Octupole correlations in neutron-rich145,147Lanuclei: Coriolis-limit-coupling bands with alignedh11/2proton

Autor: R. W. Lougheed, A. V. Ramayya, M. F. Mohar, J. K. Hwang, Raul Donangelo, J. Kormicki, K. J. Moody, C. Y. Gan, L. Y. Zhu, S. Y. Chu, W. E. Collins, W. C. Ma, Ming Li, Gui-Lu Long, L. K. Peker, J. H. Hamilton, A. O. Macchiavelli, I. Y. Lee, M. W. Drigert, J. O. Rasmussen, S. J. Asztalos, K. E. Gregorich, J. D. Cole, B. R. S. Babu, R. Aryaeinejad, Stanley G. Prussin, S. J. Zhu, J. Gilat, A. V. Daniel, J. K. Deng, E. F. Jones, M. A. Stoyer, T. N. Ginter, D. Shi, Meng Wang, J. F. Wild, Yu. Ts. Oganessian, G. M. Ter-Akopian, G. Drafta
Rok vydání: 1999
Předmět:
Zdroj: Physical Review C. 59:1316-1323
ISSN: 1089-490X
0556-2813
Popis: Several new high-spin states are observed in the prompt $\ensuremath{\gamma}$-rays emitted from the neutron-rich, odd-$Z$ ${}^{145,147}\mathrm{La}$ fragments produced in the spontaneous fission of ${}^{252}\mathrm{Cf}.$ Alternating parity bands are extended up to spins 41/2 and 43/2 in ${}^{145,147}\mathrm{La},$ respectively. A new band completes the evidence for two sets of parity doublets expected for octupole correlations. Eight $B(E1)/B(E2)$ ratios (four new) between two bands in ${}^{145}\mathrm{La}$ are all essentially constant and somewhat larger than similar ratios in ${}^{143,144}\mathrm{Ba},$ where stable octupole deformation and/or correlations are reported. The new ratios out of the ${31/2}^{\ensuremath{-}}$ levels in both nuclei show a sharp spike compared to other states, presumably from a strong reduction in $E2$ strengths in this backbending region. In ${}^{145}\mathrm{La},$ collective bands show competition and coexistence between symmetric and asymmetric shapes. Band crossings occur in both nuclei around $\ensuremath{\Elzxh}\ensuremath{\omega}\ensuremath{\approx}0.26--0.30 \mathrm{MeV}.$ Their backbends are associated with the alignment of two ${i}_{13/2}$ neutrons according to cranked shell model calculations.
Databáze: OpenAIRE
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