Nonfission Inelastic Events in Uranium and Thorium Induced by High-Energy Protons

Activation cross sections for about thirty products of high-energy proton-induced disintegration of U²³⁸ and Th²³² have been measured by the radiochemical method. These products range from polonium ($Z=84$) to neptunium ($Z=93$). The energy dependence of some of these cross sections has been determined for formation from U²³⁸. Because of fission competition, the spallation cross section of U²³⁸ is considerably less than that of Th²³². The data suggest that light isotopes of uranium are primarily responsible for the fission generally associated with high-energy particle bombardment of U²³⁸.