γ-rigid model for heavy transitional nuclei /sup 186,188,190,192/Os

The level energies and the electromagnetic properties of heavy transitional nuclei /sup 186,188,190,192/Os are studied using a semimicroscopic model. In this model the nucleus is assumed to be γ rigid but soft in the β degrees of freedom. The asymmetry parameter γ is determined from the ratio of the experimental energies of the first 2+ and second 2+ states assuming a rigid asymmetric rotor model. The symmetry parameter β for each J is obtained from the minimization of energy approximately projected from a triaxially symmetric intrinsic wave function. The pairing +QxQ interaction of Baranger and Kumar is employed to obtain the intrinsic wave function. Within our γ-rigid model, and without explicitly introducing the hexadecapole term in the Hamiltonian, it has been possible to get good agreement with experiment for the calculated level energies of the ground band, γ band, and K = 4+ band, the B(E2) values, electromagnetic moments, and E2 and E4 matrix elements. The success in describing the properties of each of these nuclei taking only one value of γ suggests that these nuclei may have rather stable triaxial shapes