Two new features of superdeformed (SD) bands in the A≊190 region emerge from a study of ${}_{}{}^{194}{}_{}{}^{}\mathrm{Hg}$ with the Gammasphere detector array. A decrease of the dynamic moment of inertia is observed for rotational frequencies ħω≥0.4 MeV, confirming long standing expectations based on mean field calculations with pairing. Evidence for a small staggering in the SD transition energies is also observed, suggesting the presence of terms with fourfold symmetry in the SD Hamiltonian.

• Received 17 November 1993

DOI:https://doi.org/10.1103/PhysRevLett.72.3150