Upload
joseph-armstrong
View
234
Download
0
Tags:
Embed Size (px)
Citation preview
LCWS06@IISc CMS Calorimeter 1
Understanding the Performance of CMS Calorimeter
Seema Sharma,TIFR
(On behalf of CMS HCAL)
LCWS06@IISc 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
LCWS06@IISc CMS Calorimeter 4
TB2004 Setup
2 wedges of HCal Barrel2 slices of HCal endcap6-trays of HO for 3 ringsMock-up of CMS magnetTail catcher iron7 X 7 ECal crystal matrixMock-up of material between ECal and HCalBeam line trigger counters
LCWS06@IISc CMS Calorimeter 5
HCAL on a Table
HB
HE
HO
ECAL
pivot
beam
Pivot of table = IP at LHC
A phi slice of CMS HCAL
LCWS06@IISc CMS Calorimeter 10
80 GeV/c
SCI_VLE
CK2
CK3
WC A,B,C
HCAL
HCALECAL
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
LCWS06@IISc CMS Calorimeter 12
• Done using Co60 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
LCWS06@IISc CMS Calorimeter 13
• 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
LCWS06@IISc CMS Calorimeter 14
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
LCWS06@IISc 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.
LCWS06@IISc CMS Calorimeter 19
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
LCWS06@IISc CMS Calorimeter 20
Energy Resolution
0.92 GeV measured
Larger noise
than HB1
(0.4GeV in 3x3)
because of
individual layer
readout in HB2.
LCWS06@IISc CMS Calorimeter 21
Two G4 physics models show difference at high energy.
Event selection – MIP in ECAL.
Longitudinal Shower Profile
LCWS06@IISc 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.