Two branches are observed feeding the ${38}^{+}$ level of the yrast line in ${}_{}{}^{158}{}_{}{}^{}\mathrm{Er}$. Two ∼1.2-MeV cascade transitions constitute a fast (∼1 ps) collective component, probably with only minor changes in shape and structure from those at lower spin. Four slower $\gamma$ rays (>2 ps) suggest a transition to a different shape and structure, most likely to an oblate ${46}^{+}$ state with all valence particles maximally aligned, a band termination.

• Received 26 August 1985

DOI:https://doi.org/10.1103/PhysRevLett.55.2405