Shape transitions in hot rotatingYb158nuclei

The finite-temperature Hartree-Fock-Bogoliubov cranking equation predicts the most probable shape for ${}_{}{}^{158}{}_{}{}^{}\mathrm{Yb}$ nuclei. At a spin-dependent critical temperature, there is a transition from prolate collective rotation to oblate noncollective rotation. For spins above $39\hslash$, there is oblate noncollective rotation at all temperatures. However, inclusion of thermal shape fluctuations produces an average shape which is prolate collective at spins 40 and $50\hslash$ and thermal excitation energy $E^{*}\approx 10$ MeV.