One-nucleon pickup reactions on 32S:: Experimental results and shell-model calculations

The S-32(d,He-3)P-31 and S-32(He-3,alpha)S-31 reactions have been investigated at incident energies of E-d = 27 MeV and E-3He = 25 MeV. The experimental values of excitation energies (0 less than or equal to E-x(MeV) less than or equal to 8) have been compared with the predictions of a complete sd-shell space, shell-model calculation. Spectroscopic factors obtained for 22 levels of S-31 through the DWBA analysis of the experimental angular distributions have also been compared with the shell-model predictions. In order to reconcile the experimental and shell-model predicted values of the spectroscopic factors, the geometrical parameters of the spin-orbit part of the transferred nucleon potential are required to be smaller than those of the central part as it was previously observed in studies of the one-proton (He-3,d) stripping reaction. The experimental fragmentation of the 1d(5/2) and 2s(1/2) strengths is correctly reproduced by the shell-model calculations. Twenty pairs of levels were identified as mirror states in the S-31 and P-31 nuclei and the ambiguities concerning the J(pi)-values of eleven S-31 levels could be removed. (C) 1999 Elsevier Science B.V. All rights reserved.