The interaction strengths of the ground band with the S band are extracted by using observed states of both bands as well as observed relative E2 transition rates for γ decay to yrast and nonyrast states. The signature dependence of the strength observed in the negative-parity yrast sequences of ${}_{}{}^{157}{}_{}{}^{}\mathrm{Ho}$ is explained, if a relatively strong n-p Q’’⋅Q’’ interaction is introduced in the conventional axially symmetric particle-rotor model. The Q’’⋅Q’’ interaction is supposed to take care of the possible shape-driving effect due to the presence of aligned quasiparticles.

• Received 22 April 1992

DOI:https://doi.org/10.1103/PhysRevC.46.838