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Focus on readiness for Physics Case for Pixel Upgrade TDR Tracking Performance

Pixel Phase 1 Physics/Simulations Harry Cheung ( Fermilab ) for the Tracker Upgrade Simulations Group. Focus on readiness for Physics Case for Pixel Upgrade TDR Tracking Performance Software and Computing Issues for Physics Case. Simulation Studies. Simulation software for TDR studies

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Focus on readiness for Physics Case for Pixel Upgrade TDR Tracking Performance

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  1. Pixel Phase 1 Physics/SimulationsHarry Cheung(Fermilab)for the Tracker Upgrade Simulations Group Focus on readiness for Physics Case for Pixel Upgrade TDR Tracking Performance Software and Computing Issues for Physics Case CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  2. Simulation Studies • Simulation software for TDR studies • Using CMSSW release CMSSW_4_2_3_SLHCx with CMSSW_4_4_X tracking (handles high PU better) • Not moving releases until we have results on the ZHbb analysis for TDR • Full (GEANT4) simulation used for tracking studies: tracking efficiency and fake rates, b-tagging studies • Modified Fastsimulation for physics studies (but see later) • Results to be included in the TDR • Effect of new ROC (reduce data loss) • Effect of additional pixel layer • Recovery of efficiency in case of TIB inefficiency • Effect of smaller pixel size/closer radius (Phase 1b) • Effect of upgrade on a physics channel (boosted ZHbb) CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  3. Upgrade Tracking • Study at <PU>=50 (100) for 25 (50) ns crossing time • Data loss used in simul. due to ROC/readout limitations (from TP) • Do we have new data loss numbers for redesigned ROC chip? • Tracking steps modified for upgrade geometry and high PU • Extra layer: quadruplet seeds and efficient triplet seeding (3-out-of-4) • Tuning of tracking steps for <PU> of 50 and 100 to reduce fakes • Drop pair seeds, low pTseeds, and detached tracking steps • Optimization still ongoing CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  4. Effect of ROC Data Loss • Loss of efficiency for tracking (ttbar, <PU>=50, high purity tracks) Fake Rate Efficiency eta Fake Rate Efficiency pT No data loss With data loss Phase 1 Upgrade Geometry Current Geometry CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  5. Effect of ROC Data Loss • Worsening of b-tagging (<PU>=50, ttbar) CombinedSecondaryVertex b-tagging algorithm Phase 1 Upgrade Geometry Current Geometry CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  6. Effect of Extra Layer • Using MultiTrackValidator, ttbar sample, high purity tracks Fake Rate Efficiency eta Fake Rate Efficiency pT Current Pixel Geometry Phase 1 Upgrade Geometry <PU>=50 with (Pixel ROC) data loss <PU>=50 no data loss CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  7. Effect of Extra Layer • Improvement for b-tagging (<PU>=50, ttbar) • Already significant Improvement for upgrade geometry even without ROC data loss CombinedSecondaryVertex b-tagging algorithm <PU>=50 with (Pixel ROC) data loss <PU>=50 no data loss CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  8. Tracking Efficiency & Fake rate • Using MultiTrackValidator, ttbar sample, high purity tracks No Pileup Fake Rate Efficiency eta Fake Rate Efficiency pT Upgrade improves tracking efficiency, and fake rates at high PU Current Pixel Geometry Phase 1 Upgrade Geometry CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  9. Transverse IP Resolutions vs p • Compare Std Geometry and Phase 1 zero PU using muons Current Pixel Geometry Phase 1 Upgrade Geometry 0 < η < 1.0 1.0 < η < 1.5 1.5 < η < 2.0 2.0 < η < 2.5 CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  10. Longitudinal IP Resolutions vs p • Compare Std Geometry and Phase 1 zero PU using muons Current Pixel Geometry Phase 1 Upgrade Geometry 0 < η < 1.0 1.0 < η < 1.5 1.5 < η < 2.0 2.0 < η < 2.5 CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  11. Primary Vertex Resolution vs Ntk Transverse • Using ttbar, we want to demonstrate why the resolution gets more worse for stdgeom (still under study) No pileup <PU>=50 Longitudinal <PU>=50 No pileup Current Pixel Geometry Phase 1 Upgrade Geometry CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  12. B-Tagging Performance • Compare <PU>=100, ttbar, no tuning of b-tag algos Need tuning and optimization of tracking and b-tagging algorithms at <PU>=100. Do we show this in TDR? We are investigating the offset at high PU Relevant if we run with 50 ns crossing time at 2×1034 cm-2s-1 CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  13. Phase 1b Studies, etc. • In progress of getting results for Phase 1b • Now just doing 75x100 μm2 pixel PXB, 200 μm thk, 2000e threshold • Will make the same plots as regular pixel size (IP and PV resolutions, tracking efficiency and fake rate, b-tagging) • Not likely to get results for a physics analysis • In progress of updating PXB geometry and beampipe • Once we have results we can update the plots using this (this is the new PXB baseline with 12 faces for layer 1) • Not shown here, but we are also updating the TIB inefficiency study plots CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  14. Phase 1b Studies • Resolution plots from MTV (not plotted against absolute p) Transverse Longitudinal eta pT pT Phase 1 Smaller Pixel Size CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  15. Simulations for Physics Case • Study the boosted ZH μμbb-bar channel as in the TP • Channel still relevant in the >100 fb-1 regime • Use CMSSW simulation instead of generator analysis used in TP • Use Modified Fastsim: simhits (including PU) from fastsim but then the regular Fullsim digi steps and full track pattern recognition • Faster and lower memory usage, Fullsim digi+reco step needs >4GB RAM/job slot (max 2-3 GB/slot on GRID) • Some mismatch, need to compare eff/mass distr to use it or not • Will not do 100 PU samples ttbar: LPCCAF CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  16. “Validate” Modified Fastsim 4 Physics • Compare modified FastsimvsFullsim, ttbar, <PU>=50 • Modified Fastsim: use Fastsim for simhits & pileup only Fullsim Modified Fastsim Phase 1 geometry Current Geometry CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  17. Tracking Efficiency & Fake rate • Compare Fastsim, Muon gun (flat pT), <PU>=50 • Modified Fastsim: use Fastsim for simhits & pileup only Fullsim Modified Fastsim Phase 1 geometry Current Geometry CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  18. B-Tagging Performance • Compare Fastsim, ttbar, No Pileup • Modified Fastsim b-tagging performance similar for a wide operating CombinedSecondaryVertex b-tagging algorithm Phase 1 geometry Current Geometry CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  19. B-Tagging Performance • Compare Fastsim, ttbar, <PU>=50 • Modified Fastsim b-tagging performance similar for a wide operating range of b-jet b-tagging efficiencies (despite fake rate difference) CombinedSecondaryVertex b-tagging algorithm Phase 1 geometry Current Geometry CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  20. B-Tagging Performance • Compare Fastsim, ttbar, <PU>=50 • Modified Fastsim b-tagging performance looks similar enough at <PU>=50 to do comparative physics studies CombinedSecondaryVertex b-tagging algorithm Fullsim Modified Fastsim CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  21. B-Tagging Performance • However! Compare Fastsim, ttbar, <PU>=100 • Modified Fastsim b-tagging performance very different from Fullsim! • Need to investigate CombinedSecondaryVertex b-tagging algorithm Phase 1 geometry Current Geometry CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  22. MC Samples Requested • 10K Fullsim signal & background samples produced • Samples look okay to proceed with large samples • 10K modified Fastsim samples being validated • Fullsim GEN-SIM samples requested, being processed • Need to request digi+reco with AOD output after this • Data production team is already saying there is a problem (>2GB) • Will work with CMS VHbbAnalysisNewCode • Learning stage (more complex than generator analysis) CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  23. Issues and Concerns • We have basically in hand all the plots we had for the TP but updated to the latest CMSSW version • We are still getting the Phase 1b plots • Should have additional plots showing understanding of effect of PU • Very slow progress with physics analysis • Mainly due to lack of resources (manpower) • Expected dedicated (Tracker) physics coordinator – did not materialize • Now need to push on with the people we have (now 2 new people) • Very little time, but at least we now seem to have a team of people to work on this (names reflect my current personal understanding) • Eric Brownson/Carlos Maca, Mark Grimes, (Helena Malbouisson), Robert Stringer • Also need to push on getting the samples (CPU resources) • Should present comparisons of the high PU data (30 PU) with MC • Studies ongoing in Tracking POG but they could use help CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  24. Backup Slides CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  25. Pixel Phase 1 Geometry • Phase 1 pixel detector replacement • 4 barrel layers, outermost layer closer to TIB • 3 FPIX disks per side, split into inner and outer disks • New ROC chip, readout, power, cooling, etc.: Total material less than in current pixel detector Phase 1 BPIX geometry Current BPIX geometry CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  26. Pixel Upgrade Material Budget • Reduced material even with more layers Rad. Len. Nucl. Int. Len. Pixels Pixels Dots - std geom Green Hist - R39 CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  27. Standard Tracking Steps • 4_4_0_pre6 tracking steps: includes pair seeds, lower pT seeds, and detached tracks CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

  28. Tracking Efficiency & Fake rate • Using MultiTrackValidator Tracking efficiency = #simtrks assoc. to recotrk #simtrks (for signal sim tracks only) Tracking fake rate = #reco trks not assoc. to sim trk #reco trks (for “all” reco tracks) CMS Upgrade Workshop, 7 Nov 2011 H. W. K. Cheung (FNAL)

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