Performance of the lead/liquid argon shower counter system of the mark II detector at SPEAR

The shower counter system of the SLAC-LBL Mark II detector is a large lead-liquid argon system of the type pioneered by Willis and Radeka (1974); however, it differs in most details and is much larger than other such detectors currently in operation. It contains, for example, 8000 liters of liquid argon and 3000 channels of low noise electronics, which is about eight times the size of the system of Willis et al. in the CERN ISR. The authors report, with little reference to design, on the operation and performance of the Mark II system during approximately a year and a half of operation at the Stanford Linear Accelerator Center's e/sup +/-e/sup -/ facility, SPEAR. The design and construction of the system have previously been described, Abrams et al. (1978) and a detailed discussion of all aspects-design, construction, operation, and performance-is in preparation. (8 refs).