EVIDENCE FOR AN ANTICORRELATION EFFECT IN THE PRODUCTION OF HARD PHOTONS AND PREEQUILIBRIUM PROTONS IN HEAVY ION COLLISIONS

An exclusive study of the hard photon production in the reaction $^{40}\mathrm{Ar}$+$^{51}\mathrm{V}$ at 44 MeV/nucleon has been carried on with the $4\ensuremath{\pi}$ multidetector MEDEA. An anticorrelation effect in the emission of very energetic photons and protons has been observed for the first time. This is a strong indication for the first-chance $n\ensuremath{-}p$ bremsstrahlung production mechanism.