Lifetime measurements of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Er</mml:mi><mml:mprescripts/><mml:none/><mml:mn>162</mml:mn></mml:mmultiscripts></mml:math>: Evolution of collectivity in the rare-earth region
L. Knafla, G. Häfner, J. Jolie, J.-M. Régis, V. Karayonchev, A. Blazhev, A. Esmaylzadeh, C. Fransen, A. Goldkuhle, S. Herb, C. Müller-Gatermann, N. Warr, K. O. Zell
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.