Gamma–alpha Reactions in the Light Nuclei of Nuclear Emulsions

Abstract

Ilford E.l nuclear emulsions were loaded with various amounts of glycerine to vary the content of carbon and of oxygen, and were then irradiated in the beam of the University of SasBatchewan betatron. The numbers of single alpha-particle traclcs and of four-pronged alpha-particle stars were correlated to the oxygen content of the plates and the number of three-pronged stars to the carbon content. The yields for the reactions OIG(?, a)CX2, OIG(y, 4a), and CI2(?, 3a) for bren~s-strahlung of 24-Mev maxirnum energy were found without confusion wlth reactions in other nuclides of the emulsion and without having to rely on mornentuln balances for identification of the events. I t was shown that the method of identification of OIG(?, a)C12 events by the measurement of the track of the C12 was not reliable. The large number of alpha tracks in the energy range 4 to 5 Mev, few of which showed a C12 track, was shown to be due largely to reactions in OIG. I t was also possible, by irradiating en~ulsions a t 17-and a t 24-Mev maximum bremsstrahlung energy, to find the energy levels in OIG and in C12 through which the reactions passed.