Shell-model relationships between negative-parity states of even-massA=30?40 nuclei

Abstract

Simple relationships between the negative-parityenergy level structures of the even-mass nuclei pairsA=30 and 32, 34 and 40, 34 and 36, 34 and 38, 40 and 38 are established along lines similar to the well-known Pandya transformation between the particle-hole spectrum of40K and the particle-particle spectrum of38Cl. The relationships are generated within the framework of thejj-coupling shell model, using standard Racah algebra, and no assumption is made about the physical nature of the nuclear two-body interaction. Candidates for the 1f7/2 and 2p3/2 multiplets are selected on the basis of their measured spectroscopic strengths inl=3 or 1 single-particle transfer reactions with due allowance for member fragmentation and mixing between the two configurations in terms of the calculation of spectroscopic-strength weighted centroids. The calculated correlated energy spectra are discussed with reference to the results of previous interaction-dependent shell-model calculations, especially those employing the modified surface delta interaction. Consideration is also given to uncertain or ambiguous spin and parity assignments, deduced two-body interaction matrix elements, and the isospinT=0 and 1 and single-particle 1f7/2 and 2p3/2 splittings.