THE CALIBRATION AND MONITORING-SYSTEM FOR THE PHENIX LEAD-SCINTILLATOR ELECTROMAGNETIC CALORIMETER

The calibration and monitoring system for the PHENIX lead-scintillator electromagnetic calorimeter is described along with the experience ob tained in using this system to calibrate calorimeter modules with cosm ic rays. The system is based on a UV laser which delivers light to eac h module through a series of optical fibers and splitters that is moni tored at various points using silicon and vacuum photodiodes. Results are given from a prototype system based on a nitrogen laser which was used to monitor the stability of several modules, as well as to set th e gains of the phototubes and establish the energy calibration of all calorimeter modules before installation into the final detector. A des cription of the final system to be used in PHENIX, based on a high pow er YAG laser, is also given.