REACTION-MECHANISM OF B-11(P, ALPHA)BE-8 REACTION AT ASTROPHYSICALLY RELEVANT ENERGIES

The experimental angular distributions for the reaction B-11(p, Lu)Be-8 at incident energies of 398, 498 and 780 keV below the Coulomb barrier are analyzed with the finite-range distorted-wave Born-approximation (FRDWBA) formalism including both the direct and the exchange processes. In addition to the direct-reaction mechanism, the compound process was included. The spectroscopic amplitudes used in the present analysis are obtained so as to fit the experimental angular distributions for the same reaction at the proton bombarding energy of 45.0 MeV. Using the folding procedures with the alpha alpha and the p alpha effective interactions, the optical-model potential in the exit channel and the real interaction between the incident proton and the cluster Be-8 in the target nucleus are deduced, respectively. Good agreements of theoretical calculations with experiments are obtained in regard to both the shape and the absolute magnitude of the differential cross section in the B-11(p, a)8Be reaction. Numerical calculations show that the direct-reaction mechanism is dominant for this reaction; in particular, the exchange process plays an important role in reproducing the experimental angular distributions in the energy ranges studied here.