Optical model potentials involving loosely bound p-shell nuclei around 10 MeV/nucleon - art. no. 024612

We present the results of a search for optical model potentials for use in the description of elastic scattering and transfer reactions involving stab le and radioactive p-shell nuclei. This was done in connection with our pro gram to use transfer reactions to obtain data for nuclear astrophysics, in particular for the determination of the astrophysical S-17 factor for Be-7( p, gamma)B-8 using two (Be-7,B-8) proton transfer reactions. Elastic scatte ring was measured using Li-7, B-10, C-13 and N-14 projectiles on Be-9 and C -13 targets at or about E/A = 10 MeV/nucleon. Woods-Saxon type optical mode l potentials were extracted and are compared with potentials obtained from a microscopic double folding model. Several nucleon-nucleon effective inter actions were used: M3Y with zero range and finite range exchange term, two density dependent versions of M3Y and the effective interaction of Jeukenne , Lejeune, and Mahaux. We find that the latter one, which has an independen t imaginary part, gives the best description. Furthermore, we find the reno rmalization constant for the real part of the folding potential to be nearl y independent of the projectile-target combination at this energy and that no renormalization is needed for the imaginary part. From this analysis, we are able to eliminate an ambiguity in optical model parameters and thus be tter determine the asymptotic normalization coefficient for B-10-->B-9 +p. Finally we use these results to find optical model potentials for unstable nuclei with emphasis on the reliability of the description they provide for peripheral proton transfer reactions. We discuss the uncertainty introduce d by the procedure in the prediction of the distorted wave Born approximati on cross sections for the (Be-7,B-8) reactions used in extracting the astro physical factor S-17(0).