1. Cosmic Rays Data Analysis with CMS-ECAL Mattia Fumagalli (Università di Milano Bicocca) CIAO!

2. Mattia Fumagalli - Summer Student Session 20082 Brief Review of CMS-ECAL. BARRELL: 36 supermodules ENDCAPS: 2 dees each ECAL BARREL: 61200 PbWO4 scintillating crystals equipped with APD Crystals point to the Interaction Vertex

3. Mattia Fumagalli - Summer Student Session 20083 CMS-ECAL Calibration Strategy PRECALIBRATION: 120 GeV electron TEST BEAM (2006): 1/4 of the ECAL barrel. 0.3% in reproducibility Cosmic Muons at Point H4: precision 1.3% to 2% depending of η. To have… FINAL CALIBRATION! PHYSICS EVENTS @ LHC: Phi-Symmetry and Calibration with Pions Z  ee and W  e processes: intercalibration of different regions absolute Energy scale setting. we need

4. Mattia Fumagalli - Summer Student Session 20084 In Situ Calibration with Cosmics CRUZET RUNS: no magnetic field almost every part of CMS working ~70M events taken in 3 sessions (5-7 days each) (4th CRUZET coming!) INTERCALIBRATION: Independent check of the previous Calibrations with the detector already In-Situ! Tracker ECAL HCAL Muons Drift Tubes

5. Mattia Fumagalli - Summer Student Session 20085 Muon Events at ECAL BEST EVENTS ! Cluster made of just one Crystal (GOLDEN MUONS) SEED CRYSTAL Cosmic Muons are Minimum Ionizing Particles _ No Electromagnetic Shower _ Energy deposited just in the hit Crystals _ Energy proportional to Path Lenght

6. Mattia Fumagalli - Summer Student Session 20086 Two Cluster Events Delta  between clusters > 90° Impact Parameter < 10 cm Cosmic Muons that point to the Interaction Vertex Muon Path almost parallel to the Crystal Axis   Interaction Vertex Impact Parameter NOT IN SCALE! Selecting the Events

7. Mattia Fumagalli - Summer Student Session 20087 Energy and Paths GOAL! Cross Check of the ECAL Pre-Calibration According to the Behaviour of a MIP Peak at 0.012 GeV/cm  Comparison between the Energy deposited and the Path Length (Inter)Calibration coefficients Inverse Matrix Tecnique ECAL

8. Mattia Fumagalli - Summer Student Session 20088 Occupancy Statistics on each Crystals   Energy Distribution on the ECAL SHAFT

9. Mattia Fumagalli - Summer Student Session 20089 What’s good…and what’s bad! Low Statistics, depending on eta. Calibration not possilbe everywhere Data from other parts of CMS Possibility of Track Reconstruction

10. Mattia Fumagalli - Summer Student Session 200810 Future Work Fully Exploit the Statistics Implementation of a Calibration Algorithm Coefficients to cross check previous Calibrations …and Thanks! GRAZIE!