High-spin structures of¹³⁶₅₄Xe,¹³⁷₅₅Cs,¹³⁸₅₆Ba,¹³⁹₅₇La and¹⁴⁰₅₈Ce: a shell model description

Abstract

In the present work recently available experimental data [A. Astier et al,\nPhys. Rev. C 85, 064316 (2012)] for high-spin states of five N=82 isotones,\n$^{136}_{54}$Xe, $^{137}_{55}$Cs, $^{138}_{56}$Ba, $^{139}_{57}$La, and\n$^{140}_{58}$Ce have been interpreted with state-of-the-art shell model\ncalculations. The calculations have been performed in the 50-82 valence shell\ncomposed of $1g_{7/2}$, $2d_{5/2}$, $1h_{11/2}$, $3s_{1/2}$, and $2d_{3/2}$\norbitals. We have compared our results with the available experimental data for\nexcitation energies including high-spin states, occupancy numbers and\ntransition probabilities. As expected the structure of these isotones are due\nto proton excitations across Z=50 shell. The structure of the positive-parity\nstates are mainly from $(\\pi g_{7/2}\\pi d_{5/2})^n$ and $(\\pi g_{7/2}\\pi\nd_{5/2})^{n-2}(\\pi h_{11/2})^2$ configurations, while the negative-parity\nstates have $(\\pi g_{7/2}\\pi d_{5/2})^{n}(\\pi h_{11/2})^1$ configuration.\nAdditionally, for the $^{136}_{54}$Xe, $^{137}_{55}$Cs and $^{138}_{56}$Ba\nisotones the excitation of the neutrons across N=82 gap is important.\n