Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 328.882 LHC PhysicsExperimental Methods and MeasurementsDetectors: Muons[Lecture 11, March 11, 2009]C.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 2Organization Project 1 (charged track multiplicity)●no one handed in so far... well deadline is tomorrow Recitation this week●usual time: 12pm at MIT == 17:00 CERN Project 2 (upsilon cross section)●project is out●due April 6‘09The Physics Colloquium SeriesThursday, March 12 at 4:15 pm in room 10-250Margaret MurnaneJILA, University of Colorado at Boulder and NIST "Harnessing Attosecond Science in the Quest for Coherent X-Rays " SpringFor a full listing of this semester’s colloquia, please visit our website at web.mit.edu/physicsColloquium SeriesPhysicsC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 4Lecture Outline Detectors: Electron/Muon Detection and Particle Id●electromagnetic calorimetry●muon chambers●particle identification systems●dE/dx in drift chamber●TOF – Time-Of-Flight detectors●RICH – Ring Imaging CHerenkov detectors●DIRC – Detection of Internal Reflected Cherenkov lightC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 5Why Muons and Electrons? Leptons●rare in pp (<1% of the tracks), often related to very interesting physics processes●taus special case (m = 1.777 GeV, cτ = 87.11 μm)●decay well before they reach the silicon detector, lifetime more then a factor of five smaller then for B mesons●can also produce hadrons in decay, more difficult to identify●always involve neutrino in decay (incomplete reconstruction) ●muons have very characteristic signature●penetrate the calorimetry, are detected in the muon chambers●leave minimally ionizing signature●electrons have very characteristic signature●maximal ionization in tracking system●get absorbed completely in ECAL no signature in the HCAL●shower shape in ECAL is short and broadC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 6Particle Flux Predicted for CMSCharged particle flux (hadrons and muons) at full LHC lumi (1034 cm-2s-1) from simulationC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 7CDF Muon Detection System Muon detection starts at the muon chambers CMU●on HCAL●|η| < 0.6 CMUP●add steel●|η| < 0.6 CMX●0.6<|η|<1.0 IMU●1.0<|η|<1.5●no triggerC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 8CDF Muon Detection SystemC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 9CDF Muon Detection SystemC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 10CDF Muon Detection SystemC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 11CDF Muon Detection System More details on CMU(P)/CMX:●up to 8 drift chamber planes ●1-2 scintillator layers●incorporated in the trigger (low+high momentum muons) More details on IMU●4 planes of drift chambers●2 scintillator layers●high backgrounds prevent triggering on those countersC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 12CDF Muon Detection System taken from the design report for the CDF II detectorC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 13CDF Muon Triggers Trigger at hadron collidersex. Tevatron, LHC●collision rate 3-40 MHz●writing rate: order 100 Hz●trigger absolutely crucial to see muons●muons are ideal candidate for trigger●muons often connected to interesting physics●muon trigger in CDF already at level 1 needs tracker informationC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 14Muons for the Analysis How do I get a clean and unbiased muon?●no way for single muon●irreducible background●decays (kaons, pions)●punch though, sail through●clean muon?●use clean muon based signal●J/ψ → μμ, many, O(10M)●Upsilon → μμ, higher momenta●apply sideband subtraction●subtract irreducible background●unbiased muon? (trigger)●use single muon trigger●use independent triggerC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 15Example for Sideband Subtraction Determine primary distribution (mostly masses)●select signal, sideband areas●make histograms for both areas●scale sideband and subtract from signal area plotC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 16Muon Signatures in Muon DetectorColors: muon, pion, kaon, protonDistance of muon stub fromextrapolated positionTracker is neededC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 17Signature in Non-Muon Detectors Colors: muon, pion, kaon, protonC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 18Look at CMSthe futureC.Paus, LHC Physics: Introductory Lecture 19CMS – Compact Muon Solenoidcompact does not mean smallvolume smaller than Atlas by ~5.6, butweights 30% more than the Eiffel towereye catcher: brilliant design in separately removable slices12,500 ton weight, 15 m diameter, 22 m longC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 20CMS Muon Systems Drift Tubes, DT, barrel only Cathode Strip Chambers, CSC, endcap only Resistive Plate Chambers, RPC, barrel and endcapsC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 21CMS Muon System PerformanceC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 22CMS Drift Tubes Drift tube design ●layers for effective production●again geometry and wire position crucialC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 23Cathode Strip Chambers Advantages●good spacial resol. (50μm)●fast (close wire spacing)●readout: strips and wires●two dimensional position●strips can align such that azimuthal angle measured●loose conditions for gas system●intrinsic alignment very preciseC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 24RPC Principle The signal is induced on the read-out electrodesC.Paus, LHC Physics: Detectors: Electron/Muon and Particle Id 25RPC Principle Mode to operate gas detector●usually: streamer mode●high field●intense enough to initiate spark breakdown●CMS runs in avalanche mode●lower field but multiplication●multiplication proportional Performance●timing resolution 1-2 nsspace resolution ≈ cmrate capability good (avalanche mode)low cost design and