Triaxial strongly deformed structures in the even-even Hf nuclei

Two rotational bands of distinct character have been identified in Hf-164 from a recent experiment at Gammasphere. They are suggested to correspond to the long-anticipated triaxial strongly deformed (TSD) bands predicted by theoretical studies. The bands are substantially stronger in intensity and are located at lower spins than the previously observed TSD bands in Hf-168, and have been linked to the known states, hereby making Hf-164 the best even-even system for the study of TSD structures in the A similar to 160 mass region. Cranking calculations based on the modified-oscillator model suggest that the bands are associated with four-quasiparticle configurations involving high-j intruder (i(13/2))(2) proton orbitals. Wobbling mode has not been observed in Hf-164 and the possible reasons are discussed.