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Outer Tracker

Outer Tracker. Performance. OT Residual (unbiased). μ = 0.0001 σ = 0.221 μ = 0.0005 σ = 0.290. -MC -data. Residual [mm]. already a good resolution of 290 μm. Timing. Adjusted once the entire OT time together. T1. T2. T3. 0 ns. 75 ns. List of excluded Front end boxes.

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Outer Tracker

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  1. Outer Tracker Performance

  2. OT Residual (unbiased) μ = 0.0001 σ = 0.221 μ = 0.0005 σ = 0.290 -MC -data Residual [mm] already a good resolution of 290 μm

  3. Timing • Adjusted once the entire OT time together T1 T2 T3 0 ns 75 ns

  4. List of excluded Front end boxes • Broken FEB are replaced: • T1L0Q1M1 • Placed working FEB 428 • T1L1Q2M8 • Replaced by working FEB 313 • T2L3Q0M9 • Replaced by working FEB 8027

  5. LV and HV status • Low voltage stably running • 2 (912) fuses blown, replaced • spare Maraton power supply in repair • High voltage ok. • work to identify single problematic wires continued this week • HV power supplies are now upgraded • from 0.2 mA to 3 mA maximum currents • Central steering of OT HV OFF generally fine

  6. List of HV problems • T1L0Q3FE1HV3, CH 64 trip at 1480V, trained at 1700V, now ok at 1600V • T1L1Q1FE8HV4, CH114, 119 trips at 1550V • T1L1Q2FE8HV4, instabilities at 1500V (100μA) • T1L2Q2FE5HV3, difficult to reproduce • T2L1Q1FE5HV1, infrequent trips at 1550V • T2L3Q2FE9HV4, trip at 1260V, CH96 removed • T3L1Q1FE8HV3, trip at 300V, CH81 removed • T3L3Q1FE1HV2, trip at 800V, CH63 to be removed

  7. List of noisy channels • Noisy channels: • more than 10-3 noise at 900mV threshold • T1L1Q2M1 CH65 • T1L3Q0M3 CH9-10, CH115-118 • T2, T3 none • Front end boxes that had a lot of noise in the 2009 runs where replaced

  8. Noisy channels

  9. missing Missing Hits in DAQ • Missing hits in noise scans • Was a problem in 5 FE boxes, all FE boxes are replaced • In most cases it was directly correlated to noisy channels • The ASDBLR oscillates at high noise levels and does not give hits Threshold [DAC values] Channel

  10. Other missing hits ? • T2L0Q3M9 OTIS3 • T2L1Q2M9 OTIS3 • T2L2Q3M1 OTIS1 (lost DLL lock earlier) • T3L0Q1M2 OTIS0 • T3L2Q1M5 OTIS1,2

  11. Problems in 2009 runs: T1 repaired repaired repaired missing filled repaired repaired repaired

  12. T2 ? ? ? repaired repaired

  13. T3 missing repaired ? repaired repaired repaired repaired ? identified

  14. Summary • 12 Front end boxes were replaced • HV problems in most cases related to single channels • 7 (53760) noisy channels (>10-3 noisy at 900mV) • 0 (53760) channels missing / too high noise • 6 groups of 32 channels miss hits unexpectedly • 2 permanent PVSS error messages due to broken sense lines

  15. Backup Slides

  16. TR-relation and Module T0’s for 2009 data On behalf of Alexandr Kozlinskiy (see OT meeting 27 January)

  17. Outline • Module T0’s • TR-relation fit (data and MC) • Drift time residual bias (effect of magnetic field?)

  18. Module T0’s Module T0 VS Module N • T0’s are obtained with preprocessed DST’s (first 20K events). • Track χ2 < 9 • Track unbiased χ2 < 4 • Outliers removed • Outside modules (module numbers: 1, 2) don’t have hits in first 2 stations (use values from quarter T0’s for this modules). • With red arrows marked 3 modules that are quite far from main trend (module numbers: 288, 305, 406 – outside modules in station 3). Module T0 VS Module N (TOF corrected)

  19. Residuals χ2 for all tracks From χ2 plot one sees that TR-relation sigma (currently 3 ns) is still underestimated (use 4ns?). The asymmetry in the residual plots around zero are due to truncation of t(r) calculated from distance. Distance residual (track χ2 < 9) Unbiased residual (track χ2 < 9) Sigma = 270μ Sigma = 350μ

  20. TR-relation fit Drift Time VS Unbiased Distance TR-relation: Standard (TR-relation from beam test used currently in reconstruction): t(r) = 8.2 ∙ r + 2.4 ∙ r2 σt(r) = 3 Fit: t(r) = 8.8 ∙ r + 2.1 ∙ r2 σt(r) = 2.33 + 0.9 ∙ r – 0.1 ∙ r2 As it will be seen from next slide the value of TR-relation sigma is underestimated by the fit (around 20% smaller). So the real sigma should be around 4ns. Drift Time Sigma VS Distance

  21. TR-relation fit (MC 450 GeV) Drift Time VS Unbiased Distance for MC This is a simple exercise to see if the fit works correctly with MC data. TR-relation: Standard (linear): t(r) = 17.1 ∙ r σt(r) = 3.4 Fit: t(r) = 17.3 ∙ r + 0.1 ∙ r2 σt(r) = 2.8 • It seems that fit underestimates drift time sigma. • Introduce scale?

  22. Drift time residual bias (effect of magnetic field?) Mean drift time residual VS Hit ‘X’ position • The distribution of mean drift time VS hit ‘X’ position is quite stable. • The small ‘zigzags’ can be due to per straw TOF corrections that are not taken in to account in this Module T0 calibration. • There is bias in distribution of mean drift time VS hit ‘Y’ position (bias is around 1.5 ns/m): • First thought: smaller propagation time (current value – 4 ns/m), but the effect is to high • Not alignment – it can give only constant offsets. • More real explanation – effect of magnetic field on drift time (TR-relation). Mean drift time residual VS Hit ‘Y’ position

  23. Mean drift time residual VS Hit ‘|Y|’ position Station 1 The slope of the bias is almost the same for all stations (would expect difference due to different magnetic field value in stations). Station 2 Station 3

  24. Mean drift time residual VS Hit ‘Y’ position (MC 450 GeV) Mean drift time residual VS Hit ‘Y’ position In MC the bias is also present but it is much smaller (0.2 ns/m) and it has non linear (quadratic) form. Can be due to usage of approximate corrections for TOF in magnetic field (in OTMeasurementProvider) and presence of tracks that are not coming from center of interaction. But still can not describe bias in real data.

  25. Mean drift time residual VS Hit ‘Y’ position (tprop = 3ns/m) This plot is obtained by reconstructing tracks with tprop = 3ns/m (directly modified propagation speed in DeOTModule). Here bias is smaller (around 0.8 ns/m). This way of getting rid of bias is not really good way. In reality one needs to introduce description of TR-relation from hit Y position. But the changing of propagation speed is much easier (if it really works – need to be studied). Mean drift time residual VS Hit ‘Y’ position

  26. Conclusion • The databases location with Module T0’s are: • With fitted TR-relation and drift time sigma • /afs/cern.ch/user/a/akozlins/public/OT/LHCBCOND/Collision09_OT_ModuleT0s_220110.db • With drift time sigma set to 4ns: • /afs/cern.ch/user/a/akozlins/public/OT/LHCBCOND/Collision09_OT_ModuleT0s_220110_sigma4ns.db • Should we update MC TR-relation to the currently used for real data. • Work is going on with studying the effect of magnetic field on TR-relation.

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