Levels inRu99populated by the(3He,2nγ) reaction: Complete particle-core multiplets

The energy-level structure of ${}_{}{}^{99}{}_{}{}^{}\mathrm{Ru}$ was studied using the ${}_{}{}^{98}{}_{}{}^{}\mathrm{Mo}$ ${(}^3$He, 2nγ${)}^{99}$Ru reaction at a bombarding energy of 13 MeV, in an attempt to populate an extensive set of non-yrast states. The experiments included γ-ray excitation functions, γ-γ coincidence measurements, γ-ray angular distributions, and γ-ray linear polarization measurements. A large number of non-yrast states were observed, with angular momenta ranging from (1/2) to (17/2). The comparison of experimental energies and electromagnetic transition properties to the predictions of a particle-rotor model is presented. This interpretation suggests that several complete particle-core multiplets have been populated. The population of non-yrast states is attributable to the properties of the reaction rather than any details of the nuclear structure involved.