The yrast bands in 77Kr and 76Kr

Abstract

High-spin states of both parities in 77Kr have been studied in the reaction 63Cu( 16O, pn). On the basis of γγ- and nγ-coincidence experiments, we extended the yrast bands up to spin I π = 25 2 + and 21 2 t-. Doppler-shift attenuation and recoil-distance measurements have been performed for some fifteen states. In addition, lifetimes of some yrast states in 76Kr have been determined in the reaction 63Cu( 16O, p2n). Transition energies and E2 strengths in 76Kr have been interpreted with the IBA-2 and different collective and microscopic triaxial rotor models, those in 77Kr with the triaxial rotor plus quasiparticle model.