Köln 2004 – scientific programme
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HK: Physik der Hadronen und Kerne
HK 18: Instrumentation and Applications II
HK 18.3: Talk
Tuesday, March 9, 2004, 16:00–16:15, C
Performance of the Trigger System of the HADES Detector in C+C reactions at 1-2 AGeV — •Jörg Lehnert1, Alberica Toia1, Roukaia Djeridi1, Ingo Fröhlich1, Wolfgang Koenig2, Wolfgang Kühn1, Tiago Perez1, James Ritman1, Daniel Schäfer1, and Michael Traxler2 — 1II. Physikalisches Institut Univ. Gießen — 2Gesellschaft für Schwerionenforschung Darmstadt
The HADES detector at GSI Darmstadt investigates the dilepton production in hadron and heavy ion induced reactions up to 2 AGeV. The second level trigger system (LVL2) is designed to reduce the event rate by selecting lepton pairs within a given invariant mass window. The hardware-based LVL2 consists of Image Processing Units (IPU) which perform pattern recognition to detect lepton signatures in different subdetectors and a Matching Unit (MU) which combines the position and momentum information of these signatures into tracks to select events with lepton pairs of given invariant mass.
Since the recognition of Cherenkov rings is the most selective algorithm of the trigger, its behavior has been studied with the help of simulations and by comparing it to the offline analysis algorithm. This allowed to study and optimize the performance of the second level trigger and to improve the analysis of the dilepton content of the analyzed C+C reaction at 1-2 AGeV in terms of efficiency and purity of the signal. Results collected during the experiment runs in November 2001 and November 2002 are presented.