The excitation of γ-radiation in processes of proton capture

1. Introduction It is found th at many light elements emit γ-radiation during bombardment by protons of high energy. Excitation curves relating the intensity of the emitted γ-radiation with the energy of the incident protons do not increase smoothly with increasing bombarding voltage, but show, in most instances, pronounced maxima. The resonance character of these excitation curves is most naturally explained by assuming that the γ-radiations arise in the process of capture of protons by nuclei, and measurements of the quantum energies of these radiations lend general support to the assumption that the γ-rays have this origin. In a previous paper (Curran, Dee and Petrzilka 1938) the results of an investigation of the process of proton capture by the four light elements, beryllium, boron, carbon and fluorine, have been given. The experiments have now been extended to include the five elements lithium, sodium, magnesium, phosphorus and chlorine. The form of the excitation curve for the intensity of the capture γ-radiation has been determined for incident protons of energy up to 10⁶ eV, and in each case the quantum energy of the radiation has been measured. An attem pt has also been made to detect the capture of protons by deuterium but no definite evidence of the occurrence of this process could be obtained.