Configuration and Spin Assignments of Yrast Band for Doubly Odd Nucleus ¹²²Cs

Energy spectrum of yrast band for ¹²²Cs is studied by using particle-rotor model (PRM) of odd-odd nuclei, in which special attention is paid to the model basis accounting for the effect of the instability γ vibration perturbation around axial symmetry. In order to check the assignments of this band, two calculation schemes are put into practice. The first one is for previous πh_11/2 vg_7/2 configuration with bandhead spin I₀ = (6^-) which was obtained from cranked shell model (CSM) calculation, and the other one is for πh_11/2 vh_11/2 configuration with I₀ = (9⁺) supported by the systematic analyses of experimental data. A qualitative comparison between the present PRM calculation and that of CSM has also been made. The results indicate that, rather than πh_11/2 vg_7/2 I₀ = (6^-), πh_11/2 vh_11/2 with I₀ = (9⁺) is a more reasonable assignment to the yrast band in ¹²²Cs.