Trigger and data acquisition system for the N-N experiment

The trigger and data acquisition system for the N-N experiment at the Institute Laue-Langevin at Grenoble is described along with CAMAC modules especially designed for this experiment. The trigger system is organized around three logical levels; it works in the presence of a high level of beam-induced noise, without beam pulse synchronization, looking for a very rare signal. The final trigger rate is 4 Hz, not very different from the beam off rate, while the trigger efficiency for the antineutron annihilation detection is >0.7. The data acquisition is based on a MicroVAX II computer, in a cluster with four VaxStations, interfaces to CAMAC, and uses a modified version of the DAQP software developed at CERN. The system, has been working for a year with high efficiency and reliability.<
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