The levels of ${}_{}{}^{80}{}_{}{}^{}\mathrm{Kr}$ have been investigated using in-beam $\gamma$-spectroscopy techniques via the ${}_{}{}^{70}{}_{}{}^{}\mathrm{Zn}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},2n){}_{}{}^{80}{}_{}{}^{}\mathrm{Kr}$ reaction with 38.4 MeV ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ions. The energies, relative intensities, and angular distributions of the $\gamma$ rays were measured. The proposed level scheme shows four bands: three of even parity and one of odd parity. Two-quasiparticle-plus-rotor calculations for ${}_{}{}^{80}{}_{}{}^{}\mathrm{Kr}$ suggest that the even-parity band built on the ($8^{+}$) state at 3701.6 keV has primarily a proton ${\left(g_{\frac{9}{2}}\right)}^2$ configuration and the odd-parity band built on the $5^{-}$ state at 2861.0 keV has an essentially pure two-quasiproton $(f_{\frac{5}{2}},g_{\frac{9}{2}})5^{-}$ configuration. The observed backbending in the yrast band is attributed to the crossing of the ground band and the excited positive-parity band.

NUCLEAR REACTIONS ${}_{}{}^{70}{}_{}{}^{}\mathrm{Zn}({}_{}{}^{12}{}_{}{}^{}\mathrm{C},2n)$, $E=33.0\mathrm{}-38.4$ MeV; measured $E_{\gamma }$, $I_{\gamma }$, $\gamma \left(\theta \right)$ DCO; deduced ${}_{}{}^{80}{}_{}{}^{}\mathrm{Kr}$ levels, $J$, $\pi$, and $\gamma$ branching; performed two-quasiparticle-plus-rotor model calculations.

• Received 24 November 1980

DOI:https://doi.org/10.1103/PhysRevC.23.2086