Isomer and in-beam spectroscopy of medium-spin states in Zr-91,Zr-92

Abstract

Near-yrast states have been identified in the stable Zr-91,Zr-92 isotopes using the fusion evaporation reaction Se-82(C-13,xn)Zr95-x at an incident beam energy of 50 MeV. Gamma-ray spectroscopy of states above the reported tau = 6 mu s, I-pi=(21)/(+)(2) isomer in Zr-91 are reported for the first time with consequences for stimulating new shell model calculations which incorporate either the breaking of the N=50 shell closure and/or the inclusion of the negative parity h(11/2) neutron intruder orbital.