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Test TPC Off-line analysis. Marian Ivanov. TPC commissioning. Test of TPC 2 TPC sectors not full TPC operational, no magnetic field Cosmic test 3 voltages settings 1 nominal voltage (statistic ~ 2000 triggered events (~10000 tracks)) +- 50 volts (statistic ~ 300 events) Laser test

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Tpc commissioning
TPC commissioning

  • Test of TPC

    • 2 TPC sectors

      • not full TPC operational, no magnetic field

    • Cosmic test

      • 3 voltages settings

        • 1 nominal voltage (statistic ~ 2000 triggered events (~10000 tracks))

        • +- 50 volts (statistic ~ 300 events)

    • Laser test

      • Drift velocity determination, monitoring

      • Alignment

        • Stability test – important for ExB correction


Data flow
Data flow

Raw data – Date format format

Rootification

Raw data – Root format forma

Reconstruction (Clusterization, tracking)

ESD – Tracks – default mode

Clusters and Signals (calibration mode)

Offline

Post processing Calibration


Data volume
Data volume

  • Raw data – One run (given sector ,voltage setting)

    • 60 files x 1.5 GBy ~ 90 GBy

    • Public access - Castor path /castor/cern.ch/user/m/miranov/testtpc2006/rawdata

  • Rootified data

    • 60 files x 0.65 GBy ~ 40 GBy

    • Public access - Castor path /castor/cern.ch/user/m/miranov/testtpc2006/rootdata

  • Reconstructed data

    • 60 files x (AliESDs.root ~ 0.4 MBy + TPCtracks.root ~ 0.8 MBy + FitSignal.root ~ 100 MBy) ~ 6 GBy

    • Public access - Castor path /castor/cern.ch/user/m/miranov/testtpc2006/rec0606

      • Further reconstruction pass with new directory created


Cpu requirements
CPU requirements

  • Raw data to Rootified data

    • Downloading of the data to local storage

      • 60 x 3 min ~ 3 hours

    • Rootification

      • 60 x 3 min ~ 3 hours

    • Downloading and rootification done in bunches of files (Done in parallel)–Response time ~ 3 hours

  • Reconstruction

    • 60 x 40 min

    • Done in parallel on LSF batch system

    • Response time ~ 1-2 hour (waiting time in batch queue)

  • Total response time given mainly by data transfer

    • In optimal condition – Direct storage of rootified data on CASTOR + High priority in the batch queue ~ 1 hour


Offline reconstruction cluster finder
Offline Reconstruction (Cluster finder)

  • Find clusters

    • TPCRecPoints.root (Default mode)

  • + In Mode without pedestal subtraction

    • Estimation of pedestal event by event

    • Pedestal and noise calibration (histograming and fitting of amplitude spectra)

    • Signal fitting (optimization of parameters for tail cancellation)

  • Reconstruction per file


Offline reconstruction tracking
Offline Reconstruction (Tracking)

  • ESD

    • AliESDs.root(Default mode)

  • + In calibration mode

    • Full TPC track stored

      • Clusters belonging to track

      • Extrapolation point at each pad row intersection (position, angle, estimated uncertainty, estimated shape parameters)

        • Calibration: Parameterization of space point resolution and shape


Offline analysis
Offline analysis

  • Gain measurement

  • Space point resolution, response function

  • Signal fitting, processing

  • Calibration


Offline analysis1
Offline analysis

  • Input data

    • Tracks and clusters – chain of Tree of tracks

      • TPCtracks.root

    • Pedestal & noise – chain of tree of fitted parameters histogram of amplitude spectra (mean –pedestal estimation, sigma – noise estimation)

      • TPCsignal.root

    • Signal shape – chain of tree with fitted signals (parameters of fit, graphs and position (sector, pad, row))

      • FitSignal.root


Analysis
Analysis

  • .L TestAnalisys.C

  • AddChains(runNumber);

    • Loop over all files with given run number add trees to the chain

  • Select();

    • Make default selection

    • Example:

      • Track.fN>60 && abs(Track.fP4)<0.001

      • Number of cluster per track bigger than 60, remove tracks with big curvature (most probably delta electrons)

  • Do predefined plots

    • See following slides

  • Analysis done per run


Noise analysis
Noise Analysis

  • NoiseSector(“Sector==3”,”Run 872 sector 3 (V(A3_IROC) =1400 V)



Gain analysis
Gain analysis

  • Statistic not sufficient for pad by pad calibration

  • 3 default plot

    • Gain as function of pad-row

    • Gain as function of pad position (phi angle)

    • Gain as function of z position (electron capture)


Gain analysis run872
Gain analysis (run872)

  • ProfileMaxRow(“Cl.fDetector==49”, “Sector 49”,100)

    • Arguments: cut, comment, binning





Gain analysis1
Gain analysis

  • ProfileMaxPhi(“Cl.fDetector==49”, “Sector 49”,25)

    • Arguments: cut, descriptor, binning



Gain electron capture run 567
Gain - electron capture (run 567)

  • The Q total (Total charge in the cluster) as function of Z position

    • Relative decrease ~7 % (mainly due to electron capture + threshold effect) on full TPC drift (bigger statistic needed to be not influenced by Landau fluctuation


Response function
Response function

  • PRFYZ(cut, “Run 872”)

    • Arguments : selection, comment


Response function1
Response function

  • PRFZZ(cut, “Run 872”)

    • Arguments : selection, comment


Space resolution
Space Resolution

  • Left side Run 872

    • Command ResYZ(cutinner, cutouter, comment)

  • Right side Run 567


Signal processing
Signal processing

  • Signal fitting added to analysis chain to tune parameters for tail cancelation

    • Plans to include also Bernardo Mota algorithm to estimate tail cancellation parameters


Signal processing1
Signal processing

  • The signal fitting

    • Fit function – convolution of Gaussian distribution with the sum of two exponential distributions

      • Two exponential distributions approximate k/time distribution

      • Possibility to reduce exponential components


Signal processing2
Signal processing

  • Lambda 0 parameter

  • Command P3Z(“Sector==3”,”Sector==39”, comment)


Signal processing run872
Signal processing (Run872)

  • Lambda 1 parameter

  • Command P5Z(“Sector==3”,”Sector==39”, comment)


Conclusion
Conclusion

  • Ongoing work on automatization of the analysis chain

    • Currently ~ 4 hours for analysis chain (mainly due data transfer ~ 100 GBy per one run)

    • Will be reduced

  • The default histograms and pictures defined

  • Next plan:

    • Calibration

      • Gain calibration

      • Time offset calibration

    • Alignement



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