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CMS Commissioning and first Physics Data

CMS Commissioning and first Physics Data. Tim Christiansen, CERN for the CMS Collaboration CERN Joint EP/PP Seminar 21 July 2008. Beam Pipe: installed and baked-out (June 08). Commissioning with Cosmic Muons End-to-end Analyses Computing Challenges

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CMS Commissioning and first Physics Data

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  1. CMS Commissioning and first Physics Data Tim Christiansen, CERN for the CMS Collaboration CERN Joint EP/PP Seminar 21 July 2008 T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  2. Beam Pipe: installed and baked-out (June 08) • Commissioning with Cosmic Muons • End-to-end Analyses • Computing Challenges • First Collisions: Strategies and Physics Beam-Pipe: installed & baked-out (June ‘08) T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  3. Installing the last “Bits” Installation of first ECAL Endcap (July 18) Si-Pixel Barrel Pixel arrived at CERN last week, installation this week T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  4. Detector Readiness  Commissioning • Systems Integration • Power, cooling, gas, safety controls, detector electronics, trigger, DAQ, run-control, slow-control • Automated, fast, reproducible and safe procedures • Pre-synchronization (cosmics triggers) • Demonstrated Level-1 triggers from all muon detectors (DT, CSC, RPC) and calorimeters (ECAL, HCAL), 300-400 Hz cosmics rate • Calibration/test triggers at approx. 100Hz (in abort-gap), mixed-in • High-rate tests: few 10s of kHz rndm. triggers to stress-test the readout • Deployed HLT (High-Level Trigger) filtering, streaming, test of startup trigger menu, timing • Integrated real-time monitoring • Real-life data flow to the CAF (CMS Analysis Facility) and Tier-0,1,2’s • Data Quality Monitoring & prompt reconstr. at Tier-0 on ALL data • Optical alignment data flow tested • Since June: 1 week of 24/7 operation every month, 3 shifts/day in Cessy/ Pt. 5, Meyrin and at the Fermilab Remote Operation Center T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  5. The Magnet is cold, tested to B=4T in 2006 MTCC: Inside CMS Assembly Hall (surface) Magnet Test & Cosmic Challenge Summer/Autumn 2006 Cosmic track at B = 3.8 T ECAL Magnet HCAL Tracker Muon chambers measured  direction, charge, pT, ... Solenoid: - tested to B = 4T - mapped field CMS B-Field Map preliminary T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  6. % CMS 5/07 6/07 7/07 8/07 9/07 11/07 3/08 5/08 6/08 7/08 Global Runs For Illustration; Subdetector and trigger considered separately - 17 items, each equally weighted - box size represents approx. fraction included (25%, 50%, 75%, 100%) Muon Tracks in Si-Strip Tracker preliminary Reached scale of ’06 Magnet Test & Cosmic Challenge Final DAQ hardware,final services First  coincidence of 2 subsystems Upgrade to final DAQ software architecture First cosmic muon triggers underground T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  7. CMS Preliminary CMS Preliminary Innermost chamber: (x) / cm 2nd station: (x) / cm [cm] [cm] CMS Preliminary CMS Preliminary Outermost chamber: (x) / cm 3rd station: (x) / cm [cm] [cm] Few Commissioning Results ... Muon Drift Tube System (DT) August ‘07 Global Run ECAL HCAL (off) MB1 2 y 3 x 4 Cosmic m.i.p. signal in ECAL (DT trigger) First results from cosmic data: single-hit resolution of barrel drift tubes (DT): < 250 m T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  8. preliminary preliminary bottom probe probability z (at surface) [cm] x (at surface) [cm] x (at surface) [cm] Muon Tag & Probe on Cosmics Data For cosmics: top muon sectors are timed-in (delayed) w.r.t. bottom sectors  “di-muon”-like signal (here: Drift Tubes) May/June data: muon origin extrapolated to the surface: “X-ray” image of the shaft Avg. prob. to find 1 segment in bottom sectors - tag (top) & probe (bottom): Shaft-muons are softer linear scale T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  9. Run 43439, May ‘08 (-90˚  vertical) Rate [Hz] — after — before preliminary Steady increase of trigger rate over 45 minutes!?!? Direction  = atan(py/pz) [˚] Events with reconstructed muon tracks preliminary ratio Time [sec] Indeed, increase of cosmic rate correlated with shaft opening! Change comes from one direction only The Bouchon - Opening of the Shaft preliminary total drift tube trigger T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  10. CSC & RPC Muon Systems RPC Barrel CSC (endcap) Cathode Strip Chambers Resistive Plate Chambers Status March 08: station 2, + side in just 4 months! preliminary July 08: 97% of chambers operational! (& problems on remaining understood) preliminary + endcap preliminary Efficiency in % Use 5 RPC chambers in a sector to monitor the 6th - endcap (CRuZeT 3) T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  11. Prerequisites: infrastructure, -trigger, DAQ integration, r/o synchronization, muon calibration, reconstruction/tracking, etc. ... First Global Tracks: Tracker + Drift Tubes Global Run July ‘08 Muon System Tracker ECAL HCAL Tracker Only few hours after first attempt to integrate TK in global running! T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  12. Global Tracks continued ... • Di-muon Trigger: • Drift-Tube coinc. in top+bottom, each  2 station segments • Muon signals traced through • muon system • Tracker TOB+TIB • ECAL • HCAL • Global track fit • Excellent data - being used for alignment Muon System ECAL Tracker HCAL T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  13. Quick Alignment Exercise on a few Runs taken just 1 1/2 weeks ago Inner Barrel — Track alignment — Surveys — ”Engineering geometry” Outer Barrel — Track alignment — ”Engineering geometry” Preliminary about 90k tracks from 3 runs Residual [cm] z- z+ <residuals> [m] Geometry:  “Eng. geom.”  Track-aligned Geometry:  “Eng. geom.”  Track-aligned TIB+TOB layers T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  14. Cluster-to-Muon-Track matches (1 single run) preliminary  in detector units Cluster Energy [GeV] (Drift-Tube triggered events)  in detector units ECAL, all-Barrel Included in the trigger (m.i.p. signals as di-e/ trigger), synchronized to muon & HCAL triggers preliminary (dashed lines roughly illustrate the muon trigger acceptance for this run) T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  15. HB, HE & HF have - by construction - same timing HB vs. barrel- triggers HE vs. endcap- triggers All of HCAL included in global Runs: HB, HE, HF Cosmic trigger from coincidence of m.i.p. signals in top and bottom part of HB (synchronized to muon triggers) Cosmic Muons in HCAL preliminary HB: Barrel HCAL HE HF Inter-synchronization of barrel & endcap during open configuration Open configuration T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  16. Expectations from First Data & First Physics at CMS Disclaimer: The following MC studies to be shown are from simulations of pp collisions with 7 TeV beam energy with complete detector But first: The tools ... T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  17. Common Computing Readiness Challenges CCRC08 - May ‘08 • A multi-experiment computing scale test of the Tier-0/Tier-1/Tier-2 infrastructure • Goal: simultaneous end-to-end stress test • In parallel to cosmics data-taking & CSA08 Challenge! - Distributed data transfers: • T0T1 • T1T1 • T1T2 • Transfer P5T0 & repacking - Reprocessing at T1’s - Analysis at T2 ... Data storage at CERN T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  18. (and CSA08 - Calibration, Software, Analysis) CCRC08 CSA08, CCRC08 T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  19. CSA08: Calibration, Software & Analysis • Goals for the 4-weeks exercise: • Complete & deploy physics analysis tools, calibration & alignment • Vertical integration of physics plan • From Detector Physics Groups to “final publication plot” • Commission “physics analysis paths” • from Tier-0 to Tier-1 & Tier-2 - perform analysis • In parallel: • Trigger table definition, monitoring • Definition of primary dataset, streams, Express Line ... (May ‘08) Rehearsal: as if this were real data, exercise data, calibration/alignment and analysis work flows for few “first physics” key analyses (on “realistic” MC samples) Test of the procedures, logistics, corrections, interdependencies etc. in “quasi-real-time” fashion. T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  20. CSA08 Alignment/Calibration Workflow • Initial mis-alignments & mis-calibrations similar to LHC startup • Event signatures & “rates” typical to low luminosity: min-bias,QCD,,Z,W...) • Full Complexity of almost 20 concurrent alignment & calibration end-to-end workflows (with interdependencies!) Al/CaReco’s ready Daily meetings. Regular use of CMS center. Simultaneous to Global-Run Analysis Al/Ca task 1 Constants Validation Al/Ca task 2 Constants Validation Al/Ca task 3 Constants Validation CAF Constants in DB Al/CaReco’s copied to CAF Signoff: Constants ready for reprocessing Test Reconstruction Al/CaReco production Re-Reconstruction T1 T0 Analysis: T2 + CAF Initial calibr./alignmnt. Reconstruction T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  21. ECAL Calibration  symmetry 0 calibration Z  ee HCAL Calibration  symmetry with noise subtraction Isolated-track calibration Di-jet balancing ( flat response in ) HO (“Outer HCAL”) calibration for muons Muon Calibration T0 calibration vdrift calibration Si-Tracker Calibration Strip dE/dx Strip Lorentz angle calib. Pixel Lorentz angle calib. Tracker Alignment Various tracking algorithms on min-bias, muons pT>5 GeV & 11 GeV, cosmics, di-muons Muon System Alignment Global tracks Muon-system standalone Al/Ca Tasks Exercised in CSA08 Multiple samples: min-bias, noise, QCD jets, cosmics, J/, Z, ... 2 Scenarios: 1 pb-1 and 10 pb-1 T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  22. One CSA08 Al/Ca Example: Tracker • For the first time, startup scenario with large initial misalignments studied on big scale • Exercise with several tracking algorithms 2 samples/scenarios: ---“S43” with Ldt = 1 pb-1 — “S156” with Ldt = 10 pb-1  Tracker overall r- precision:  35 m preliminary Si-Pixel Modules all tracker pT = 100 GeV muon gun preliminary r* [cm] T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  23. re-reco 10 pb-1 reco 25 pb-1+jet pT(jet) pT() Response = Electrons CSA08 Express Analyses • Inclusive charged particle spectrum & underlying event • Di-muons: J/, (1S) & Z; Tag & Probe  efficiency corr. • Electrons: Zee, Tag & Probe, same/opposite sign, Z+jets, ... • Jets: from jet-energy scale (JES) corr. to di-jet mass spectra, various jet algorithms, data driven methods Data-driven JES and resol. •  response: • jet-pT balancing in di-jet events, soft-radiation corrected •  response flat in  • pTresponse: • Using +jet events • |jet| < 1.2, || < 1.2 Example Z  ee: endcap e + barrel e: preliminary (preliminary) jet-pT T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  24. Physics with (few) pb-1 … T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  25. 3<||<5 HF Minimum Bias using HF (Forward HCAL) Min-bias trigger: Number of HF trigger towers over threshold > N: any side (OR), or on both sides (AND) of I.P. Unfolding the effect of HF min-bias triggering on physical measurements preliminary preliminary Re-weighted charged-particle multiplicity per evt. AND OR all evts Inverse weighting   T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  26. d2N/dydpT  Simulation “Data” K p k p k  p dE/dx (MeV/cm)  CMS Si-Strip CMS Si-Pixel 0 1 2 pT (GeV) 0.1 1 10 pT (GeV) 0.1 1 10 pT (GeV) Charged-Hadron Spectra • One of the first measurements to be done: charged-hadron spectrum • Important tool for calibration, alignment & understanding of detector response • Min-bias and/or Zero-bias trigger • Statistics: ~ 2 million events T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  27. pT > 900 MeV Trigger samples Transverse region 10 1 CMS Preliminary  (uncorrected) “raw” reconstr. 10 1 CMS Preliminary  Underlying Event • Measuring the underlying event activity • Observe d2N/ddandd2pTsum/dd Leading jet ||<60 Look in region  to jet activity: transverse region “away” region ||>120  Important ingredient for jet & lepton isolation, energy flow, jet-tagging, …  sensitive to test multiple-parton interaction (MPI) tunes of QCD … T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  28. Physics with 10 pb-1 to 100 pb-1 … T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  29. ET(e) > 30 GeV We Using appropriate mis-alignment/ mis-calibration for early data /Z  ee and W  e • Single isol. electron trigger • Electron selection: • ECAL cluster with track match • Shower shape & H/E cuts • Track (& Calo) isolation • Developed strategies to determine efficiencies from data: QCD to be determined from data (inverted isol. criteria...) • “Tag & Probe” in Zee events in the vicinity of MZ efficiencies T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  30. W  T&P vs. MC Truth Using appropriate mis-alignment/ mis-calibration for early data Z   and W   • Single-muon trigger • Muon selection: • Tracker + muon-system match • Track isolation R<0.3 pT < 3 GeV • pT > 20 GeV, (m() > 40 GeV) m() [GeV/c2] Z   • Developed strategies for first data: • Study MET & MT shape for W directly from Z as function of Z-pT • “Tag & Probe”  efficiencies • QCD from data... T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  31. q q’ from ET balancing in di-jet events (soft-radiation corrected) b Resolution (pT)/ pT  b  Top Physics with first Data: ttbar  jet response flat in : Semi-leptonic ttbar events: -channel Data-driven method vs. MC-truth: Jets at LHC Trigger • Very first data, so avoid b lifetime-tags & Missing-ET (MET) as much as possible: • exactly 1 tightly isolated muon, pT()> 30 GeV, || < 2.1 •  4 jets, || < 2.4, ET(1) > 65 GeV, ET(2,3,4) > 40 GeV • min(R(,ji)) > 0.3 (reduces QCD) • 3 jets with max(ET)  M3 Very tight cuts to reduce QCD contribution as much as possible (as QCD is hard to simulate properly)  Measure QCD contribution with data signal 10% T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  32. ttb+qqb Entries M3 [GeV/c2] 10 pb-1 tteb+b signal N(jets) Jets and ttbar physics • JES from ttb+qqb: • Tight candidate selection (pT, isolation, jet- & muon separation ...) • Find best 4-jet-to-bbqq assignment with a likelihood  kinematics, b-tag ... • Global fit to world-avrg. Mt & MW, vary light-quark & b-jet energies  maximize fit probability on the whole sample  1 % JES possible with 100 pb-1 • X-section from ttlb+lb: pT(l) > 20 GeV, pT(jet) > 30 GeV, isolation... but w/o b-lifetime tags • e channel: cleanest, nearly background-free • ee/: require Z-veto, Missing-ET ... (bgd. is dominated by DY+jets) Expect with 10 pb-1: 13 % (stat.) e alone 10 % (stat.) incl. & ee T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  33. New Physics with High-ET Di-Jets • Jet-E scale will dominate error: • ~ 10% JES uncertainty for first 10 pb-1 • Measure QCD jet-pT spectra up to (>)1 TeV • Contact interactions: large rate at high-pT, with 10pb-1 sensitive to 3 TeV scale C.I. …further use di-jet ratios, m(jj) … 10 pb-1 10% JES sys. err. PDF uncertainty 1 2 TeV q’ 100 pb-1 5 TeV Fractional difference compared to QCD excited quarks? Di-jet mass -1 T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  34. CMS is nearly complete Detector Commissioning & Data Taking Ever increasing scope Various (combined) triggers  pre-synchronization Cosmics  reconstruction, pre-alignment/calibration 24/7 shift operation Tens of millions of -events Computing Challenges Successful test of expected 2008 data (transfer) load From Point 5 to Tier-2’s Distributed re-processing & analysis (>100k jobs/day) Calibration & Software Analysis Challenge From first data to first physics in a month next-to-realistic conditions Real-life calibration & alignment workflows tested First Physics / Physics Object Commissioning Underlying event & charged-hadron spectra SM candles (Z, W, top, ...) And all of the above more or less in parallel! Summary T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  35. Plenty of Data Taking, 24/7 Shifts ... Exhausted but happy CMS collaborators after a long night shift (of data taking) Even without collisions, CMS is already taking loads of interesting data to commission the detector It’s time for collisions... Computing and analysis challenges successfully demonstrate readiness for beam! T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  36. Backup Material ... T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  37. - (tt) ~ 100 times larger than at the Tevatron Towards (precision) Measurements ... Huge statistics for SM physics: ~ 107W evts/100 pb-1 ~ 106Z evts/100 pb-1 ~ 105tt evts/100 pb-1 “Minimum-bias” High-pT QCD jets • Alignment/Calibration: • ECAL uniformity • e/-E scale • HCAL uniformity • jet-E scale (JES) • Tracking alignment • Muon alignment W, Z production Gluon-to-Higgs fusion (light) Squarks, Gluinos (m~ 1 TeV) improve Early data: Zee, Z, QCD jets, Z/+jet(s), Wjj in tt, ... T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  38. CMS Installation... in Pictures January 2008 Touch-down for the last heavy structure of CMS: Inner Endcap Yoke with Muon Chambers & Endcap ECAL+HCAL T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008 T. Christiansen, CERN · Renc. de Moriond EW 2008 · La Thuile, Mar. 1-8, 2008

  39. Beam-Pipe and Trial Pixel Insertion Beam-pipe: +z side view, June ‘08 T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  40. CSA08 Al/Ca Examples ECAL Calibration: Zee ECAL Calibration: 0 min-bias + QCD samples ECAL 1 barrel + 1 endcap e M(ee) in Zee before and after -symmetry and MZ corrections CSA08 statistics insufficient to calibrate individual crystals:With 10-100 pb-1 of real data, expect crystal level calibration 1% T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  41. MB1 MB2 MB3 Wheel0 MB4 CSA08 Al/Ca Examples ... continued • Ttrig Calibration performed using high-pT muon samples • fit rising edge of the TDC spectrum • Constant resolution of 200 m, except MB4 (only two superlayers) T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  42. Minimum Bias using HF (Forward HCAL) 4343 beam-bunch pattern • Min-bias trigger: • No. of HF trigger towers over threshold > N, any side or on both sides. HF 3<||<5 preliminary • “Ideal” min-bias data: events with single pp collision, no pileup • At low luminosity, min-bias trigger most effective (zero-bias  empty) • At medium lumi, zero-bias useful T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  43. (view  beam) track jet axis IP d0 udsg b c CMS Combined tagging discriminator A Glance at B-Tagging ... • significance d0 /(d0) • all jet tracks  Likelihood • also 3D, vertex finding ... N.B.: Life-time b-tags work even with misaligned tracker (d0<0 if track crosses jet-axis on opposite side of IP) b-tag efficiency with independent (from tt) sample: semi-leptonic bb Use -jet + (tagged) away-jet samples: (MC truth) Measure eff. with first data rather than trust MC only: Tested methods developed at the Tevatron (pTrel based) Algorithm for combined 2ndary-vertex tagging (incl. topological & kinematical observables) (smallest MC dependence) T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

  44. preliminary preliminary m(ZSSM) = 2 TeV m(ZSSM) = 1 TeV CMS preliminary 5 reach Z’  Z Z’  ZSSM Outlook at Z’, and HiggsWW* • A glance at • HWW*ll (l=,e): • 2 isol. leptons, pT-cut • central-jet veto • kinematical variables  • Boosted Decision Tree: New resonances in the di-lepton spectrum 100 pb-1 at first glance ... T. Christiansen · CMS Commissioning & First Physics · CERN EP/PP Seminar · 21 July 2008

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