PHOTO-ALPHA PARTICLES FROM SILVER AND BROMINE IRRADIATED WITH 70 MEV. BREMSSTRAHLUNG

The energy spectrum of the α particles ejected from silver and bromine nuclei has been studied in a nuclear research emulsion irradiated with 70 Mev. brems-strahlung from the Queen's University synchrotron. The main feature of the observed spectrum is a broad group with a peak at about 11 Mev. Evidence for particles of energies less than 6 Mev. is inconclusive.Calculations have been made on the basis of the nuclear evaporation theory and give a predicted spectrum which is consistent in shape and peak position with the observed results.