Breakup density in spectator fragmentation

Abstract Proton–proton correlations and correlations of protons, deuterons and tritons with α particles from spectator decays following 197 Au + 197 Au collisions at 1000 MeV per nucleon have been measured with two highly efficient detector hodoscopes. The constructed correlation functions, interpreted within the approximation of a simultaneous volume decay, indicate a moderate expansion and low breakup densities, similar to assumptions made in statistical multifragmentation models.