High-spin state spectroscopy of /sup 88,90/Zr

The high-spin states of /sup 88/Zr and /sup 90/Zr were studied up to approx.12-MeV excitation via the /sup 74,76/Ge(/sup 18/O,4n..gamma..)890Zr fusion evaporation reactions. Decay schemes were constructed on the basis of gamma-ray excitation functions, angular distribution and linear polarization measurements, ..gamma..-..gamma.. coincidences, and level lifetimes determined from both Doppler shift attenuation and recoil distance measurements. An effort was made to make as definite spin-parity assignments as possible and to delineate the reliability of these assignments. Probable spins up to approx.20h were formed in both nuclei. The experimental results are compared to preliminary results of a large-scale shell model calculation. The yrast spectra of both nuclei can be interpreted as arising from intrinsic modes of excitation with no evidence for collective behavior.