High-Energy Gamma-Ray Emission in Heavy-Ion Collisions

Energy and angular distributions were measured for high-energy ($E_{\gamma }>10\mathrm{}$ MeV) gamma rays from collisions of ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ on Pb, Zn, and C at beam energies of $\frac{E}{A}=20, 30, \mathrm{and} 40$ MeV. The gamma-ray energy spectrum was measured to about 120 MeV at $\frac{E}{A}=40\mathrm{}$ MeV and to about 80 MeV at $\frac{E}{A}=20\mathrm{}$ MeV. For $E_{\gamma }>20\mathrm{}$ MeV the spectra are roughly exponential with characteristic slope parameters ranging from 10.0 MeV for ${}_{}{}^{14}{}_{}{}^{}\mathrm{N}$ + Pb at $\frac{E}{A}=20\mathrm{}$ MeV to 14.2 MeV at $\frac{E}{A}=40\mathrm{}$ MeV. Reasonable agreement is obtained with a model employing bremsstrahlung from individual neutron-proton collisions in the heavy-ion collision.