VERY ENERGETIC PHOTONS FROM HEAVY-ION COLLISIONS

For the first time single photons with energies up to 6 times the beam energy per nucleon have been measured in a heavy-ion reaction. The re action studied was Kr+Ni at 60 A MeV. In the nucleon-nucleon center of mass system the spectra exhibit an exponential shape with an inverse slope parameter E(o) = 20 MeV. Bremsstrahlung in individual NN collisi ons is the origin of the highest energy photons, as for the lower ener gy ones.