Lifetimes of rotational states inTh232

Lifetimes of the $4^{+}$ through ${10}^{+}$ members of the ground-state rotational band in ${}_{}{}^{232}{}_{}{}^{}\mathrm{Th}$ have been measured by the Doppler-shift recoil-distance technique. These states were Coulomb excited by 152-MeV ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ ions, and measurements were carried out in coincidence with the backscattered projectiles. The half-lives for the $4^{+}$ through ${10}^{+}$ states are 164 ± 13, 66.2 ± 5.1, 25.1 ± 2.3, and 11.2 ± 1.7 ps, respectively. The $B\left(E2\mathrm{}\right)\mathrm{}$ values deduced for these states are systematically about 10% smaller than rigid-rotor values; however, the constancy of the transition quadrupole moments is interpreted as an indication of rotational behavior.