Emission temperatures and freeze out densities from light particle correlation functions in Au+Au collisions at 1 A GeV

A study of emission temperatures extracted from excited state populations and of freeze out radii from light particle intensity interferometry is presented. Three high resolution dE-E-Hodoscopes with a total of 216 detectors are combined with the ALADiN setup in order to study Au+Au collisions at 1 A GeV. In contrast to measurements with the isotope thermometer the extracted apparent temperatures do not vary with impact parameter thus with excitation energy. From the extracted radii a freeze out density was determined which decreases from $0.2\rho_0$ for the most peripheral to less than $0.1\rho_0$ for the most central collisions. A density--dependent feeding correction is applied to the different temperature measurements.