Understanding the Performance of CMS Calorimeter

1. Understanding the Performance of CMS Calorimeter Seema Sharma,TIFR (On behalf of CMS HCAL) CMS Calorimeter

2. CMS Calorimeter

3. CMS Calorimeter HCAL : Scintillator-Brass Sampling Calorimeter 2-3 longitudinal samplings from 17-19 layers of Scnt. ECAL: PbWO4 Crystal Homogeneous Calorimeter of ~26 Χ0 CMS Calorimeter

4. TB2004 Setup • 2 wedges of HCal Barrel • 2 slices of HCal endcap • 6-trays of HO for 3 rings • Mock-up of CMS magnet • Tail catcher iron • 7 X 7 ECal crystal matrix • Mock-up of material between ECal and HCal • Beam line trigger counters CMS Calorimeter

5. HO HB HE pivot beam HCAL on a Table Pivot of table = IP at LHC A phi slice of CMS HCAL ECAL CMS Calorimeter

6. ECAL Module CMS Calorimeter

7. Hadron Calorimeter HB2 HO HB1 VM CMS Calorimeter

8. Readout Configuration CMS Calorimeter

9. Beam Line Counters WC-A WC-B S1 S2 S3 S4 WC-C CMS Calorimeter

10. WC A,B,C V3,V6 CK2 80 GeV/c ECAL VM CK3 HCAL SCI_VLE Beam Line at H2 VLE tag against punchthrough muon P-ID: CK2- electron CK3- pion / kaon / proton V3, V6, VM – muon WC single hit to reject interaction in beam line CMS Calorimeter

11. Data Sets CMS Calorimeter

12. Source Calibration Source position • Done using Co60 source at the tip of a stainless steel wire. • With the source at ηboundaries, adjacent tiles receive some signal. • Contributions from adjacent tiles are added. CMS Calorimeter

13. Source Calibration (continued…) Source position • Calibration constant corresponds to a least square fit across the tile. • An iterative procedure is followed to get final calibration constants. CMS Calorimeter

14. Calibration with Muons at 150 GeV • Fit the pedestal distribution with a Gaussian. • Fit muon signal with a convolution of Landau and Gaussian distributions. • Float the relative contribution of the pedestal. • The peak of the fitted LandauGauss function is used as the calibration constant. CMS Calorimeter

15. Correlation Between Source and Muon Calibration • A straight line fit through all the points gives χ2/ndf of 18. • Some correlation is observed between the calibration constants • obtained using the two methods. CMS Calorimeter

16. Energy Measurement 300 GeV 150 GeV HB m 30 GeV 100 GeV HB e- ECAL ECAL CMS Calorimeter

17. Comparison with GEANT4 Simulation (LHEP) CMS Calorimeter

18. Energy Measurements at Low Energies CMS Calorimeter

19. π/e Response LHEP without scintillation saturation effect (Birks’ law) shows a reasonable agreement with data for EC+HB combined system. Need more beam clean up and better understanding of systematic errors before making more definitive conclusion, especially HB alone data, (not shown today) … pions proton CMS Calorimeter

20. 0.92 GeV measured Energy Resolution Larger noise than HB1 (0.4GeV in 3x3) because of individual layer readout in HB2. CMS Calorimeter

21. Longitudinal Shower Profile Event selection – MIP in ECAL. Two G4 physics models show difference at high energy. CMS Calorimeter

22. Summary • Test beam data were taken during 2004 with the final(?) electronics modules. • A large data set was collected with pions and electrons with the energies in the range 3-300 GeV with proper particle identification especially at low energies. • Test beam results are compared with the GEANT4 simulations. LHEP physics list describes the data most closely. • Energy response and resolution obtained from various physics lists match closely and only difference is seen in longitudinal shower profiles at high energies. • HCAL team plans to continue with testing the calorimeter modules with improved VLE beam and better PID. CMS Calorimeter