Wobbling Excitations in Strongly Deformed Hf Nuclei?

Abstract

Two Gammasphere experiments have been performed in order to establish the possible triaxial nature of strongly deformed (SD) bands in174Hf. A lifetime measurement, using the Doppler-shift attenuation method, confirmed the large deformation of the four previously observed bands in this nucleus with transition quadrupole moments ranging from 12.6 to 13.8 b. These values are significantly larger than those predicted for triaxial minima by ultimate cranker (UC) calculations. A thin-target, high-statistics experiment was also carried out to search for linking transitions between the SD bands. No such transitions, which represent an experimental signature for wobbling modes, were observed. Four additional SD bands were found in174Hf together with a single SD band in173Hf. These results indicate that the strongly deformed sequences of N≈102 Hf isotopes behave differently than the triaxial strongly deformed (TSD) bands found in Lu nuclei near N=92. The interpretation of these bands in terms of possible stable triaxial deformation is confronted with the experimental findings and UC predictions.