Calibration

1. Calibration S.Maselli for DT CAL Team Muon Barrel Workshop – 28/09/2010 • Status of the art – the first tTrig calculated from data • Update of the calibration workflow • Preliminary vDrift results DT Calibration - Muon Barrel Workshop

2. DT Calibration for collision at 7 TeV The DT Calibration Team Presented in Bodrum First results from pp collisions at 7 TeV: ~ 1 pb-1 of statistics to perform DT calibration. Production of calibration constants Data Base (ttrig DB) with an automatic calibration workflow which has been tested since Cosmic Ray data taking periods. The DT Calibration Work Flow: • ttrig are the pedestals from fit to rising-edge of time box, with super-layer granularity. This quantity is used to compute the drift time. • Uncertainty in fitting the time box requires a further correction to remove the bias in residuals.From the distributions of residuals between hits and reconstructed segment a quantity <Residual>/vdrift is computed to correct the tTrig. TDC counts [ns] Before and after residual correction applied to the tTrig Residuals [cm] Residuals [cm] DT Calibration - Muon Barrel Workshop

3. DT Calibration for collision at 7 TeV Presented in Bodrum Dedicated DT calibration ALCARECO data set suffers from large background from cosmics. Then the MuonDPG_skim in the Commissioning PD is used + event selection useful for calibration process. Events are selected according to: DT activity + collision events + at least 1 GLB or TRK muon in the barrel. Production of the first calibration constants for time pedestals. They are loaded to _express, _prompt, _offline and _hlt data bases since version 38x. tTrig [ns] 1  12 1  12 1  12 1  14 Run range 138845 - ~142000 MB1 MB2 MB3 MB4 Chambers and Sectors DT Calibration - Muon Barrel Workshop The DT Calibration Team

4. DT Calibration for collision at 7 TeV • tTrig Calibration Workflow has been monitored regularly every high statistic run intervals – The choice to run the calibration is according to human criteria. • Minor changes in the recently tTrig DB calculated in run range 142000 – 144000 have been observed probably due hardware issues. • Three main questions arise: • Decide the criteria when to run the Calibration Workflow • Since calibration constants are stable, under stable conditions, define a fast work flow which does not start from Time Boxes measurements, but directly from the Residual Correction • Use the Calibration Quality Test tool to compare the produced constants with a set of reference constants. next topic: Update of the Calibration Workflow DT Calibration - Muon Barrel Workshop

5. Update of Calibration WorkflowDecide the criteria when to run the Calibration • Proposal to update the constants each time the hardware configuration changes – automatic notification? • DT Trigger Configuration twiki page has book keeping of the changes: • Two examples: • Run range 138845 - ~142000 STARTUP10_06dttf10_TSC_12 (Bodrum Calibration) • Run range 142000 - ~144000 STARTUP10_08dttf10_TSC_12 (tTrig in next slides) Define fast Calibration Workflow from Residual Correction • A new version of the workflow starts from the tTrig table stored in the Global Tag • or from a sqlite tTrig table and: • compute the residuals at the SL level with LocalReco • correct the tTrig value with the bias observed in the residuals • e.g.: dtCalibration ttrig residuals --run=138828 --runselection=138828-140400 • --trial=1 --datasetpath=/Commissioning/Run2010A-MuonDPG_skim-v6/RAW-RECO • --globaltag=GR_R_38X_V9 --templatepath=templatesRAW • --preselection=CalibMuon.DTCalibration.dtCalibOfflineSelection_cff:dtCalibOfflineSelection • --inputDB=ttrig_ResidCorr.db DT Calibration - Muon Barrel Workshop

6. Update of Calibration WorkflowCalibration Quality Tests to be checked by shifter • Main DT Calibration twiki page: https://twiki.cern.ch/twiki/bin/view/CMS/DTCalibration2010 • Calibration shifter manual: https://twiki.cern.ch/twiki/bin/view/CMS/TheDTCalib2010manualNEW • Instruction about the plots • Comparison with reference plots • Results of calibration production and validation • CMSSW version installed centrally in the dedicated afs Calibration area. (ideally it would be better to use the same version for Calibration and Prompt Offline) • Keep the number of plots to monitor as low as possible (at present ~ 30) • Use reference quality tests for the certification • Report of the certification will be done to the Calibration Expert on shift who decide the actions to be taken (e.g. load a new DB). DT Calibration - Muon Barrel Workshop

7. Examples of Calibration Quality Plots • Difference of calculated tTrig DB wrt the reference tTrig DB in the Global Tag • 1 plot per wheel: SLs versus Sector number • 3 quality degrees (colors): • - green = good DtTrig < 3 ns • - yellow = warning 3 ns < DtTrig < 6 ns • - red = bad DtTrig > 6 ns • - The 3 levels can be set by external card. DT Calibration - Muon Barrel Workshop

8. Examples of Calibration Quality Plots • Results from the Validation Quality Tests using the residual distributions. • <Mean or residual calculated at SL granularity> is good if < 200 mm • <Sigma or residual calculated at SL granularity> is good if <1 mm • Distribution of the <Mean> of residuals, all phi SLs (equivalent plot for Theta SLs) • Global Summary plot on residual results: number of SLs with good value of <Mean> and <Sigma> as a function of Wheel/Sector (e.g. “black” = 13 SLs with good <Mean> and <Sigma>) - Color palette to be adjusted - 1) • 3) Summary of quality tests for each Wheel as a function of Sector/SLs (“white” = yes, “black” =no) 2) 4) Equivalents plots for <Sigma> distributions DT Calibration - Muon Barrel Workshop

9. vDrift Calibration • Definition of vDrift Calibration • vDrift calibration workflow: • Meantimer calculation with calibrated tTrig DB • vDrift and Resolution calculation • recompute tTrig using calibrated tTrig+vDrift Foreword to the vDrift analysis: An independent analysis will be presented in the DPG session (Nicola) performed using the calculation of vDrift with the t0seg method. Some discrepancies between the two results have still to be understood. DT Calibration - Muon Barrel Workshop

10. The vDrift with Meantimer technique • The quality of calibration constants is monitored/defined using the Local Reconstruction and calculating the residuals on distance: Residual on distance = |x measured (xRecHit)| – |x extrapolated (xextr)| • In the residual distribution is impossible to disentangle the effects of miscalibration of ttrig and vdrift. With the newly tTrig constants measured with the collision data we can start to calibrate the vDrift. • The vDrift calibration algorithm uses the Meantimers. This strongly depend on the precision of the ttrig calculation. • The vDrift value is obtained from the fit of the meantimer distributions (by SL) and all the considered angles are taken into account because the calculation implements different meantimer formulas for different track patterns • At present the vDrift DB is filled with constant value of 54.3 mm/ns. • From CRAFT data we learned that: • the DT system has approximately a constant effective vDrift of 54.3 mm/ns for all chambers except for MB1 in external wheels where it was measured of 53.4 mm/ns. (See paper) • The effective vDrift depends strongly from the magnetic field and from the angles of the segments, so to be conservative a fixed starting value of 54.3 mm/ns was adopted. •  Next topic: vDrift calibration DT Calibration - Muon Barrel Workshop

11. VDrift Calibration first look with collision data The Meantimer technique compute a constant drift velocity at the SL granularity: Example of Meantimer distribution Vdrift = L/2 * 1/<Tmax> Resolution = Vdrift * <sTMax> TMax is the Meantimer which has different formula for different pattern <TMax>, <sTMax> computed as weighted mean of each formula DT Calibration - Muon Barrel Workshop

12. tTrig Calibration workflow results Run range 142000 - 144000 tTrig Calibration Workflow using constant vDrift at 54.3 mm/ns tTrig [ns] 1  14 1  12 1  12 1  12 MB1 MB2 MB3 MB4 DT Calibration - Muon Barrel Workshop

13. Calibration Quality Plots for the tTrig DB calculated in run range 142000 - 144000 • Difference of calculated tTrig DB wrt the reference tTrig DB in the Global Tag • 1 plot per wheel: SLs versus Sector number • 3 quality degrees (colors): • - green = good DtTrig < 3 ns • - yellow = warning 3 ns < DtTrig < 6 ns • - red = bad DtTrig > 6 ns • - The 3 levels can be set by external card. DT Calibration - Muon Barrel Workshop

14. VDrift Calibration first look with collision data Run range 142000 – 144000 + tTrig DB of previuos slide vDrift [cm/ns] Vdrift = L/2 * 1/<Tmax> Resolution = Vdrift * <sTMax> • vDrift values not far from the values loaded in the DB. • Slightly higher vDrift in MB1 external chambers. • Resolution better than the one in DB = 500 mm MTResol [cm] 1  12 1  12 1  12 1  14 MB1 MB2 MB3 MB4 DT Calibration - Muon Barrel Workshop

15. tTrig Calibration using calibrated vDrift Run range 142000 – 144000 + tTrig DB and vDrift DB calculated in previuos slides Similar values, within 2 ns, in MB1 external wheels systematically higher tTrig DT Calibration - Muon Barrel Workshop

16. Conclusion • Update of the documentations with Quality Checks and comparison of the newly calibrated tTrig with the reference one into Global Tag. A tool for the Offline Shifter. • First results of vDrift calibration calculated with collision data: • The values do not differ dramatically from the value already present in the DB • Nevertheless it is important to load into the DB tTrig and vDrift values calculated from data and not fake values. • Update of the vDrift python config files in CVS in CalibMuon/DTCalibration package. • Update of some modifications of the Calibration Quality Checks in DQM/DTMonitorClient and DQMOffline/CalibMuon packages. DT Calibration - Muon Barrel Workshop