1. Project Presentations August 5th, 2004
Muon identification in CMS
Andrew Wagner
CERN summer student 2004
Supervisor: Norbert Neumeister

2. Introduction Research CMS detector
Design an algorithm capable of identifying tracks as Muons based on information supplied by the CMS Calorimeters and Muon system
CMS detector
Calorimetry
Electromagnetic Calorimeter (Ecal)
Hadronic Calorimeter (Hcal and HO)
Muon system
Drift Tubes (DT)
Cathode Strip Chambers (CSC)
Resistive Plate Chambers (RPC)
Motivation:
Muon Identification complements Muon Reconstruction for physics analysis
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3. Compact Muon Solenoid Detector
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4. Muon Detectors
Three types of gaseous particle detectors for muon identification:
Drift Tubes (DT) in the central barrel region
Cathode Strip Chambers (CSC) in the endcap region
Resistive Plate Chambers (RPC) in both the barrel and endcaps
The DT and CSC detectors are used to obtain a precise measurement of the position and thus the momentum of the muons, whereas the RPC chambers are dedicated to providing fast information for the Level-1 trigger
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5. Muons in CMS
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6. Approach Strating point: Reconstructed Tracks in Tracker
First Step: extrapolate reconstructed track to calorimeter and muon system taking into account the magnetic field and energy loss and multiple scattering
Energy deposition in calorimeters
Muons are Minimum Ionizing Particles (MIPs) and leave a distinctive signal in the Ecal, Hcal and HO that can be cut on
A sample of Monte Carlo generated single muons is compared to a sample of jets for the purpose of determining this cut
Muon System
Identification can be made based on reconstructed Hits, and Segments
Both Hits and Segments are multidimensional objects (1-4) which are the measurements used to perform the track fit (5 parameters)
Compatibility of Hits and Segments with a Track is determined using a 2 criterion
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7. Ecal Barrel and Endcap Muon Sample
Expected MIP energy in Barrel ~ 300 MeV
Threshold : 60 MeV per Crystal
Expected MIP energy in Endcap ~ 400 MeV
Threshold : 150 MeV per Crystal
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8. Hcal Signal and Background
Blue: Jet Sample
Red: Muon Sample
Expected MIP energy in Barrel ~ 2 GeV
Threshold : .5 GeV
Expected MIP energy in Barrel ~ 3 GeV
Threshold : .5 GeV
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9. HO Signal and Noise Muon Sample
HO only in Barrel Expected MIP energy ~ 1 GeV varies with Eta
High Thresholds ~.5 GeV applied at readout
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10. 2 Distribution Muon DT Hits
Muon Sample: Example shows DT Hits
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11. Conclusions
The MIP signal in the Ecal and Hcal is an efficient means of identifying Muons and can be used to compliment Muon Reconstruction
Understanding the 2 and probability distributions for hits in the Muon Stations will allow for a further improvement in efficiency for Muon identification
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12. Thanks Norbert Neumeister Jean Krisch
The University of Michigan, Ford, and CERN
All of my fellow students for helping to make this summer so much fun!
5th August 2004