The decay of ${}^{154}\mathrm{Eu}\to {}^{154}\mathrm{Gd}$ has been studied by $\gamma$-ray singles and $\gamma -\gamma$ coincidence spectroscopy using an array of 20 Compton-suppressed $\mathrm{Ge}$ detectors. The primary goal of the work was to investigate the structure of ${}^{154}\mathrm{Gd}$ above $1\mathrm{MeV}$: The outcome is the removal of 11 levels from the previously adopted ${}^{154}\mathrm{Eu}$ decay scheme, the addition of 40 new $\gamma$-ray assignments, and upper limits set on 75 $\gamma$-ray transitions which had been previously assigned to the ${}^{154}\mathrm{Gd}$ level scheme. The current results, combined with data from other spectroscopic techniques, indicate that states which were previously interpreted as “two-phonon” excitations are either spurious or are shown to be of a different nature. These results provide a deeper understanding of the structure of ${}^{154}\mathrm{Gd}$ and the $N=90$ isotones.

• Received 5 December 2003

DOI:https://doi.org/10.1103/PhysRevC.69.064309