Transition probabilities inGd154: Evidence for X(5) critical point symmetry

Abstract

Lifetime measurements in $^{154}\mathrm{Gd}$ were performed by means of the recoil distance Doppler-shift method. Excited states of $^{154}\mathrm{Gd}$ were populated via Coulomb excitation with a $^{32}\mathrm{S}$ beam at $110\phantom{\rule{0.3em}{0ex}}\text{MeV}$ delivered by the FN tandem accelerator of the University of Cologne. The determined transition probabilities as well as the low-spin level scheme of $^{154}\mathrm{Gd}$ demonstrate a good agreement with the predictions of the critical point symmetry X(5). Comparison of specific experimental observables for the $N=90$ rare earth isotones with the calculations of the X(5) model clearly show that $^{154}\mathrm{Gd}$ is one of the good examples of the realization of the X(5) dynamical symmetry. In addition, the experimental data are compared to fits in the framework of the IBA and the general collective model.