Architecture of the HERA-B data acquisition system

The HERA-B experiment was dedicated for the measurement of charge conjugation space inversion (parity) (CP)-violation in decays of neutral B-mesons and for investigating the physics of charmed particles. One of the experimental requirements is a highly selective on-line filtering of data due to high interaction rates and a low signal-to-background ratio. This demands a hierarchical trigger and a high bandwidth data acquisition system. The challenge for the data acquisition (DAQ) system is a readout free of deadtime, which requires an unprecedented speed of storing and processing the data. In this paper, we will outline the general architecture and hardware implementation of the HERA-B DAQ.