Electromagnetic properties ofTh230studied by Coulomb excitation

The Coulomb excitation of ${}_{}{}^{230}{}_{}{}^{}\mathrm{Th}$ by 135 MeV ${}_{}{}^{32}{}_{}{}^{}\mathrm{S}$ ions was studied using the particle-gamma coincidence technique. Scattered projectiles were detected within an angular range of ${30}^{\circ }\le \Theta \le {172}^{\circ }$, and the impact-parameter dependence of the gamma-ray intensities was measured. Excitation of the ground-state rotational band was observed up to the ${10}^{+}$ state, while the $\beta$- and $\gamma$-vibrational bands were seen up to the $4^{+}$ and $8^{+}$ states, respectively. Levels belonging to the $K^{\pi }=0^{-} \mathrm{and} 1^{-}$ octupole vibrational bands were also identified. From the scattering-angle dependent gamma-ray intensities $E2\mathrm{}$ transition matrix elements within the ground band and interband matrix elements connecting levels of the $\gamma$ band with the ground band are deduced. Gamma-ray branching ratios for transitions from the $\gamma$- and octupole-vibrational bands to ground-band levels are also determined. Both transition matrix elements and branching ratios are compared with nuclear-model predictions.