Lifetimes of Rotational States From Heavy-Ion Reactions

The half-lives of several transitions in the ground-state collective bands of ${}_{}{}^{160}{}_{}{}^{}\mathrm{Er}$, ${}_{}{}^{158}{}_{}{}^{}\mathrm{Er}$, and ${}_{}{}^{156}{}_{}{}^{}\mathrm{Er}$ produced by (${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar},4n$) reactions have been measured by a recoil-distance Doppler-shift method. These lifetimes are compared with those of several models. The mean time interval between the reaction and the population of the ground band was also determined.