The multi-level trigger system of the HADES detector

Collaboration
Jul, 2001

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Abstract: (AIP)
HADES is a second-generation di-electron spectrometer currently under commissioning at GSI Darmstadt. Its multi-level trigger system allows to select dilepton events in hadron- and heavy-ion induced reactions, leading to a suppression of events lacking lepton pairs by up to 4 orders of magnitude. The first level trigger is based on the charged particle multiplicity measured in a time-of-flight wall. The second level trigger performs dilepton candidate selection by exploiting electron signatures using information from a hadron blind RICH detector with gas radiator, a detector sensitive to electromagnetic showers as well as a TOF wall. Exploiting azimuthal and polar angular correlations after deflection in the toroidal magnetic field, lepton pair candidates within a selectable range of invariant masses can be identified. Programmable logic devices, such as FPGAs and CPLDs, as well as DSPs are widely used to gain flexibility and provide common solutions. A third level trigger is foreseen which yields further suppression of background by exploiting tracking information from the drift chambers. The trigger concept as well as first results from the commissioning runs are presented.
  • talk: Berkeley 2001/07/30
  • trigger: multiple
  • charged particle: multiplicity
  • dilepton: signature
  • RICH
  • angular correlation
  • electronics
  • track data analysis
  • magnetic detector: HADES
  • Darmstadt SIS