In the framework of the triaxial rotor model of Davydov and Filippov, deformation parameters $\beta$ and $\gamma$ are extracted from both level energies and $E2\mathrm{}$ transition rates in even-even Hf-Hg nuclei. Three results emerge: the two sets of $\beta$ and $\gamma$ values—energy-based and transition-rate-based—are in good agreement, with only a few exceptions, thus giving confidence in the extracted values; both $\beta$ and $\gamma$ follow smooth trajectories against $N_p{N}_n;$ and the $\beta$ and $\gamma$ values themselves are correlated, pointing to the possibility of a simpler description of structural evolution.

• Received 23 August 1996

DOI:https://doi.org/10.1103/PhysRevC.55.206