Production of Deuterons in High-Energy Nucleon Bombardment of Nuclei and Its Bearing on Nuclear Charge Distribution

Abstract

A study has been made of deuterons produced at wide angles to a beam of 300-Mev neutrons and a beam of 300-Mev protons. The cross-section dependence on atomic number for these deuterons for light elements can be written as $\ensuremath{\sigma}=k{A}^{1.2}$. This fact and the energy spectra and angular distribution of the deuterons show that the process that forms these deuterons is related to the indirect pick-up process described by Bransden. This is a two-step process in which the incident nucleon, or its collision partner, is scattered and then picks up a deuteron-forming partner in the same nucleus. A yield of tritons has also been observed which has the same $A$-dependence and is presumably made by a similar process. The $A$-dependence of the deuteron-production cross section also suggests that these deuterons are made on the nuclear surface. Because of this $A$ dependence, a comparison of the deuteron yields using an incident neutron beam and an incident proton beam can give information about the relative numbers of neutrons and protons on the surface of the nucleus. An analysis of this sort leads to a possible conclusion that for heavy nuclei there is a nuclear skin rich in neutrons. For light nuclei the effect is not observed. If this skin is composed only of neutrons its thickness must be about 0.8\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}13}$ cm for lead.