Excited states in ${}_{}{}^{76}{}_{}{}^{}\mathrm{Kr}$ have been investigated via the ${}_{}{}^{66}{}_{}{}^{}\mathrm{Zn}$(${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, $2n$) reaction at a beam energy of 39 MeV. Gamma-ray energies, intensities, spins, parities, and mean lives of excited states were extracted from measurements of the $\gamma$ rays which were emitted in-beam. The energies of 25 excited levels were deduced from $\gamma -\gamma$ coincidence data, and all but three of these levels are members of bandlike structures which persist to high spin. The Doppler shift attenuation method was used to extract the lifetimes of thirteen excited levels. The $E2$ strengths are highly collective. The positive parity yrast band to spin (${12}^{+}$) has been observed with a forward bend at low spin, but with no backbending in the moment of inertia below ${12}^{+}$. A positive parity band with even- and odd-spin members to ($6^{+}$) and ($9^{+}$) respectively, has been observed, and is interpreted as a $\Delta J=1\mathrm{}$ quasigamma band. Negative-parity bands built on $5^{-}$ and ($6^{-}$) levels have been observed to spins of (${13}^{-}$) and (${12}^{-}$), respectively. Finally, the first excited $0^{+}$ state and a $2^{+}$ level built on it have been identified and are assigned to a near spherical configuration which coexists with the ground state that has an unusually large deformation.

NUCLEAR REACTIONS ${}_{}{}^{66}{}_{}{}^{}\mathrm{Zn}$(${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$,$2n$) $E=39\mathrm{}$ MeV; measured $E_{\gamma }$, $I_{\gamma }$, $\gamma \left(\theta \right)$, DCO, DSAM; deduced ${}_{}{}^{76}{}_{}{}^{}\mathrm{Kr}$ levels, $J$, $\pi$, $B\left(E2\right)$, $\delta$, and $\gamma$ branching.

• Received 7 December 1981

DOI:https://doi.org/10.1103/PhysRevC.25.1941