Aerogel Čerenkov Detectors
The Photonis XP PMTs are inserted into a modified xxx shield (see figure)
The PMTs are held in place by weather stripping.
Without further shielding, the stray field at the detector location is approximately 5 gauss. During the 2005 run, an iron bunker was built around the entire detector stack. This reduced the stray field to roughly 2.5 gauss, still enough to significantly degrade PMT collection efficiency. For compensation of this residual field, a bucking coil had been wrapped around the PMTs. This coil consisted of ...
LED Calibration System
For the 2005 run of E01-011, only three segments, one in each layer, had been equipped with an LED. These were pulsed with short amplified NIM level pulses.
For the 2009 run of E05-115, a new pulsing system will be employed. This system consists of three LED pulsers. Each pulser will couple into seven optical fibers that will carry the light to the individual detector segments.
The LED driver circuit is based on the design of J.S. Kapustinsky and colleagues .
The fibers are ~ 1 m long Optical Grade Plastic Light Guide 1000 Micron with 1 Fiber, Edmund Optics NT02-536; this is ESKA acrylic fiber optics developed and manufactured by Mitsubishi.
The following LEV voltages allow for single electron calibrations
 J .S . Kapustinsky, Nucl. Instr. Meth. A241 (1985) 612-613 doi:10.1016/0168-9002(85)90622-9