Shape coexistence scenario in Sm150 from a γ−γ fast-timing measurement

Abstract

Lifetimes are measured for low lying states of $^{150}\mathrm{Sm}$, populated from ${\ensuremath{\beta}}^{\ensuremath{-}}$ decay of $^{150}\mathrm{Pm}$ produced through $(p,n)$ reactions with a $^{150}\mathrm{Nd}$ target. The VENTURE array comprising of eight fast ${\mathrm{CeBr}}_{3}$ detectors is used for lifetime measurement with $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ fast timing technique. The lifetime of ${0}_{3}^{+}$ level of $^{150}\mathrm{Sm}$ is measured for the first time to be 36(10) ps. The ${0}_{3}^{+}$ level is found to have enhanced decay strengths to the ${K}^{\ensuremath{\pi}}={0}_{2}^{+}$ structure compared with ${K}^{\ensuremath{\pi}}={0}_{1}^{+}$. A high ${\ensuremath{\rho}}^{2}(E0)$ strength for the ${0}_{3}^{+}\ensuremath{\rightarrow}{0}_{2}^{+}$ decay confirms shape coexistence and shape mixing in $N=88\phantom{\rule{4pt}{0ex}}^{150}\mathrm{Sm}$.