Hard-Photon Emission from Colliding Nuclei

Abstract

Direct photon emission observed in nucleus-nucleus collisions at intermediate beam energies (0.3 ⩽ β ⩽ 0.4) shows some very interesting features, especially when comparing it to pion production in such collisions. Valuable information is gained through the fit of a standard black-body radiation formula to the data as well as by a comparison to classical bremsstrahlung theory. A photon production in the early phase of the collision is indicated; in the bremsstrahlung picture this corresponds to a rather sudden slowing down of the relative motion.