Results in online data processing with the data acquisition system of the ALEPH TPC

The ALEPH detector collects data on e/sup +/e/sup -/ collisions provided by the LEP (Large Electron Positron Collider) storage ring at CERN. The ALEPH TPC (time projection chamber) data acquisition (DAQ) system is based on 768 triple width Fastbus modules, and 36 double width Fastbus modules. The performance and the implementation of the TPC DAQ system are presented. It is shown how online data processing is used to obtain a substantial reduction of the data volume.<
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