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

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 5th August 2004

Compact Muon Solenoid Detector 5th August 2004

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 5th August 2004

Muons in CMS 5th August 2004

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 5th August 2004

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 5th August 2004

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 5th August 2004

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 5th August 2004

2 Distribution Muon DT Hits Muon Sample: Example shows DT Hits 5th August 2004

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 5th August 2004

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