Shell-model calculation of non-normal parity states in mass 39, 40 and 41 nuclei

Abstract

First-order Tamm-Dancoff calculations including the complete 2s, 1d and 1f, 2p shells have been performed for non-normal parity states in mass 39, 40 and 41 nuclei. All matrix elements are taken from previous work with the exception of the particle-hole interaction between 1 f 7 2 and 1 d 3 2 nucleons which is determined by a least-squares fit to 37 selected levels. A rms deviation of 250 keV is achieved. Spectroscopic factors and electromagnetic transition rates are in reasonable agreement with the experimental data. Limitations of the model, e.g. due to the neglect of 3 h ̷ ω excitations, are discussed. Evidence for a ground-state correlation energy in 40Ca exceeding those for mass 39 and 41 nuclei by 0.6 MeV is obtained. The calculation casts doubt on previous weak coupling interpretations of the 2p-lh spectrum of mass-41 nuclei.