A lifetime experiment, using the Doppler-shift attenuation method, has been performed at Gammasphere to measure the transition quadrupole moments $Q_t$ of strongly deformed bands in ${}^{171}\mathrm{Hf}$ and ${}^{172}\mathrm{Hf}$. The measured value of $Q_t$ $~$ 9.5 $e$ b for the band labeled ED in ${}^{171}\mathrm{Hf}$ strongly supports the recent suggestion that this sequence and several structures with similar properties in neighboring Hf isotopes are associated with a near-prolate shape with a deformation enhanced relative to that of normal deformed structures. The measured values of $Q_t$ $~$ 14 $e$ b for the bands labeled SD1 and SD3 in ${}^{172}\mathrm{Hf}$ confirm that these sequences are associated with a prolate superdeformed shape, a property inferred in earlier work from other measured characteristics of the bands. Similar bands in ${}^{173-175}\mathrm{Hf}$ are also likely to be associated with superdeformed shapes. The observations are in contrast to predictions of cranking calculations performed with the ultimate cranker code.

• Received 9 February 2011

DOI:https://doi.org/10.1103/PhysRevC.83.044311