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Report from the Calibration Working Week 25-29 September, Paris

This report summarizes the activities and discussions during the Calibration Working Week, focusing on the calorimeter upgrade, online calibration methods, and calibration goals for physics. Topics covered include EM-calibration, jet energy scale, computer work, and software tutorials. The aim is to bring together interested people, experts from Run I and related areas of Run II software, and discuss MC production requests, tools, and tasks/manpower. More information can be found at the provided link.

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Report from the Calibration Working Week 25-29 September, Paris

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  1. Report from the Calibration Working Week 25-29 September, Paris • Monday: Introduction • Calorimeter Upgrade Leslie Groer • Online Calibration Melissa Ridel • Sampling Weights Lee Sawyer • Calibration Goals for Physics Gregorio Bernardi • Tuesday: em-calibration • Run I methods Ursula Bassler • Electron Reconstruction and Triggers Michele Jaffre • Soft Electron Reconstruction Frederic Fleuret • -intercalibration Patrice Lebrun • ee Morgan Lethuillier • Zee Elemer Nagy • -dependence of em-sampling weights Pierre Bonamy • TriggersOleg Kuznetsov

  2. Wednesday: Jet Energy Scale • Run I methods Bob Hirosky • Jet Reconstruction Laurent Duflot • +jet Vipin Bhatnagar • Z+jet Steve Muanza • JES in Atlas Irene Vichou • E/p for single  in AtlasCatherine Biscarat • e/ reconstruction in jetsLaurent Duflot • Trigger on displaced verticies Arnaud Duperin • Thursday: Computer Work & Software Tutorials Laurent Duflot/Patrice Lebrun • Friday: Discussions: • MC production requests • Tools • Tasks/Manpower • Aim: start the effort on the in-situ calibration by putting together • the interested people (especially from Europe) • and the experts from Run I and related areas of Run II software: • 24 participants, including 7 PhD Students and 4 US-collaborators • Information/Transparencies: • http://d0-france.in2p3.fr/WORKING_GROUPS/CALORIMETRY/CALO_CAL_OFF/

  3. E.M. Calibration: • uniformisation of calorimeter response: • use  symmetry • intercalibration "regions" (cells?) with same  and depth • needs high statistics process • improves constant term in resolution • absolute scale determination/linearity: • resonances at different energy scales • E/p comparison at low energy

  4. Run I:  intercalibration - Et flow Ph. D. - Qiang Zhu D0-note 796 - Paul Grannis • the number of events above a given threshold pt0 should be equal for each -module of the calorimeter Method I: determine ipt,i0 = pt,ref0 such that Ni=Nref Method II: fit to spectrumlog Ni=A0+A1 ipt,i0 Method III: equalize pt,i0- < pt,i> (less precise) • Datasets: • Run 1a: triggers requiring 1 electron with pt>20 GeV  2.3 M events • special run: trigger with L1 pt>5GeV and L2 pt>7GeV •  3.5 M events • precision better than 0.5 % • Verification on W-mass spectrum: • HG: 81.27 0.36 79.40  0.33 • MG: 79.93 0.20 79.84  0.20 • LG: 78.71 0.31  80.04  0.15

  5. Run II: pT-distribution of We? • simulation using D0 parameters in ATLFAST++, Pythia 6.131 • energy Resolution used : 15%/E  3% • selection efficiency (PT > 10 GeV): 95% in e, 45% in e • method: comparison of < PT>, • < PT> = 31.4 GeV does not depend on h • 50% of the events at h<1

  6. Run II : First Accuracy Estimation • accuracy of pT: • 2.5% with 200 evts • 1% with 1200 evts • precision limit 0.6% • 10 % shift on the selection threshold at PT =10 GeV • error of 0.7 % on the relative calibration constants. • the effect of the energy resolution is small. cell of =0.1rad, =0.1 at =0.05 0.6 % • Next Steps:Patrice Lebrun + Pierre-Antoine Delsart • evaluate different methods + process: • systematic errors: cell size, threshold effects… • iterative methods? • study with full MC+trigger • sampling fraction study.

  7. Run I: Energy Scale Determination from Resonances • E =  Emeas +   determination of  and from Z, J/ and 0 • m = 2 E1E2 ( 1- cos )  E1, E2: electron energies, : opening angle • MZ   m+  f with kinematic factor f = (E1+E2) ( 1- cos )/m • f max= 2 for electrons back to back • m/ = f sensitivity to an • offset  varies with f D0-note 1819 - Ulrich Heintz D0-note 2209 - Ulrich Heintz D0-note 2298 - I. Adam et al. PRD 58-12002 - W-mass Run 1a PRD 58-92003 - W-mass Run 1b

  8. Run II: Expected Numbers of Events • trigger efficiencies very approximate…. • high J/ x-section due to b J/, but electron less isolated

  9. Run II:ee Trigger -trigger, UPS_CC: L2EM(2,3,e,fpi) - 2 em towers • - with ET > 3GeV • - electron type • fpi quality • ANDL2IM(e,3,e,3,9,1000) • - invariant mass of ele 1,2 at 3 • with [9,1000] GeV • approximated efficiencies • (no quality requirement) • for a 3 GeV threshold on both e: •  =13.7 % N=2675 evts/pb-1 • Is it possible to lower the mass threshold to 8.5 GeV? • 25% more events

  10. Run II ee : method verification • linear likelihood fit of Meas= -(/)f + (1/)Mtrue • check of fitting value measvs mis-calibration factor applied true • different dispersion values applied to true to simulate imperfect intercalibration • find estimator to determine necessary precision on intercalibration

  11. Run II: -calibration using Zee? • using localization of electrons to calibrate  regions • likelihood function:L= - evt ln pevt(Mevt/Mz) • pevt: probability density that mevt=mZ • M2evt= 2 E1kE2l(1-cosevt) with Etrue= Emeas+ :  supposed 0, or known • M2evt= mevt(1+k)(1+l) • minimization in terms of f:: correction factors in a given zone • estimating the method by applying miscalibration factors true: • bias: b= f -true error:  = (f -true)2- b • full simulation and reconstruction: 22k events from MC99 using Pythia • selection: 2 em-clusters with 1.1 or 1.52.5 • 87  Mevt  101 GeV

  12. Run II - Zee in -regions: accuracy • 48 zones, 7000 events, 1% miscalibration • b= -0.751 10-3  0.959 10-3 • = 0.6 %  0.7% • bad zones with 3% miscalibration • recovered at the 1% level • other zones are not affected

  13. EM Scale - Next Steps: • Ursula Bassler, Pierre-Antoine Delsart, Morgan Lethuilllier, • Elemer Nagy, Muriel Pivk • Low energies: • extend  study to J/ • feasibility of 0 and ? • E/p comparisons • influence of increased dead material? • combine -calibration method with f-binning method?

  14. Run I: +jet calibration • choose your jet algorithm • subtract contribution of underlying event from the jet • normalize overall response from CC and EC • determine relative response correction in  (di-jet events) • apply absolute hadronic response correction • … while taking into account all systematic effects • energy dependence • luminosity dependence • showering effects • trigger and reconstruction thresholds • bias from background…

  15. signal:152 M evts bkgd: 47.1 M evts signal: 64.8k evts bkgd: 650 evts /Z+jet QCD (udsg) QCD (cbt) W+jet, Z+X, VV Run II: +jet/Z+jet • fast simulation using D0-toy detector L = 2fb-1 • +jet: Run I method – jet calibration possible up to 250 GeV • Z+jet: lower statistics, but clean sample, useful at low energies, x-check!

  16. peak: 82.6 peak: 86.8 b-jet calibration • using b-tagged events in +jet sample? • expected number of tagged events: 1.2 M • but: sensitive! fractional imbalance I= (pT() - ET(jet))/ pT() • no b-tagged events: -2.2% b-tagged events: +5.2% • Z bb: difference in reconstructed mass w.r.t Z  qq • but: only possible with STT (2002)

  17. Jet Energy Scale – Next Steps: • Gregorio Bernardi, Vipin Bhatnagar, Eric Chabanat, Jerome Coss, • Bob Hirosky, Karl Jakobs, David Meder, Steve Muanza, Melissa Ridel • -symmetry of cells in HCAL • E/p for single low energetic  • -jet: • study of new jet algorithms • new variables for energy response corrections • use for detector oriented calibration: hadronic layer weight optimization? • CNN algorithm:apply e/ specific corrections? • Z+jet: • carry out similar analysis as for -jet • b-jet: • study of +b production mechanism • extraction of Zbb w.r.t. QCD background?

  18. Tools development: • use “standard” D0 packages: full simulation/PMCS • xxx_analyze • standardize datacards for MC generation (Steve Muanza) • provide access to GEANT Layer information (Lee Sawyer) • trigger simulation and efficiency determination (Oleg Kuznetsov) • extend SEM-reco for low energy electron calibration? (Frederic Fleuret) • develop “miscalibrator” (Laurent Duflot) • provide Root Analysis framework (Laurent Duflot/Patrice Lebrun) • common software “pool”

  19. MC production request • production to be started at the CC-Lyon asap

  20. Next Meetings: • 14/15 November – Lyon • 6 December – Fermilab • If you want to join, contact • Steve (muanza@in2p3.fr) or • Ursula (bassler@in2p3.fr )

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