Conveners
NPRP: Clustering and Break-up
- Steven Karataglidis (University of Johannesburg)
NPRP: Applications of Radio-Activity
- Richard Newman (iThemba LABS NRF)
NPRP: High Energy Physics
- Simon Connell (University of Johannesburg)
NPRP: Nuclear Structure and Theory
- Simon Mullins (iThemba LABS (Gauteng))
NPRP: Radio-Active Beams
- Sifiso Senzo Ntshangase (University of Cape Town / iThemba LABS)
NPRP: Giant Resonances
- Anthony Cowley (Stellenbosch University)
NPRP: Accelerators, applications and ion sources
- Nico Orce (University of the Western Cape)
Description
Nuclear, Particle and Radiation Physics
Quantum condensation of alpha particles is believed to occur in cluster states of the self-conjugate alpha nuclei 12C and 16O. This phenomenon is similar to the Bose-Einstein condensation observed through the laser cooling of atoms such as Rb or Na. A state of this nature, which must be of 0+ character, is expected to exist just above the 5 alpha decay threshold in 20Ne. In this region,...
Motivated by several theoretical cluster calculations that predict the existence of the 06+ state in 16O located at 15.1 MeV as a very good candidate for the equivalence of the Hoyle state in 12C, a high resolution measurement of 16O spectrum in coincidence with the 16O decay products was proposed using a (p,t) reaction at...
In our experiments devoted to studying of a new ternary decay of low excited heavy nuclei called “collinear cluster tri-partition” (CCT) a specific CCT mode was observed based on double magic 132Sn cluster. Pre-scission configuration which presumably gives rise to the mode under discussion can be obtained. The Sn cluster can "move" as a whole along the cylinder-like configuration that...
Cluster-like structures in the shell-model description of the ground state of nuclei can be conveniently studied by means of knockout reactions. Of these the (p, p alpha) reaction is perhaps the simplest, especially from the viewpoint of the tractability of theoretical calculations used to interpret experimental results. The distorted wave impulse approximation (DWIA) is a versatile theory...
In heavy ion reactions the emission of Intermediate Mass Fragments (IMFs) at forward angles is dominated by the direct break-up process. To improve our understanding of this process in the reaction mechanisms involving the interaction of light projectiles with light to heavy target nuclei, a coincidence measurement was performed at iThemba LABS. Standard ΔE-E detector telescopes were used...
The fusion evaporation reaction is mainly used to populate high spin states in atomic nuclei. Using stable beams, a large number of β + unstable nuclei were studied i.e. those nuclei on the neutron deficient side of the valley of stability. A plethora of experimental data is available in a wide range of mass A ∼ 20 to A ∼ 250 and was used to test the statistical model codes such as PACE,...
Saldanha Bay on the West Coast of South Africa is surrounded by various nature reserves and protected areas which amongst other includes heritage sites like the West Coast Fossil Park. Large parts of these sensitive areas were however exposed to anthropogenic activities, which includes farming and mining as well as training and preparation for war. This article investigates the prospect...
Gold mine tailings dams contain considerable amounts of Ra-226 and have therefore been identified as large sources of radon. In this contribution we will discuss measurements at a disused Kloof mine dump near Carletonville to investigate the radon exhalation from the dump as well as the gamma radiation from the dump. We have also taken soil samples in order to find the activity...
In this work a 7.5 cm x 7.5 cm NaI (Tl) detector was used to study activity concentrations of primordial radionuclides in soil and sand samples. The detector and the sample were placed inside a lead castle to reduce background measurements from the surroundings such as the wall and the floor. The samples were placed inside a 1L Marinelli beaker which surrounds the detector for better...
The goal of any measurement and data-analysis technique should always be to minimize uncertainties, whether it is statistical or systematic. Although uncertainties are unavoidable, one can find ways to reduce them depending on the circumstances. High-precision measurements play a crucial role in constraining various quantities. Recently a new inorganic scintillation detector has become...
Radiopharmaceuticals is compounds labelled with a radioactive isotope that are used for studying different organs in the human body. Technetium-99m (99mTc) labelled iminodiacetic acid (IDA) derivatives are commonly used as hepatobiliary imaging agents. Radiopharmaceuticals used for hepatobiliary imaging are divided into two groups based on the physiologic function of the liver they are...
This work is part of a program based on the electro-production of baryonic resonances. In part, the physics goals are to assess the relevant degrees of freedom appropriate to describe high momentum transfer exclusive reactions. In particular, the interest is in the region where the four – momentum transfer squared, t ~ Q2 varies beyond the validity of the constituent quark model (CQM),...
The measurement of the isolated di-photon cross-section at the LHC is crucial as these events constitute an irreducible background to new physics processes, such as a Higgs boson or graviton decaying to two photons. These events also provide important information for the understanding of QCD processes. The di-photon cross-section has been measured in ATLAS using the full 2010 data sample,...
The H -> ZZ(*) -> 4leptons channel is one of the most promising channels for a low-mass Higgs boson, as it has both a clean signature and a large branching fraction for Higgs mass below a few hundred GeV. The ATLAS experiment has explored this channel using the LHC collisions data at a center-of-mass energy of 7 TeV, using data-driven background estimation techniques. Some Abelian Hidden...
Experiments at the Large Hadron Collider (LHC) aim to address fundamental questions in particle physics such as the origin of mass for elementary particles, the matter/anti-matter asymmetry in the universe, the nature of Dark Matter, the state of matter in the early universe, etc. The ATLAS detector is one of the four major detectors being exploited at the LHC to shed some light on the...
Recent theoretical work has suggested that some nuclei in the rare earth region might exhibit tetrahderal deformations. Several nuclei have been studied at iThemba LABS, resulting in evidence against the possibility of low-lying tetrahedrally deformed bands. In a continued study of the region, further gamma-ray spectroscopy experiments have been performed at iThemba LABS, populating low...
The nuclei 158,15968Er are classic examples of many phenomena in the study of nuclei at high spin. However, although the multi-quasi particle structures of 158,15968Er are well established, there is not much spectroscopic information on the vibrational structures in 158Er or how these couple to the odd neutron in 159Er. Additionally, there are several bands where the spins and/or parities...
Negative-parity side bands in nuclei localized in the vicinity of N = 90 are known to have strong electric dipole transitions from each level to the ground-state band, with weak or unseen E2 transitions (E2s) in the medium (~15h) to low-spin region. These structures have always been regarded as octupole vibrational bands. On the other hand, Dudek et al. recently proposed that these...
Nuclei near N=90 are considered transitional, since they lie between nuclei that display vibrational spectra and nuclei that display rotational spectra. The structure of these transitional nulei, in particular the nature of the low-lying first excited states |0+2> still pose a great challenge with various theoretical models competing. A new perspective to the understanding of the structure...
The Coulomb excitation of light nuclei can provide unique information on the matrix elements for excited states. This contribution will discuss experiments to measure such excitation as well as ab initio large shell model calculations calculations that can be tested by these measurements.
The notion of mirror symmetry is well-established for nuclei on or near the valley of stability, and this has its roots in the (largely) charge independent nature of the nuclear force. We have applied this assumption to nuclei near or beyond the drip lines, in particular, the mass-15 system for 15F and 15C. Using information on the bound states in 15C we predicted states in 15F in 2006...
A feasibility to develop a radioactive beam facility at iThemba LABS has commenced. The proposal envisages the addition of a new cyclotron, a k70 negative-ion accelerator. Such an accelerator can supply two beams simultaneously, one to be used for isotope production and neutron therapy, the other to create radioactive ions. These can be post accelerated by the existing SSC accelerator to...
A survey of the fine structure phenomenon of the Isovector Giant Dipole Resonance (IVGDR) was investigated, using the newly commissioned Zero-degree Facility of the K = 600 magnetic spectrometer of iThemba LABS. Measurements were performed for inelastic proton scattering at an incident energy of 200 MeV for targets ranging from 27Al to 208Pb. Targets of areal density...
A systematic experimental investigation of the phenomenon of fine structure, with emphasis on the region of the Isoscalar Giant Quadrupole Resonance (ISGQR), in nuclei across stable even-even neodymium isotopes has been performed. Measurements were made using the K600 Magnetic Spectrometer of iThemba Laboratory for Accelerator Based Sciences, a facility which is situated at Faure near Cape...
P-LABS at Necsa consists of two linear particle accelerator facilities; a Van de Graaff with terminal potential up to 4 MV and two radio frequency quadrapole (RFQ) accelerator systems that can accelerate D+ ions to 3.7 - 5.1 MeV (or protons to 1.8 – 2.5 MeV). Depending on the beam target used these accelerators can produce fast neutrons (and associated gamma rays) at a rate of 10^6 - 10^12...
Graphite composite comprising of 64 wt% of natural graphite, 16 wt% of synthetic graphite and 20 wt% of phenolic resin binder heat treated at 1800 0C have been used to encapsulate the TRISO coated fuel particles in the PBMR and considered to serve in the initial state of neutron moderation as well as heat conduction. The structural and thermal properties of the pristine and irradiated...
In recent years the need to produce low charge state ion beams with good beam quality and ion sources with good gas efficiency are on an increasing demand. The various applications of these specific ion beams are ranging from radioactive ion beam production to high energy ion implanters. The Accelerator Physics Department at iThemba LABS has developed a prototype microwave ion source. The...
Heavy ion beams at iThemba LABS have been produced in a 10GHz Minimafos electron cyclotron resonance ion source (ECRIS) for the past two decades. The typical values for the injection and extraction coil current are in the range of 1000A. The operating pressure is about 10-6 mbar depending of the ion produced. The Minimafios ECRIS allow the use of supporting gas like helium, oxygen etc. It...
