Data Preprocessor and Compactor for the Soudan 2 Nucleon Decay Experimet

This paper describes a prototype preprocessor data-compaction system for the Soudan 2 proton decay search experiment. The Soudan 2 experiment will have nore than three million potential data words per event to examine, while less than one percent of these data words will have valid data for typical events. In an effort to reduce the amuount of data to be stored and analyzed, a data preprocessor was developed which scans the data words. If a data word is valid (ADC count above a preset threshold), that data word is passed to the host computer for experiment monitoring and storage on magnetic tape. To obtain fast data compression, a hardware comparator is used. The hardware comparator places valid data into a FIFO (first in first out stack) where the host computer can acquire the data through CAMAC. The comparator and FIFO are controlled by a inicroprocessor (8086 CPU), and the microprocessor is programnmed for decisionmaking and comnmunication between the compactor, CAMAC, the host computer and a local terminal.