Levels inGd158populated in the decay of 46-minEu158

The series of investigations of level properties in even gadolinium nuclei has been extended to ${}_{}{}^{158}{}_{}{}^{}\mathrm{Gd}$. $\gamma$ rays emitted in the radioactive decay of ${}_{}{}^{158}{}_{}{}^{}\mathrm{Eu}$ were studied with large volume Ge(Li) detectors in both singles and coincidence modes to reveal a total of 132 transitions, 94 of which were incorporated in a level scheme involving 31 excited states. Several of the level assignments clarified conflicting data in the literature and 12 of the levels had not been observed previously. The coincidence measurements have provided reliable branching ratios for members of the $\gamma$-vibrational band and members of $K=0^{-}\mathrm{and}{1}^{-}$ octupole bands. Analyses of the data for the octupole bands are compared with theory. In ${}_{}{}^{154}{}_{}{}^{}\mathrm{Gd}$ and ${}_{}{}^{156}{}_{}{}^{}\mathrm{Gd}$ the $K=0^{-}$ octupole band lies lower than the $K=1^{-}$ band, in agreement with theoretical expectations that the $K=0^{-}$ component of the $\lambda =3\mathrm{}$ vibration is the most collective. However, in ${}_{}{}^{158}{}_{}{}^{}\mathrm{Gd}$ this trend is reversed and the $K=1^{-}$ component is lowest.