HADES, the new electron-pair spectrometer at GSI

The High Acceptance DiElectron Spectrometer HADES is presently set up at GSI, Darmstadt, for the systematic study of hadron properties inside nuclear matter. Resonance widths and effective masses of vector mesons as well as electromagnetic transition formfactors of neutral mesons and baryon resonances will be investigated in the low in variant mass region M inv ≤ 1 GeV/c 2 with a resolution Δ M inv /M inv ≅ 1% (σ).