Thermodynamic observables in gold on gold collisions

Thermodynamic observables characterizing the breakup states of spectator decays in 197Au + 197Au collisions at relativistic bombarding energies were deduced from data collected with the ALADIN spectrometer at SIS. The interferometry with light charged particles confirms the low density of the breakup configuration. Temperatures deduced from the new isotope thermometer TBeLi exhibit a pronounced rise at high excitation energy and are consistent with the previously studied THeLi. The determination of the excitation energy at breakup with calorimetric methods is difficult because of non-equilibrium contributions to the kinetic energies of nucleons and fragments