Experimental investigation of high-spin states in Zr-90

High-spin states of Zr-90 have been investigated using the heavy-ion fusion-evaporation reaction Se-82(C-13, 5n) at a beam energy of 60 MeV. Excited levels of Zr-90 have been observed up to an excitation energy of approximate to 13 MeV and a spin of approximate to 20h with the addition of thirty-two new y-ray transitions to the proposed level scheme. Structures of both the positive- and negative-parity states up to the highest observed spin have been interpreted with shellmodel calculations using the GWBXG interaction and a Ni-68 core. Calculations suggest the role of neutron excitations across the N = 50 shell gap for states with greater than 7 MeV excitation energy. High-spin states in these bands are interpreted to be generated by the recoupling of stretched proton and neutron configurations.