High-energy gamma-ray production in light-ion induced reactions.

Abstract

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/sub /gamma//>20 MeV) from the reactions /sup 2/H on C, Zn, and Pb at E/A = 53 MeV, and /sup 4/He on C, Zn, and Pb at E/A = 25 and 53 MeV. The gamma-ray energy spectra are roughly exponential, and for /sup 2/H at E/A = 53 MeV extend out to the full available energy (/similar to/00 MeV). The angular distributions of the gamma rays are slightly forward peaked in the laboratory frame, but are symmetric about 90/sup 0/ 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.