Dresden 2000 – scientific programme

Parts | Days | Selection | Search | Downloads | Help

HK: Physik der Hadronen und Kerne

HK 13: Postersitzung / Instrumentation und Anwendungen

HK 13.38: Poster

Thursday, March 23, 2000, 10:15–12:45, B 117

The Three Level Trigger System of the HADES Detector — •R.J. Becker, I. Fröhlich, W. Kühn, J. Lehnert, C. Lichtblau, E. Lins, M. Petri, H.-W. Pfaff, M.-A. Pleier, J. Ritman und M. Traxler — II. Physikalisches Institut, Universität Gießen

The HADES detector at GSI, Darmstadt will investigate the production of e⁺e⁻ pairs in hadron and heavy ion induced reactions up to 2 AGeV. The online trigger system (raw event rate 10⁶ Hz) is designed to reduce the event rate by a factor of 10000.

The first level trigger is based on the charged particle multiplicities detected in the TOF wall and reduces the event rate by a factor 10. The hardware based second level trigger selects e⁺e⁻ pairs within an invariant mass window, leading to a rate reduction of 100. A software based third level trigger employs fast tracking algorithms, yielding to a further event rate reduction of 10.

The second level trigger is implemented with FPGAs and CPLDs, which are programmed by VHDL-code as well as high performance DSPs (SHARC 21060). Pipelined and massively parallel algorithms for fast pattern recognition (RICH, electromagnetic shower detection, TOF) are used to guarantee a trigger decision on average each 10 µs, processing raw data of approximately 3 GB/s. The whole system comprises 60 interconnected VME boards. Various features of the trigger and readout boards and experiences from recent beamtimes are presented. This work was supported in part by BMBF (06-GI-849-I TP4), NATO (SA.11-1-05-OUTREACH (CRG.960674)) and GSI (GIKÜHK).