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RUN11 MTD calibration with cosmic ray data

RUN11 MTD calibration with cosmic ray data. Xinjie Huang,Xianglei Zhu 04/13/2011. Motivation. In run year 10 STAR implemented a cosmic ray trigger to study the performance of its several subsystems, including TPC, MTD, TOF etc.

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RUN11 MTD calibration with cosmic ray data

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  1. RUN11 MTD calibration with cosmic ray data Xinjie Huang,Xianglei Zhu 04/13/2011

  2. Motivation • In run year 10 STAR implemented a cosmic ray trigger to study the performance of its several subsystems, including TPC, MTD, TOF etc. • Because the cosmic rays are primarily muons, we were able to get rid of the hadron background from material interactions in the MTD analysis, as seen in previous studies with data from physical collisions. • Also the cosmic ray data offers us significant amount of muon tracks with pt > 2 GeV/c, and these high momentum particles have less interaction with the material than the lower momentum particles therefore we can calculate the tracking information more precisely.

  3. MTD Set

  4. Data Set • RUN 11 st_tof cosmic data stream for Full Field and Reversed Full Field • Selected cosmic ray tiggered events with Tigger ID 310811, 310812, 310813 • Global tracks were used

  5. QA Plots (GeV/c) (ns)

  6. Method tMTD: calculated by averaging the times from two ends of an MTD. tTOF1 and tTOF2: calibrated times associated with TOF hits due to the cosmic ray muons tTPC : calculated time of flight between two TOF trays 1 and 2 with the pathlength and momentum information from TPC. tSteel : time of flight from MTD to TOF, also calculated with TPC information The time difference between TOF+MTD measured time and TPC measured time is deltaT = (tTOF2 – tTPC + tTOF1)/2 – tMTD – tSteel

  7. Matching • Track matching:nHitsFit>14, |eta|<1.5 and p>2 GeV/c for each half. |p1-p2|/p1<0.27, where p1 and p2 are the momenta for the two halves. • Raw matching for the TPC tracks : nFitPoints >= 25, Pt >= 2.0 GeV/c, TpcPhi&TpcZ are in the area showed in ppt2,where Z is the position along the beam pipe, TpcZ and TpcPhi are extroplated Z and Phi values for a track from TPC. • TPC tracks & MTD hits matching: |TpcZ-MtdZ| < 6 cm and |TpcPhi-MtdstripPhi| < 0.015.

  8. INL Correction When we get a MTD hit time form a tdc, we apply INL correction to it.

  9. TOF Timing Resolution • TOF timing resolution~56ps. • All calibration parameters are used.

  10. T0 Offset Correction I • Got deltat of each strip • Fit deltat histograms with a Gaus function • Subtract the obtained mean value

  11. MTD Timing Resolution Before Calibration

  12. MTD Timing Resolution Before Calibration

  13. Slewing: Deltat vs Tot Tot = sqrt(MTDEasttot*MTDWesttot)

  14. Slewing Fit deltats in each tot bin with gaus function, get the Gaus mean. Fit gaus means with a 5th order polynomial function. Subract the function value from tMTD according to its Tot .

  15. MTD Timing Resolution after slewing

  16. MTD Timing Resolution after slewing

  17. Find two peaks

  18. Check magnetic field direction B- B+ 4 3 1 2

  19. Check runid

  20. Deltat vsrunid Runid= 12111025 Runid~= 12175000 1 2 3 4 runid Deltat+ Deltat+ Deltat- B- B+

  21. MTD Timing resolution in different time 2 1

  22. Final Timing resolution:MTD0 1 2

  23. Final Timing resolution:MTD1 1 2

  24. Final Timing resolution:MTD2 1 2

  25. Final Timing resolution:MTD3 1 2

  26. Position Resolution:Z (cm)

  27. Position Resolution:Z (cm)

  28. Position Resolution:Z (cm)

  29. Position Resolution:Z (cm)

  30. Position Resolution:phi

  31. Position Resolution:phi

  32. Summary TOF timing resolution:~56ps

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