Calorimeter1 Understanding the Performance of CMS Calorimeter Seema Sharma,TIFR (On behalf of CMS HCAL)

Calorimeter2

Calorimeter3 HCAL : Scintillator-Brass Sampling Calorimeter 2-3 longitudinal samplings from layers of Scnt. ECAL: PbWO 4 Crystal Homogeneous Calorimeter of ~26 Χ 0

Calorimeter4 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

Calorimeter5 HCAL on a Table HB HE HO ECAL pivot beam Pivot of table = IP at LHC A phi slice of CMS HCAL

Calorimeter6 ECAL Module

Calorimeter7 Hadron Calorimeter HO VM HB1 HB2

Calorimeter8 Readout Configuration

Calorimeter9 Beam Line Counters WC-A WC-B WC-C S1 S4 S3 S2

Calorimeter10 80 GeV/c SCI_VLE CK 2 CK 3 WC A,B,C HCAL ECAL V3,V6 VM P-ID: CK2- electron CK3- pion / kaon / proton V3, V6, VM – muon VLE tag against punchthrough muon WC single hit to reject interaction in beam line Beam Line at H2

Calorimeter11 Data Sets

Calorimeter12 Done using Co 60 source at the tip of a stainless steel wire. With the source at η boundaries, adjacent tiles receive some signal. Contributions from adjacent tiles are added. Source Calibration Source position

Calorimeter13 Calibration constant corresponds to a least square fit across the tile. An iterative procedure is followed to get final calibration constants. Source Calibration (continued…) Source position

Calorimeter14  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. Calibration with Muons at 150 GeV

Calorimeter15 Correlation Between Source and Muon Calibration A straight line fit through all the points gives χ 2 /ndf of 18. Some correlation is observed between the calibration constants obtained using the two methods.

Calorimeter GeV150 GeV 100 GeV 30 GeV HB ECAL HB  e-e- Energy Measurement

Calorimeter17 Comparison with GEANT4 Simulation (LHEP)

Calorimeter18 Energy Measurements at Low Energies

Calorimeter19 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) … proton pions π/e Response

Calorimeter20 Energy Resolution 0.92 GeV measured Larger noise than HB1 (0.4GeV in 3x3) because of individual layer readout in HB2.

Calorimeter21 Two G4 physics models show difference at high energy. Event selection – MIP in ECAL. Longitudinal Shower Profile

Calorimeter22 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 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.