeting DTSTART;VALUE=DATE-TIME:20180627T120000Z DTEND;VALUE=DATE-TIME:20180627T124000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-348@events.saip.org.za DESCRIPTION:Speakers: phil ferrer (wits)\nhttps://events.saip.org.za/event /100/contributions/348/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/348/ END:VEVENT BEGIN:VEVENT SUMMARY:Partnership Opportunities in Hosting Business/Industry Events\, Me etings and Conferences DTSTART;VALUE=DATE-TIME:20180628T101000Z DTEND;VALUE=DATE-TIME:20180628T103500Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-349@events.saip.org.za DESCRIPTION:Speakers: SA National Convention Bureau ()\nhttps://events.sai p.org.za/event/100/contributions/349/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/349/ END:VEVENT BEGIN:VEVENT SUMMARY:The Multimessenger Universe - A New Era of Astronomy DTSTART;VALUE=DATE-TIME:20180627T163000Z DTEND;VALUE=DATE-TIME:20180627T173000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-350@events.saip.org.za DESCRIPTION:Speakers: Markus Bottcher (North-West University)\nhttps://eve nts.saip.org.za/event/100/contributions/350/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/350/ END:VEVENT BEGIN:VEVENT SUMMARY:Updated orbital parameters for LMC P3 with SALT/HRS DTSTART;VALUE=DATE-TIME:20180628T104000Z DTEND;VALUE=DATE-TIME:20180628T110000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-351@events.saip.org.za DESCRIPTION:Speakers: Brian van Soelen (University of the Free State)\nLMC P3 is the most recently discovered\, and the most luminous\, γ-ray binar y. The source was discovery with Fermi-LAT γ-ray observations which showe d a 10.301 ± 0.002 day period. The γ-ray emission is associated with the previously detected point-like X-ray source CXOU J053600.0-67350\, within the supernova remnant DEM L241\, and this binary was previously classifie d as a high mass X-ray binary where the optical companion is a O5III(f) st ar. The source has also been detected at very high energies with the H.E.S .S. gamma-ray telescope\, though in only one phase bin. We have used the H igh Resolution Spectrograph (HRS) with the Southern African Large Telescop e (SALT) to obtain the best binary solution so far for this source\, showi ng that source is slightly eccentric (~0.4) and constrained the phases of superior and inferior conjunction. The Fermi-LAT and H.E.S.S. results are discussed in relation to the new binary solution.\n\nhttps://events.saip.o rg.za/event/100/contributions/351/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/351/ END:VEVENT BEGIN:VEVENT SUMMARY:Non-specialist talk: GW170817 - The South African Perspective DTSTART;VALUE=DATE-TIME:20180627T124000Z DTEND;VALUE=DATE-TIME:20180627T132000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-353@events.saip.org.za DESCRIPTION:Speakers: Markus Bottcher (North-West University)\nThe joint d etection of a gravitational-wave event from a binary-neutron-star merger\, GW170817\, by LIGO/VIRGO and a short gamma-ray burst\, GRB170817A\, by Fe rmi-GBM and INTEGRAL\, ushers in a new era of true multi-messenger astrono my. It triggered the most intensive\, world-wide multi-wavelength follow-u p observing campaign ever conducted to date\, involving almost 3\,700 astr onomers around the world. This talk will review the observations of this e vent\, highlighting the contributions by southern African observatories (e .g.\, H.E.S.S.\, SALT\, MeerKAT). These will be put into the broader conte xt of recent developments in multi-messenger astronomy\, including the pos sible association of high-energy neutrinos detected by IceCube\, with flar ing gamma-ray sources. Future prospects for multi-messenger astronomy and the Southern African involvement in these exciting developments will be di scussed.\n\nhttps://events.saip.org.za/event/100/contributions/353/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/353/ END:VEVENT BEGIN:VEVENT SUMMARY:Structural and optical properties of spin coated graphene oxide th in films DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-354@events.saip.org.za DESCRIPTION:Speakers: Boitumelo Tladi (UFS)\nGraphene oxide (GO) is a deri vative of graphene\, consisting of an atomic layer of carbon bonded to oxy gen functional groups such as hydroxyl and epoxide\, which make it insulat ing and hydrophilic. This novel material it has attracted much research re cently\, although there is varying information in the literature because t he properties may depend on the synthesis technique and form (powder\, thi n film\, solution). An investigation of the structural and optical proper ties of spin coated GO thin films was made. GO powder was purchased from S igma Aldrich (15-20 sheets\, 4-10% edge-oxidized) and used to prepare a GO suspension in distilled water (1 mg/ml) which was ultrasonicated and cent rifuged. The supernatant black solution was spin coated on silicon substra tes to produce thin films. The solution was characterized using photolumin escence (PL) and UV-vis absorption measurements\, while the GO powder and thin films were assessed using X-ray diffraction (XRD). A broad absorption band was observed at 273 nm\, although subsequent PL measurements showed that this was not an efficient excitation wavelength. Instead\, the weak b lue luminescence observed at 444 nm could be excited at 325 nm. Blue lumin escence has been attributed to thoroughly exfoliated GO suspensions while red emission (not observed here) to poorly dispersed suspensions. The Rama n peak of water was observed on the short wavelength side of this emission . The XRD pattern for the commercial GO powder had a peak near 2θ = 13.3 °. This low angle\, compared to the corresponding peak of graphite (27°) \, indicates much wider spaced interplanar layers as a result of oxidation \, but showed that the GO was stacked in multiple layers. A weak band near 30° suggested that the powder probably also contained a small amount of graphite. This was absent for the thin film since it was likely removed by centrifuging. The XRD peak of the thin film was shifted to 2θ = 13.8°\, indicating a small reduction in the interplanar spacing. Although the XRD data corresponded to stacked GO\, the optical properties suggest that sig nificant reduction was present in the commercial powder.\n\nhttps://events .saip.org.za/event/100/contributions/354/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/354/ END:VEVENT BEGIN:VEVENT SUMMARY:Design and testing of a BGO-SiPM based electron beam dispersion mo nitor DTSTART;VALUE=DATE-TIME:20180629T080000Z DTEND;VALUE=DATE-TIME:20180629T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-355@events.saip.org.za DESCRIPTION:Speakers: Elijah Niyoyadutumye (University of Johannesburg)\nA novel position-sensitive electron detector has been developed\, which is able to detect each electron in a dispersed beam individually using silico n photo-multipliers (SiPMs) technology. SiPMs consist of an array of Geige r-mode Avalanche Photo-Diodes (APDs). When the APDs are operated in Geiger -mode\, i.e. with the applied reverse voltage being greater than the break down voltage of the diode\, the APDs produce large gain such that they can be used to detect light at very low intensities i.e. small numbers of pho tons\, and\, in fact they can even detect single photons. These low photon intensities that are detected by SiPMs match the intensities of scintilla tion light that is produced by the passage of a single electron through a BGO scintillator. Therefore SiPMs can enable detection and counting of the scintillation photons. The geometrical layout of detector consists of a s ingle BGO crystal with two regular equal and parallel octagonal faces and a thickness of 6mm. The radius of the circle inscribed in the regular octa gonal perimeter of the octagonal surface of the scintillator is 17mm. On e ach of the 8 rectangular faces of the scintillator is mounted a pair of Si PMs. The electron beam position is reconstructed by the differential amoun ts of photons recorded by the SiPMs. Different algorithms for the reconstr uction have been used. The design and performance of the detector is discu ssed.\n\nhttps://events.saip.org.za/event/100/contributions/355/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/355/ END:VEVENT BEGIN:VEVENT SUMMARY:Structural and optical properties of NiO nanopowders prepared by c o-precipitation method for gas sensing applications DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-356@events.saip.org.za DESCRIPTION:Speakers: Teboho Mokoena (University of the Free State)\nPromp t technological and industrial advances uninterruptedly cause the release of hazardous and toxic gases that are harmful to human life\; as a result sensing devices that are sensitive and selective to such gases are desirab le. Presently\, gas sensors based on semiconductor metal oxide (SMO) mater ials are pleasing more consideration\, because of their evident change in electrical resistance when exposed to the target gases such as reducing an d oxidizing gases [1]. Amongst the semiconductor metal oxide\, p-type nick el oxide (NiO) was found to be promising candidate for gas sensing applica tions due to its wide bandgap (~ 3.6 - 4 eV) [2]\, high specific surface a rea\, excellent structural stability. Therefore\, we report on the gas sen sing characteristics of NiO nanostructures prepared by co-precipitation me thod at various reaction times ranging from 2 to 24 hours. X-ray diffracti on patterns revealed that nanostructures are polycrystalline\, displaying average crystallite sizes of ~ 10 - 12 nm. The physical variation of colou r from green to black after heat treatment was assigned with the non-stoic hiometric property of NiO which was confirmed from photoluminescence and e lectron paramagnetic resonance studies. The effects of non-stoichiometry a nd energy bandgap on the gas sensing properties of NiO based sensor have b een investigated towards various oxidizing and reducing gases at various o perating temperatures.\n \nKeywords: surface area\, adsorption\, desorptio n\, gas sensing.\n\nReferences\n[1]. T.-H. Kim\, J.-W. Yoona\, Y.C. Kang\, F. Abdel-Hady\, A.A. Wazzan\, J.-H. Lee\, Sensors and Actuators B 240 (20 17) 1049–1057.\n[2]. A. Yazdani\, H. Zafarkish\, K. Rahimi\, Materials S cience in Semiconductor Processing\, 74 (2018) 225 – 231.\n\nhttps ://events.saip.org.za/event/100/contributions/356/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/356/ END:VEVENT BEGIN:VEVENT SUMMARY:Hα images of nearby galaxy groups\; NGC 193 and NGC 940 DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-357@events.saip.org.za DESCRIPTION:Speakers: Sumari Hattingh (North-West University)\nA significa nt fraction of the baryons in galaxy groups and clusters is not locked up in stars and the interstellar medium (ISM)\, but exists in the form of ext ended multi-phase gas. The advantage of nearby galaxy groups is that this multi-phase gas can be studied via hot X-ray (≈Hα filaments) via optica l emission line observations. Another advantage of groups is that the gala xies' heating process effects are more visible due to lower density and ma ss\, containing few galaxies\, as opposed to rich clusters. Interaction be tween the different phases is important for galaxy formation and evolution due to the fact that at least 50% of galaxies can be found in groups and clusters.\n\nThe Complete Local-Volume Groups Sample (CLoGS) is an optical ly selected sample of 53 groups within 80 Mpc of which the X-ray observati ons (Chandra / XMM-Newton) have already been done and can be used to infer important physical properties of galaxy groups\, such as gas temperature and X-ray luminosity. In this project the Hα images\, observed using the WIYN 0.9m telescope on Kitt Peak\, are analysed with the aim to compare th e Hα filaments to the X-ray emission images. Here we present preliminary results and a multi-wavelength comparison for two rich galaxy groups \, wh ere the central member is an X-ray bright radio galaxy with a powerful cen tral jet\, and \, where the brightest member is an X-ray faint radio galax y with only a weak radio point source.\n\nhttps://events.saip.org.za/event /100/contributions/357/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/357/ END:VEVENT BEGIN:VEVENT SUMMARY:Bayesian TiRiFiC DTSTART;VALUE=DATE-TIME:20180628T084000Z DTEND;VALUE=DATE-TIME:20180628T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-359@events.saip.org.za DESCRIPTION:Speakers: Eric Maina (Rhodes University)\nThe tilted-ring mode l describes a galaxy as a set of rotating rings\, each of which is paramet erized by a set of parameters representing surface brightness\, rotation s peed\, and orientation of the disk. Our implementation of the tilted-ring model\, TiRiFiC ("Tilted-Ring-Fitting-Code") works by directly fitting gal axy models to spectroscopic data cubes (as observed with the SKA and its p rogenitors) and is most suitable to be used for radio surveys of emission lines\, e.g. with the SKA and its progenitors. While the method is well te sted\, it currently lacks a solid approach to quantify statistical errors and correlations between parameters. We attempt to overcome this problem b y making use of a robust Bayesian statistical framework\, which enables a full exploration of the posterior probability distribution and can be used to estimate errors and quantify the correlation between parameters. This forms a report of the implementation of this technique.\n\nhttps://events. saip.org.za/event/100/contributions/359/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/359/ END:VEVENT BEGIN:VEVENT SUMMARY:ANALYSIS OF TYPE 1 DIABETES WITH MACHINE LEARNING METHODS DTSTART;VALUE=DATE-TIME:20180627T084000Z DTEND;VALUE=DATE-TIME:20180627T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-360@events.saip.org.za DESCRIPTION:Speakers: Thokozile MANAKA (University of the Witwatersrand)\n ANALYSIS OF TYPE 1 DIABETES WITH MACHINE LEARNING METHODS\n\nABSTRACT\n\nB ig data is a term that we can use for data sets with large\, diverse and c omplex data structures that are difficult to analyse or visualize using tr aditional computing methods and approaches. Health care sectors rely on in terpreting data gathered from patients\, which ranges from graphic scans t o medical images of which there is a limitation on its analysis by medical practitioners. It is this same limitation for datasets and advances in bi g-data methodology that sparked interest an interest in this sector as wel l. We proposed to use the Type 1 Diabetes (T1DM) data from INDEPTH VA as a test case for applying modern machine learning (ML) methods to analyse th e data. Due to a high prevalence of Type 1 Diabetes (T1DM) it has huge amo unts of data available from on-going researches\, and there are possible m isclassifications of such data in past researches. In collaboration with D r Alisha Wade(DG\,Johannesburg) and a study by Prof Justine Davies (KCL\,L ondon\,UK) which aimed to estimate the numbers of deaths in people with T1 DM and the causes of those deaths by using VA data in the under 40 age-gro up across all INDEPTH sites. The same data will be processed by classifica tion algorithms based on machine learning. The basic idea is that the algo rithm automatically learns to make accurate predictions based on past obse rvations. For this particular case\, it will learn the features present in diabetic patients\, thereby able to identify patients with high chances o f unidentified T1DM. One of the advantages of this approach is that it can avoid human bias\, but to not fall prey to any training bias\, and unders tand the correlation between different properties\, inputs from medical ex perts will also be necessary.\nThe feasibility of this approach will be st udied to see if accuracy obtained with current methods can be reached or b ettered. If this preliminary study is successful\, the scope can be expand ed. For this study\, we will use Tensorflow [2] or Scikit Learning [3]\, t wo of the most popular deep learning libraries to classify the dataset. Th ey are both open source software.\n\nhttps://events.saip.org.za/event/100/ contributions/360/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/360/ END:VEVENT BEGIN:VEVENT SUMMARY:Output power stability of an all-fibre Erbium doped fibre laser DTSTART;VALUE=DATE-TIME:20180627T092000Z DTEND;VALUE=DATE-TIME:20180627T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-361@events.saip.org.za DESCRIPTION:Speakers: jean jacques monga kaboko (university of johannesbur g)\nStable and single-longitudinal-mode Erbium-doped fiber ring lasers (ED FRLs) have been studied intensively due to their wide range application in field like optical communication and fiber sensors. Because of the fiber vulnerability to perturbation of temperature and vibration\, it has been d emonstrated that the output power of the conventional fiber ring lasers ar e unstable. In this report\, the output power and stability of a narrow li newidth Erbium-doped fiber ring lasers as a function of the laser paramete rs was experimentally investigated. The fiber laser configuration include two narrow spectral bandwidth optical filters namely\, fiber Bragg grating and fiber Fabry-Perot tunable filter. Without changing the basic scheme o f the fiber laser\, the study focuses on the optimization of key parameter s of the fiber laser cavity namely\, Erbium-doped fiber length\, pump powe r\, output coupling ratio and Erbium ions concentration. We have demonstra ted that the output power as well as the power stability of the fiber lase r increase as the output coupling ratio increase. The maximum power fluctu ation of the output power of 7.52 %\, corresponding to 0.24 dB is observed for 10 % output coupling. The power stability of 0.71 % and 0.8 % were ob served for 80 % and 90 % coupling ratio respectively. To improve the power stability we have introduced 1.5 m umpumped Erbium-doped fiber into the f iber laser system. A stable output power was obtained for all coupling rat io during a measurement period of 120 min.\n\nhttps://events.saip.org.za/e vent/100/contributions/361/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/361/ END:VEVENT BEGIN:VEVENT SUMMARY:Fine structure of the IsoScalar Giant Monopole Resonance (ISGMR) i n 40\,42\,44\,48Ca using alpha inelastic scattering at zero degrees DTSTART;VALUE=DATE-TIME:20180626T092000Z DTEND;VALUE=DATE-TIME:20180626T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-363@events.saip.org.za DESCRIPTION:Speakers: Sunday Olorunfunmi (School of Physics\, University o f the Witwatersrand\, Johannesburg.)\nPrevious studies have shown that fin e structure in the excitation energy spectra of nuclear giant resonances c an be attributed to different physical processes. For example\, character istic energy scales of the fine structure for the IsoScalar Giant Quadrupo le Resonance (ISGQR) arise mainly from the collective coupling of the ISGQ R to low-lying surface vibrations\, while on the other hand it has been sh own that Landau damping is the main mechanism leading to the fine structur e phenomenon in the IsoVector Giant Dipole Resonance (IVGDR). It is import ant to determine which processes are responsible for the fine structure in the ISGMR\, particularly in the 40\,42\,44\,48Ca isotope chain with its s ystematic increase in neutron number. Moreover\, study of the ISGMR is of special significance because knowledge of its excitation energy provides d irect information on nuclear incompressibility. Experiments were performed using the Separated Sector Cyclotron of iThemba LABS\, together with the K600 magnetic spectrometer using inelastic scattering of 200 MeV alpha par ticles at zero degrees from 40\,42\,44\,48Ca for measurements in the regi on of ISGMR with a good energy resolution of 86 keV (FWHM). In addition\, following the application of Autocorrelation analysis\, J п = 0+ level densities can be extracted also. Preliminary results will be presented.\n\ nhttps://events.saip.org.za/event/100/contributions/363/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/363/ END:VEVENT BEGIN:VEVENT SUMMARY:Assessing opportunities in highly efficient perovskite solar cells DTSTART;VALUE=DATE-TIME:20180629T082000Z DTEND;VALUE=DATE-TIME:20180629T084000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-364@events.saip.org.za DESCRIPTION:Speakers: Mmantsae Diale (University of Pretoria)\nPerovskite- based solar cells have made spectacular progress in terms of increased ef ficiency in the past few years. This rapid progress has created a situati on where the technological advances measured by power-conversion efficien cies have proceeded much more quickly than the basic science necessary to understand working of the devices. In this presentation\, discussion of ga ps and possible solutions to perovskite solar cell will be presented\, wit h special reference to defects\, carrier diffusion length and minority ca rrier lifetime.\n\nhttps://events.saip.org.za/event/100/contributions/364/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/364/ END:VEVENT BEGIN:VEVENT SUMMARY:Effect of temperature on the structure and dynamic properties of m etal sulphide nanostructures via molecular dynamics simulation DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-366@events.saip.org.za DESCRIPTION:Speakers: Mofuti Mehlape (University Of Limpopo)\nMetal sulphi de nanostructures via molecular dynamics (MD) simulations at different tem peratures are presented and discussed in order to understand their structu re and dynamic properties. Nanostructured metal sulphides have attracted t he attention of researchers in the fields of materials science\, physics a nd chemistry. They have enhanced structure and dynamic properties due to t heir large surface-to-volume ratio\; hence making them desirable to a wide range of industries. They are promising materials for catalysis\, batteri es and photovoltaic\, however the understanding on the structure and dynam ic conditions of large-scale nanostructures are still to be explored more. Computational modelling technique\, MD was performed to provide atomic or molecular level insights of the structure and dynamic properties of nanos tructured metal sulphides. The effect of temperature on different sizes of nanostructures are analysed in a form of structure and dynamic properties \; namely radial distribution functions\, potential energy and diffusion c oefficient. The results showed that temperature associated with the meltin g transition and stability increased with an increase in the nanoparticle size. New insight into MD study of nanostructured metal sulphides is obtai ned and providing guidance to experiments.\n\nhttps://events.saip.org.za/e vent/100/contributions/366/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/366/ END:VEVENT BEGIN:VEVENT SUMMARY:Luminescence properties of Bi3+ doped YPO4 p owder produced using combustion synthesis DTSTART;VALUE=DATE-TIME:20180629T102000Z DTEND;VALUE=DATE-TIME:20180629T104000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-367@events.saip.org.za DESCRIPTION:Speakers: M M I Beriama (UFS)\nPhosphor materials\, which abso rb energy and emit light\, have numerous applications and continue to deve lop as technology progresses. Past studies have identified YPO4 as a suita ble host material for luminescent rare earth ions. However\, Bi ions also show luminescence in various regions of the spectrum depending on their va lence state as well as the host material and are being investigated as an alternative to expensive rare earth elements. Bi3+ doped YPO4 was synthesi zed by the combustion method at 600 °C using urea as the fuel. Samples we re then reduced in a mixture of hydrogen gas (5%) in argon at different te mperatures. The structure was confirmed by X-ray diffraction. Photolumines cence measurements excited at 230 nm resulted in broad band emission in th e ultraviolet range of 280 - 400 nm\, with the peak at 330 nm attributed t o the 3P1 → 1S0 transition of Bi3+ ions. The optimum Bi doping concentra tion and annealing temperature were established as 0.5 mol% and 800 °C\, respectively. The excitation and emission wavelengths are similar to those reported for Ce doped YPO4\, suggesting that Bi may be considered as an a lternative to this rare earth element. Although this ultraviolet emitting phosphor cannot be used for lighting or display applications\, it could be used for ultraviolet lamps which have forensic\, medical and industrial a pplications.\n\nhttps://events.saip.org.za/event/100/contributions/367/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/367/ END:VEVENT BEGIN:VEVENT SUMMARY:All Sky Imaging with PAPER DTSTART;VALUE=DATE-TIME:20180628T100000Z DTEND;VALUE=DATE-TIME:20180628T102000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-368@events.saip.org.za DESCRIPTION:Speakers: James Chege (Rhodes University)\nThe Precision Array to Probe the Epoch of Reionization (PAPER\, http://eor.berkeley.edu) was built to measure the redshifted 21-cm line from cosmic reionization. Here\ , I will present the analysis of the last season of PAPER observations\, w ith particular focus to image and characterize the foreground emission\, a crucial task in order to detect the much fainter 21-cm emission.\n\nhttps ://events.saip.org.za/event/100/contributions/368/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/368/ END:VEVENT BEGIN:VEVENT SUMMARY:The Dependence of Raman Signal Enhancements on Chain-lengths of Al kanethiols functionalized on gold nanoparticles DTSTART;VALUE=DATE-TIME:20180627T134000Z DTEND;VALUE=DATE-TIME:20180627T140000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-370@events.saip.org.za DESCRIPTION:Speakers: Ndivhuwo Shumbula (university of witwatersrand)\nSur face-enhanced Raman spectroscopy (SERS) has been widely studied for decade s and has attracted many researchers in various fields due to its advantag eous characteristics such as a low limit of detection\, easy sample prepar ation\, non-destructive nature and high sensitivity. Recent studies have f ocused more on enhancing the Raman signal by manipulating various paramete rs of SERS. SERS signals are heavily dependent on the substrates and molec ules (Raman reporters) adsorbed on a substrate. Recently the focus has bee n on trying to develop materials with different and enhanced properties to be employed as SERS substrate. As such\, gold nanoparticles (AuNPs) are a type of material that has received much attention. Unlike most transition metals\, AuNPs are biocompatible\, stable in the harsh environment and mo st importantly they can provide extremely strong electromagnetic field aro und the hot spots due to the excitation of surface plasmons. However\, the effect of chain-length of Raman reporter molecules functionalized on SERS substrates has not been investigated in a wide range. Herein we investiga te the effect of the chain-lengths of 1-alkanethiols (1-pentanethiol\, 1-d ecanethiol\, and 1-pentadacanethiol) functionalized AuNPs on the Raman sig nal enhancement. AuNPs were synthesized using chloroauric acid (HAuCl4) as a precursor and trisodium citrate as a capping and reducing agent. The na noparticles were then functionalized with 1-pentanethiol\, 1-decanethiol\, and 1-pentadecanethiol\, thus resulting in the formation of self-assemble d monolayers. UV-Vis spectroscopy confirmed the plasmon resonance of gold nanoparticles at 520 nm\; HR-TEM illustrated monodispersed spherical nanop articles with an average diameter of 14 nm. The SERS experiments revealed the increase in Raman signal as the chain-length of alkanethiol decreases. \n\nhttps://events.saip.org.za/event/100/contributions/370/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/370/ END:VEVENT BEGIN:VEVENT SUMMARY:Deconvolution method for obtaining directly the original in-depth distribution of composition from the measured sputter depth profile DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-371@events.saip.org.za DESCRIPTION:Speakers: Xin Liang Yan (Shantou university\, China)\nIt is sh own that the original in-depth distribution of composition can be directly obtained by the deconvolution of measured depth profiling data using the MRI (Mixing-Roughness-Information) depth resolution function\, as demonstr ated for the case that the original depth-concentration distribution is ei ther a smooth function or a square wave function. To overcome the ill-cond itioned problem that is often experienced in the deconvolution procedure\, the regularization method and the TV-Tikhonov algorithm are applied. The noise influences from measured data points on the deconvolution procedure are discussed quantitatively.\n\nhttps://events.saip.org.za/event/100/cont ributions/371/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/371/ END:VEVENT BEGIN:VEVENT SUMMARY:Deriving thermospheric neutral density from SuperDARN radar data DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-373@events.saip.org.za DESCRIPTION:Speakers: Eva Gnegy (University of Michigan)\nKnowledge of the rmospheric neutral density\, above 200 km altitude\, is important for appl ications such as satellite drag\, which give satellite lifetime\, and long -term climatic trends such as global warming. We have successfully applied theory (ion momentum equation) to incoherent scatter radar (ISR) data (e. g.\, EISCAT) to extract the thermospheric neutral density above 300 km. Ho wever\, ISRs provide poor coverage and are expensive to operate. Hence\, w e now focus on coherent scatter radars\, which provide great coverage and are cheap to operate. Simplification of the ion momentum equation applied to the ionosphere shows that from the rate of change in ion velocity we ca n derive the ion-neutral collision frequency\, and from this we can calcul ate the neutral density if the atmosphere is a mono-species or of known co mposition. The SuperDARN radar global network of 35 radars covers much of the northern and southern hemisphere polar regions. \nNormally\, the radar s observe each beam at a cadence of once per minute. For this novel experi ment\, we operated selected radars on a single beam with a cadence of one second. This project consists of applying the theory to selected radar dat a sets\, all of which are available. The resultant thermospheric neutral d ensity estimate will be compared to the standard MSIS model.\n\nhttps://ev ents.saip.org.za/event/100/contributions/373/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/373/ END:VEVENT BEGIN:VEVENT SUMMARY:SQUID Magnetometer Data Analysis DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-374@events.saip.org.za DESCRIPTION:Speakers: Abigail Huff (University of Michigan)\nThe observati on of very low magnetic fields is of primary importance for a better under standing of Earth and environment\, as well as for early warning of potent ial hazards coming from space. Recent scientific studies have shown that m agnetometers based on Superconducting QUantum Interference Devices (SQUID ’s) are able to detect P waves emitted during earthquakes or magnetic st orms in the upper atmosphere with sensitivity far better than that of conv entional magnetometers. During thunderstorms there are several types of TL Es (Transient Luminous Events)\, the most common being sprites. Sprites ar e flashes of bright red light that occur above thunderstorm systems\, and can be observed with ultrasensitive high-speed cameras. During January and February 2018 SANSA embarked on a sprite campaign in the centre of South Africa. Significant sprites were identified during at least 3 nights and t hese occurrences are GPS time stamped. During the same time SQUID data wer e recorded from the SQUID located at SANSA Space Science in Hermanus. The aim of this project will be to correlate data from the sprite observations with data from the SQUID in Hermanus to establish if the magnetic signatu re of sprites can be identified in SQUID data. During a previous study the magnetic signatures of sprites were identified in the data from a low-Tc SQUID\, located underground at the Low Noise Laboratory (LSBB)\, France\, and partially shielded. The SQUID operating in Hermanus is a High Tc SQUID \, with higher intrinsic noise levels\, and operating completely unshielde d in the geomagnetic field. The main aim of the project would be identific ation of magnetic sprite signatures in SANSA Squid data.\n\nhttps://events .saip.org.za/event/100/contributions/374/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/374/ END:VEVENT BEGIN:VEVENT SUMMARY:Ionospheric Diurnal Double Peak Structures DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-376@events.saip.org.za DESCRIPTION:Speakers: Joe Taylor (University of Michigan)\nThe study of io nospheric disturbances and irregularities is beneficial to both the scient ific advancement of knowledge as well as the practical applicability to hi gh frequency (HF) communications\, navigation\, surveying and understandin g various aspects of space weather effects on technological systems. Studi es have shown that ionospheric disturbances have characteristic features\, such as diurnal double peak structures\, that differ from effects associa ted with major geomagnetic storm\, Pi et al (1995). Diurnal double peak st ructures have been observed to have varying magnitudes with respect to the background ionosphere. In addition there has not been convincing evidence that these structures are caused solely by geomagnetic disturbances\, Kat amzi et al (2012). In fact\, a study by Katamzi et al. (2016) in a case st udy showed evidence of tides having an influence on their generation\, fro m the observations of sporadic E layer. However\, this needs further inves tigation. Therefore the student will use long-term ionosonde and GPS data to investigate the relationship between sporadic E layer and double peak s tructures over South Africa.\n\nhttps://events.saip.org.za/event/100/contr ibutions/376/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/376/ END:VEVENT BEGIN:VEVENT SUMMARY:ATLAS Tile Calorimeter online software configuration and Perfomanc e study of the super-drawer components DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-377@events.saip.org.za DESCRIPTION:Speakers: Thabo Masuku (University of the Witwatersrand)\nTo o perate the Tile Calorimeter\, the Tile Online software which is a set of T rigger and Data Acquisition (TDAQ) is required for configuration. The modu larity and configurability of TDAQ enables it to be used as data acquisiti on system for test setups\, test beams\, detector calibration\, ect. Parti tions which are the starting point that defines a DAQ configuration are cr eated to readout\,transport\, and store Physics data originating from pro ton-proton collisions from the Large Hadron Collider. In ATLAS a partition is a synonym for data taking configuration.Tests are performed on the sup er-drawer which contains the components of the front-end electronics of th e ATLAS detector. The performed tests will enable us to improve the perfor mance of the components that are used for data taking.\n\nhttps://events.s aip.org.za/event/100/contributions/377/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/377/ END:VEVENT BEGIN:VEVENT SUMMARY:Student ideas on Vector direction in Kinematics graphs DTSTART;VALUE=DATE-TIME:20180626T080000Z DTEND;VALUE=DATE-TIME:20180626T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-378@events.saip.org.za DESCRIPTION:Speakers: Ignatius John (CPUT)\nUnderstanding graphs is a prim ary skill in any discipline\, physics in particular. Students frequently d o not know whether to extract the desired information from the slope or he ight of a graph. This is a pilot study to understand the interpretation of direction of a vector in a kinematics graph. We used a questionnaire cons isting of three graphs to study the understanding of kinematics graphs of first-year university students in various contexts. The study was conducte d on Extended Curriculum Students (ECP) and main stream students who were registered for various courses in a UoT. The students were asked to determ ine the direction of movement of the objects in various graphs within diff erent contexts. The result from the study shows that the students are enga ging with the shape of the graphs rather than the variables in each axis. This paper presents the outcome from three different graphs and their reas oning for their responses\, and the comparison between the two groups.\n\n https://events.saip.org.za/event/100/contributions/378/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/378/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigating the difference in FRI and FRII AGN jet morphology wi th relativistic hydrodynamic simulations DTSTART;VALUE=DATE-TIME:20180628T080000Z DTEND;VALUE=DATE-TIME:20180628T082000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-379@events.saip.org.za DESCRIPTION:Speakers: Izak van der Westhuizen (University of the Free Stat e)\nRelativistic hydrodynamic simulations have become a powerful tool used to simulate the dynamics of jets produced in radio-loud Active Galactic N uclei (AGN). These AGN jets consist of plasma ejected by a central engine moving at relativistic velocities. Observational studies of AGN jets have shown that they emit variable emission over the whole of the electromagnet ic spectrum. The spectral energy distribution (SED) of these sources show dominant components of synchrotron and Inverse-Compton emission produced w ithin relativistic jets originating from the nucleus. While simulations of AGN jets have been able to reproduce many of the observed structures (e.g . radio lobes\, hot spots and super-luminal emission components) the physi cal properties relating to the FRI/FRII division are not well understood. In this study the PLUTO RHD code was used to investigate the parameters re quired to reproduce structures consistent with both FR I and FRII jets. In the first simulation a Lorentz factor of 10 and supersonic flow of Mach 3 00 were chosen\, while for the second simulation a Lorentz factor of 1.001 4 with a supersonic flow of Mach 4 were used. Over similar distances scale s the first case shows a well collimated beam with a strong shock at the i nterface between the jet and ambient medium while the second case shows a less stable beam and larger cocoon. To determine whether the physical stru ctures simulated by the PLUTO code are consistent with the observable FR I /II structures\, the synchrotron emission has been calculated to produce r adio maps at a single frequency of 1.5 GHz. The first case showed emission structures similar to that of FR II radio galaxies with hotspots at the h ead of the jet while the second case was more consistent to that of an FR I source with the highest intensity occurring within the beam of the jet. Calculating the multi-wavelength (radio - gamma-ray) SED of a synchrotron self-Compton model for these simulations is very computationally intensive . We are\, therefore\, currently investigating the use of Monte-Carlo code s in conjunction with the hydrodynamical simulations. These codes can prov ide us with a time-dependent\, multi-zone emission model to compare to obs ervations. Our progress thus far is also presented.\n\nhttps://events.saip .org.za/event/100/contributions/379/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/379/ END:VEVENT BEGIN:VEVENT SUMMARY:SuperDARN radar estimates of thermospheric neutral density DTSTART;VALUE=DATE-TIME:20180626T092000Z DTEND;VALUE=DATE-TIME:20180626T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-380@events.saip.org.za DESCRIPTION:Speakers: Michael Kosch (SANSA)\nUsing the ion-momentum equati on in the F-region ionosphere\, simplified for field-perpendicular ion mot ion only\, we derive an expression for the ion-neutral collision frequency that depends primarily on the temporal and spatial variability of the ion velocity. The ion-neutral collision frequency is primarily a function of neutral density in the thermosphere. SuperDARN radars are very suited to t his type of observation because of their large coverage of the F-region io nosphere\, mesoscale range resolution and frequency agility. Multi-frequen cy observations at one second integration have been performed by the UNIS Longyearbyen radar using natural backscatter\, and the University of Leice ster CUTLASS-Hankasalmi radar using EISCAT Heater-generated artificial str iations. Both show that realistic estimates of thermospheric neutral densi ty\, compared to the MSIS model\, can be obtained with minute cadence or l ess. Since HF radio wave propagation refracts in the F-region ionosphere\, a functional comparison is only possible with ray tracing. This works wel l\, at least for low geomagnetic activity.\n\nhttps://events.saip.org.za/e vent/100/contributions/380/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/380/ END:VEVENT BEGIN:VEVENT SUMMARY:Synthesis of MXene nanoribbons with Onion-like carbons for superca pacitors DTSTART;VALUE=DATE-TIME:20180627T124000Z DTEND;VALUE=DATE-TIME:20180627T130000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-381@events.saip.org.za DESCRIPTION:Speakers: Irfan Habib (Wits University)\nA new family of 2D ma terials called MXenes have recently been discovered\, which can be synthes ized from MAX phases via chemical etching of the A group elements. The pro perties of MXenes can be tuned by changing their terminal functional group s\, and they further allow for the easy creation of thin films\, increasin g their versatility. Their 2D structure allows for fast redox reactions at their surface\, which creates an excellent candidate for supercapacitor e lectrode material for high power density applications. We doped Ti2C with onion-like carbons\, a material known for excellent conductivity and highl y accessible surface area\, and studied its physical properties as a catho de for applications in supercapacitor storage. We will further comment on its applicability in conjunction with photovoltaic panels.\n\nhttps://even ts.saip.org.za/event/100/contributions/381/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/381/ END:VEVENT BEGIN:VEVENT SUMMARY:Cathodoluminescence degradation of Bi doped SrO phosphor powder DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-382@events.saip.org.za DESCRIPTION:Speakers: Mogahid Abdelrehman (University of the Free State)\n Luminescence from Bi ions can be useful in obtaining blue to red emitting phosphors using different hosts when excited by ultraviolet light due to e fficient conversion to longer wavelengths. The alkali-earth oxide phosphor SrO:Bi offers a potential low-cost alternative to lanthanide-based blue p hosphors. SrO powder doped with 0.2 mol% Bi was synthesized by the sol-gel combustion method and annealed at 1100°C in air for 2 h\, since these co nditions were found to optimize its photoluminescence (PL) intensity. The structure of the powder was confirmed as face-centred cubic using X-ray di ffraction. An electron beam of energy 2 keV and beam current 6.2 µA produ ced blue cathodoluminescence (CL) centred around 445 nm. Auger electron sp ectroscopy (AES) was employed to analyze the surface chemical composition of the powder after pumping to a vacuum pressure of 2.6×10−8 Torr and c onfirmed the presence of all major elements\, namely Sr and O\, but Bi was not observed due to its low concentration. C and Cl were also detected an d attributed to adventitious impurity species on the surface. By simultane ous monitoring of the CL and AES peak-to-peak heights over time for 22 h t he CL degradation of the phosphor was investigated. The CL intensity had s lightly reduced after irradiation of about 50 C/cm2 and stabilized thereaf ter\, while most of the C was removed from the surface during this process . The degradation was also evaluated in an O2 environment by back-filling the vacuum system with O2 to a pressure of 1.0×10−7 Torr. The CL intens ity had reduced slightly more and at a higher rate in the O2 atmosphere\, due to the reaction of O2 with the adventitious C to form volatile compou nds on the surface of the irradiated sample. A new less luminescent surfac e layer may have formed after the removal of C\, which caused the CL inten sity to decrease slightly more than in the case of the vacuum. The degrada tion\, however was only around 20%. Except for the initial degradation\, t he blue emitting Bi doped SrO powder was found to be stable under electron bombardment in the base vacuum and O2 environments\, which makes it suita ble for use in lighting and display applications.\n\nhttps://events.saip.o rg.za/event/100/contributions/382/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/382/ END:VEVENT BEGIN:VEVENT SUMMARY:Modelling the acceleration of energetic particles at travelling he liospheric shocks DTSTART;VALUE=DATE-TIME:20180627T092000Z DTEND;VALUE=DATE-TIME:20180627T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-383@events.saip.org.za DESCRIPTION:Speakers: Phillip Prinsloo (Centre for Space Research\, North- West University)\nPropagating shocks are observed to form ahead of the sol ar material expelled into interplanetary space following coronal mass ejec tions (CMEs). During the passage of these CME-driven shocks\, spacecraft o ften observe energetic particle enhancements commonly associated with part icle acceleration. In this study\, the acceleration of energetic particles at halo-CME-driven shocks is investigated\, with a particular focus on th e acceleration of particles from the suprathermal solar wind (SW). A set o f stochastic differential equations\, derived from the Parker transport eq uation and including the effects of diffusive shock acceleration (DSA)\, i s solved numerically to model this process. The SW particle velocity distr ibution is described by a Kappa distribution in the solar wind frame and p rescribed as a source function at the shock. The injection energy is calcu lated from first principles\, but can also be changed to investigate the e ffect thereof on model solutions. With the further application of physical ly representative transport coefficients\, the model results are presented and their accuracy evaluated against how well they reproduce observations of protons and heavier ions during selected shock passage events. The res ults illustrate the significance of the DSA mechanism in accelerating ener getic particle populations in the near-Earth environment.\n\nhttps://event s.saip.org.za/event/100/contributions/383/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/383/ END:VEVENT BEGIN:VEVENT SUMMARY:Lighting the future: perspectives on solid state lighting\, energy efficiency and phototherapy DTSTART;VALUE=DATE-TIME:20180625T113000Z DTEND;VALUE=DATE-TIME:20180625T121500Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-384@events.saip.org.za DESCRIPTION:Speakers: Odireleng Ntwaeaborwa (University of the Witwatersra nd)\nhttps://events.saip.org.za/event/100/contributions/384/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/384/ END:VEVENT BEGIN:VEVENT SUMMARY:Influence of Mn doping on the Room Temperature Gas Sensing Charact eristics of TiO2 nanostructures DTSTART;VALUE=DATE-TIME:20180626T084000Z DTEND;VALUE=DATE-TIME:20180626T090000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-385@events.saip.org.za DESCRIPTION:Speakers: zamaswazi portia Tshabalala (DST/CSIR National Centr e for Nano-Structured Materials\, Council for Scientific and Industrial Re search\, Pretoria\, 0001\, South Africa)\nImperative increase has been obs erved over the years in the need of enhanced performance of gas sensor dev ices for the detection of toxic and combustible gases in working and livin g environments. The demand for accurate\, fast\, stable and portable devic es rises with technology advances and wide application fields. Enhanced se nsitivity\, fast response\, total recovery\, and good selectivity are the main characteristics of a good sensor. With advances in nanotechnology\, t itanium dioxide (TiO2) nanostructures display great properties from their bulk characteristics contributing to promising sensor performance. Various processes have been attempted to modify the structure and properties of T iO2 such as sensitizing and metal ion doping in order to enhance its perfo rmance\, mostly sensitivity. In this study\, we report on the ultra-high s ensitive and selective Mn doped TiO2 nanoparticles prepared by a microwave assisted hydrothermal method with various amounts of Mn 1.0\, 1.5\, 2.0\, 2.5\, 3.0 mol% added. Findings revealed a higher response of the Mn doped samples when exposed to NH3 gas at room temperature. The Mn doped TiO2 na noparticles contains higher concentration of Ti3+ and singly ionized oxyge n vacancies contributing to gas sensing properties. An enhanced UV–Vis e mission and a broad shoulder at 540 nm were observed denoting defects indu ced by the substitution of Ti4+ ions with Mn2+. The Mn2+ ions improved sur face activity of the sensing layer resulting in reduced gas surface chemis orption activation energy. The sensing mechanism towards NH3 gas is also p roposed.\n\nhttps://events.saip.org.za/event/100/contributions/385/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/385/ END:VEVENT BEGIN:VEVENT SUMMARY:Investigation of a specifically targeted photosynthetic nanopartic le drug delivery system for enhanced photodynamic therapy treatment of met astatic melanoma DTSTART;VALUE=DATE-TIME:20180629T094000Z DTEND;VALUE=DATE-TIME:20180629T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-386@events.saip.org.za DESCRIPTION:Speakers: Channay Naidoo (Laser Research Centre\, University o f Johannesburg)\nMetastatic melanoma is the 6th most common cancer diagnos ed worldwide\, with approximately 100\, 000 annual related deaths. Photody namic therapy (PDT) is a photochemotherapeutic cancer treatment that utili zes a photosensitizer (PS) drug that\, when activated by laser light at a specific wavelength\, yields reactive oxygen species (ROS)\, which in turn induces cell death. However\, due to the passive diffusion of PSs\, norma l surrounding cells are sometimes affected and their targeted concentratio ns in cancer cells tends to be minimal\, thus limiting the effectiveness o f this treatment. Therefore a multicomponent drug targeting strategy is of ten applied to improve PS specific delivery and concentration in cancer ce lls only\, which in turn can improve the effectiveness of PDT. Thus the in tention of this study was to improve the photosynthetic drug delivery of z inc sulfothiolphthalocyanine (ZnPcSmix) in metastatic melanoma cells\, by enhancing its chemical structure. ZnPcSmix was successfully conjugated to pegylated gold nanoparticles in order to maximize its solubility and stabi lity\, as well as bound to active tumour-associated antibody-antigens (ant i-MIA) to aid in specific targeted PS delivery. In in vitro co-cultured me tastatic melanoma (A375) and fibroblast (WS1) cells\, this molecular drug conjugate proved to have enhanced cellular uptake within cancer cells only \, while normal cells remained unaffected. Furthermore\, after conducting in vitro PDT experiments with A375 cells\, a significant amount of cell d eath and cytotoxicity was noted. Overall\, this molecular drug conjugation combination of ZnPcSmix with AuNP and anti-MIA\, proved to enhance the tr eatment capabilities of PDT for this form of cancer.\n\nhttps://events.sai p.org.za/event/100/contributions/386/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/386/ END:VEVENT BEGIN:VEVENT SUMMARY:Dark Matter gets DAMPE DTSTART;VALUE=DATE-TIME:20180627T092000Z DTEND;VALUE=DATE-TIME:20180627T094000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-387@events.saip.org.za DESCRIPTION:Speakers: Geoff Beck (University of Witwatersrand)\nThe Dark M atter Particle Explorer (DAMPE) satellite mission recently announced an ex cess is the observed electron/positron spectrum occurring around the TeV s cale. This has been conjectured to be explicable in terms of the annihilat ion of a heavy leptophilic WIMP particle. Additionally\, this hypothesis r equires the presence of a dense clump of dark matter within 1 kpc of the E arth\, in order for the required WIMP annihilation cross-section to fall i nto territory that is largely unconstrained by experiments like Fermi-LAT. We will explore the astrophysical consequences of this model\, the impact of current data on its parameter space\, the observability of the conject ured dark matter clump\, and the projections for up-coming experiments lik e KM3NET. We confirm the inability of Fermi-LAT to probe the required para meter space and show that the LOFAR array is well positioned to hunt for t he nearby dark matter clump in radio frequencies and that KM3NET can deepl y probe the muon coupling of such a dark matter model.\n\nhttps://events.s aip.org.za/event/100/contributions/387/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/387/ END:VEVENT BEGIN:VEVENT SUMMARY:Search for gamma-ray emission from the newly discovered close bina ry system AR Scorpii DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-388@events.saip.org.za DESCRIPTION:Speakers: Quinton Kaplan (University of the Free State)\nDetai led multi-frequency studies of the white dwarf pulsar AR Scorpii (AR Sco) revealed a Spectral Energy Distribution (SED) that showed optically thin s ynchrotron emission between IR and X-ray energies. This implies that AR Sc o is a site of particle acceleration and associated pulsar-like synchrotr on emission\, which makes AR Sco an interesting source to search for poss ible gamma-ray emission in available Fermi-LAT data (100 MeV – 100 GeV). The focus of this MSc project is to do a complete analyses of the total F ermi-LAT data (2008-2018) by utilizing the upgraded Fermi-LAT Pass 8 data analysis pipeline to search for pulsed and un-pulsed gamma-ray emission. T he possible detection of gamma-rays from AR Sco will be a strong motivatio n for possible CTA and H.E.S.S. follow-up studies. A positive detection w ill also be invaluable to the field of gamma-ray astronomy\, establishing close binaries containing fast rotating\, highly magnetic white dwarfs\, a s a new class of gamma-ray source.\n\nhttps://events.saip.org.za/event/100 /contributions/388/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/388/ END:VEVENT BEGIN:VEVENT SUMMARY:Imaging using Ptychographic iterative algorithms DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-389@events.saip.org.za DESCRIPTION:Speakers: Anneke Erasmus (Stellenbosch University)\nPtychograp hy is a lensless imaging technique. Light that is transmitted through a sa mple is measured. Through iterative algorithms this transmitted light’s relative amplitude and phase is reconstructed. This information can be use d to create an image of the sample. In ptychography\, sections of the samp le are illuminated individually and a diffraction pattern of each section is detected in the far field. In doing so\, the intensity information of t he sample is measured\, but the phase information is lost. By ensuring sig nificant spatial overlap between neighbouring illuminated sections of the sample\, the reconstruction converges to the corresponding relative phase of the sample. A ptychographic iterative engine (PIE) algorithm is employe d to reconstruct the amplitude and phase of the light transmitted by the s ample from the measured diffraction patterns. The PIE algorithms that are discussed here were simulated\, and then implemented to reconstruct real s amples. Preliminary representative reconstruction results will be shown. F actors that limit the imaging resolution include the quality of the angula r spectrum that is captured by the detector. This label free imaging techn ique has the advantage of imaging deep within the sample\, because the opt ical setup is not limited by a lens’s working distance. Also\, the recon struction of the phase allows for phase contrast imaging of transparent bi ological samples.\n\nhttps://events.saip.org.za/event/100/contributions/38 9/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/389/ END:VEVENT BEGIN:VEVENT SUMMARY:Constraining the TeV Gamma-ray Emission Regions with Gamma-Gamma A bsorption DTSTART;VALUE=DATE-TIME:20180626T130000Z DTEND;VALUE=DATE-TIME:20180626T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-390@events.saip.org.za DESCRIPTION:Speakers: Drikus Du Plooy (University of the Free State)\nGamm a-ray binaries are a class of high-mass binary systems\, which are disting uished by having spectral energy distributions which peak above 1 MeV. Gam ma-ray binaries consist of a compact object\, either a neutron star or bla ck hole\, orbiting a massive O or B type star. While there is some debate around how the gamma-rays are produced\, in two systems\, PSR B1259-63 and PSR J2032+4127\, the compact object is known to be a young pulsar\, and t he gamma-ray production is due to particle acceleration in the shock that forms between the pulsar and stellar winds. It has been suggested by some studies that there may be different sights of particle acceleration in the se systems\, with the GeV and TeV emission being produced in different loc ations. Gamma-gamma absorption of the TeV emission could significantly mod ify the observed emission. This may provide a mechanism to constrain the l ocation of the production of TeV gamma-rays. In this project we plan to mo del the effect of gamma-gamma absorption in all known gamma-ray binary sys tems\, in order to investigate how this will modify the observed spectrum. This may be used to place constraints on the location when combined with the observations of the TeV emission. We will investigate this for the upc oming Cherenkov Telescope Array (CTA). We present the initial results from this project.\n\nhttps://events.saip.org.za/event/100/contributions/390/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/390/ END:VEVENT BEGIN:VEVENT SUMMARY:Extracting a vibrational Raman spectrum from a broadband Coherent Anti-Stokes Raman Scattering measurement DTSTART;VALUE=DATE-TIME:20180628T130000Z DTEND;VALUE=DATE-TIME:20180628T150000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-391@events.saip.org.za DESCRIPTION:Speakers: Ruan Viljoen (Stellenbosch University)\nProbing the vibrational energy states of molecules can be done by Coherent Anti-Stokes Raman Scattering (CARS) Spectroscopy. Traditionally two or three differen t laser beams are employed to pump and probe the vibrational spectrum of m olecules\, probing the molecules one wavelength at a time. With the introd uction of a coherent broadband light source it is possible to pump and pro be multiple states simultaneously\, with a single broadband beam. Increasi ng the pump bandwidth has the disadvantage of increasing the non-resonant CARS signal which drowns out and masks the spectrum-containing resonant si gnal. For broadband single beam CARS\, the question is: how does one extra ct the Raman spectrum from the mix of resonant and non-resonant CARS? In t his presentation we introduce novel techniques that answer this question. We simulate these techniques to illustrate the expected single beam CARS m easurements and how a vibrational Raman spectrum can be extracted. Compari sons are made between these simulations and experiments on liquid and crys talline samples to prove the techniques.\n\nhttps://events.saip.org.za/eve nt/100/contributions/391/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/391/ END:VEVENT BEGIN:VEVENT SUMMARY:Using optical tweezers to measure the forces exerted by molecular motors in onion cells DTSTART;VALUE=DATE-TIME:20180627T140000Z DTEND;VALUE=DATE-TIME:20180627T142000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-392@events.saip.org.za DESCRIPTION:Speakers: Anneke Erasmus (Stellenbosch University)\nOptical tw eezers demonstrate how light can be applied to exert piconewton forces on a microscopic particle. This allows for the particle to be spatially manip ulated in three dimensions. Optical tweezing is achieved by creating an op tical trap. In this work\, a single beam optical trap is created using a h igh numerical aperture microscope objective to focus a near infrared laser into a sample. The sample used for calibration of the setup is micron siz ed\, dielectric particles suspended in a fluid. The particles have a highe r refractive index than the fluid in which the particles are suspended. Af ter the light refracts through a particle\, a net force is applied to the particle that causes it to move into the focus of the beam due to conserva tion of momentum. When moving the trap position relative to the sample\, t he optical trap acts as optical tweezers moving the particle(s) currently in trap relative to the sample. Optical tweezers have been developed for v arious applications. However\, here the optical tweezers is used to invest igate the forces needed to stall the motion of molecular motors in onion ( Allium cepa) cells. To do this\, the optical tweezers were constructed and the forces applied to micron sized particles in the trap were calibrated. An integrated microscopy imaging setup was used to see and trap vesicles transported by molecular motors in the cells. The force calibration was th en used to determine the intracellular forces of the molecular motors.\n\n https://events.saip.org.za/event/100/contributions/392/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/392/ END:VEVENT BEGIN:VEVENT SUMMARY:Growth and electronic structure charaterization of 2D germanene/Pt (111) DTSTART;VALUE=DATE-TIME:20180626T094000Z DTEND;VALUE=DATE-TIME:20180626T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-393@events.saip.org.za DESCRIPTION:Speakers: Carmel Dansou (Department of Physics\, University of Johannesburg\, PO Box 524\, Auckland Park 2006\, Johannesburg\, South Afr ica.)\nIn the last decade\, a new class of solids known as “2D Dirac mat erials” has led to an outburst of research activities in condensed matte r physics and materials science. The low-energy quasiparticles in these ma terials are described by the relativistic (2+1) Dirac equation rather than Schrodinger’s equation. The relativistic effect in these systems confer s to them some unusual properties not observed in the usual Schrodinger-ty pe systems. This makes them very attractive for fundamental research as we ll as for technological applications. Recently\, germanene has been predic ted not only to be a 2D Dirac material but also to show some behavior beyo nd those of other 2D Dirac materials (such as graphene and silicene). In p articular Its predicted quantum spin Hall effect makes germanene appealing to semiconductor and spintronics industries. We report on the fabrication of germanene on Pt(111)\, its characterization by combined X-ray photoemi ssion spectroscopy (XPS) and low energy electron diffraction (LEED) and it s Dirac cone structure by use of angle-resolved photoemission spectroscopy (ARPES). LEED and XPS analysis suggest that germanene forms a (2 x 2) sup erstructure on Pt(111) and shows strong interaction with Pt substrate. The germanene-substrate interaction is seen to play an important role in the electronic structure revealed by ARPES. This result confirms this interact ion to be an important parameter to be exploited in the synthesis of germa nene on suitable substrates.\n\nhttps://events.saip.org.za/event/100/contr ibutions/393/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/393/ END:VEVENT BEGIN:VEVENT SUMMARY:Development of a Quantification Software/Programme for Li-Mn-O Com posite Nanoarchitectures DTSTART;VALUE=DATE-TIME:20180626T094000Z DTEND;VALUE=DATE-TIME:20180626T100000Z DTSTAMP;VALUE=DATE-TIME:20260418T202831Z UID:indico-contribution-100-394@events.saip.org.za DESCRIPTION:Speakers: DONALD HLUNGWANI (UL)\nThe integrated layered-spinel manganese composites are the most desired cathode materials for lithium i on batteries due to their enhanced safety\, inexpensive and non-toxic prop erties. They are preferred over Ni- and Co- containing compounds due to th eir greater stability (retention of the Oxygen) in their charged state. It has been reported that the spinel and layered integrated composites impro ve the electrochemical properties of lithium ion batteries\, depending on the concentration of the layered Li2MnO3 component and spinel LiMn2O4 comp onent. In this study\, we develop a program aimed at quantifying the laye red-spinel Li-Mn-O in the layered-spinel composite nanomaterials synthesiz ed computationally using the amorphization and recrystallization technique . The program was developed using C# programming language and helps with b etter investigation of the impact associated with their respective quantit ies on the electrochemical performance of the cathode materials. The spine l content in the layered-spinel Li-Mn-O nanomaterial was found to be appro ximately 30 %. Capabilities of the program is to quantifying the amount of LiMn2O4 in layered-spinel Li-Mn-O composite nanomaterials which will add valuable insights to the design of such electrode materials associated wit h their performance.\n\nhttps://events.saip.org.za/event/100/contributions /394/ LOCATION: URL:https://events.saip.org.za/event/100/contributions/394/ END:VEVENT END:VCALENDAR