Browsing by Author "Bark, R.A"

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    Observation of the 0+ 2 and γ bands in 98Ru, and shape coexistence in the Ru isotopes
    (Elsevier, 2020) Garrett, P.E; Makhathini, L.; Bark, R.A; Rodríguez, T.R.; Valbuena, S.; Wirth, H.F.; Vyfers, E.C.; Triambak, S.; Singh, B.; Rebeiro, B.; Orce, J.N; Nzobadila Ondze, J.C.; Ntshangase, S.S.; Ngwetsheni, C.; Mukwevho, N.J.; Mthembu, S.H.; Mehl, C.; Lawrie, E.A; MacLean, A.D.; Leach, K.G; Lawrie, E.A.; R., Kamil; R. Dubey; T. Faestermann; C. Burbadge; T.D. Bucher
    Excited states in 98Ru were investigated using γ-ray spectroscopy following the β-decay of 98Rh, and via the 100Ru(p,t) reaction. Combining the results from the two experiments, two states were revised to have spin-parity of 4+ and subsequently assigned to the 02+ and “γ” bands, respectively. The observed structures in 98Ru are suggested to be deformed and rotational, rather than spherical and vibrational, and fit well into the systematics of these excitations in the Ru isotopes. The 02+ excitation is suggested as a shape coexisting configuration. This observation eliminates some of the last remaining candidates for nearly harmonic vibrational nuclei in the Z≈50 region. Beyond-mean-field calculations are presented that support shape coexistence throughout the Ru isotopes with N=52–62, and suggest a smooth evolution of the shapes
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    Search for tetrahedral bands in yb isotopes
    (University of the Western Cape, 2007) Maliage, Shumani Maurice; Bark, R.A
    Calculations by Dudek et al. predict shell gaps for tetrahedrally shaped nuclei at various proton and neutron numbers. 160Yb is expected to be a favourable nucleus, with tetrahedral bands predicted to lie 1 MeV above the ground state. A search for such states has been performed using the Afrodite Ge detector array at iThemba LABS. A 73MeV 160 beam bombarded a 147Sm target of thickness 3mg/cm2 to produce 160Yb at low spin and high excitation energy. After analysis of the data, new rotational bands have been added to the level scheme. Although these bands are in the expected energy interval for the tetrahedral states, they do not show the expected decay properties of the tetrahedral bands. Rather, we interpret them as vibrational y and 13 bands.