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Analysis on TB0904 Data

Analysis on TB0904 Data. Jianchun Wang Syracuse University. The Telescope. VELO. Scint. Pixel. Pixel. Pixel. Y. 120 GeV proton beam. Z. X. YX. Y. YX. RR( F). Pixel & VELO use independent DAQ systems, sharing trigger signals from the same source.

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Analysis on TB0904 Data

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  1. Analysis on TB0904 Data Jianchun Wang Syracuse University

  2. The Telescope VELO Scint Pixel Pixel Pixel Y 120 GeV proton beam Z X YX Y YX RR(F) • Pixel & VELO use independent DAQ systems, sharing trigger signals from the same source. • VELO events and pixel events are matched offline. • Pixel stations / modules are aligned within its own system and generate tracks. • Velo sensors are aligned with respect to the pixel tracks. • Pixel track event, corresponding Velo event ID and Velo alignment parameters are saved in tracking data files. • Pixel tracking data are fed to Vetra. • Real VELO studies of R/F and irradiated RR sensors. Just a reminder Jianchun Wang

  3. Introduction • Track is reconstructed from pixel hits and fit to straight line. • Pixel hit resolutions. • Track fit probability issue. • Track projection error and multiple scattering effect. • Alignment precision (not estimated yet). • Analysis of R/f data. • Cluster size vs pitch and track angles. • Eta curve of charge sharing. • Velo R resolution. • Analysis of irradiated RR sensors ( ongoing, not included). Jianchun Wang

  4. Residual On the 5th Station Ncol = 1 Ncol > 1 Different Scale Number of Entries (Arb. Unit) Nrow = 1 Nrow > 1 Measurement – Track Projection (mm) Binary readout 5 pixel stations Simulated through iterations  track proj. error ~ 4.9 mm Jianchun Wang

  5. Track Probability Issue Tracks (arb. Unit) Exclude Ncol = 1 Prob (c2, ndof) Expect Tracks (arb. Unit) Non-gaussian Seen Uniform dist for Ncol=1 Gaussian for the rest Prob (c2, ndof) With multiple scattering Jianchun Wang

  6. Tracking Error 5 pixel stations X Log ( number of tracks ) Y • Multiple scattering contributes 1.7-2.1mm to track projection error. • One can select events of better tracking error. • Measurements of Ncol=1 improve track projection precision, although distort the track probability distribution. Tracking Error from Pixel (mm) Calculated without multiple scattering Jianchun Wang

  7. Look at R/F Data Matched Hits Y ( mm) Signal (ADC) Pixel coverage X ( mm) We took data at nominal 0, 4, 8, 12 degrees rotated around horizontal axis. The effective angle is smaller due to concentric strips. Effective Track Angle (degree) Jianchun Wang

  8. Charge Sharing (I) Strip pitch (40, 50) mm R sensor of R/f pair Nstrip = 2 Nstrip = 1 All pitches & track angle Percentage of Hits Nstrip = 3 Effective Track Angle (Degree) Range: angle0.5 Seed threshold = 6 ADC ~ 9.6 Ke Side threshold = 3 ADC ~ 4.8 Ke Cluster Size Jianchun Wang

  9. Charge Sharing (II) Pitch ( mm) 40 – 50 50 – 60 60 – 70 70 – 80 80 – 90 90 – 100 Angle (  ) -0.5 – 0.5 2.5 – 3.5 6.5 – 7.5 10.5 – 11.5 (Nstrip > 1) / N total (%) (Nstrip > 1) / N total (%) Effective Track Angle (Degree) Strip Pitch (mm) R/f data is split into 1 of angle & 10 mm of pitch sub-samples. Sub-samples of 0, 3, 7 and 11 are with reasonable large statistics. Jianchun Wang

  10. The Eta Curve One strip shift due to tracking precision Only Strip N+1 has Charge All pitches & angles Nstrip = 1 removed Cluster Fraction Only Strip N has Charge Track Hit Fraction Center of Strip N Center of Strip N+1 Jianchun Wang

  11. The Eta Curves Of Small Pitches Angle=3 Angle=0 Pitch = (40-50) mm Nstrip = 1 removed Cluster Fraction Angle=11 Angle=7 Track Hit Fraction Jianchun Wang

  12. The Eta Curves Of Small Pitches Angle=3 Angle=0 Cluster Fraction Angle=11 Angle=7 Track Hit Fraction Pitch = (40-50) mm Cluster fraction=0 or1 correspond to nstrip=1, indicating how charge sharing varies with hit position. Jianchun Wang

  13. Velo Resolution Measurement • Resid = 18.0 mm <strk> = 5.1 mm Nevent = 12.5K • <Resid = 19.2 mm <strk> = 8.0 mm Nevent = 175K Rvelo – Rtrack (mm) Rvelo – Rtrack (mm) Error < 6 mm Tracking Error from Pixel (mm) Trk error = (pixel)1.85mm (multi-scatt.) <strk> = quadratic average over all trks To improve tracking precision one has to sacrifice statistics. Jianchun Wang

  14. Resolution vs Pitch R sensor of R/f pair Angle (  ) - 0.5 – 0.5 2.5 – 3.5 6.5 – 7.5 10.5 – 11.5 Preliminary !. Velo Hit Resolution (mm) Tracking projection uncertainty removed from resolution. Tracking precision is determined for each point ( ~ 4.7–5.4 mm). Error bar represents only statistic error. Linear charge weighting, eta-correction not applied yet. Strip Pitch (mm) Seed threshold = 6 ADC ~ 9.6 Ke Side threshold = 3 ADC ~ 4.8 Ke Jianchun Wang

  15. Tracking Precision Angle (  ) - 0.5 – 0.5 2.5 – 3.5 6.5 – 7.5 10.5 – 11.5 For each track the projections on Velo and projected errors in both X and Y directions are calculated using the corresponding pixel resolutions. R and error in R is calculated from X/Y. For each sample (point), the projection error is quadratically averaged over all tracks used. Projection error due to multiple scattering is ~1.85 mm obtained from simulation. The alignment error is to be determined. R Error From Track Projection (mm) Strip Pitch (mm) Jianchun Wang

  16. Resolution vs Track Angle Pitch ( mm) 40 – 50 50 – 60 60 – 70 70 – 80 80 – 90 90 – 100 Velo Hit Resolution (mm) Effective track angle is determined in plane perpendicular to the strip. Sub-samples of 0, 3, 7 and 11 are with reasonable large statistics. Other angles are due to concentric strip, thus with small amount of hits. Effective Track Angle (Degree) Jianchun Wang

  17. Summary • Pixel charge sharing is consistent with expectation. • Velo hit resolution is measured. The trend is as expected. But the value is not as good as we hoped. • RR studies are on going. • Explanation on Fanl tb09 VELO data, pixel tracks and supporting software can be found in 08/21/09 presentation. http://indico.cern.ch/getFile.py/access?contribId=5&resId=1&materialId=slides&confId=66615 • Velo data, pixel data and pixel tracks (pixel track files will be updated with better alignment) are in /castor/cern.ch/lhcb/testbeam/lhcbvelo/fnaltb09 • Track tool and a small example code ( Example.cpp, PixelTracks.cpp, PixelTracks.h, IPixelTracks.h ) can be found at http://phy.syr.edu/~jwang/projects/tb09/ Jianchun Wang

  18. Data Sets Jianchun Wang

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