Momentum distribution of nucleons in the nuclear surface

Abstract

The results of the 40 MeV (p, 2p) experiments of Griffiths and Eisberg are analysed on the basis of a model for the total momentum transfer. Assuming two-body collisions and the impulse approximation and representing the momentum distribution of bound protons by a Fermi distribution whose maximum momentum is p f , it is almost certain that 0.5 MeV < p f 2/2 m < 1.5 MeV. Assuming a semiclassical model for the reaction it is shown that the events observed in this experiment occur in the extreme nuclear surface. Thus the experiment is strong evidence in support of the Thomas-Fermi approximation for nucleons in a finite nucleus. Representing the main bulk of the nucleus by an absorbing sphere, it is shown that the observed ratio of (p, 2p) to (p, p′) events is consistent with the assumption that direct interactions all proceed from initial two-body collision.