Recoil Studies of High-Energy Proton Reactions in Bismuth

Abstract

The ranges in bismuth of ${\mathrm{Sr}}^{91}$, ${\mathrm{Ba}}^{129}$, and ${\mathrm{Ba}}^{133m}$ recoil fragments from bombardment of bismuth with protons of 50 Mev to 2.2 Bev have been measured. The kinetic energies of the fragments have been calculated from the measured ranges and other reported range-energy data for fission fragments. The kinetic energy of the strontium recoils for all energies, and that of the barium recoils up to 450 Mev, can be explained as resulting from high-energy fission where most of the mass of the target is divided between two heavy fragments. At 2.2 Bev, the kinetic energy of the bariums recoils is substantially smaller, consistent with a complimentary fragment of about 20 mass units.