A laser-based calibration system for the CDF plug upgrade calorimeters

A laser-based calibration and monitoring system for the plug upgrade calorimeter is described. A pulsed nitrogen ultraviolet laser excites all of the about 1000 photomultiplier tubes (PMTs) in each plug calorimeter. The light is focused into a quartz fiber and routed first to a primary distributor (PD) and from there to 12 secondary distributors (COWs), which feed the individual PMTs. The system will be used as a debugging tool during calorimeter rigging and will help the wire source calibration system in initially equalizing the PMT gains. In addition, an LED imbedded in each COW can set a continuous DC level on each PMT, allowing for PMT burn-in and gain conditioning.