Status Report of The CMS Experiment Christos Leonidopoulos

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

The Collaboration AACHEN-1, AACHEN-3 A, AACHEN-3 B, 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, CCCSUWE, 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, KHARKOVISC, KHARKOV-KIPT, KHARKOV-KSU, KONKUK-UNIV, KOREA-UNIV, KYUNGPOOK, LAPPEENRANTA-LUT, LIP, LIVERMORE, LONDON-IC, LOUVAIN, LYON, MADRID-CIEMAT, MADRID-UNIV, MARYLAND, MEXICOIBEROAM, MEXICO-IPN, MEXICO-PUEBLA, MEXICO-UASLP, MILANO-BICOCCA, MINNESOTA, MINSK-INP, MINSKNCPHEP, MINSK-RIAPP, MINSK-UNIV, MISSISSIPPI, MIT, MONS, MOSCOW-INR, MOSCOW-ITEP, MOSCOWLEBEDEV, 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-CALUMET, RAL, RICE, 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, SOFIAUNIV, 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 2

Reminder: we went from this… 3. 8 T Superconducting Solenoid Lead tungstate E/M Calorimeter (ECAL) Hermetic (|η|<5. 2) Hadron Calorimeter (HCAL) [scintillators & brass] All Silicon Tracker (Pixels and Microstrips) Redundant Muon System (RPCs, Drift Tubes, Cathode Strip Chambers) 3

…to this First 7 Te. V collisions in CMS – 30 March 2010

…and this, just three months later

Life did not begin in a vacuum with the first collisions

One Billion Cosmic Muons before collisions 7

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

Detector understanding • “Why should we believe that the simulation correctly describes the detector performance? ” • Excellent question! • Te. Vatron experience: it takes a long time to commission & understand collider experiments ØAccelerator, 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

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

Operations

Integrated luminosity L≈ 1030 cm-2 s-1 L≈ 1027 -1029 cm-2 s-1 7 h( T ): V e arc (*) ) f M red % o e (~88 d v n i e e -1 del ded c Sin nb ecor 0 r 10 nb-1 88 (*) Stable beams only • ~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 12

Subdetectors status PIXEL TRACKER STRIP TRACKER PRE-SHOWER ECAL END-CAP ECAL BARREL HCAL FORWARD HCAL ENDCAP HCAL BARREL MUON-RPC MUON-DT MUON-CSC 90 91 92 93 94 95 96 HCAL ECAL MUON- HCAL ECAL FORWA ENDCSC DT RPC BARREL ENDCAP BARREL RD CAP Series 1 98. 5 99. 8 98. 8 99. 9 100 99. 9 99. 3 98. 9 97 STRIP 98 PIXEL 99 PRESHOWE TRACKE R R R 99. 8 98. 1 98. 2 100 Alignment/calibration status, dead/masked channels mirrored in MC 13

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

DAQ/Trigger • L 1/DAQ rate: 45 k. Hz, @<0. 5 MB/evt • High-Level Trigger: have successfully deployed online trigger menus spanning luminosities from 1 E 27 through 2 E 30 o Very smooth running throughout (200 -400 Hz) • HLT CPU-performance: 49 ms/evt o Primary contributors: commissioning and early analysis triggers Run 138737 o Contingency: factor of 2 Overflows taken into o Constantly on watch list account in the mean 15

Trigger Performance • HLT muon efficiency wrt L 1 • L 1 objects matched to offline objects • ~90% efficiency at the plateau • Photon efficiency wrt offline “super clusters” • For barrel & endcaps • Nearly 100% efficient 16

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

Predicting trigger rates: MC vs. data 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. 6 E 29 rates 18

Predicting trigger rates: MC vs. data 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. 2 E 29 rates to predict 4. 6 E 29 rates 19

Calibration Trigger Streams • Calibration triggers have access to full L 1 rate, and they output small fraction of event • Feature unique to CMS HLT • Calibration starts online! 20

Trigger calibration streams • Calibration triggers have access to full L 1 rate, and they output small fraction of event • π0 peak reconstructed offline 200 seconds into 7 Te. V run 30 March 2010 21

LHC has delivered Trigger has accepted CMS will analyze 22

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

Physics production

3+1 CMS papers since May 25

CMS paper at 7 Te. V “Transverse Momentum and Pseudorapidity Distributions of Charged Hadrons in pp Collisions at √s=7 Te. V”, submitted to PRL • Rise of the particle density at (2. 36) 7 Te. V steeper than in models • Careful tuning effort of the MC generators is ongoing 26

Detector & Physics Performance Calorimetry Tracking Jets b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

Detector & Physics Performance Calorimetry Tracking Jets b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

Calorimetry: π0 and η → γγ MC based correction applied according to cluster η and energy 1. 46 M of π0 → γγ PT(γ) > 0. 4 Ge. V, PT(pair) > 1 Ge. V DATA MC 0. 43 nb-1 1. 46 M π0 25. 5 K η → γγ PT(γ) > 0. 5 Ge. V, PT(pair) > 2. 5 Ge. V DATA MC 0. 43 nb-1 25. 5 k η • 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

Calorimetry: Missing ET Calorimetric MET (Ge. V) Jets reconstructed with the anti-k. T R=0. 5 algorithm • Dijet selection : Jet PΤ > 25 Ge. V, Δφ > 2. 1, |η| < 3 • Loose ID cuts on number of components and neutral/charged energy fraction • 30

Detector & Physics Performance Calorimetry Tracking Jets b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

Calorimetric di-jet events s t je Di s a m Δφ(j 1, j 2) # of Calo Towers Fraction of EM energy in Calo-Jets 32

Detector & Physics Performance Calorimetry Tracking Jets b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

Tracking distributions

Muon distributions “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) 35

Tracking distributions η distribution φ distribution p. T spectrum 36

Tracker Material Budget η distribution φ distribution 37

Tracker Material Budget η distribution φ distribution pixel cluster charge 38

Tomography 39

Detector & Physics Performance Calorimetry Tracking Jets b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

b-tagging 3 D IP significance 3 D impact parameter value and significance all tracks with p. T> 1 Ge. V belonging to jets with p. T > 40 Ge. V and |η| < 1. 5 - PFlow Jets anti-k. T R=0. 5) Excellent alignment and general tracking performance 41

b-tagging example Two b-jets candidate 42 42

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

CMS experiment at LHC, CERN Run 136100 / Event 256858438 2010 -25 -5 03: 48 CEDT B- → J/y. K- candidate All other tracks: p. T > 1. 0 Ge. V/c

Detector & Physics Performance Calorimetry Tracking Jets b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

Particle Flow • Particle Flow: Full Event reconstruction Ø Topological matching between charged particle momenta measured with tracker with clusters in calorimeter Ø Corrects for energy loss along trajectories Ø Better precision, full event info • High-level object: requires holistic detector view Ø Excellent tracker Ø High E/M calorimeter granularity (0. 017 × 0. 017) Ø Strong magnetic field to separate tracks • CMS very well suited for P-Flow reconstruction 46

Particle Flow MET 47

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

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

Detector & Physics Performance Calorimetry Tracking Jets b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

J/ψ → μ+μ− 56 nb-1 Signal events: 4150 ± 222 Sigma: 43. 1 ± 1. 9 (stat. ) Me. V M 0 : 3. 094 ± 0. 001 (stat. ) Ge. V S/B= 5. 2 χ2/Νdof = 1. 0 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 51

J/ψ → μ+μ− : The Best Of 56 nb-1 Selection of central (barrel), high-quality dimuons: • Resolution: 43. 1 Me. V → 21. 0 Me. V 52

J/ψ → μ+μ− plus friends 60 nb-1 53

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

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

Z →μ+μ− observation • Event selection: Ø Muon id cuts Ø Loose isolation, p. T cuts • Monte Carlo: Event count normalized to integrated luminosity #of candidate = 25 #of expected signal = 24. 7 #of expected background = 0. 08 Z→μμ candidate 60 nb-1 56

Detector & Physics Performance Calorimetry Tracking Jets b-tagging Muon EWK/Onia Particle Flow Electron EWK/Onia

J/ψ → e+e− 37 nb-1 Signal events: 132 ± 14 Sigma: 98 ± 12 (stat. ) Me. V M 0 : 3. 070± 0. 013 (stat. ) Ge. V • • • Higher background, tighter selection compared to muon channel Challenging analysis, Particle-Flow selection crucial Very promising preliminary results, signal clearly established 58

W± →e±ν observation Two event selections: Ø Basic electron ID, no MET cuts Ø More advanced electron ID, cuts on ET, MET, ΣET 196 candidates with MT > 50 Ge. V MC: Sig =176, Bkg =11 173 candidates with MT > 50 Ge. V MC: Sig=163, Bkg=5 51 nb-1 59

Z →e+e− observation • Event selection: Ø Two electrons with ET > 20 Ge. V • Monte Carlo: Event count normalized to integrated luminosity #of candidate = 18 #of expected signal = 19 #of expected background = 0. 8 Z→ee candidate 52 nb-1 60

Summary

7 Te. V collisions: a very exciting run! • The CMS detector is working according to design Ø First performance results are very encouraging Ø Its behavior can be reproduced in Monte Carlo simulation Ø 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

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

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

Backup 65

The CMS Detector Superconducting Coil, 4 Tesla CALORIMETERS HCAL ECAL Plastic scintillator/brass 76 k scintillating Pb. WO 4 crystals sandwich Steel YOKE TRACKER Pixels Silicon Microstrips 210 m 2 of silicon sensors 9. 6 M (Strip) & 66 M (Pixel) channels MUON BARREL Resistive Plate Drift Tube Chambers (DT) (RPC) MUON ENDCAPS Cathode Strip Chambers (CSC) Resistive Plate Chambers (RPC) 66

Muon p. T resolution with cosmics 1 B 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 12% resolution at 1 Te. V 67

0 πs and ECAL calibration π0 → γγ η, Φ distributions Relative calibration precision ~ 2% target ~ 0. 5% at 10 pb-1 ECAL Barrel π0 and Φ symmetry

HLT: CPU performance & pile-up • 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 69

J/ψ → μ+μ− • Run range: 132440 -139370 • Common selection: Ø No scraping Ø Tracker Muons of opposite charge Ø Pixel layers >= 2 Ø Tracker hits >= 12 Ø Tracker chi 2 < 3 Ø Mu p. T > 2. 5 Ø Mu segments >=2 Ø Matched L 1 Double. Mu. Open Ø vertex Prob > 0. 05 70

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