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Understanding the Performance of CMS Calorimeter. Seema Sharma,TIFR (On behalf of CMS HCAL). CMS Calorimeter. HCAL : Scintillator-Brass Sampling Calorimeter 2-3 longitudinal samplings from 17-19 layers of Scnt. ECAL : PbWO 4 Crystal Homogeneous Calorimeter of ~26 Χ 0.

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understanding the performance of cms calorimeter

Understanding the Performance of CMS Calorimeter

Seema Sharma,TIFR

(On behalf of CMS HCAL)

CMS Calorimeter

slide3

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

slide4

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

slide5

HO

HB

HE

pivot

beam

HCAL on a Table

Pivot of table

= IP at LHC

A phi slice of

CMS HCAL

ECAL

CMS Calorimeter

ecal module
ECAL Module

CMS Calorimeter

hadron calorimeter
Hadron Calorimeter

HB2

HO

HB1

VM

CMS Calorimeter

readout configuration
Readout Configuration

CMS Calorimeter

beam line counters
Beam Line Counters

WC-A

WC-B

S1

S2

S3

S4

WC-C

CMS Calorimeter

slide10

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

data sets
Data Sets

CMS Calorimeter

slide12

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

slide13

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

slide14

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

slide15

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

slide16

Energy Measurement

300 GeV

150 GeV

HB

m

30 GeV

100 GeV

HB

e-

ECAL

ECAL

CMS Calorimeter

slide19

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

slide20

0.92 GeV

measured

Energy Resolution

Larger noise than HB1 (0.4GeV in 3x3) because of individual layer readout in HB2.

CMS Calorimeter

slide21

Longitudinal Shower Profile

Event selection – MIP in ECAL.

Two G4 physics models show difference at high energy.

CMS Calorimeter

slide22

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