Lifetime measurements inPt180

Abstract

Lifetimes of the yrast states in $^{180}\mathrm{Pt}$ have been measured from ${4}^{+}$ to ${8}^{+}$ using the recoil distance Doppler-shift technique in the coincidence mode. These states were populated by the reaction $^{156}\mathrm{Gd}(^{28}\mathrm{Si},4n)^{180}\mathrm{Pt}$ at a beam energy of 144 MeV. The differential decay curve method was applied to determine the lifetimes from experimental coincidence data. The $B(E2)$ values extracted from lifetimes increase with increasing spin, implying rotor behavior, but do not show the typical shape coexistence where the $B(E2)$ values present a rapid increase at very low spins. Calculations based on the triaxial projected shell model were performed for the yrast states in $^{180}\mathrm{Pt}$ and the results of both energies and $E2$ transition probabilities reproduce the experimental data very well. The result also shows that a better description of the yrast band in $^{180}\mathrm{Pt}$ requires consideration of the $\ensuremath{\gamma}$ degree of freedom.