First Results from the SLD Silicon Calorimeters

The small-angle calorimeters of the SLAC Large Detector (SLD) were successfully operated during the recent SLAC Linear Collider (SLC) engineering run. The Luminosity Monitor and Small-Angle Tagger (LMSAT) covers the angular region region between 28 and 68 mrad from the beam axis, while the Medium-Angle Silicon Calorimeter (MASC) covers the 68-190-mrad region. Both are silicon-tungsten sampling calorimeters; the LMSAT employs 23 layers of 0.86 X/sub 0/ sampling, while the MASC has 10 layers of 1.74 X/sub 0/ sampling. The authors present results from the first run of the SLC with the SLD on beamline. The calorimeters and electronics performed reliably with no major problems during a 15-week period with no access. Bhabha events were easily identified, and the 36-68-mrad region of the LMSAT was found to be approximately=100% efficient and background-free, which made it possible to measure L to be 14.4+or-0.5 nb/sup -1/ for this run.<>