Research Articles (Physics)

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Browsing by Author "Abrahams, K"

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    Coulomb excitation of and a change in structure approaching N = Z = 40
    (American Physical Society, 2021) Gillespie, S; Henderson, J; Abrahams, K; Ali, F
    Background: Nuclei approaching are known to exhibit strongly deformed structures and are thought to be candidates for shape coexistence. In the krypton isotopes, are poorly characterized, preventing an understanding of evolving deformation approaching . Purpose: The present work aims to determine electric quadrupole transition strengths and quadrupole moments of in order to better characterize their deformation. Conclusions: Comparison of measured and values indicates that neutron-deficient () isotopes of krypton are closer to axial deformation than other isotopic chains in the mass region. A continuation of this trend to higher may result in Sr and Zr isotopes exhibiting near-axial prolate deformation. Methods: Sub-barrier Coulomb excitation was employed, impinging the isotopes of krypton on and targets. Utilizing a semiclassical description of the safe Coulomb-excitation process matrix elements could then be determined. Results: Eleven new or improved matrix elements are determined in and seven in . The new value in disagrees with the evaluated value by , which can be explained in terms of deficiencies in a previous Coulomb-excitation analysis.
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    Modern African nuclear detector laboratory: Development of state-of-the-art in-house detector facility at the University of the Western Cape
    (SpringerLink, 2021) Kapoor, K.; Orce, J.N; Abrahams, K; Akakpo, E; Bester, Z; Jenkins, D.G; Jordaan, K.L; Jones, M.Y.; Kamedien, M.A.; Lindsay, R.; Lomberg, B; Masango, S.; Ngwetsheni, C.; Ntshangase, S.S.; Radebe, N.; Triambak, S; Zyl, J.J. van,
    The upcoming detector facility aims at developing new state-of-the-art particle detectors as well as providing hands-on training to postgraduate students using both analog and digital signal processing from nuclear radiation detectors. The project is two-fold and aims at developing: 1) ancillary detectors to be coupled with the new GAMKA array at iThemba LABS. Of particular interest to our group is the determination of nuclear shapes, which depend on the hyperfine splitting of magnetic substates; 2) PET scanners for cancer imaging using a cheaper technology. Performance of NaI(Tl) inorganic scintillator detectors has been evaluated using PIXIE-16 modules from XIA digital electronics. Gamma-ray energy spectra were acquired from 60Co and 137Cs radioactive sources to calculate the detector resolution as well as to optimize the digital parameters. The present study focuses on improving and optimizing the slow and fast filter parameters for NaI(Tl) detectors which can eventually be used in the list mode of data aquisition.