Properties ofGd156levels populated in the decay of 15.2 dayEu156

Abstract

$\ensuremath{\gamma}$ rays emitted in the radioactive decay of 15.2 day $^{156}\mathrm{Eu}$ have been studied with large volume Ge(Li) detectors in both singles and coincidence modes. A total of 95 $\ensuremath{\gamma}$-ray transitions were observed in the $^{156}\mathrm{Eu}$ decay and 84 of these are placed in the $^{156}\mathrm{Gd}$ level scheme which consists of 26 excited states. Seven of these levels are assigned here for the first time. Many of the inconsistencies that have complicated the interpretation of previous work have been resolved in these studies. In particular, it has been possible in the extensive coincidence measurements to resolve several multiplets in the $\ensuremath{\gamma}$-ray spectrum and, therefore, to obtain accurate branching intensities for members of both the $\ensuremath{\gamma}$-vibrational band and two ${K}^{\ensuremath{\pi}}={0}^{+}$ excited bands.RADIOACTIVITY $^{156}\mathrm{Eu}$ (from $n$ capture on $^{154}\mathrm{Sm}$); measured ${E}_{\ensuremath{\gamma}}$, ${I}_{\ensuremath{\gamma}}$, $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coin; deduced $log\mathrm{ft}$. $^{156}\mathrm{Gd}$ deduced levels, $J$, $\ensuremath{\pi}$, ICC. Enriched $^{154}\mathrm{Sm}$ target, Ge(Li) detectors.