Performance of the electronics for the Sudbury Neutrino Observatory

The Sudbury Neutrino Observatory (SNO) is a second generation solar neutrino water Cherenkov detector using 1000 tonnes of D/sub 2/O viewed by almost 10000 20 cm photomultiplier tubes. The observatory, located 6800 ' below ground in INCO Ltd's Creighton mine near Sudbury Ontario, recently began full time operation. The SNO electronics provides deadtimeless sub-ns time and 0.1-1000 photoelectrons (pe) of charge measurement. While the solar neutrino event rate is low, the electronics must handle backgrounds in excess of 1 kHz and bursts in excess of 1 MHz. The integrated trigger system handles multiple independent triggers via 10000:1 analog sums. The electronics use three full custom integrated circuits plus standard commercial chips. There are 14 different printed circuit boards mounted in custom crates and racks. The DAQ interface is VME compatible.