The scattering of high-energy neutrons by protons and the law of interaction between nucleons

Abstract

Calculations have been carried out of the angular distribution and total collision crosssection to be expected in the case of the scattering of neutrons of energy in the range 83 to 250 MeV by protons. Bom’s approximation has been used in these calculations, and a large variety of possible shapes and ranges for the radial variation of the interaction potential have been investigated. For each case the radial variation of the central and non-central parts of the interaction was taken to be the same. The conditions for the validity of this approximation are discussed. Although only fair at the lower end of the energy range studied it should give reasonable results at the upper end of the range, especially in the case of potentials other than the spherical well. The exchange properties of the interaction should be capable of deduction from the general shape of the angular distribution of the scattering curves. It is more difficult to obtain evidence about the exact form of the radial variation of the interaction potential from the angular distribution curves because, for any given potential shape, a wide variety of different predicted angular distributions are obtained by varying the range of the interaction. Potentials of the exponential and Yukawa type, however, show a greater concentration of the scattering into angles near 0 and 180° than is the case for a spherical well interaction. The total collision cross-section depends quite markedly both on the exchange properties and radial variation of the interaction. Closest agreement with the measurements of total cross-section for 90 MeV neutrons are given for a symmetrical interaction with a radial variation in the form of a Yukawa potential of range 1*18 x 10~13 cm., although this interaction predicts too large a value for the ratio of the differential cross-section at 180° to that at 90°.