S-matrix Description of Refractive Effects in One-nucleon Stripping Reactions Induced by \(\alpha \)-particles on \(^{28}\)Si

Abstract

We analyze the angular distributions for the (α, 3 He) and (α, t) reactions on 28 Si for projectile energies ranging from 50 to 120 MeV based on the partial-wave representation of the transfer amplitude expressed in terms of the S-matrices for the entrance and exit channels, with an emphasis on identifying Airy minima of various orders. The calculations have been performed using a six-parameter S-matrix model and S-matrix parameters obtained from the analysis of elastic scattering data. The first-and (or) second-order Airy minima are clearly identified in the analyzed transfer reaction angular distributions at intermediate angles. The detected Airy minima are found to be due to the interference between several inner and surface partial waves. The impact parameters of these waves are in the range of 1-6 fm, the upper boundary of which is less than the strong absorption radius.