Mixing between gamma-, and beta- and groundstate bands in even deformed nuclei; a phenomenological approach

This thesis describes a detailed analysis of transition probabilities of transitions connecting gamma-, beta- and groundstate bands in even-even deformed nuclei in the mass region A=152-192 (Sm, Gd, Dy, Er, Yb, Hf, W, Os, Pt), for all cases in which experimental data were available. The employed phenomenological models are based upon the separation of the rotational and the intrinsic motion, which yields very simple expressions for the relative energies and transition probabilities. Deviations from these adiabatic rules are caused by band mixing and are usually described in first-order perturbation theory, Then, the B(E2) branching ratios of transitions from members of the gamma- and beta band to different members of the groundstate band become simple functions of only one parameter each (zsub(γ), zsub(β)), if the interaction between the gamma and the beta can be neglected. A basis for improvement is a consistent description of the admixed wave functions for the typical case of multi-level mixing in which only two levels are close in energy. The implications of this concept of 'local mixing' upon the evaluation of measured mixing ratios delta(E2/M1) and X(E0/E2) are discussed. Special attention is given to the sign and magnitude of delta(E2/M1)