Lifetime measurement of excited states in Ce144 : Enhanced E1 strengths in a candidate for octupole deformation

Abstract

A lifetime measurement of excited states in $^{144}\mathrm{Ce}$ using the $^{142}\mathrm{Ce}(^{18}\mathrm{O},^{16}\mathrm{O})$ reaction with a beam energy of 67 MeV and the recoil distance Doppler-shift method was performed at the Cologne FN Tandem accelerator. Lifetimes of the three lowest yrast states in $^{144}\mathrm{Ce}$ have been measured as well as for the ${3}_{1}^{\ensuremath{-}}$ state and an effective lifetime of the ${4}_{2}^{+}$ state. Reduced $E2$ transition strengths determined using these results have been compared to predictions from recent shell-model calculations. From the interband transitions reduced $E1$ strengths could be determined, which are strongly enhanced.