Threshold effects in nuclear reactions

Abstract

We explore the idea that between the colliding particles or the reaction products of a nuclear reaction the interaction in the immediate neighbourhood of the nuclear surface may be represented by a static attractive potential. The Wigner-Eisenbud theory of nuclear reactions is readily reformulated to take this ‘surface potential’ into account, whereupon quasi-bound states of the compound system are found to appear, with high probability, very close to the various thresholds for two-particle channels. Consequently, the cross section of a reaction close to any threshold should have a certain resonance-like behaviour. The relevant experimental data are reviewed and are found to support all the predictions of the theory.