Excited levels in ${}^{92}\mathrm{Kr}$, ${}^{96}\mathrm{Zr}$, and ${}^{98}\mathrm{Mo}$ nuclei were reinvestigated using high-statistics multiple-$\gamma$ coincidence data measured with the EXILL and FIPPS Ge arrays, following neutron-induced fission of ${}^{235}\mathrm{U}$ and neutron capture on a ${}^{97}\mathrm{Mo}$ target, respectively. The experimental goal was to search for new levels, especially with low spins, as well as to firm up spin-parity assignments to known levels. In total of 16 new levels with 64 new or corrected decays and 35 new or improved spin-parity assignments were observed in the three nuclei. We also performed large-scale shell-model calculations to learn more about the microscopic structure of levels in these nuclei. The evolution of collectivity in $N=56$ isotones is discussed, stressing the important role of various single-particle excitations, in particular of the $\pi g_{9/2}$ orbital, in the shape evolution in the region.

• Received 14 March 2023
• Revised 11 May 2023
• Accepted 21 July 2023

DOI:https://doi.org/10.1103/PhysRevC.108.024302