Lifetimes for Levels above the "Rotational Phase Change" inEr158

Recoil-distance decay curves for ground-band transitions in ${}_{}{}^{158}{}_{}{}^{}\mathrm{Er}$ were measured using a $\gamma -\gamma$ coincidence technique and the reaction ${}_{}{}^{130}{}_{}{}^{}\mathrm{Te}({}_{}{}^{32}{}_{}{}^{}\mathrm{S},4n){}_{}{}^{158}{}_{}{}^{}\mathrm{Er}$. We find that the mean lifetimes for the ${14}^{+}$, ${16}^{+}$, and ${18}^{+}$ levels are, respectively, 3.0 ± 0.7, 2.5 ± 0.9, and < 2.2 psec. These results are consistent with the rotational model in spite of the severe "backbending" of the level spacings.