Alpha-Particle Production: Direct And Compound Contribution In The Reaction Li-7+Si-28 At Near-Barrier Energies

The production of alpha particles in the Li-7+Si-28 reaction was studied at near-barrier energies. Angular distributions were measured at four energies, namely 9, 10, 11, and 13 MeV. The data were treated in a statistical model and DWBA framework to disentangle the degree of competition between direct and compound channels in the reaction and its energy evolution near the barrier. It was found that whereas the compound mechanism is substantial, d transfer and possibly t transfer are the dominant mechanism at near-barrier energies. The influence of the reaction channels on the optical potential threshold anomaly is discussed.