Browsing by Author "Shi, Z."

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    “Stapler” mechanism for a dipole band in 79Se
    (American Physical Society, 2019-10-24) Li, C. G.; Chen, Q. B.; Zhang, S. Q.; Xu, C.; Hua, H.; Wang, S. Y.; Bark, R. A.; Wyngaardt, S. M.; Shi, Z.; Dai, A. C.; Wang, C. G.; Li, X. Q.; Li, Z. H.; Meng, J.; Xu, F. R.; Ye, Y. L.; Jiang, D. X.; Han, R.; Niu, C. Y.; Chen, Z. Q.; Wu, H. Y.; Wang, X.; Luo, D. W.; Wu, C. G.; Wang, S.; Sun, D. P.; Liu, C.; Li, Z. Q.; Sun, B. H.; Jones, P.; Msebi, L.; Sharpey-Schafer, J. F.; Dinoko, T.; Lawrie, E. A.; Ntshangase, S. S.; Kheswa, B. V.; Shirinda, O.; Khumalo, N.; Bucher, T. D.; Malatji, K. L.
    The spectroscopy of 79 Se is studied via the 82 Se(α, α3n)79Se fusion-evaporation reaction. A negative-parity magnetic dipole band in 79Se is established for the first time. Based on the calculations by the self-consistent tilted axis cranking covariant density functional theory, this new dipole band can be classified as a “stapler” band, which has a relatively stable symmetric prolate deformation as a function of rotational frequency. Hence, it is demonstrated that the stapler bands exist not only in the oblate and triaxial nuclei, but also in prolate nuclei. By examining the angular momentum coupling, it is found that the five valence nucleons in the high-j orbitals play a major role in the closing of the stapler.
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    β and γ bands in N = 88 , 90, and 92 isotones investigated with a five-dimensional collective Hamiltonian based on covariant density functional theory : vibrations, shape coexistence, and superdeformation
    (American Physical Society, 2019-06-05) Majola, S. N. T.; Shi, Z.; Song, B. Y.; Li, Z. P.; Zhang, S. Q.; Bark, R. A.; Sharpey-Schafer, J. F.; Aschman, D. G.; Bvumbi, S. P.; Bucher, T. D.; Cullen, D. M.; Dinoko, T. S.; Easton, J. E.; Erasmus, N.; Greenlees, P. T.; Hartley, D. J.; Hirvonen, J.; Korichi, A.; Jakobsson, U.; Jones, P.; Jongile, S.; Julin, R.; Juutinen, S.; Ketelhut, S.; Kheswa, B. V.; Khumalo, N. A.; Lawrie, E. A.; Lawrie, J. J.; Lindsay, R.; Madiba, T. E.; Makhathini, L.; Maliage, S. M.; Maqabuka, B.; Malatji, K. L.; Masiteng, P. L.; Mashita, P. I.; Mdletshe, L.; Minkova, A.; Msebi, L.; Mullins, S. M.; Ndayishimye, J.; Negi, D.; Netshiya, A.; Newman, R.; Ntshangase, S. S.; Ntshodu, R.; Msebi, L.; Mullins, S. M.; Ndayishimye, J.; Negi, D.; Netshiya, A.; Newman, R.; Ntshangase, S. S.; Ntshodu, R.; Nyako, B. M.; Papka, P.; Peura, P.; Rahkila, P.; Riedinger, L. L.; Riley, M. A.; Roux, D. G.; Ruotsalainen, P.; Saren, J. J.; Scholey, C.; Shirinda, O.; Sithole, M. A.; Sorri, J.; Stankiewicz, M.; Stolze, S.; Timar, J.; Uusitalo, J.; Vymers, P. A.; Wiedeking, M.; Zimba, G. L.
    A comprehensive systematic study is made for the collective β and γ bands in even-even isotopes with neutron numbers N = 88 to 92 and proton numbers Z = 62 (Sm) to 70 (Yb). Data, including excitation energies, B(E0) and B(E2) values, and branching ratios from previously published experiments are collated with new data presented for the first time in this study. The experimental data are compared to calculations using a five-dimensional collective Hamiltonian (5DCH) based on the covariant density functional theory (CDFT). A realistic potential in the quadrupole shape parameters V (β,γ ) is determined from potential energy surfaces (PES) calculated using the CDFT. The parameters of the 5DCH are fixed and contained within the CDFT. Overall, a satisfactory agreement is found between the data and the calculations. In line with the energy staggering S(I) of the levels in the 2γ + bands, the potential energy surfaces of the CDFT calculations indicate γ -soft shapes in the N = 88 nuclides, which become γ rigid for N = 90 and N = 92. The nature of the 02 + bands changes with atomic number. In the isotopes of Sm to Dy, they can be understood as β vibrations, but in the Er and Yb isotopes the 02 + bands have wave functions with large components in a triaxial superdeformed minimum. In the vicinity of 152Sm, the present calculations predict a soft potential in the β direction but do not find two coexisting minima. This is reminiscent of 152Sm exhibiting an X(5) behavior. The model also predicts that the 03 + bands are of two-phonon nature, having an energy twice that of the 02 + band. This is in contradiction with the data and implies that other excitation modes must be invoked to explain their origin.