Test TPC Off-line analysis

1. Test TPC Off-line analysis Marian Ivanov

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. Offline analysis • Gain measurement • Space point resolution, response function • Signal fitting, processing • Calibration

9. 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

10. 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

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

12. Noise analysis

13. 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)

14. Gain analysis (run872) • ProfileMaxRow(“Cl.fDetector==49”, “Sector 49”,100) • Arguments: cut, comment, binning

15. Gain analysis (run872)

16. Gain – Run 567

17. Gain – Run 568

18. Gain analysis • ProfileMaxPhi(“Cl.fDetector==49”, “Sector 49”,25) • Arguments: cut, descriptor, binning

19. Gain analysis

20. 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

21. Response function • PRFYZ(cut, “Run 872”) • Arguments : selection, comment

22. Response function • PRFZZ(cut, “Run 872”) • Arguments : selection, comment

23. Space Resolution • Left side Run 872 • Command ResYZ(cutinner, cutouter, comment) • Right side Run 567

24. 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

25. 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

27. Signal processing • Lambda 0 parameter • Command P3Z(“Sector==3”,”Sector==39”, comment)

28. Signal processing (Run872) • Lambda 1 parameter • Command P5Z(“Sector==3”,”Sector==39”, comment)

29. 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

30. Conclusion