Photon production in heavy-ion collisions and nuclear equation of state

Photon-production cross sections in 12C+12C, 40Ca+40Ca and 93Nb+93Nb collisions at Elab = 84 and 200 MeV/A are calculated within the framework of the quantum molecular dynamics approach. The sensitivity of the photon-production cross section to the different types of nuclear equation of state and the momentum dependence in the in-medium NN interaction is studied in detail. Although we found some difference between the soft and hard equation of state in the calculated photon-production cross section, it is suppressed strongly by the momentum dependence in the interaction. There is a sizeable difference between the results calculated with or without taking into account the momentum dependence in the in-medium interaction. The time dependence of the production of the high-energy photons arising from incoherent pn collisions is also studied. The heavier the masses of colliding nuclei, the more number of energetic photons are produced after the system reaches the maximum density, at the expansion stage. Therefore, the photon-production data for heavy colliding nuclei might provide some information on the in-medium NN interaction during the time evolution of the heavy-ion reaction. (orig.)