Differential cross sections for the reaction He4(gamma, p)H3 from 55 to 165 MeV

Differential cross sections have been measured for the reaction He4 (y,p)H3 for incident photons of 55 to 165 MeV. Outgoing protons and tritons from a low temperature He target were detected in coincidence at three angular settings in the 1aboratqry: (8p ' 8T) = (59.5, 106°), (88.5°, 75°), and (118°, 47.5°). The triton detection system consisted of three semiconductor detectors followed by a plastic scintillator. The proton detection system consisted of four plastic scinti11ators and was large enough to cq11ect all protons correlated with tritons in the triton system. The pulses from the calibrated detectors were used to identify the particles and measure their energies. The results show an exponential decrease in the differential cross sections with increasing gamma ray energy with possible leveling off at the region of pion threshold. The angular distribution of the protons is peaked more strongly forward as the energy increases. A simple calculation relates the differential cross sections at the, several angles to a common function of the proton or triton momentum. Results of this calculation are compared with the data.U of I OnlyThesi