The n-p bremsstrahlung in heavy ion collision processes

The goal is to summarize the current status of the interpretation of energetic gamma-rays in heavy ion collisions via the n-p-bremsstrahlung mechanism. An essential element of the topic is a transport equation to approximate the fast non-equilibrium nucleon-nucleon cascade/emission stage of the heavy ion reactions. It is during this stage that it was expected that the n-p-bremsstrahlung processes produced energetic photons. The Boltzmann master equation (BME) model which will be used as the transport code is briefly described, deferring to earlier works for a more complete description, and present but a single representative comparison with an experimental neutron emission spectrum. The status of the elementary n-p-gamma cross section needed to extend the transport code to photon emission in heavy ion reactions, and the status of these comparisons with data are summarized.