Structure of N = 56 isotones with 36 ≤ Z ≤ 42 protons

Excited levels in Kr92, Zr96, and Mo98 nuclei were reinvestigated using high-statistics multiple-γ coincidence data measured with the EXILL and FIPPS Ge arrays, following neutron-induced fission of U 235 and neutron capture on a Mo97 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 πg9/2 orbital, in the shape evolution in the region.