Shown above is a schematic view of the HADES detector system [Summary article EPJA].  The system is divided into 6 identical sectors surrounding the beam axis; the picture above shows a two-dimensional slice to demonstrate HADES' large angular acceptance, which stretches between 16 and 88 degrees.  HADES is comprised of the following components:

  • A diamond START and VETO system, composed of two scCVD and pcCVD diamond sensors placed 2 cm upstream and 50 cm downstream, respectively, of the HADES segmented target.
  • A Ring Imaging Cherenkov (RICH) gas radiator for electron identification with a position sensitive photon detector, covering the full azimuthal range.  A high angular resolution of the RICH is needed to assure that the lepton direction deduced from the detector hits can be match to the one deduced from the tracking system (see below).
  • Two sets of Multiwire Drift Chambers (MDC) before and after the magnetic field region form HADES tracking system.  It allows a precise determination of a track path inside a magnetic field and accurate measurement of the specific energy loss needed for particle identification. 
  • A superconducting toroidal magnet with 6 coils in separate vacuum chambers.  The coil cases are aligned with the frames of the MDC's to reduce dead space in the spectrometer.  The magnet provides the momentum kick necessary to obtain charged particle momenta with a resolution of about 1%.
  • A multiplicity/electron trigger array consisting of granular Pre-shower detectors at forward angles (between 18° and 45°) and two time of flight walls: a scintillator based time-of-flight wall (TOF) at angles above 45° and the RPC wall built from resistive plate chambers at angles below 45°.