Hard photon intensity interferometry in heavy ion reactions

Intensity correlations between hard photons produced in heavy ion collisions have been measured for [ital E][sub [gamma]][ge]25 MeV in the reaction [sup 86]Kr+[sup nat]Ni at 60[ital A] Mev bombarding energy. The observed correlation pattern is interpreted in terms of intensity interference. A correlation length of [ital C][sub [sigma]]=16[plus minus]4 MeV is found and the deduced photon source extent is discussed.