Dilepton spectra from HADES

Abstract

In-medium effects on K and ω mesons, which have been reported in the past, confirm the importance of experiments which study hadron properties in excited and normal nuclear matter with penetrating probes. The HADES experiment at GSI uses proton and nuclear beams to record experimental data on elementary and nuclear collisions. This second generation high acceptance detector system allows to detect and separate electron-positron pairs in a high multiplicity environment with a hadron suppression factor of 10−9. Preliminary results on dilepton production in C+C collisions at 2 GeV per nucleon are presented. The comparison with UrQMD calculation shows agreement at the 20% level except at invariant masses below 100 MeV where deviations of up to 50% have been traced to shortcomings in the analysis.