Bochum 1998 – wissenschaftliches Programm
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HK: Hadronen und Kerne
HK 56: Postersitzung
HK 56.66: Poster
Mittwoch, 18. März 1998, 17:00–19:00, Foyer
The HADES Trigger System — •J. Lehnert, W. K"uhn, C. Lichtblau, E. Lins, M. Petri, and J. Ritman — II. Physikalisches Institut, Heinrich-Buff-Ring 16, 35392 Gie"sen for the HADES Collaboration
The HADES detector system is designed to investigate high mass dielectron events in hadron and heavy ion induced reactions. The extremely low production rates require a selective three level trigger for event reduction.
The first level multiplicity trigger initiates the detector readout at a rate of 105 events per second. The second level trigger(LVL2) achieves an event reduction by a factor of 100. It performs pattern recognition for electron signatures (Cherenkov rings and electromagnetic clusters) on large detector pad planes. To provide a trigger decision each 10 microseconds, massively parallel arrays of FPGAs as well as pipelined algorithms are used. Online data processing for time of flight electron/hadron discrimination is done by high performance DSP’s. A matching unit correlates the electron signatures from the several subdetectors.
The third level trigger matches LVL2 electron candidates with additional drift chamber information and gains another factor of 10 in event reduction.
The trigger concept and prototypes of the trigger and readout boards will be presented.
*supported by BMBF (contract number 06GI849I1(TP4) ) and by GSI