Pronounced shape change induced by quasiparticle alignment

Mean lifetimes of high-spin states of ⁷⁴Kr have been determined using the Doppler-shift attenuation method. The high-spin states were studied using the ⁴⁰Ca(⁴⁰Ca,{α}2p)$ reaction at a beam energy of 160 MeV with the GASP ${γ}$-ray spectrometer. The ground-state band and negative parity side band show the presence of three different configurations in terms of transitional quadrupole deformations. A dramatic shape change was found along the ground-state band after the S-band crossing. The deduced quadrupole deformation changes are well reproduced by cranked Woods-Saxon Strutinsky calculations.