Results are presented for high-energy gamma-ray production in light-ion induced reactions. Energy spectra and angular distributions were measured for high-energy gamma rays ($E_{\gamma }$>20 MeV) from the reactions ${}_{}{}^2{}_{}{}^{}\mathrm{H}$ on C, Zn, and Pb at E/A=53 MeV, and ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ on C, Zn, and Pb at E/A=25 and 53 MeV. The gamma-ray energy spectra are roughly exponential, and for ${}_{}{}^2{}_{}{}^{}\mathrm{H}$ at E/A=53 MeV extend out to the full available energy (∼100 MeV). The angular distributions of the gamma rays are slightly forward peaked in the laboratory frame, but are symmetric about 90° when transformed to the nucleon-nucleon center-of-mass frame. For the carbon target data the angular distribution in the nucleon-nucleon frame shows a substantial dipole component. This suggests that the major high-energy gamma-ray production mechanism is bremsstrahlung from first collisions of projectile and target nucleons.

• Received 8 August 1988

DOI:https://doi.org/10.1103/PhysRevC.38.2526