Browsing by Author "Shirinda, O."
Now showing 1 - 9 of 9
Results Per Page
Sort Options
- ItemAngular correlation measurement with the iThemba LABS segmented clover detector(Jagellonian University, 2019) Shirinda, O.; Lawriea, E. A.; Buchera, T. D.; Mthembua, S. H.; Dinoko, T. R. S.; Easton, J. L.; Mtshali, W. X.; Noncolela, S. P.; Duprez, D.; Lawrie, J. J.Measurements of the angular correlation function W(θ) were performed with the iThemba LABS segmented clover detector. A set of measurements with radioactive sources and irradiated targets was carried out to check the performance of the detector. At short detector-to-source distance, the detector covers the whole range of angles needed for precise angular correlation measurements. Preliminary results show that our detector can measure precisely angular correlation functions, including for transitions with large multipole order such as E3, M4, E4, etc., and deliver mixing ratios δ of mixed magnetic and electric nature.
- ItemChiral bands in 193Tl(Jagiellonian University, 2017-03) Ndayishimye, J.; Lawrie, E. A.; Shirinda, O.; Easton, J. L.; Wyngaardt, S. M.; Bark, R. A.; Bvumbi, S. P.; Dinoko, T. R. S.; Jones, P.; Kheswa, N. Y.; Lawrie, J. J.; Majola, S. N. T.; Masiteng, P. L.; Negi, D.; Orce, J. N.; Papka, P.; Sharpey-Schafer, J. F.; Stankiewicz, M.; Wiedeking, M.Since the introduction of chirality in nuclei, the search for chiral candidates in different mass regions has been a hot topic for about two decades. At iThemba LABS, a new chiral symmetry region, the thallium isotopes with mass A ≥ 90 was found. Candidate chiral bands were suggested in 198Tl and then in 194Tl. Most importantly, a comparison of the properties in the chiral partner bands in 194Tl showed that this nucleus is one of the best chiral candidates to date. A search for chiral symmetry in the neighboring thallium isotopes was undertaken. The results from a y-ray spectroscopy study in 193Tl performed at iThemba LABS, South Africa, are discussed.
- ItemCompetition of rotation around the intermediate and long axes in 193Tl(American Physical Society, 2019) Ndayishimye, J.; Lawrie, E. A.; Shirinda, O.; Easton, J. L.; Lawrie, J. J.; Wyngaardt, S. M.; Bark, R. A.; Bucher, T. D.; Bvumbi, S. P.; Dinoko, T. R. S.; Jones, P.; Kheswa, N. Y.; Majola, S. N. T.; Masiteng, P. L.; Negi, D.; Orce, J. N.; Sharpey-Schafer, J. F.; Wiedeking, M.High-spin states in ¹⁹³Tl were studied and the level scheme was revised and extended including the observation of new rotational bands. A surprising competition between bands built on the same πh9/2⊗νi13/2⁻² nucleon configurations is observed. It is suggested that it is generated by two different rotational modes of this triaxial nucleus: (i) a rotation around the intermediate nuclear axis, producing a pair of chiral symmetry bands, and (ii) a rotation around the long nuclear axis, producing a third band with lower alignment.
- ItemEvolution from quasivibrational to quasirotational structure in 155Tm and yrast 27/2− to 25/2− energy anomaly in the A ≈ 150 mass region(American Physical Society, 2019) Liu, L.; Wang, S. Y.; Wang, S.; Hua, H.; Zhang, S. Q.; Meng, Jie; Bark, R. A.; Wyngaardt, S. M.; Qi, B.; Sun, D. P.; Liu, C.; Li, Z. Q.; Jia, H.; Li, X. Q.; Xu, C.; Li, Z. H.; Sun, J. J.; Zhu, L. H.; Jones, P.; Lawrie, E. A.; Lawrie, J. J.; Wiedeking, M.; Bucher, T. D.; Dinoko, T.; Makhathini, L.; Majola, S. N. T.; Noncolela, S. P.; Shirinda, O.; Gal, J.; Kalinka, G.; Molnar, J.; Nyako, B. M.; Timar, J.; Juhasz, K.; Arogunjo, M.Excited states in 155Tm have been populated via the reaction 144Sm(16O, p4n)155Tm at a beam energy of 118 MeV. The ground-state band has been extended and a new side band of the ground-state band is identified. E-GOS curves and potential energy surface calculations are employed to discuss the structure evolution of the ground-state band. The newly observed side band in 155Tm is discussed based on the spin/energy systematics. In particular, the phenomenon of seniority inversion is proposed in 155Tm, and a systematic study of this phenomenon in the A ≈ 150 mass region is performed.
- ItemMultiple chiral bands built on the same many-particle nucleon configuration In the 100 mass region(Jagellonian University, 2018) Shirinda, O.; Lawrie, E. A.Multi-particle-plus-triaxial-rotor (MPR) model calculations were performed for chiral partner bands associated with the multi-particle πg¯¹9/2⊗ vh²11/2 nucleon configuration in the 100 mass region. Multiple chiral systems were found, but they may not necessarily form well-defined pairs of near-degenerate bands.
- ItemNear-degenerate rotational bands in the Tl isotopes(Jagellonian University, 2018) Lawrie, E. A.; Ndayishimye, J.; Masiteng, P. L.; Shirinda, O.Sets of near-degenerate rotational bands built on configurations involving nh9/2 particle and vi13/2 holes were observed in the neighbouring 193;194Tl isotopes. Such sets of bands, involving particle and hole configurations and occurring in nuclei with triaxial shape, are caused by chiral symmetry formed in angular momentum space. Each nuclear chiral system is expected to generate a pair of near-degenerate partner bands. However, several sets of three partner bands were observed in these Tl isotopes, raising questions whether one or two chiral systems are formed, and which two bands are partners in the chiral pair. Many-particle-rotor model calculations reproduce well the features of the observed negative-parity bands in 193;194Tl and support the suggested chiral geometry of the angular momenta.
- ItemProportional crosstalk for the iThemba LABS clover detector(Jagiellonian University, 2017-03) Noncolela, S. P.; Bucher, T. D.; Lawrie, E. A.; Dinoko, T. R. S.; Easton, J. L.; Erasmus, N.; Lawrie, J. J.; Mthembu, S. H.; Mtshali, W. X.; Shirinda, O.; Orce, J. N.Measurements of the proportional crosstalk were performed for the iThemba LABS segmented clover detector. More than 1000 crosstalk parameters were determined and a crosstalk correction algorithm was implemented successfully.
- ItemSpectroscopic study of the possibly triaxial transitional nucleus 75Ge(American Physical Society, 2018) Niu, C. Y.; Dai, A. C.; Xu, C.; Hua, H.; Zhang, S. Q.; Wang, S. Y.; Bark, R. A.; Meng, Jie; Wang, C. G.; Wu, X. G.; Li, X. Q.; Li, Z. H.; Wyngaardt, S. M.; Zang, H. L.; Chen, Z. Q.; Wu, H. Y.; Xu, F. R.; Ye, Y. L.; Jiang, D. X.; Han, R.; Li, C. G.; Chen, X. C.; Liu, Q.; Feng, J.; Yang, B.; Li, Z. H.; Wang, S.; Sun, D. P.; Liu, C.; Li, Z. Q.; Zhang, N. B.; Guo, R. J.; Li, G. S.; He, C. Y.; Zheng, Y.; Li, C. B.; Chen, Q. M.; Zhong, J.; Zhou, W. K.; Zhu, B. J.; Deng, L. T.; Liu, M. L.; Wang, J. G.; Jones, P.; Lawrie, E. A.; Lawrie, J. J.; Sharpey-Schafer, J. F.; Wiedeking, M.; Majola, S. N. T.; Bucher, T. D.; Dinoko, T.; Magabuka, B.; Makhathini, L.; Mdletshe, L.; Khumalo, N. A.; Shirinda, O.; Sowazi, K.The collective structures of 75Ge have been studied for the first time via the 74Ge(α,2p1n) 75Ge fusionevaporation reaction. Two negative-parity bands and one tentative positive-parity band built on the νp1/2, νf5/2, and νg9/2 states, respectively, are established and comparedwith the structures in the neighboringN = 43 isotones. According to the configuration-constrained potential-energy surface calculations, a shape transition from oblate to prolate along the isotopic chain in odd-A Ge isotopes is suggested to occur at 75Ge. The properties of the bands in 75Ge are analyzed in comparison with the triaxial particle rotor model calculations.
- ItemSpectroscopy of low-spin states in 157Dy : Search for evidence of enhanced octupole correlations(American Physical Society, 2019) Majola, S. N. T.; Bark, R. A.; Bianco, L.; Bucher, T. D.; Bvumbi, S. P.; Cullen, D. M.; Garrett, P. E.; Greenlees, P. T.; Hartley, D.; Hirvonen, J.; Jakobsson, U.; Jones, P. M.; Julin, R.; Juutinen, S.; Ketelhut, S.; Kheswa, B. V.; Korichi, A.; Lawrie, E. A.; Masiteng, P. L.; Maqabuka, B.; Mdletshe, L.; Minkova, A.; Ndayishimye, J.; Nieminen, P.; Nyako, B. M.; Peura, P.; Rahkila, P.; Riedinger, L. L.; Riley, M.; Roux, D.; Ruotsalainen, P.; Saren, J.; Sharpey-Schafer, J. F.; Scholey, C.; Shirinda, O.; Sithole, A.; Sorri, J.; Stolze, S.; Timar, J.; Uusitalo, J.; Zimba, G.Low-spin states of ¹⁵⁷Dy have been studied using the JUROGAM II array, following the ¹⁵⁵Gd (α, 2n) reaction at a beam energy of 25 MeV. The level scheme of ¹⁵⁷Dy has been expanded with four new bands. Rotational structures built on the [523]5/2⁻ and [402]3/2⁺ neutron orbitals constitute new additions to the level scheme as do many of the inter- and intraband transitions. This manuscript also reports the observation of cross I⁺ →(I–1) ⁻ and I⁻ →(I–1)⁺ E1 dipole transitions interlinking structures built on the [523]5/2⁻ (band 5) and [402]3/2⁺ (band 7) neutron orbitals. These interlacing band structures are interpreted as the bands of parity doublets with simplex quantum number s=–i related to possible octupole correlations.