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The Performance of the Outer Tracker of LHCb

The Performance of the Outer Tracker of LHCb. 1. LHCb detector 2. Outer Tracker 3. Performances. Hervé Terrier on behalf of the Outer Tracker Collaboration. The 2007 Europhysics Conference on High Energy Physics Manchester, England 19-25 July 2007.

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The Performance of the Outer Tracker of LHCb

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  1. The Performance of the Outer Tracker of LHCb 1. LHCb detector 2. Outer Tracker 3. Performances Hervé Terrier on behalf of the Outer Tracker Collaboration The 2007 Europhysics Conference on High Energy Physics Manchester, England 19-25 July 2007.

  2. The Large Hadron Collider beauty experiment Outer Tracker protons protons Hervé Terrier

  3. Outer Tracker Hervé Terrier

  4. The Outer Tracker of LHCb • Requirements : • εcell ~ 98% → tracking efficiency ~ 95% (εtracks (Bs→DsK) ~ 80%) • σ ~ 200 µm → δp/p ~ 0.4% (mass resolution (Bs→DsK) ~ 10 MeV/c2) Hervé Terrier

  5. The Outer Tracker module OT 5 m IT TT 340 mm T3 6 m T2 T1 - Straw tube : 2.5 mm radius and 2.5 m length - CountingGas : Ar/CO2 70/30, flush at 1 volume (18 l) / 2hr - 1 large module is made of 2*128 channels (220 modules ~ 54000 channels in total) - Each OT Station consists of 4 planes XUVX - 3 OT Stations T1,T2,T3 high-flux region (2%): Si detector (Inner Tracker) remaining area (98%): straw drift-tubes (OT) all modules are produced and installed in the pit Hervé Terrier

  6. FE box GOL TDC ASD FE box Outer Tracker Readout Scheme TELL1 DAQ PCs TDC L0 Buffer Zero suppression GOL ASD ~100 m 200 fC Expected Radiation 10 kRad / 10y counting room HV LV TFC ECS Cooling Power / Control Electronics Service Box FE Electronics on the detector (FE built for 1:2 MRads) Hervé Terrier

  7. σ Test FE performances during production at NIKHEF • Tests of FE-boxes: • Threshold scan • Pulse amplitude scan • Delay scan • Latency scan • Dark noise scan 1 channel Status of electronics : - all components produced - ~ 50% assembled and being installed 128 channels Hervé Terrier

  8. Drift time resolution σΔt = 0.97 bins = 0.36 ns First commissioning tests - using a Commissioning Rack - Test Pulse - cosmics runs under way Hervé Terrier

  9. source Ratio Plot: I(after)/I(before) Gas flow • During R&D phase, high rate ageing test were performed on prototype : • - proton irradiations • - irradiations in X-ray facility (9keV) with 1m test modules • → studies on long term effect with high irradiation dose (0.5-3 C/cm) • showing no aging detected... • However, mass production modules showed unexpected gain deterioration with γ and β sources (irradiation time ~ 150h) Ageing (1) Many investigations : cause traced back to outgassing of the AY103 araldite Hervé Terrier

  10.  Relative Gain  Irradiation Time (hours) 1st HV training 2nd HV training 3rd HV training • Beneficial effects: • Flushing • HV Training • Heating Ageing (2) Flushing: A special tool is being built that allows to heat modules in situ Hervé Terrier

  11. S = scintillators P = silicon planes Test beam set-up and goals Set-up : Final detector modules Final prototype electronics 6 GeV electrons at DESY Measure : Efficiency Resolution Noise Cross talk HV Amplifier threshold Position along straw vs See: LHCb-2005-076 Hervé Terrier

  12. 2.45 mm 2.45 mm rt-relation: efficiency profile: Test beam : main results (1) Efficiency, εε Drift time (ns) r (mm) r (mm)  Resolution and efficiency for different HV and amplifier threshold Hervé Terrier

  13. Resolution (mm) Efficiency,ε 1550 HV(V) Test beam : main results (2) Good efficiency and resolution for HV >1520 V ε~ 98% σ~ 200 µm Hervé Terrier

  14. Resolution (µm) Efficiency, εε Amplifier Threshold (mV) Test beam : main results (3) Good efficiency and resolution for 700< thr < 900 mV • ε~ 98% • σ~ 200 µm (corresponds to 3 – 5.5 fC) Electronic noise at 750 mV : ~5 kHz / straw ~0.03% occupancy acceptable Hervé Terrier

  15. Conclusion • Installation of detectors completed • Services and DAQ systems close to completion • Unexpected ageing problem investigated and traced back to outgassing from Araldite : flushing + heating proved to prevent the gain loss, while HV training effective in "repairing" gain losses • Detector commissioning started Hervé Terrier

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