Shell-model study of spin-dipole strength in 12C and 16O

Abstract

We have studied effects of tensor correlations and couplings to 3ħω excitations on the quenching of spin-dipole strengths in 12C and 16O by large scale shell model calculations. We found that the transition strengths in the energy range E x = (20–40) MeV in 12C are quenched by about 20% due to the coupling to the 3ħω configuration space, and by additional 10% due to the tensor interaction. There is also a similar quenching of spin-dipole strengths for 1 − states in 16O. The calculated results are compared with available experimental data of spin-dipole states observed by charge exchange ( p, n) and ( d , 2He) reactions on 12C. An astrophysical implication of spin-dipole strengths in 16O for detections of supernova neutrinos is also discussed.