J-DEPENDENCE IN L=2(3HE,ALPHA) REACTIONS ON 24MG, 28SI AND 30SI

In order to investigate a possible j-dependence in the l = 2 angular distributions of 3He induced direct reactions in the region of the ld-shell nuclei, (3He, α) reactions on the target nuclei 24Mg, 28Si and 30Si were measured at incident energies Einc of 18 and 20 MeV. The stability of the shape of the angular distributions against variations of Einc demonstrates that the direct reaction contribution prevails even at backward angles in the region of small cross sections. There is a difference between the shape of the Δj = 3 2+ and Δj = 5 2+ angular distributions at θc.m = 45° which is common to all nuclei studied; at this angle the Δj = 3 2+ curves show a deep minimum which is absent in the case of the Δj = 5 2+ angular distributions. This systematic experimental j-dependence can be reproduced by DWBA calculations; the theoretical results agree well with the experimental ones in the region of large cross sections up to about 60°. © 1969.