Centrifugal stretching along the ground state band ofHf168

Abstract

The lifetimes of the ${J}^{\ensuremath{\pi}}={4}^{+}$, ${6}^{+}$, ${8}^{+}$, and ${10}^{+}$ levels along the ground state band in $^{168}\mathrm{Hf}$ were measured by means of the recoil distance Doppler shift (RDDS) method using the New Yale Plunger Device (NYPD) and the SPEEDY detection array at Wright Nuclear Structure Laboratory of Yale University. Excited states in $^{168}\mathrm{Hf}$ were populated using the $^{124}\mathrm{Sn}(^{48}\mathrm{Ti},4n)$ fusion evaporation reaction. The new lifetime values are sufficiently precise to clearly prove the increase of quadrupole deformation as a function of angular momentum in the deformed nucleus $^{168}\mathrm{Hf}$. The data agree with the predictions from the geometrical confined $\ensuremath{\beta}$-soft (CBS) rotor model that involves centrifugal stretching in a soft potential.