Excited states in the $N=Z+1\mathrm{}$ nucleus ${}^{73}\mathrm{Kr}$ have been investigated using the ${}^{40}\mathrm{Ca}{(}^{36}\mathrm{Ar},2pn)$ and ${}^{40}\mathrm{Ca}{(}^{40}\mathrm{Ca},\alpha 2pn)$ reactions at 145 and 160 MeV, respectively. $\gamma$ rays were detected using the Gammasphere array and events were recorded in coincidence with charged-particle and neutron detectors. The three previously observed bands were extended to high spin, and a new unfavored positive-parity band has been observed. The alignment characteristics and decay properties of the bands are all consistent with large-deformation prolate rotation, with no clear evidence for oblate bands or shape coexistence. This is quite different from neighboring ${}^{72,74}\mathrm{Kr},$ indicating a strong shape-stabilizing role for the valence neutron. The experimental results are compared to extended total Routhian surface, cranked Nilsson Strutinsky, and cranked relativistic mean-field calculations. The results suggest that the paired calculations lack some important physics. Neutron-proton correlations may be the missing ingredient. There is also evidence for an unusual band crossing in the negative-parity bands, which may indicate the presence of $T=0\mathrm{}$ pairing correlations. At high spin all the models can reproduce the experimental data.

• Received 6 December 2001

DOI:https://doi.org/10.1103/PhysRevC.65.044331