Optical and Scintillation Properties of Lead Tungstate Crystals: a statistical approach

The Compact Muon Solenoid (CMS) is one of the five experiments foreseen at the Large Hadron Collider at CERN. The Electromagnetic Calorimeter (ECAL) of CMS will be the largest crystal calorimeter ever constructed. Over 34000 lead tungstate (PbWO4) crystals representing more than half of the barrel part of the ECAL were fully analyzed till present for their optical and scintillation properties as a part of the ECAL modules construction activity. This huge quantity of information may also be used in order to emphasize general properties of the material and find possible correlations between optical and scintillation parameters measured on large crystals produced at industrial scale. Such correlations proved to be useful tools for the crosscheck between LY and optical transmission measurements, the improvement of the ECAL crystals inter-calibration precision and for tuning the quality of crystals produced at industrial scale.