CMS: Hadronic Calorimetry

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CMS Hadronic Calorimetry
Jet/ Performance V.
Daniel Elvira
Fermilab (For
the CMS Collaboration)
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Outline

• Detector descriptions and physics motivation
• The Hcal Test Beam 2002 experiment noise, pulse
  shape, attenuation, single pion energy response
  resolution
• Monte Carlo studies on the HCal ability to
  measure jets, mass, missing transverse energy
• Monte Carlo production and Data Challenge 2004

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The CMS Detector
HF (extend to h5)
8.6 m
HB (hlt1.3)
HO
HE ( extend to h3)
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The CMS Physics
The search for the Higgs boson, SUSY particles,
new phenomena constitute the core of the CMS
physics program
HCal crucial tool for jet and measurements
(signature)
Example SM Higgs discovery channels
qq (H -gt ZZ/WW -gt llll, llnn) (120 lt mH lt 500)
H jet(H-gt gg), (mH lt 120) H-gt gg
inclusive, qqH (H-gtWW-gt llnn),
qqH (H-gttt-gt l t-jet), WH-gt ln gg, ttH (H-gtbb),
qqH (H-gt gg), WH-gt ln bb

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HB Calorimeter (central)
Sampling calorimeter brass (passive)
scintillator (active) Coverage
hlt1.3 Depth 5.8 lint (at h0)
segmentation f x h p resolution
120 / 0.087x0.087
17 layers longitudinally, f
x h 4 x 16 towers
Completed assembled
20o
f

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HO Calorimeter (outer)
Total number of lint till the last sampling layer
of HB is lt 8 HO 2 scint. layers around first m
layer (extend to11 lint )
Test Beam 2002
5 of a 300 GeV p energy is leaked outside the
HB HO improves p resolution by 10 at 300 GeV
linearity
Ring 0
Ring 2
Ring 1
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HE Calorimeter
Sampling calorimeter brass (passive)
scintillator (active) Coverage
1.3lthlt3 Depth 10 lint
segmentation f x h p resolution
120/ 0.087x0.087



19 layers longitudinally
20o
Completed, assembled, HE-1 installed



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HF Calorimeter
Steel absorbers, embedded quartz fibres // to the
beam Fast (10 ns) collection of Cherenkov
radiation. Coverage 3lthlt5
segmentation f x h Depth
10 lint 10o x 13 h towers
Fibre insertion finished by Nov 03
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HF Calorimeter
HF used to tag forward jets in qq (H -gt ZZ/WW
-gt llll, llnn) Higgs searches, to reduce QCD
background by a factor of 10.
HF acceptance for tagging quarks of ETgt30 GeV No
q 1 q 2 qs 0.47 0.46
0.07
120 at 50 GeV 20 at 400 GeV
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HCal 2002 Test Beam
Small scale experiment to demonstrate that HCal
works 49 ECal crystals, 144 HB channels, 16 HO
channels.
HO Panels
ECal 7x7 Crystal Matrix (movable)
Over 100 Million Events!
beam
m- 225 GeV e- 20,30,50,100 GeV p-
20,30,50,100, 300 GeV
Moving table
Read out with a 29.6 ns period
Aluminum Slab
2 HCal HB Modules
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HCal 2002 Test Beam
97 of energy contained in a 3x3 crystal matrix
99 of energy contained in a 5x5 HB tower matrix
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HCal 2002 Test Beam
Noise in HB
HB Pulse out of the QIE ( Charge
Integration Electronics)
1/Response attenuation as the light travels
longer distances to the QIE from central h towers
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HCal 2002 Test Beam
Measurement of HO muon signal for RPC trigger
(Goal use the HO as part of muon trigger)
225 GeV muon
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TB02 Simulation (OSCAR/G4 )
An accurate Monte Carlo simulation is critical
detector design calibration, data analysis
Validation of GEANT4/OSCAR by June03 for M.C.
production towards DC04 physics TDR)
Crystal 25
Based on 1-5,000 p- events onto the (h,f)(6,2)
tower of the HB and crystal 25 of the ECal matrix
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TB02 Simulation (OSCAR/G4 )
Angle view of the full TB02 detector
10 GeV electron
HO
ECal
100 GeV pion
Beam Line
HB
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TB02 p sE/E and e/p




50 GeV pions
Data energy resolution for 50 GeV pions (EcalHB,
no HO)
Pions showering in the crystals

Background subtracted pion peak
Muon background
Pion peak
sE/E 20.3
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TB02 p sE/E and e/p
Resolution
Linearity
Shape difference e/h (e.m. nuclear x-sec),
leakage?
The agreement is excellent in all the energy range
Data systematic error analysis in progress
Validate GEANT4 physics models
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Summary on TB Program

• Goals for the 2002 HCal testbeam,
• Operation of 144 channels at 33.79 MHz
• Absolute calibration using beam/source
• Determination of pulse shape
• Measurement of h attenuation
• Determination of Layer-0 weighting
• Measurement of muon signal (HO) for RPC trigger
• Control of HV, front end, and moving source
• have been met!

Move on to TB03... Repeat TB02 tests,more,
local synch in all channels, HB-HE boundary, m
signal for calibration, remote monitoring
analysis
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Jet Resolution
Squarks/gluinos of M500 GeV decaying to jets
PYTHIA CMSIM ORCA single jets (R0.5 cone
algorithm)
39 at 20 GeV 12 at 100 GeV
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Mass Resolution
gg -gt f -gt hh -gt 2g 2b, mf300
GeV, mh125 GeV
( Jet cone algo. R 0.5 )
L2x1033 cm-2 s-1
No tracking correction
With tracking correction
h, DRb-jet
lt 1.2, lt 0.1 lt 2, lt 0.1 lt1.2,
lt0.3
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DC04 Calib. bkgnd.
Data Challenge 2004 (DC04) test data
reconstruction chain, validate Monte Carlo,
optimize detector parameters, develop particle
algorithms calibration techniques, and perform
physics prospect studies.
Data Format a Root Tree will be created from
DST files

• (a) Calibration background Samples
• ? jet for jet calibration
• W (W -gt l? ) N Jets
• Standard one e/m background process (N1,2,3,4)
  
• Top quark pair production tt -gt l?l?bb
• - higher W pT, jets,
• QCD dijet background

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DC04 Physics

• (b) Physics Samples
• Higgs Production
• qq H ( H ? l?l?jj ) for optimization of HF
  and TB studies, forward jet
  tagging,
• WLWL ? WLWL scattering
• - qq ? WWqq ? WWqq ? l?jjjj strong dynamics
  for EW symmetry breaking, jets,
  , CompHEP-PYTHIA comparisons
• Z search
• qq ? Z ? qq (useful for energy resolution
  studies)
• SUSY particle search
• gluino/squark ? energetic central jet, large

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Summary

• HB and HE hadronic calorimeters completed and
  assembled. HF fibre insertion finished by the end
  of 2003
• Goals for the HCal 2002 test beam experiment have
  been met, moving on to TB03 program
• Looking forward to M.C. production DC04 for
  simulation and reconstruction validation,
  detector optimisation, physics prospects

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Acknowledgments
I would like to thank the members of the HCal and
JetMET groups who contributed the material
included in this talk