Abstract
The J π = 3 2 − and 1 2 − states in 49Sc generated by the configurations {(1 f 7 2 ) 8 (2 p 3 2 , 1 2 )} are discussed. Excitation energies. M1 transitions, and E2 transitions among the seven 3 2 − and five 1 2 − levels, including the 3 2 − analog state at E x = 11.56 MeV and a putative excited analog 1 2 − state at ≈ 13.6 MeV, were calculated and compared with experiment where possible. The β-decay of 49Ca to the 3 2 − level at 3.08 MeV and the (presumably) 1 2 − level at 4.49 MeV (the lowest-lying 3 2 − and 1 2 − levels) were also calculated. Two interactions were used, the well-known Kuo-Brown (KB) force and a new interaction which we call the PMM force, the latter being derived mainly from direct-reaction cross sections of nucleons on various nuclei. Both KB and PMM interactions lead to cancellations which cut down both the β-decay of 49Ca and the M1 decay of the A-state to the lowest-lying 3 2 − and 1 2 − states, as observed experimentally. In addition, strong M1 decays to several 3 2 − and 1 2 − levels with excitations of 7–11 MeV are predicted, as is observed experimentally. The E2 decays of all the predicted 3 2 − states to the 7 2 − ground state were also calculated. In the case of the E2 decay of the A( 3 2 − ) state, comparison with experiment is hampered by the role of fine structure; experiment is weaker than theory by a factor of ≈ 50. The (1 f 7 2 ) 8 group of levels in 48Sc were also calculated ( J π = 0 + → 7 +). The PMM force gave excellent agreement with recent experimental results while the KB force gave relatively poor agreement, as might be expected from the severe truncation of the shell-model basis. The suggestion is that the phenomenological basis of the PMM force corresponds physically to the (1 f 7 2 ) 8 space of 48Sc as well as the (1 f 7 2 −) 8 (2 p 3 2 or 2 p 1 2 ) space of 49S
Published Version
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