HADES — A High Acceptance DiElectron Spectrometer

A High Acceptance DiElectron Spectrometer (HADES) has been proposed at the SIS accelerator of GSI in order to measure e + e − pairs produced in proton, meson and heavy ion induced collisions. HADES will be able to operate at the highest luminosities available at SIS in an environment of high hadron and photon background. A Ring Imaging Cerenkov Counter (RICH) serves for electron identification. Momentum measurement is achieved with a magnetic spectrometer consisting of superconducting toroidal coils and mini drift chambers for tracking. Arrays of pre-shower detectors and TOF wall are positioned behind the drift chambers for electron trigger purposes and for measuring the charged particle multiplicity. The detector features have been investigated in detailed simulations. The expected performance of the system in terms of efficiency, resolution and residual background are presented.