Multipole Expansion of Bremsstrahlung in Intermediate Energy Heavy Ion Collisions

Using a multipole expansion of the radiated field generated by a classical electric current, we present a way to interprete the bremsstrahlung spectra of low energy heavy ion collisions. We perform the calculation explicitely for the system ^{12}C+ ^{12}C at 84AMeV and compare the result with the experimental data of E. Grosse et al. Using simple model assumptions for the electromagnetic source current we are able to describe the measured data in terms of coherent photon emission. In this context, the information contained in the measured data is discussed.