Soudan 2 Data Acquisition and Trigger Electronics

The 1.1 kton Soudan 2 calorimetric drift-chamber detector is read out by 16K anode wires and 32K cathode strips. Preamps from each wire or strip are bussed together in groups of 8 to reduce the number of ADC channels. The resulting 6144 channels of ionization signal are flash-digitized every 200 ns and stored in RAM. The raw data hit patterns are continually compared with programmable trigger multiplicity and adjacency conditions. The data acquisition process is managed in a system of 24 parallel crates each containing an Intel 80C86 microprocessor, which supervises a pipe-lined data compactor, and allows transfer of the compacted data via CAMAC to the host computer. The 80C86's also manage the local trigger conditions and can perform some parallel processing of the data. Due to the scale of the system and multiplicity of identical channels, semi-custom gate array chips are used for much of the logic, utilizing 2.5 micron CMOS technology.