Thermal Parameters in Heavy Ion Collisions at SPS and RHIC: Centrality Dependence

The centrality dependence of thermal parameters describing hadron multiplicities and intermediate-mass dilepton spectra in heavy-ion collisions at SPS and RHIC is analyzed. From hadron multiplicities we deduce evidence for strangeness saturation at high energy and maximum centrality. The dilepton spectra can be parameterized by a centrality independent temperature.