Compact Muon Solenoid Surapat Ek-In École Polytechnique Fédérale de Lausanne

Compact Muon Solenoid Surapat Ek-In École Polytechnique Fédérale de Lausanne

Outline Introduction Electromagnetic Calorimeter Muon Chamber Application Conclusion Outline 2

LHC Experiments ~ 100 m https://cms.cern.ch/ https://cms.cern.ch/ Introduction 3

CMS Collaboration Over 5000 active people 200 Institutes 46 Countries. https://cms.cern.ch/ Introduction 4

Physics Programs The Standard Model - Higgs Physics - Top Physics - B Physics - Heavy-Ion Physics Introduction Beyond the Standard Model - Dark Matter production - Extra Dimensions - Supersymmetry - Heavy Gauge Boson - Mini Black Hole - 5

Compact Muon Solenoid Compact - Small but dense! Muon - Specialize in detecting muons Solenoid - Use a large solenoid magnet https://cms.cern.ch/ Introduction 6

Compact Muon Solenoid Muon Positron Charged Hadron Neutral Hadron Photon https://cms-docdb.cern.ch/ Introduction th April 4, 2017 7

Electromagnetic Calorimeter (ECAL) Principle - Detect particles which have electromagnetic interaction, e.g. charged particles. - Create EM shower which is composed of e- and. Dominant processes - Pair production ( ) - Bremsstrahlung (e-) Radiation Length Extract from a lecture note by D. Bortoletto, U. of Oxford ECAL 8

Electromagnetic Calorimeter (ECAL) Simple Shower Model - Assume that E0 > Ec - Electron losses ~ 63 % of its initial energy after X0 - After passing t = x/x0, the remaining energy is E(t) = E0/2t - A particle stops if E < Ec = E0/2t,max - Example, Extract from a lecture note by D. Bortoletto, U. of Oxford ECAL 9

Electromagnetic Calorimeter (ECAL) CMS ECAL PbWO4 (X0 = 0.89 cm). ~ 23 cm in length. 61,200 crystals in the barrel section. 7,324 crystals in each of endcaps. http://cms.web.cern.ch/news/electromagnetic-calorimeter ECAL 10

Muon Chamber Drift tube chambers (DTC) - Barrel section - 250 DTs Cathode strip chambers (CSC) - Endcap section - 540 CSCs track Resistive plate chambers (RPC) - Between DTC and CSC - 610 RPCs Layout of Muon System of CMS detector CMS Physics Technical Design Report Muon Chamber 11

Muon Chamber High energy muon mostly loses energy via ionisation. η < 1.2 Low muon rate. Relatively small background. 85% Ar and 15% CO2 B field is mostly uniform with strength below 0.4 T. Signals are used to calculate momentum of muon from its curvature. 0.9 < η < 2.4 Higher muon rate. High background. 50% CO2 40% Ar, and 10% CF4 B field is strong and non-uniform. Signals are used to calculate momentum of muon from its curvature. CSC has faster response time to deal with large BG. Resistive Plate Chambers - Act as an additional triggering detector system. Double-gap chambers, operating in avalanche mode to ensure reliable operation at high rates. Locate between DTC and CSC upto η = 1.6 Provide a fast, independent trigger. Extract from CMS Technical Design Report, https://cms.cern.ch/, and arxiv:1306.6905 Muon Chamber 12

Higgs Event https://cdsweb.cern.ch/record/1459462/ Application 13

Monojet Event Application 14

Monojet Event Application 15

Conclusion Compact muon solenoid or CMS is a multipurpose detector to study validity of the Standard Model and search for new physics. Electromagnetic Calorimeter is used to absorb energies of particles that can interact through an EM interaction by creating EM shower. Muon Chamber is responsible for detecting muons from its ionization in gas detector. Conclusion 16

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BACKUP

Monojet Event Journal of Physics: Conference Series 645 (2015) 012008 Backup 19

Magnetic Field Backup 20

DTC Backup 21

CSC Backup 22

RPC Backup 23