1. Calibration Status of the art – the first tTrig calculated from data
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
28/09/2010
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]
28/09/2010
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.
tTrig [ns]
MB1
MB2
MB3
1  
1  
MB4
Chambers and Sectors
Production of the first calibration
constants for time pedestals.
They are loaded to
_express, _prompt, _offline
and _hlt
data bases since version 38x.
Run range ~142000
28/09/2010
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 – 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
28/09/2010
DT Calibration - Muon Barrel Workshop

5. DT Calibration - Muon Barrel Workshop
Update of Calibration Workflow Decide 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 ~ STARTUP10_06dttf10_TSC_12 (Bodrum Calibration)
Run range ~ 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= runselection=
--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
28/09/2010
DT Calibration - Muon Barrel Workshop

6. DT Calibration - Muon Barrel Workshop
Update of Calibration Workflow Calibration Quality Tests to be checked by shifter
Main DT Calibration twiki page:
Calibration shifter manual: NEW
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).
28/09/2010
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.
28/09/2010
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
28/09/2010
DT Calibration - Muon Barrel Workshop

9. DT Calibration - Muon Barrel Workshop
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.
28/09/2010
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
28/09/2010
DT Calibration - Muon Barrel Workshop

11. first look with collision data
VDrift Calibration
first look with collision data
The Meantimer technique compute a constant drift velocity at the SL granularity:
Vdrift = L/2 * 1/<Tmax>
Example of Meantimer distribution
Resolution = Vdrift * <sTMax>
TMax is the Meantimer which has different formula for different pattern
<TMax>, <sTMax> computed
as weighted mean of each formula
28/09/2010
DT Calibration - Muon Barrel Workshop

12. tTrig Calibration workflow results
Run range
tTrig [ns]
1  12
 12
1  
MB4
MB1
MB2
MB3
tTrig Calibration Workflow
using constant vDrift at 54.3 mm/ns
28/09/2010
DT Calibration - Muon Barrel Workshop

13. DT Calibration - Muon Barrel Workshop
Calibration Quality Plots for the tTrig DB calculated in run range
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.
28/09/2010
DT Calibration - Muon Barrel Workshop

14. first look with collision data
VDrift Calibration
first look with collision data
MTResol [cm]
vDrift [cm/ns]
1  
1  
MB4
MB1
MB2
MB3
Run range – +
tTrig DB of previuos slide
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
DT Calibration - Muon Barrel Workshop
28/09/2010

15. tTrig Calibration using calibrated vDrift
Run range – +
tTrig DB and vDrift DB
calculated in previuos slides
Similar values, within 2 ns,
in MB1 external wheels systematically higher tTrig
28/09/2010
DT Calibration - Muon Barrel Workshop

16. DT Calibration - Muon Barrel Workshop
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.
28/09/2010
DT Calibration - Muon Barrel Workshop