Speaker
Mr
Kgashane Malatji
(iThemba LABS / Stellenbosch University)
Description
Most stable and extremely low abundance proton-rich nuclei with A>110 are thought to be produced by the photodisintegration of s- and r- process seed nuclei. However, this so-called p-process is insufficient to explain the observed low abundance (0.012%) of the 180Ta isotope. Hence combinations of several processes are considered to reproduce the observed abundance of 180Ta in the cosmos, provoking debates and making it a unique case study. Significant uncertainties in the predicted reaction rates in p-nuclei arise due to large uncertainties in nuclear properties such as the nuclear level densities (NLD) and gamma-ray strength functions (γSF) (S. Goriely et al., 2001), as well as the actual astrophysical environments. An experiment was performed in October 2014 to extract the NLD and γSF below the neutron threshold (Sn) in 180,181,182Ta isotopes which provide important 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(3He,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). Using the SiRi array at backward angles (64 silicon particle telescopes) and the CACTUS array (26 NaI(Tl) detectors), the NLD and γSF were simultaneously extracted below Sn from particle-γ coincidence matrices through iterative procedures using the Oslo method (A. Schiller et al., 2000). The experimental results have been used to determine the corresponding neutron capture cross sections, which in turn were utilized to extract Maxwellian averaged cross sections. The latter were further used in astrophysical s- and p-process network calculations to investigate the galactic production mechanism of 180Ta. In this talk I will present final results on the statistical properties of 180,181,182Ta and their implications for the nucleosynthesis of 180Ta.
This work is based on the research supported in part by the National Research Foundation of South Africa Grant Number 92600 and the IAEA under research grant number 20454.
Supervisor details<br><b>If not a student, type N/A.</b><br>Student abstract submision<br>requires supervisor permission:<br>please give their name,<br> institution and email address.
Dr. Mathis Wiedeking
iThemba LABS
wiedeking@tlabs.ac.za
| Please confirm that you<br>have carefully read the<br>abstract submission instructions<br>under the menu item<br>"Call for Abstracts"<br><b>(Yes / No)</b> | Yes |
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| Consideration for<br>student awards<br><b>Choose one option<br>from those below.</b><br>N/A<br>Hons<br>MSc<br>PhD | PhD |
Primary authors
Prof.
Andreas GÖRGEN
(University of Oslo)
Dr
Ann-Cecilie Larsen
(University of Oslo)
Mr
Christiaan Brits
(University of Stellensbosch)
Dr
Darren BLEUEL
(Lawrence Livermore National Laboratory)
Dr
Eda Sahin
(University of Oslo)
Mr
Fabio ZEISER
(University of Oslo)
Dr
Francesca GIACOPPO
(Helmholtz Institute Mainz and GSI Helmholtzzentrum für Schwerionenforschung)
Dr
Frank Bello Garrote
(University of Oslo)
Dr
Gry Tveten
(University of Oslo)
Dr
Hilde NYHUS
(University of Oslo)
Dr
Kasia HADYNSKA-KLEK
(University of surrey)
Mr
Kgashane Malatji
(iThemba LABS / Stellenbosch University)
Prof.
Lionel Siess
(Université Libre de Bruxelles)
Prof.
Magne GUTTORMSEN
(University of Oslo)
Dr
Malin KLINTEFJORD
(University of Oslo)
Dr
Mathis Wiedeking
(iThemba LABS)
Prof.
Stephane Goriely
(Université Libre de Bruxelles)
Dr
Sunniva Rose
(University of Oslo)
Prof.
Sunniva Siem
(University of Oslo)
Dr
Therese RENSTRØM
(University of Oslo)
Dr
Trine Hagen
(University of Oslo)
Mr
Vetle INGEBERG
(University of Oslo)
Dr
Vincent Kheswa
(University of Johannesburg)
