Evidence for thermal equilibration in multifragmentation reactions probed with bremsstrahlung photons - art. no. 022701

The production of nuclear bremsstrahlung photons (E-gamma > 30 MeV) has bee n studied in inclusive and exclusive measurements in four heavy-ion reactio ns at 60A MeV. The measured photon spectra, angular distributions, and mult iplicities indicate that a significant fraction of the hard photons is emit ted in secondary nucleon-nucleon collisions from a thermally equilibrated s ystem. The observation of the thermal component in multifragment Ar-36 + Au -197 reactions suggests that the breakup of the thermalized source produced in this system occurs on a rather long time scale.