Speaker
Mr
Kgashane Malatji
(Physics Department, University of Stellenbosch, Matieland, 7602, South Africa)
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) [1], as well as the actual astrophysical environments. An experiment was performed in October 2014 to extract the NLD and γSF below the neutron threshold 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') and 181Ta(3He, 4He) reactions with 34 MeV beam, 181Ta(d, d') and 181Ta(3He, t) reactions with 15 MeV beam , and 181Ta(d, d') and 181Ta(d, p) reactions with 12.5 MeV beam at the Oslo Cyclotron Laboratory. 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 the neutron separation energy from particle-γ coincidence matrices through iterative procedures using the Oslo method [2]. 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 can be used in astrophysical network calculations to investigate the galactic production mechanism of 180Ta. In this talk I will present results of this investigation of statistical properties for 180,181,182Ta and the corresponding (n, γ) cross sections.
[1] S. Goriely et al., A&A J. 375, L35 (2001).
[2] A. Schiller et al., Nucl. Instrum. Methods Phys. Res. A 447, 498 (2000).
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.
Primary author
Mr
Kgashane Malatji
(Physics Department, University of Stellenbosch, Matieland, 7602, South Africa)
Co-authors
Prof.
Andreas GÖRGEN
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Dr
Ann-Cecilie LARSEN
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Dr
Bonginkosi Kheswa
(Department of Physics, University of Johannesburg, Johannesburg, 1850, South Africa)
Mr
Christiaan Brits
(Physics Department, University of Stellenbosch, Matieland, 7602, South Africa)
Dr
Darren BLEUEL
(Lawrence Livermore National Laboratory, Livermore, California 94551, USA)
Dr
Eda SAHIN
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Mr
Fabio ZEISER
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Dr
Francesca GIACOPPO
(Helmholtz Institute Mainz, 55099 Mainz, Germany and GSI Helmholtzzentrum fur Schwerionenforschung, 64291 Darmstadt, Germany)
Mr
Frank BELLO GARROTE
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Dr
Gry TVETEN,
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Dr
Hilde NYHUS
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Dr
Kasia HADYNSKA-KLEK
(INFN, Laboratori Nazionali di Legnaro Padova, 35020 Legnaro, Italy)
Prof.
Magne GUTTORMSEN
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Dr
Malin KLINTEFJORD
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Sunniva Rose
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Prof.
Sunniva SIEM,
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Dr
Therese RENSTRØM
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Dr
Trine HAGEN
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Mr
Vetle INGEBERG
(Department of Physics, University of Oslo, NO-0316 Oslo, Norway)
Dr
mathis wiedeking
(Department of Subatomic Physics, iThemba LABS, Old Faure Road, 7131, South Africa)
