Browsing by Author "Ndayishimye, Joram"
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- ItemAlpha cluster structure and scattering in 20Ne, 44Ti, 94Mo, 136Te and 212Po(Stellenbosch : University of Stellenbosch, 2011-03) Ndayishimye, Joram; Wyngaardt, Shaun M.; Perez, S. M.; University of Stellenbosch. Faculty of Science. Dept. of Physics.ENGLISH ABSTRACT: We investigate the nuclei 20Ne, 44Ti, 94Mo, 136Te and 212Po using a model of an α-cluster orbiting a closed shell core. A purely phenomenological cluster-core potential is found to provide a successful description of the spectra, B(E2↓) transition strengths, and α-decay rates of the low-lying positive parity states of these nuclei. We then use the same potential as the real part of an optical model potential to describe the α elastic scattering by 16O, 40Ca, 90Zr and 208Pb. The experimental differential cross-section data are reasonably well reproduced with the imaginary potential depth as the only free parameter. The special case of the 8Be system is also analysed.
- ItemMultiple chiral bands in 193Tl(Stellenbosch : Stellenbosch University, 2016-03) Ndayishimye, Joram; Wyngaardt, Shaun M.; Lawrie, Elena A.; Stellenbosch University. Faculty of Science. Dept. of PhysicsENGLISH ABSTRACT : In order to extend knowledge about chirality in A ∼ 190 mass region, experiments were performed at iThemba LABS for γ−spectroscopy studies in 192,193Tl. Previous level scheme of 193Tl was considerably modified and extended. Level scheme of 192Tl was also significantly extended. Spins and parities were assigned to most of the levels. The yrast band in 192Tl is associated with πh9/2⊗νi13/2 configuration which is suitable for chiral symmetry. A side band with close excitation energies was observed, suggesting that the two bands in 192Tl might form a chiral pair. More interestingly three bands in 193Tl have similar properties and were associated with the same πh9/2 ⊗νi13/2 2. These bands might represent a multiplet of chiral bands in 193Tl. Theoretical calculations using the Cranked Nilsson-Strutinsky (CNS) model, the multi-particle rotor (MPR) model, and the two-quasiparticle-plus-triaxial rotor model (TQPRM) support the presence of chiral symmetry in 192,193Tl.