Lifetime measurements of Er162 : Evolution of collectivity in the rare-earth region

Abstract

Lifetimes of low-lying yrast states in $^{162}\mathrm{Er}$ are measured using the electronic $\ensuremath{\gamma}\text{\ensuremath{-}}\ensuremath{\gamma}$ fast-timing technique. Excited states were populated in a $^{154}\mathrm{Sm}(^{12}\mathrm{C},4n)^{162}\mathrm{Er}$ fusion-evaporation reaction and $\ensuremath{\gamma}$ rays were detected in a combined setup of high purity germanium and ${\mathrm{LaBr}}_{3}$(Ce) scintillation detectors. The lifetimes of the ${4}_{1}^{+}$ and ${6}_{1}^{+}$ states are determined for the first time and the lifetimes of the ${2}_{1}^{+}$ and ${7}^{\ensuremath{-}}$ states are remeasured with higher precision. Reduced transition probabilities are extracted and well reproduced by theoretical calculations in the framework of the confined $\ensuremath{\beta}$ soft model and the interacting boson model.