0+states in deformed actinide nuclei by the(p,t)reaction

Abstract

By means of the $(p,t)$ reaction we study the excitation spectra of ${0}^{+}$ states in the deformed nuclei $^{228}\mathrm{Th}$, $^{230}\mathrm{Th}$, and $^{232}\mathrm{U}$, using the Q3D magnetic spectrograph facility at the Munich tandem accelerator. At small reaction angles the ${0}^{+}$ transfer angular distributions have steeply rising cross sections which allow us to identify these states in otherwise very complicated and dense spectra. For each of these nuclei we resolve typically about ten excited states with safe ${0}^{+}$ assignments. The studied excitation energies range up to 2.5, 2.7, and $2.3\phantom{\rule{0.3em}{0ex}}\text{MeV}$, respectively, and the summed transfer strengths add to more than $60%$ of the ground state strength. As in a recent study of $^{158}\mathrm{Gd}$ we compare with interacting boson approximation (IBA) calculations in the $spdf$ boson space. This highly schematic collective model description, including octupole collectivity, but neglecting other relevant degrees of freedom, gives numbers of excited ${0}^{+}$ states in these actinide nuclei that are rather close to the observed ones.