High-energy gamma-ray emission in heavy-ion collisions

Energy and angular distributions were measured for high-energy (E/sub ..gamma../>10 MeV) gamma rays from collisions of /sup 14/N on Pb, Zn, and C at beam energies of E/A = 20, 30, and 40 MeV. The gamma-ray energy spectrum was measured to about 120 MeV at E/A = 40 MeV and to about 80 MeV at E/A = 20 MeV. For E/sub ..gamma../>20 MeV the spectra are roughly exponential with characteristic slope parameters ranging from 10.0 MeV for /sup 14/N+Pb at E/A = 20 MeV to 14.2 MeV at E/A = 40 MeV. Although the mechanism responsible for high-energy gamma-ray emission is not well understood, reasonable agreement is obtained with a model employing bremsstrahlung from individual neutron-proton collisions in the heavy-ion collision.