The high-spin states of ${}_{}{}^{88}{}_{}{}^{}\mathrm{Zr}$ and ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$ were studied up to ∼12-MeV excitation via the ${}_{}{}^{74}{}_{}{}^{}$,76Ge${(}^{18}$O,4nγ)${}^8$ 8,90Zr fusion evaporation reactions. Decay schemes were constructed on the basis of gamma-ray excitation functions, angular distribution and linear polarization measurements, γ-γ 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 ∼20ħ 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.

• Received 7 May 1984

DOI:https://doi.org/10.1103/PhysRevC.31.1184