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The Outer Tracker

The Outer Tracker. Cosmic data 2008 Cosmic data 2009 Collision data 2009. Hardware status Space Alignment Time Alignment Event distributions Ageing. The LHCb Detector. Muon System. Vertex Locator. RICH Detectors. Interaction Point. Tracking System. Calorimeters.

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The Outer Tracker

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  1. The Outer Tracker • Cosmic data 2008 • Cosmic data 2009 • Collision data 2009 Hardware status Space Alignment Time Alignment Event distributions Ageing Nikhef Jamboree, N. Tuning

  2. The LHCb Detector Muon System Vertex Locator RICH Detectors Interaction Point Tracking System Calorimeters Nikhef Jamboree, N. Tuning

  3. The LHCb Detector Muon System Vertex Locator RICH Detectors Interaction Point Tracking System Calorimeters Nikhef Jamboree, N. Tuning

  4. Outer Tracker 5 m Total nr of channels: 53.760 34 cm • One module: • 34 x 490 cm2 • 4 x 64 = 256 straw tubes Nikhef Jamboree, N. Tuning

  5. Nikhef Jamboree, N. Tuning

  6. Hardware status • ~98% channels functional ! Huge Nikhef effort: Tom, Albert, Ad, + ½ of PhDs in bfys group • DAQ • 99% of FE electronics running fine • 4 (432) disabled FE boxes (replace in Jan) • 0.22% noisy channels (without HV) • not much extra noise with HV on • 90% noisy channels in 2% of FE • LV and HV • LV: 2(912) fuses blown, replaced • HV: 7(1680) channels have HV trips • HV power supplies: CAEN upgrades units from 0.2 mA to 3 mA max currents • Gas System • Prepare to add 1-2% O2 Nikhef Jamboree, N. Tuning

  7. The road to where we are now: Cosmics • Debug DAQ • Software Framework • Noise • Spacial alignment • Time alignment Jan Amoraal, Thomas Bauer, Besma M’Charek, Roel Aaij Nikhef Jamboree, N. Tuning

  8. Cosmics: commission detector Jan Amoraal Top view: • Hitmap: • Holes are filled up in due time 2009 - collisions 2009 - cosmics 2008 - cosmics Nikhef Jamboree, N. Tuning

  9. Alignment • Positioning of OT • Special attention to avoid rotations • Carefully checked reproducibility • At nominal to <1.5(3) mm in x(z) • Knowing position • Survey accuracy • to <0.5 mm Software Alignment Antonio Pellegrino Nikhef Jamboree, N. Tuning

  10. Alignment: framework Jan Amoraal, Wouter Hulsbergen, Gerhard Raven Find track parameters a: • LHCb alignment framework developed by Wouter, Gerhard and Jan • Implemented generically for all subdetectors • Extract misalignment from residual histograms • Need to deal with correlations • Minimal chi-square method • Minimize chi-square simultaneously wrt. alignment parameters and track parameters With n tracks, find alignment parameters β: • Complication… • Some combination of parameters are poorly constrained: ‘weak modes’ Nikhef Jamboree, N. Tuning

  11. Alignment: results (cosmics 2008) • Internal alignment of OT C-frames • Fix 2 C-frames, align the rest • Good agreement with survey • Modules • Allow modules to move within C-frame • Checked consistency by splitting sample • Ready for beam! A-side C-side Forward/backward Odd/even evt nr A-side C-side Full detail in Jan Amoraal’s thesis! Jan Amoraal Nikhef Jamboree, N. Tuning

  12. Alignment: collisions Wouter Hulsbergen Modules: Δx (mm) • Framework well tested • Now, try on collisions • Magnet on • Different track distribution • Adjustments wrt. survey <1 mm ! T3 T2 T1 (IT) (IT) (IT) C-frames: ± 1 mm Nikhef Jamboree, N. Tuning

  13. Time alignment drift time • Hardware: hit needs to fall in readout window… particle Nov 2009 Dec 2009 Hits Hits Shift Miss events! Raw time Raw time • Software: determine t0 constants 5 mm (Slope comes from time of flight) Module t0 (ns) Drift Time (ns) ~45 ns t0 Aleksandr Kozlinskiy, Distance (mm) Nikhef Jamboree, N. Tuning

  14. A look at collision data Nikhef Jamboree, N. Tuning

  15. Roel Aaij Nikhef Jamboree, N. Tuning

  16. Roel Aaij Nikhef Jamboree, N. Tuning

  17. Roel Aaij Nikhef Jamboree, N. Tuning

  18. Roel Aaij Nikhef Jamboree, N. Tuning

  19. Roel Aaij Nikhef Jamboree, N. Tuning

  20. Roel Aaij Nikhef Jamboree, N. Tuning

  21. Roel Aaij Nikhef Jamboree, N. Tuning

  22. Roel Aaij Nikhef Jamboree, N. Tuning

  23. Roel Aaij Nikhef Jamboree, N. Tuning

  24. A look at collision data: alignment • Ks: close enough to the PDG… PDG m=497.3±0.6 MeV Nikhef Jamboree, N. Tuning

  25. A look at collision data: Drift time • ~80k events from 11 Dec 2009 • Drift time as expected • Inside readout window of 75ns • Max drift time ~45ns T1 tmeas=tdrift+ttof+tprop+t0 T2 T3 T1 T2 T3 75 ns Raw TDC Calibrated Drift Time ~45 ns Nikhef Jamboree, N. Tuning

  26. A look at collision data: Occupancy • Very few holes • Every hole is understood • Will be fixed in January • More hits close to the beampipe T1 T2 T3 T1 T2 T3 Zoom Zoom Zoom Nikhef Jamboree, N. Tuning

  27. A look at collision data: Efficiency Herve Terrier • Check for hit if predicted by track • Monitor plateau efficiency r<1.3 mm • Average efficiency over detector >96% 2.45 mm Wire locators Straw length  Nikhef Jamboree, N. Tuning

  28. A look at collision data: Efficiency Herve Terrier • 98% of detector working! • Three handful FE-modules have problems: T1 T2 T3 Nikhef Jamboree, N. Tuning

  29. A look at collisions: Track types in LHCb T track Upstream track Long track VELO track Downstream track Long Tracks  highest quality for physics Downstream Tracks  Ks finding Upstream Tracks  for RICH1 pattern recognition T Tracks  for RICH2 pattern recognition VELO Tracks  for Primary Vertex reconstruction Nikhef Jamboree, N. Tuning

  30. A look at collisions: Event distributions as expected Area normalized No beam-gas correction applied Nr of tracks / event Nr of OT hits / event Nr of tracks with OT / event Z Vertex (mm) Nikhef Jamboree, N. Tuning

  31. A look at collisions: OT Track distributions as expected All tracks with T-segment Area normalized (scaled by +20%) Pseudo-rapidity (in T-stations) Momentum (MeV) Nikhef Jamboree, N. Tuning

  32. Ageing • It’s the di-isopropyl-naphthalene(CAS 38640-62-9) inside the glue AY103-1 • AY105 does not contain any plastifier • Just produced one module with AY105 • Decided to add 1.5% O2 to gas • Large currents cure! • HV=1900V : large dark currents / discharges • HV=1800V, with source scanning over damage • Increase argon • Heating also cures  same process? • Is it feasible to just crank up the HV during beam for a few hours? • Can the power supplies handle such an instable situation of huge HV + LHC beam? HV scan area After Barbara Storaci, Daan van Eijk + 3 masters: Ivan Mous. Mathieu Blom, Erwin Visser Nikhef Jamboree, N. Tuning

  33. Summary • Electronics in good shape • Alignment close to design requirement • Ageing stays a worry Outlook • Data archiving and re-analysis • Data quality monitoring with reconstructed quantities • Tracking • Efficiency algorithm (also for ageing detection) • Continue comparison data / MC Nikhef Jamboree, N. Tuning

  34. Backup Nikhef Jamboree, N. Tuning

  35. Efficiency: compare data/MC • Data: Plateau includes dead channels Wire locators Y (A.U) X (pitch) X (pitch) FE module • MC: Ionization length 325um instead of 850 um Eff lower close to beampipe , due to higher occupancy? Y (A.U) X (pitch) X (pitch) FE module Nikhef Jamboree, N. Tuning

  36. Occupancy per Quarter “Discrete” due to nr of tracks, 1,2,3, … Nikhef Jamboree, N. Tuning

  37. Beam Test 2.45 mm 2.45 mm rt-relation: efficiency profile: Drift time (ns) Efficiency, ε r (mm) r (mm)  Resolution and efficiency for different HV and amplifier threshold Nikhef Jamboree, N. Tuning

  38. 1) Reminder: effect of O2 on ageing • What is the optimal amount of oxygen? • Beneficial effect of O2 presumably due to ozone production • Ozone production maximal above 1% O2 • Between 1% and 4% no difference in ageing rate 1% O2 • NB: Need to disentangle effect of • flushing time from fraction of O2 LHCb week - N.Tuning

  39. 2) Effect on Gain • Addition of O2 to gas mixture reduces gain by ~20%: • 2.5% O2 lowers response to 90Sr by 20% • 2.5% O2 lowers 55Fe pulse height by 10% • Confirmed by Dirk, Yuri, Christian with O2 in test chamber in the pit 319 mV 286 mV 229 mV 0% O2 2.5% O2 4.5% O2 Relative gain → Summarized in LHCb-2008-064 Effects of Adding Oxygen to the Outer Tracker Gas Mixture → Shown by Mathieu Blom in LHCb week 24 Nov 2008 55Fe 90Sr ?Average path length is same for 5.9keV γfrom 55Fe and 1MeV βfrom 90Sr LHCb week - N.Tuning

  40. 2) Effect on Gain (Erwin) Magboltz/Garfield simulations What is fraction of clusters that reaches the wire?  Simulations agree with 90Sr 0% O2 Avg.=86% 1% O2 Avg.=76%  Cluster survival probability Gain loss wrt 0% O2: 90Sr 55Fe Simulation 2% O2 Avg.=67% 3% O2 Avg.=59%  r (cm) • 2% O2 gives average gain loss of 22% compared to 0% O2 • Gain loss ranges from 42% at r=2.5mm to 0% at r=0mm LHCb week - N.Tuning

  41. 3) Effect on Hit efficiency • What is probability that 0 clusters reach wire? • Use λeffective=850 µm • Simulations agree with testbeam (λeffective=850 µm fits testbeam best) Ar/CO2 70/30 2% O2 >5% loss for r>1.9mm >5% loss for r>1.5mm Magboltz/Garfield simulations LHCb week - N.Tuning

  42. Nikhef Jamboree, N. Tuning

  43. Roel Aaij Nikhef Jamboree, N. Tuning

  44. Roel Aaij Nikhef Jamboree, N. Tuning

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