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EMCal Offline Status

EMCal Offline Status. Gustavo Conesa Balbastre. EMCAL status @ Point 2. 4 Super Modules installed 2 SM in C side 2 SM in A side Trigger L0 commissioned successfully See EMCAL golden run 134908, Events with at least one cluster with 1.7 GeV Operation rather stable

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EMCal Offline Status

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  1. EMCal Offline Status Gustavo Conesa Balbastre EMCal Status

  2. EMCAL status @ Point 2 • 4 Super Modules installed • 2 SM in C side • 2 SM in A side • Trigger L0 commissioned successfully • See EMCAL golden run 134908, • Events with at least one cluster with 1.7 GeV • Operation rather stable • One RCU (1/8 of detector) missing from time to time. EMCal Status

  3. Geometry: Changes • Fixed bug for positions of modules inside SM : first module has tilt 0.75 degree. • Added Al front plate (width 1 cm) and 2 paper sheets per sampling layer (additional 0.2 mm) • The sizes have updated with last information from production drawing (end of October 2010): Face tower sizes : 12 cm*12cm • Updated geometry is called “EMCAL_FIRSTYEARV1”, changes in trunk but validation on progress. • Next year we will install full EMCAL, 6 more SM (instead of 6+2 half SM), for this geometry we will use the name “EMCAL_COMPLETEV1” • Need to update all the configuration macros. EMCal Status

  4. Geometry: Changes effects Simulation without changes in geometry compared to 2007 beam test. Need to compare changes and 2010 beam test • This might solve Task 2627 : Correct detector response, GEANT and FLUKA. • Need to update sampling fraction from 10.5 to 12.82 for G3 and check for other transport MC Changes in geometry seem shift resolution to measured values in beam test. Need more checks EMCal Status

  5. Geometry: Alignment • Alignment: Task 2533: Finalization of the detector geometry checking for overlaps. • Tasks 2630 : Study effect of misalignment in reconstruction. • History • First approach: alignment extracted from surveys, showed shift of 20 cm in z, which was wrong. We decided to not trust survey. • Second approach, calculate alignment using reverse ingeniering matching electrons with TPC. • Move SM until residuals of positive and negative charges match. • This alignment was only in the OCDB from pass 1 of half LHC10f period and pass2 of LHC10d, e … before just ideal position of old geometry. • This alignment improves reconstruction but still shows some strange behavior, see next slides. • Third approach, new survey was done with more reasonable values. We are producing the corrections. First results look reasonable. • We will commit soon to OCDB the best alignments EMCal Status

  6. Residuals after first alignment Clear improvement, now residuals centered at 0 EMCal Status

  7. Improved residuals but it should be better. Cluster X- Track X Vs Cluster X Cluster Y- Track Y Vs Cluster Y Improved residuals but it should be better. What happens here? We do not trust matching for alignment anymore Cluster Z- Track Z Vs Cluster Z EMCal Status

  8. Electron Matching and New alignment from survey Sector 1 • We got a new alignment from the survey and we applied it on the analysis • DZ vs Z slope has disappeared, but there is a difference positives vs negatives, specially in sector 1. Sector 0 EMCal Status

  9. Electron Matching and New alignment from survey • Either we have to improve our alignment or there is a problem with the matching. Sector 0 Sector 1 EMCal Status

  10. Track Matching • Task 2632: Track matching improvement • Matching done during analysis, after reconstruction (previous slides) seems now rather OK. • Matching during reconstruction is much worse, should give the same, under investigation after alignment issues are fixed. • Standard matching cuts: |Δx|<6cm, |Δy|<6cm, |Δz|<6cm, ΔR<10cm • Size of cell side is 6 cm • Loosing the selection using pt dependent cuts represented by lines improves efficiency a 10 %, still need some improvement. EMCal Status

  11. Calibration • Until recently calibration based on MIP, not enough. • Improved calibration using Pi0 channel by channel relative calibration • Machinery in place in $ALICE_ROOT/PWG4/CaloCalib • Data sets used: LHC10b+c+e • LHC10d not used since shows some deviation due to changes in Temperature in the pit. • We are working in the implementation of the temperature corrections, not yet in place. • Improved calibration used for LHC10d pass2 and from half LHC10f pass1 EMCal Status

  12. Pi0 mass and width after calibration and alignment improvements LHC10b+c pass2 LHC10e pass1, uncorrected • Plots with combinations of clusters in the same supermodule or different supermodules • Clear improvement due to corrections in misalignment and calibration. • Still deviations when combining SM in different sides, due to remaining misalignment. • Main mass pT dependence due to non linearity effect not corrected. • To be done in analysis level Run 134908, OCDB corrected EMCal Status

  13. “Golden” p+p Run 134908 pass1 10M events EMCAL Triggered run, threshold 1.7 GeV Same OCDB, reconstruction as LHC10d pass2. Cluster Energy > 0.5 GeV Asymmetry cut 0.5 Clear 0 and  signals More than in LHC10b+c+d+e … good for calibration … but for Physics? EMCal Status

  14. Raw fitting • We have implemented different fast fitters, • Slow fitters (truth for benchmarking comparisons): • kStandard: default fitter used until now, Minuit fit, too slow. • kLMS: refined version of kStandard • Fast Fitters • kFastFit • kNeuralNet • kPeakFinder • kCrude: Takes the maximum bin. • but we have still not using them, currently we reconstruct with the standard fitter. • Need to do some benchmarking tests with all the fitters with the last summer beam test data. • Fit quality: • The calculation of the raw signal fit Chi2 and NDOF can give an idea of the quality of the amplitude fit obtained. • Digits include these 2 parameters, but they are not used, right now in reconstruction. • Under study EMCal Status

  15. Redefinition of digits and related tasks • Task 2538: Correct treatment of detector signal in sdigits correct event merging implementation • A digit was an amplitude and time per channel • This approach does not take into account in simulation: • Fitting problems of the different algorithms. • Samples with different time arrival, pile-up. • How can we improve it: Produce a raw time sample from the energy lost and get the final amplitude from the fit of this sample. • What needs to be done: • Modify AliEMCALDigitizer::Digitize() so that it takes the Sdigit energy, converts it in a time sample and then fits it. The sample and the fitted energy/time is kept in the digit. • In order to have a realistic performance, we need to implement a more realistic shaper : energy to time sample. The actual shaper is not realistic at low amplitudes. • Task 2537: Verification of event merging procedures • Event merging of simulated data with the actual definition of Digits works. • Need to revisit when previous task is in place. • Need to implement the embedding (merging of real data+simulated data). • Should we merge the time samples or the fitted values? EMCal Status

  16. Time resolution in simulation • Task 2535: Implement realistic time resolution in digits. • In the code now we have a fixed time resolution of 0.6 ns • We have to implement a resolution depending on the amplitude. Investigation in parallel with raw fitting benchmarking. EMCal Status

  17. Time measurement • Task 2534: Handling of the time information from hits during digitization • No one looks into it. • Since last meeting a fixed shift on the simulated time of 600 ns is applied to match roughly the displacement seen in the data. • We are working in a procedure for the calibration of the time of the cells. • We have very first results that look promising but this task is difficult. • From run to run there are important variations. • Depends on bunch crossing ID and RCU firmware version which produce several displaced peaks that does not help, we know how to correct. Run 117220 - Pass 2 EMCal Status

  18. Trigger • We have requested to change the information stored in the ESD for the trigger. • Implementation committed to trunk, missing the filling part in EMCAL. I could not test since trunk was not working for the reconstruction. EMCal Status

  19. Clusterization • EMCAL cell size is such that pi0 decay photons start to strongly merge already at 8 GeV with the current clusterizer, which does not have a limit in the cluster size. • We need to put some restrictions to the cluster size or develop efficient splitting algorithms. • Task 2633: Cluster unfolding implementation for !=0 • Task done, code committed. • Still not in production since we need to do more tests, we are using afterburners in the analysis. • Problems: • Fitting paramters extracted from shower shape in simulation. Need to check with Beam Test Data. • Fit done with TMinuit. • New clusterizer: NxN • Limit the size for the cluster, right now hardcoded 3x3 • We plan to move to a more flexible size NxM, depending if there are two consecutive towers with a significant amount of the energy. • Problems • 3x3 is relatively small, cluster energy leakage at moderate cluster energies • Increasing to 5x5 might give the same results as current clusterizer in p+p • Not used in p+p, currently under test using afterburners, but it is the clusterizer used for Pb+Pb • We have to combine the two methods EMCal Status

  20. Clusterization • Both clusterizations unfolding+standard clusterizer and 3x3 clusterizer extend the reach of the pi0 measurement via invariant mass. Clusterizerv1 Clusterizerv1+ Unfolding 3x3 clusterizer EMCal Status

  21. Miscelanea • AliEMCALLoader owned several TClonesArrays • This issue is finally corrected • Different leaks and other related problems have been solved • Code is quite free of coverity defects • Few false positives • Other will be looked by the authors • We produce some error messages in the reconstruction logs, some corrected, some new under investigation. EMCal Status

  22. First HI events with EMCAL EMCAL components on HLT at P2 For the first time. EMCal Status

  23. First HI performance plots EMCal Status

  24. First HI performance plots EMCal Status

  25. Documentation-Changes log • Place for the documentation in • http://aliceinfo.cern.ch/Offline/Detectors/EMCALOffline.html • A document for beginners also available • http://aliceinfo.cern.ch/export/sites/AlicePortal/Offline/Detectors/EMCAL/EMCal_Beginners.pdf • It also includes a section with the ESD/AOD information stored for the calorimeters. • http://aliceinfo.cern.ch/Offline/Detectors/EMCAL/esd_aod.html • Still a lot of things to complete. • Recent changes in the code/ocdb are reported in this wiki: • https://twiki.cern.ch/twiki/bin/view/ALICE/EMCalOffline EMCal Status

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