Performance of the Lead/Liquid Argon Shower Counter System of the Mark II Detector at SPEAR

Although the cryogenic and electronic problems of a large lead/liquid argon shower system such as in the Mark II require considerable attention to detail during design, construction, and set-up, the performance of a large system equals that of small test systems and agrees well with reasonable expectations. The shower detector system of the Mark II has been mechanically, cryogenically, and electronically very reliable during eighteen months of normal operation at SPEAR. Performance has provided a good compromise among the various demands upon shower detection. The system has enabled physics measurements previously untenable to other e+e- detectors.