Semiclassical analysis of α-transfer reactions

Abstract

Semiclassical concepts are used to gain insight into α-transfer reactions. These reactions, interpreted as one-step direct reactions on the basis of DWBA analyses, are treated in analogy with single nucleon transfer reactions for which it is known that semiclassical methods are successful. In this case however the probability of transfer appears to be greatest at a distance of closest approach which is larger than the grazing distance by the order of the a-particle radius. This increase in the effective "grazing" distance is interpreted as a manifestation of the a-particle size at the time of transfer. Angular distributions are calculated semiclassically for the reactions ²⁰⁸Pb(¹⁶O, ¹²C)²¹²Po at 93 MeV and ⁴⁰Ca(¹²C, ⁸Be)⁴⁴Ti at 45 MeV lab energy. They are seen to give a reasonable fit to experiment. Partial wave amplitudes for transfer are also studied.