Development of low-mass drift chambers for the HADES spectrometer

The High Acceptance Di-Electron Spectrometer (HADES) is a detector arrangement combined with a superconducting toroid for lepton pair spectroscopy presently built up at GSI (Darmstadt). HADES is designed to cope with the high-multiplicity environment of heavy ion collisions at 1AGeV and intensities of up to 108 beam particles per second and central event rates of 105s−1. The detector has a geometrical acceptance of almost 50% for e+e− pairs and a mass resolution of 0.8% for ρ and ω mesons. Four low-mass drift chamber systems, two before and two behind the magnet, serve for charged particle track reconstruction. Design aspects of the drift chambers and first results from beam tests are presented.