Thermal photon-IMF anticorrelation: a signal of prompt multifragmentation?

The mechanism responsible for IMF emission in central ${}^{58}$Ni + ${}^{197}$Au reactions at 30 and 45 MeV/nucleon is investigated by looking at the thermal bremsstrahlung photon production. An IMF - photon anticorrelation signal is observed, for central collisions, at 45 MeV/nucleon with IMF velocity around the center of mass value. This observation is proposed as an evidence for prompt nuclear fragmentation events.