Lifetime measurements in the yrast band of the gamma-soft nuclei $^{131}$Ce and $^{133}$Pr

摘要

Lifetimes of excited states in the yrast band of the gamma-soft nuclei $^{131}$Ce and 133Pr have been measured using the recoil distance Doppler shift and Doppler shift attenuation methods. The yrast bands in $^{131}$Ce and $^{133}$Pr are based on odd decoupled neutron $??h_{11/2}$ high $Omega$ and proton $pi h_{11/2}$ low $Omega$ orbitals, respectively. Thetriaxiality parameter extracted from the experimentally deduced values of transition quadrupole moments, within the framework of cranked Hartreea€“Focka€“Bogoliubov (CHFB) and total Routhian surface (TRS) calculatons, is$gamma ~ a?’80{^o}$ for the band in $^{131}$Ce at high spins, while for the band in $^{133}$Pr, the value of $gamma$ is close to $0^{o}$. Thisagrees well with the $gamma$ shape polarization property of high and low $Omega_{11/2}$ orbitals in these gamma-soft nuclei.