High-spin states in N=50 85Br and 87Rb nuclei

The level structures of the N=50 85Br and 87Rb isotopes have been studied in the fission of the compound system formed in three different heavy-ion-induced reactions. In 87Rb many states above the previously known 9/2+ isomer have been established. The coupling of the odd proton occupying the g9/2 orbital to the yrast states in the 86Kr core can account for the first excited states above the isomer in 87Rb. A comparison with the first excited states above the 9/2+ state in 85Kr and 89Y reveals similarities in the coupling. At higher excitations similar behavior to 89Y is observed, indicating a possible presence of neutron-core excitations. In 85Br several states up to ∼5 MeV excitation energy have been established. Two states at ∼2 MeV excitation energy are candidates for the 9/2+ state originating from the odd proton occupying the g9/2 orbital. The experimental results for both isotopes are compared with predictions of the shell model