Bochum 1998 – scientific programme

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HK: Hadronen und Kerne

HK 13: Instrumentation II, Data Acquisition Systems

HK 13.5: Talk

Monday, March 16, 1998, 18:00–18:15, A

A Trigger Distribution System for the HADES Detector — •E. Lins, W. K"uhn, J. Lehnert, M. Petri, and B. Krieg — II. Physikalisches Institut, Universit"at Gie"sen, Heinrich-Buff-Ring 16, D-35392 Gie"sen for the HADES Collaboration

The dielectron spectrometer HADES at GSI consists of four sub-detectors with independent readout electronics. A multilevel trigger system provides a separate trigger signal for each trigger level. Since these signals are used to initiate the readout of the event data, i.e. pushing the read out data into the pipelined HADES data acqusition, a dedicated trigger distribution system must connect the various HADES subsystems. For the first two trigger levels a hardware trigger distribution system has been selected, based on a trigger bus distributed among several Detector Trigger Unit (DTU) modules. Due to different requirements of the particular readout electronics on the trigger system, the DTU modules have been designed as configurable Xilinx FPGA based VME-modules. They provide a common interface to the HADES trigger bus and a detector specific interface to the readout electronics. The HADES trigger system distributes a trigger signal, a trigger code, an event id as well as control and handshake signals for the first two trigger levels over two bidirectional differential busses. The trigger distribution concept will be discussed and then the electronics, which has been developed and the experiences gained during the last test beamtime will be presented.

* supported by BMBF under contract no. 06GI849I1(TP4)