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