Several rotational bands have been established in the N=77 ${}_{}{}^{135}{}_{}{}^{}\mathrm{Ce}$ nucleus following the ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$${(}^{18}$O,5nγ) reaction. At low spins, the yrast band, built on an orbital from the top of the ν${\mathit{h}}_{11/2}$ shell, exhibits a large signature splitting of ∼300 keV implying a significant deviation from axial symmetry (γ≪0°). At higher spins, three ΔI=1 bands were established. Two of these bands are built on prolate (γ∼0°) mixed neutron-proton configurations as systematically observed in several N=75 isotones. The third of these bands shows properties similar to those observed for collectively rotating (γ∼-60°) mixed neutron-proton configurations as recently reported in nearby odd-Z, doubly odd, and even-even nuclei. The present study represents the first observation of such a band in an odd-N nucleus. In addition, two decoupled ΔI=2 bands, built on oblate three-quasineutron configurations, were observed.

• Received 11 December 1989

DOI:https://doi.org/10.1103/PhysRevC.41.2624