Energetic Protons from Nuclei Exposed to 300-Mev Bremsstrahlung

Abstract

The protons ejected from various nuclei by the photon beam from the 300-Mev Cornell synchrotron have been studied with a scintillation counter telescope capable of distinguishing particles of different mass. The energy spectrum of protons from carbon and cadmium is roughly proportional to $\frac{1}{{E}^{2}}$ from 70 to 130 Mev and to $\frac{1}{{E}^{6}}$ from 130 to 240 Mev. The angular distribution of protons from carbon has a forward asymmetry which increased with proton energy. The yield per nucleus of 130-Mev protons from Be, C, Al, Cu, Cd, and Pb is proportional to $Z$. The excitation function for 105-Mev protons exhibits a steep rise in the neighborhood of a synchrotron energy of 200 Mev.The experimental results indicate the majority of the protons to be of photoelectric rather than mesonic origin. There is some evidence that the recoil particle involved in the production process carries off about half the primary photon energy, which suggests that it may be a neutron.