Photon production in nucleon-nucleon collisions

We calculate the differential cross section for nucleonnucleon bremsstrahlung in covariant way based on a realistic meson-exchange approximation for the NN-scattering amplitude. The results are discussed in comparison to semiclassical approximations and with respect to the role of internal radiation diagrams. The influence of the anomalous magnetic moment on the proton-neutron bremsstrahlung is found to contribute up to 50% for specific kinematical conditions. Recent measurements on the elementary differential cross sectionpnpn are found to be quite accurately reproduced. Furthermore, for use in proton-nucleus and nucleus-nucleus collisions, we present a parametrization of thepn cross section within a broad kinematical range.Work supported by BMFT, GSI Darmstadt and a NATO science grant