The CMS Electroagnetic Calorimeterthe CMS电磁量能器.pptVIP

The CMS Electromagnetic Calorimeter Roger Rusack The University of Minnesota On behalf of the CMS ECAL collaboration Detector Overview Goals Lead Tungstate Crystals Construction Overview Preshower Crystals and crystal production. Photodetection Readout Overview Front-End Electronics Optical Data Links Cooling Cooling Test beam : precalibration Monitor Laser System Monitoring Results from Test beam with final electronics. ?????????????????????????? ICHEP Beijing 2004 – R. Rusack MUON BARREL CALORIMETERS Silicon Microstrips Pixels ECAL Scintillating PbWO4 crystals Cathode Strip Chambers ( ) CSC Resistive Plate Chambers ( ) RPC Drift Tube Chambers ( ) DT Resistive Plate Chambers ( ) RPC SUPERCONDUCTING COIL IRON YOKE TRACKER MUON ENDCAPS HCAL Plastic scintillator/brass sandwich High Resolution calorimetry:  Stochastic term 2.7%, Constant term 0.5%, Noise term 150 – 220 MeV. Large volume: 75,848 crystals covering |h| 2.6. 90.8 tons of crystals or 10.9 m3. Operated inside a 4T magnetic field. In a radiation environment with an integrated dose of: 1013 neutrons/cm2 and 1 kGy at h = 0 to 2×1014 neutrons/cm2 and 50 kGy for h = 2.6. 40 MHz bunch crossing rate. Operate at 18o C – Temp dependence = -2.2%/OC. Radiation length – 0.83 cm Molière radius – 2.2 cm. Fast light output – 80% in 25 nsec. Relative Light Yield – 1.3% NaI  No long-lived radiation damage. But short-lived metastable color centers created by radiation – careful monitoring Transmission Emission 350 nm 10 crystals Submodule Dee 138 Supercrystals 36 Supermodules 4 Dees Module Barrel 61,200 PbWO4 crystals Readout with 122,400 APD’s Endcap 14684 crystals readout with VPT’s. Two-layer silicon preshower detector placed in front of the endcap calorimeters 2 Xo absorber 1 Xo absorber 2mm silicon strips to separate g’s from po’s and for vertex identification. Transmission at 420nm Light Yield All crystals are tested for: Radiation Hardness, Light Yie