2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/81343The 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.5 pages, 4 figures, submitted to Physical Review LettersNuclear Experimenttext