High-energy gamma-ray production from 284 MeV 3He on nuclei

Double-differential cross sections for photons above 20 MeV were measured for the He-3 + (d, C, Cu and Au) reactions at 284 MeV. The comparison of their energy spectra shows that the high-energy gamma rays are produced by the same mechanism in the very light He-3 + d system and in heavier ones like He-3 + (C, Cu and Au) or Xe + Sn, previously studied by the MSU group. A calculation of the He-3 + (C and Au) systems at 90-degrees in the laboratory was performed, assuming that photons are produced in first-chance nucleon-nucleon collisions and for a realistic momentum distribution of the nucleons in the He-3 projectile. The results are in good agreement with the experimental data which suggests that secondary collisions are not important in the production of photons above 50 MeV for nucleus-nucleus reactions at 90 MeV/nucleon.