Réaction (p, d) à 156 MeV et structure des noyaux légers

Abstract

Energy spectra and angular distributions were measured with a magnetic spectrometer for the following pick-up reactions at 156 MeV: 6Li(p, d) 5Li; 7Li(p, d) 6Li; 9Be(p, d) 8Be; 10B(p, d) 9Be; 11B(p, d) 10B; 12C(p, d) 11C; 16O(p, d) 15O; 28Si(p, d) 27Si and 40Ca(p, d) 39Ca. It is shown that, at this energy, where the separation between levels is small compared to the energies of the incoming and outgoing particles, the PWBA without cut-off radius, although not being able to reproduce the experimental angular distributions, allows a good extraction of the relative spectroscopic factors F 2 for a given l. The F 2 values agree quite well with those calculated for 1p shell nuclei with the wave functions of Cohen and Kurath and of Boyarkina; the agreement is in general also good with the F 2 extracted by DWBA at various energies. The ratio between the absolute F 2 obtained by PWBA and the theoretical F 2 might be considered as a distortion factor, which is a function of angle θ; it appears that this factor does not vary much throughout the 1p shell. The pick-up in the inner major shell is discussed; the cross section for simple 1s pick-up decreases sharply when going from 4He to 6Li target nuclei; a similar effect appears for 1p pick-up between 16O and 19F; this behaviour, probably related to the high neutron momenta involved, is not yet well understood.