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

Abstract

Lifetimes of low-lying yrast states in 162 Er are measured using the electronic γ -γ fast-timing technique. Excited states were populated in a 154 Sm( 12 C, 4n) 162 Er fusion-evaporation reaction and γ rays were detected in a combined setup of high purity germanium and 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 − states are remeasured with higher precision. Reduced transition probabilities are extracted and well reproduced by theoretical calculations in the framework of the confined β soft model and the interacting boson model.

Testing the predictive power of realistic shell model calculations via lifetime measurement of the 11/2+ state in Sb131

“…Other examples of short lifetimes measured with this technique can be found in Refs. [25][26][27]. The reduced transition probability for the 1226-keV, E2 γ decay from the 11/2 + state was deduced from the measured lifetime, its value being B(E2;11/2 + 1 → 7/2 + 1 )=1.4 +1.5 −0.6 W.u.…”

The Proxy-SU(3) Symmetry in Atomic Nuclei

“…Additional numerical results for β and γ obtained within the proxy-SU(3) approach can be found in [149][150][151]. Additional comparisons of proxy-SU(3) predictions to covariant density functional theory can be found in References [152][153][154], while comparisons to recent experimental findings can be found in [155,156]. 3) predictions for Gd-Pt isotopes for the collective variable β, obtained from Equation (10), as described in detail in Reference [89], compared with results by the D1S-Gogny interaction (D1S-Gogny) [146] and by relativistic mean field theory (RMF) [147], as well as with empirical values (exp.)…”