High-spin states in ${}_{}{}^{80}{}_{}{}^{}\mathrm{Kr}$ were studied using the ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}$${(}^{18}$O,p2n) reaction at 65 MeV. Prompt γ-γ coincidences were measured using the Pitt-FSU detector array with nine high-purity Compton-suppressed Ge detectors and a 28-element Bismuth Germanate multiplicity filter. The previous level scheme has been extended by 16 new states up to spins and parities of ${20}^{+}$ and (${19}^{\mathrm{-}}$). The known band crossing in the positive-parity yrast band of ${}_{}{}^{80}{}_{}{}^{}\mathrm{Kr}$ near ħω≊0.5 MeV may be due to a ${\mathit{g}}_{9/2}$ neutron alignment, rather than a ${\mathit{g}}_{9/2}$ proton alignment as had been previously thought, based on the predicted oblate shape by Hartree-Fock-Bogolyubov calculations. No evidence was found for a second crossing in the yrast sequence up to ħω=0.9 MeV. The new extension of the ground-state band through nonyrast states points to another band crossing at ħω≊0.62 MeV which may be caused by a ${\mathit{g}}_{9/2}$ proton alignment. A new negative-parity high-spin band shows that rotational bands do form at excitations above the strongly mixed low-spin levels as in the isotone ${}_{}{}^{82}{}_{}{}^{}\mathrm{Sr}$.

• Received 1 February 1995

DOI:https://doi.org/10.1103/PhysRevC.52.76