SHAPE CHANGES IN KR-79

High-spin states in Kr79 were studied using the Cu65(18O,p3n) reaction at 65 MeV at the Florida State University Tandem-LINAC facility. Prompt γ-γ coincidences were observed using the Pitt-FSU detector array. Twelve new states were found, along with 19 new transitions. The yrast positive- and negative-parity bands were extended up to spins of (45/2+) and (31/2-), respectively. Spin assignments were made based on directional correlation of oriented nuclei ratios whenever possible. A cranked-shell-model analysis shows some indication for a second band crossing in the positive-parity band at Latin small letter h with strokeω0.75 MeV. This crossing, probably due to an aligned g9/2 neutron pair, occurs with a much larger band interaction than the first g9/2 proton crossing. An increase in signature splitting above Latin small letter h with strokeω0.75 MeV and a return of large alternations in the B(M1)/B(E2) ratio is consistent with the theoretically predicted return to a nearly oblate shape. © 1994 The American Physical Society.