1. Status Report of The CMS Experiment Christos Leonidopoulos CERN-PH on behalf of the CMS Collaboration 102 nd LHCC Meeting, CERN 7 July 2010

2. The Collaboration 2 AACHEN-1, AACHEN-3A, AACHEN-3B, ADANA-CUKUROVA, ANKARA-METU, ANTWERPEN, ATHENS, ATOMKI, AUCKLAND, BARI, BEIJING-IHEP, BOGAZICI, BOLOGNA, BOSTON-UNIV, BRISTOL, BROWN-UNIV, BRUNEL, BRUSSEL-VUB, BRUXELLES-ULB, BUDAPEST, CALTECH, CANTERBURY, CARNEGIE-MELLON, CATANIA, CCCS- UWE, CERN, CHANDIGARH, CHEJU, ILLINOIS-CHICAGO, CHONNAM, CHUNGBUK, CHUNGLI-NCU, COLORADO, CORNELL, DEBRECEN-IEP, DELHI-UNIV, DEMOKRITOS, DESY, DONGSHIN, DUBLIN-UCD, DUBNA, EINDHOVEN, FAIRFIELD, FERMILAB, FIRENZE, FLORIDA-FIU, FLORIDA-STATE, FLORIDA-TECH, FLORIDA-UNIV, FRASCATI, GENOVA, GHENT, HAMBURG-UNIV, HEFEI-USTC, HELSINKI-HIP, HELSINKI-UNIV, HEPHY, IOANNINA, IOWA, IPM, ISLAMABAD-NCP, JOHNS-HOPKINS, KANGWON, KANSAS-STATE, KANSAS-UNIV, KARLSRUHE-IEKP, KHARKOV-ISC, KHARKOV-KIPT, KHARKOV-KSU, KONKUK-UNIV, KOREA-UNIV, KYUNGPOOK, LAPP, LAPPEENRANTA-LUT, LIP, LIVERMORE, LONDON-IC, LOUVAIN, LYON, MADRID-CIEMAT, MADRID-UNIV, MARYLAND, MEXICO-IBEROAM, MEXICO-IPN, MEXICO-PUEBLA, MEXICO-UASLP, MILANO-BICOCCA, MINNESOTA, MINSK-INP, MINSK-NCPHEP, MINSK-RIAPP, MINSK-UNIV, MISSISSIPPI, MIT, MONS, MOSCOW-INR, MOSCOW-ITEP, MOSCOW-LEBEDEV, MOSCOW-MSU, MOSCOW-RDIPE, MUMBAI-BARC, MYASISHCHEV, NAPOLI, NEBRASKA, NICOSIA-UNIV, NORTHEASTERN, NORTHWESTERN, NOTRE DAME, NUST, OHIO-STATE, OVIEDO, PADOVA, PAVIA, PEKING-UNIV, PERUGIA, PISA, POLYTECHNIQUE, PRINCETON, PROTVINO, PSI, PUERTO RICO, PURDUE, PURDUE-CALUMET, RAL, RICE, RIE, RIO-CBPF, RIO-UERJ, ROCHESTER, ROCKEFELLER, ROMA-1, RUTGERS, SACLAY, SANTANDER, SAO PAULO, SEONAM, SEOUL-EDU, SEOUL-SNU, SHANGHAI-IC, SKK-UNIV, SOFIA-CLMI, SOFIA-INRNE, SOFIA-UNIV, SPLIT-FESB, SPLIT-UNIV, ST-PETERSBURG, STRASBOURG, SUNY-BUFFALO, TAIPEI-NTU, TALLINN, TASHKENT, TBILISI-IHEPI, TBILISI-IPAS, TENNESSEE, TEXAS-TAMU, TEXAS-TECH, TIFR-EHEP, TIFR-HECR, TORINO, TRIESTE, UCDAVIS, UCLA, UC RIVERSIDE, UC SANTA BARBARA, UC SAN DIEGO, UNIANDES, VANDERBILT, VILNIUS- ACADEMY, VILNIUS-UNIV, VINCA, VIRGINIA-TECH, VIRGINIA-UNIV, WARSAW-IEP, WARSAW-INS, WARSAW-ISE, WAYNE, WISCONSIN, WONKWANG, YEREVAN, ZAGREB-RUDJER, ZURICH-ETH, ZURICH-UNIV 182 Institutions 3000 scientists and engineers 2000 Authors

3. Reminder: we went from this… 3.8T Superconducting Solenoid All Silicon Tracker (Pixels and Microstrips) Lead tungstate E/M Calorimeter (ECAL) Redundant Muon System (RPCs, Drift Tubes, Cathode Strip Chambers) Hermetic (|η|<5.2) Hadron Calorimeter (HCAL) [scintillators & brass] 3

4. First 7 TeV collisions in CMS – 30 March 2010 …to this

5. …and this, just three months later

6. Life did not begin in a vacuum with the first collisions

7. One Billion Cosmic Muons 7 before collisions

8. 23 JINST papers: March 2010 (Vol. 5) 8 Feedback into realistic simulation to help us prepare for collisions

9. Detector understanding “Why should we believe that the simulation correctly describes the detector performance?” Excellent question! TeVatron experience: it takes a long time to commission & understand collider experiments  Accelerator, detector, trigger, background, underlying event, software: very complicated problems Claim: Cosmic runs/beam tests have made a difference First data distributions agree well with simulation 9

10. CMS is still in the commissioning phase From data-taking to the plots 10 Hard work, long hours Despite early phase and complexity of experiment  Unprecedented levels of readiness  Very encouraging first results But:  Always problems seeking solutions  Hardest part is ahead of us

11. Operations

12. Integrated luminosity 12 Since end of March (7 TeV): 100 nb -1 delivered (*) 88 nb -1 recorded (~88%) ~3/4 of data recorded arrived in last 10 days Working hard to integrate full datasets for ICHEP Most performance plots use only fraction of data (*) Stable beams only L ≈ 10 27 -10 29 cm -2 s -1 L ≈ 10 30 cm -2 s -1

13. Subdetectors status 13 Alignment/calibration status, dead/masked channels mirrored in MC

14. “The Trigger does not determine which Physics Model is Right. Only which Physics Model is Left.”

15. DAQ/Trigger 15 L1/DAQ rate: 45 kHz, @<0.5 MB/evt High-Level Trigger: have successfully deployed online trigger menus spanning luminosities from 1E27 through 2E30 o Very smooth running throughout (200-400 Hz) HLT CPU-performance: 49 ms/evt o Primary contributors: commissioning and early analysis triggers o Contingency: factor of 2 o Constantly on watch list Overflows taken into account in the mean Run 138737

16. Trigger Performance 16 HLT muon efficiency wrt L1 L1 objects matched to offline objects ~90% efficiency at the plateau Photon efficiency wrt offline “super clusters” For barrel & endcaps Nearly 100% efficient

17. Predicting trigger rates: MC vs. data 17 “Building trigger menus 101”

18. Predicting trigger rates: MC vs. data 18 Monte Carlo: Only used as a cross-check at this point Some trigger paths have significant cosmic or noise distributions that are not modeled with “baseline” MC Still, impressive agreement overall Using MC to cross-check 4.6E29 rates

19. Predicting trigger rates: MC vs. data 19 Data: Most triggers exhibit fairly linear behavior vs. luminosity Extrapolation errors minimized by using most recent data to keep the rate non-linearities under control Rates of all main players are predicted within ~20% Using 1.2E29 rates to predict 4.6E29 rates

20. Calibration Trigger Streams 20 Calibration triggers have access to full L1 rate, and they output small fraction of event Feature unique to CMS HLT Calibration starts online!

21. Trigger calibration streams 21 Calibration triggers have access to full L1 rate, and they output small fraction of event π 0 peak reconstructed offline 200 seconds into 7 TeV run 30 March 2010

22. LHC has delivered Trigger has accepted CMS will analyze 22

23. Analysis Activity 23 10-20k analysis jobs running on Tier-2s continuously every day of June Routinely delivering 100k jobs per day October 09 MC Exercise 7 TeV data Winter Break

24. Physics production

25. 25 3+1 CMS papers since May

26. Rise of the particle density at (2.36) 7 TeV steeper than in models Careful tuning effort of the MC generators is ongoing “Transverse Momentum and Pseudorapidity Distributions of Charged Hadrons in pp Collisions at √s=7TeV”, submitted to PRL 26 CMS paper at 7TeV

27. Detector & Physics Performance CalorimetryJets Tracking b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

28. Detector & Physics Performance CalorimetryJets Tracking b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

29. 1.46M of π 0 → γγ P T (γ) > 0.4 GeV, P T (pair) > 1 GeV MC based correction applied according to cluster η and energy 0.43 nb -1 1.46M π 0 0.43 nb -1 25.5k η 25.5K η → γγ P T (γ) > 0.5 GeV, P T (pair) > 2.5 GeV Calorimetry: π 0 and η → γγ Statistics refer to < 0.5 nb -1 Very useful tool to intercalibrate the crystals Good agreement in width and Signal/Background ratio Masses agree with expectations to within 1% 29 DATA MC

30. Calorimetry: Missing E T Calorimetric MET (GeV) 30 Jets reconstructed with the anti-k T R=0.5 algorithm Dijet selection : Jet P Τ > 25 GeV, Δφ > 2.1, |η| < 3 Loose ID cuts on number of components and neutral/charged energy fraction

31. Detector & Physics Performance CalorimetryJets Tracking b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

32. Calorimetric di-jet events 32 Dijet mass Δφ(j1, j2) # of Calo Towers Fraction of EM energy in Calo-Jets

33. Detector & Physics Performance CalorimetryJets Tracking b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

34. Tracking distributions

35. Muon distributions 35 “Global Muons”: matched tracks from Muon system and Tracker Global Muons η and p T distributions dominated by light hadron decay muons (red) good agreement with MC prediction, including o heavy flavor decays (blue) o punch-through (black) o fakes (green) Global Muons

36. p T spectrum η distribution φ distribution Tracking distributions 36

37. η distribution φ distribution Tracker Material Budget 37

38. η distribution φ distribution Tracker Material Budget 38 pixel cluster charge

39. Tomography 39

40. Detector & Physics Performance CalorimetryJets Tracking b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

41. 3D impact parameter value and significance all tracks with p T > 1GeV belonging to jets with p T > 40 GeV and |η| < 1.5 - PFlow Jets anti-k T R=0.5) Excellent alignment and general tracking performance b-tagging 3D IP significance 41

42. 42 Two b-jets candidate b-tagging example 42

43. CMS experiment at LHC, CERN Run 136100 / Event 256858438 2010-25-5 03:43:48 CEDT B - → J/  K - candidate

44. CMS experiment at LHC, CERN Run 136100 / Event 256858438 2010-25-5 03:43:48 CEDT B - → J/  K - candidate All other tracks: p T > 1.0 GeV/c

45. Detector & Physics Performance CalorimetryJets Tracking b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

46. Particle Flow Particle Flow: Full Event reconstruction  Topological matching between charged particle momenta measured with tracker with clusters in calorimeter  Corrects for energy loss along trajectories  Better precision, full event info High-level object: requires holistic detector view  Excellent tracker  High E/M calorimeter granularity (0.017 × 0.017)  Strong magnetic field to separate tracks CMS very well suited for P-Flow reconstruction 46

47. Particle Flow MET 47

48. Particle Flow MET 48 Laser forgotten on Need cleaning strategies developed based on timing constraints

49. Particle Flow MET 49 Comparison between calorimetric and Particle-Flow MET (Minimum bias events)

50. Detector & Physics Performance CalorimetryJets Tracking b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

51. 51 J/ψ → μ + μ − Ongoing studies: Momentum scale corrections by studying mass as a function of η, p T (material budget) Efficiency studies with tag-n-probe Flight distance with determination of prompt and b→J/ψ + Χ terms Signal events: 4150 ± 222 Sigma: 43.1 ± 1.9 (stat.) MeV M 0 : 3.094 ± 0.001 (stat.) GeV S/B= 5.2 χ 2 /Ν dof = 1.0 56 nb -1

52. 52 J/ψ → μ + μ − : The Best Of Selection of central (barrel), high-quality dimuons: Resolution: 43.1 MeV → 21.0 MeV 56 nb -1

53. 53 J/ψ → μ + μ − plus friends 60 nb -1

54. 54 J/ψ → μ + μ − plus friends Not enough statistics to disentangle all resonances (yet) 60 nb -1

55. Event selection:  Muon id cuts  Isolation, p T and MET cuts Monte Carlo: Event count normalized to integrated luminosity W→μν candidate W ± →μ ± ν observation 55 # of candidate (M T > 50 GeV) = 137 # of expected signal (M T > 50 GeV) = 128 # of expected background (M T > 50 GeV) = 7 37 nb -1

56. Event selection:  Muon id cuts  Loose isolation, p T cuts Monte Carlo: Event count normalized to integrated luminosity Z →μ + μ − observation Z→μμ candidate 56 #of candidate = 25 #of expected signal = 24.7 #of expected background = 0.08 60 nb -1

57. Detector & Physics Performance CalorimetryJets Tracking b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

58. 58 J/ψ → e + e − Higher background, tighter selection compared to muon channel Challenging analysis, Particle-Flow selection crucial Very promising preliminary results, signal clearly established Signal events: 132 ± 14 Sigma: 98 ± 12 (stat.) MeV M 0 : 3.070± 0.013 (stat.) GeV 37 nb -1

59. Two event selections:  Basic electron ID, no MET cuts  More advanced electron ID, cuts on E T, MET, ΣE T W ± →e ± ν observation 59 173 candidates with M T > 50 GeV MC: Sig=163, Bkg=5 196 candidates with M T > 50 GeV MC: Sig =176, Bkg =11 51 nb -1

60. Event selection:  Two electrons with E T > 20 GeV Monte Carlo: Event count normalized to integrated luminosity Z →e + e − observation Z→ee candidate 60 52 nb -1 #of candidate = 18 #of expected signal = 19 #of expected background = 0.8

61. Summary

62. 7 TeV collisions: a very exciting run! The CMS detector is working according to design  First performance results are very encouraging  Its behavior can be reproduced in Monte Carlo simulation  Our level of understanding for this early commissioning phase is very advanced The “rediscovery” of the SM has begun We are setting the grounds for challenging it as early as the end of 2010 62

63. Epilogue The technology of the LHC accelerator and experiments is unprecedented Massive amount of work and preparation invested in building and commissioning hardware & software But: we do not forget that the real challenges are still ahead (for all of us) We should consider this truly exciting period as the beginning of a marathon 63

64. The Beginning of The Journey Credit for “Da Vinci” drawings: Sergio Cittolin Credit for material used in this talk: LHC, CMS

65. Backup 65

66. The CMS Detector MUON BARREL CALORIMETERS Pixels Silicon Microstrips 210 m 2 of silicon sensors 9.6M (Strip) & 66M (Pixel) channels ECAL 76k scintillating PbWO4 crystals Cathode Strip Chambers (CSC) Resistive Plate Chambers (RPC) Drift Tube Chambers (DT) Resistive Plate Chambers (RPC) Superconducting Coil, 4 Tesla Steel YOKE TRACKER MUON ENDCAPS HCAL Plastic scintillator/brass sandwich 66

67. Muon p T resolution with cosmics 1B events of (mostly muon) cosmic events collected make muons the best understood reconstructed object in CMS Compare muon p T in upper, lower detector halves to evaluate resolution 67 12% resolution at 1 TeV

68. π 0 → γγ η, Φ distributions Relative calibration precision ~ 2% target ~ 0.5% at 10pb -1 π 0 s and ECAL calibration π 0 and Φ symmetry ECAL Barrel

69. HLT: CPU performance & pile-up 69 First look at impact of pileup on CPU-performance 1 coll/bunch 2 coll/bunch Have deployed “multiple-vertex” trigger to facilitate pile-up studies with real data

70. 70 J/ψ → μ + μ − Run range: 132440-139370 Common selection:  No scraping  Tracker Muons of opposite charge  Pixel layers >= 2  Tracker hits >= 12  Tracker chi2 < 3  Mu pT > 2.5  Mu segments >=2  Matched L1DoubleMuOpen  vertex Prob > 0.05

71. Run 136100, Event 256858438 Measured Parameters: 3-trk vertex that is displaced from the PV by 2mm (18  ). Our background is dominated by real J/  Dimuon mass in data (points) compared to MC (hist)