Classes of β-γ mixing and E0 transitions in deformed nuclei

We investigate the effects of β-γ mixing using branching ratios between the 2_γ⁺ level and the ground state band in well-deformed nuclei. We find that the deviations from the well-known Alaga rules vary as a function of the energy separation between the 2_γ⁺ and 2_β⁺ levels. For nuclei where these two intrinsic excitations are nearly degenerate, we find two classes of behavior. For one of those, the systematics can be reproduced in a simple bandmixing formalism but only with an anomalously strong interaction strength between the 2_γ⁺ and 2_β⁺ levels, on the order of tens of keV. This result is supported by X(E0/E2;2_γ⁺→2₁⁺) values that are large for these nuclei (where measured), indicating significant K=0 components in the 2_γ⁺ levels. In the other class, there is virtually no mixing. These nuclei have previously been associated with near-SU(3) structure.