Study of the (p,pd), (p,pt) and (p,p3He) reactions on 12C and 16O at 75MeV

These experiments have been performed at the Louvain-la-Neuve cyclotron (Belgium). Protons were detected by a two-detector telescope (one of them being a 7mm thick intrinsic germanium detector) and detection of d, t, 3He was made with a three-detector telescope. The energy signals coming from these detectors together with the time difference between the two outgoing particles were registered on magnetic tapes. An off-line analysis of these data enabled to construct the excitation spectra of the residual nuclei 10B, 9B, 9Be and 14N, 13N, 13C; the energy resolution was about 400keV. For some of the levels of these nuclei, it has been possible to extract the momentum distribution of the corresponding cluster in 12C and 16O. The quasi-free scattering mechanism with distorted waves gives a good representation of the measured distributions and then seems to represent correctly the reaction mechanism. Moreover, assuming for the two and three particle spectroscopic amplitudes the values computed in the framework of the shell model with an effective interaction, it appears that the off-shell scattering cross-sections values are close to the free scattering cross-sections values taken at a proton energy which gives the same relative impulsion p-x as in the incident channel of the three body reaction. Finally, other informations can be obtained from the comparison of these data with experimental results from transfer reactions (p,3He) and (p,α): in particular, the population of the T=1 levels of 10B (1.74MeV) and 14N(2.31MeV) can be explained by the scattering of a proton on an n-p pair in singlet state (S=0) followed by a transition to the triplet state