High-resolution study of 0+and 2+excitations inEr168with the (p,t) reaction

Abstract

Excited states in the deformed nucleus $^{168}\mathrm{Er}$ have been studied with high-energy resolution, in the ($p,t$) reaction, with the Munich Q3D spectrograph. A number of 25 excited $0{}^{+}$ states (four tentative) and $63\phantom{\rule{0.3em}{0ex}}{2}^{+}$ states have been assigned up to 4.0 MeV excitation energy. This unusually rich characterization of the $0{}^{+}$ and $2{}^{+}$ states in a deformed nucleus, close to a complete level scheme, offers a unique opportunity to check, in detail, models of nuclear structure that incorporate many excitation modes. A comparison of the experimental data is made with two such models: the quasiparticle-phonon model (QPM), and the projected shell model (PSM). The PSM wave functions appear to contain fewer correlations than those of the QPM and than required by the data.