The IMB nucleon decay detector data acquisition and triggering system

The data acquisition hardware and software for a large deep underground nucleon stability detector is described. Such hardware must process the information from an array of greater than 2000 photomultiplier tubes in real time, in the presence of a cosmic-ray background of about three events per second. A hierarchical scheme of processors and memory is used to perform real time pattern recognition and event identification with negligible impact on dead time. Fast, but crude, algorithms have been developed to reduce the offline analysis work load without endangering any of the alternative physics objectives, such as neutrino oscillations or neutrino burst detection. (8 refs).