1. 26 June 2006Imaging2006, Stockholm, Niels Tuning 1/18 Tracking with the LHCb Spectrometer Detector Performance and Track Reconstruction Niels Tuning (Outer Tracker Group LHCb) NIKHEF Amsterdam, The Netherlands Tracking detectors in LHCb Detector construction Detector performance Tracking performance Many thanks to Jeroen van ! Hunen Tilburg

2. 26 June 2006Imaging2006, Stockholm, Niels Tuning 2/18 LHCb in a nutshell Both b’s are produced forward: Aim: measure CP violation and rare decays pp with  s =14 TeV L = 2.10 32 cm -2 s -1 10 12 b-hadrons per year

3. 26 June 2006Imaging2006, Stockholm, Niels Tuning 3/18 The LHCb Detector

4. 26 June 2006Imaging2006, Stockholm, Niels Tuning 4/18 The LHCb Tracking System Tracking Detectors Outer Tracker NIKHEF Cracow Heidelberg Warsaw Trigger Tracker Inner Tracker Zurich Lausanne Santiago Heidelberg Novosibirsk Vertex Locator Liverpool CERN Glasgow Heidelberg NIKHEF Syracuse

5. 26 June 2006Imaging2006, Stockholm, Niels Tuning 5/18 Tracks in LHCb

6. 26 June 2006Imaging2006, Stockholm, Niels Tuning 6/18 Vertex Locator  sensors R sensors 8mm Vertex Tank 42 mm Si sensor n + -on-n 2048 channels, analog readout non-uniform radiation environment 13(0.5) 10 13 n eq /cm 2 /yr at R=8(42)mm R sensor: pitch: 38 μm - 103μm thickness: 300μm φ sensor: pitch: 39 μm - 98μm thickness: 300 μm

7. 26 June 2006Imaging2006, Stockholm, Niels Tuning 7/18 The Trigger Tracker Silicon sensors: 9.4*9.6 cm 2, 500  m thick Long modules of 14 sensors, with max 4 sensors per front-end (Beetle)  55pF Long Kapton cables front- end  sensors 0.12 Tm TT = Station before the magnet. Used in the trigger for momentum estimate Fringe field between magnet and VELO  z(m)

8. 26 June 2006Imaging2006, Stockholm, Niels Tuning 8/18 IT occupancy: Hottest region = 2.3% Beam Pipe Outer Tracker : Inner Tracker 595 cm 450 cm The Outer and Inner Tracker OT occupancy: Average = 4.5% Hottest region = 9%

9. 26 June 2006Imaging2006, Stockholm, Niels Tuning 9/18 The Inner Tracker 3 stations (T1 – T3) 4 detector boxes per station. Per box: 4 Silicon layers 4x7 modules (1 or 2 sensors each) Beetle (0.25  m CMOS) front-end Silicon sensor: p in n-bulk, 198  m pitch, 420  m and 300  m thick. 1mm thick carbon sandwich 25  m kapton isolation Kapton hybrid 7.8cm 11cm

10. 26 June 2006Imaging2006, Stockholm, Niels Tuning 10/18 Outer Tracker 340 mm Total nr of channels:  53.760 One large straw tube module:  34 x 490 cm 2  4 x 64 = 256 straw tubes

11. 26 June 2006Imaging2006, Stockholm, Niels Tuning 11/18 Detector Beam Tests Example: Outer Tracker r (mm) Drift time (ns) rt-relation: 2.45 mm r (mm) Efficiency, ε efficiency profile:  Resolution and efficiency for different HV and amplifier threshold

12. 26 June 2006Imaging2006, Stockholm, Niels Tuning 12/18 OT Beam Test: Good Detector Performance Efficiency, ε Resolution (mm) 100 0.2 0 0 0.6 HV(V) 140015501200 1400 Good efficiency and resolution for HV > 1520 V  ε  98%  σ  200 µm Corresponds to Gain>50,000

13. 26 June 2006Imaging2006, Stockholm, Niels Tuning 13/18 LHCb Tracking VELO seeds Long track (forward) Long track (matched) T seeds Upstream track Downstream track T track VELO track T tracks  useful for RICH2 pattern recognition Long tracks  highest quality for physics (good IP & p resolution) Downstream tracks  needed for efficient K S finding (good p resolution) Upstream tracks  lower p, worse p resolution, but useful for RICH1 pattern recognition VELO tracks  useful for primary vertex reconstruction (good IP resolution)

14. 26 June 2006Imaging2006, Stockholm, Niels Tuning 14/18 VELO TT T2T3T1 Outer tracker station Tracking

15. 26 June 2006Imaging2006, Stockholm, Niels Tuning 15/18 The Expected Tracking Performance

16. 26 June 2006Imaging2006, Stockholm, Niels Tuning 16/18 Expected Tracking Performance (1) Long tracks ~38 measurements per track Efficiency >95% (for p>12GeV) Ghost rate 12GeV) Robust: track multiplicity x2: efficiency 91% ghost rate 14% N meas N tracks efficiency ghost rate

17. Expected Tracking Performance (2) IP resolution 1/p t distribution for B tracks 42 mm Vertex Locator Momentum resolution p distribution for B tracks 11cm 500cm Outer+Inner Tracker

18. 26 June 2006Imaging2006, Stockholm, Niels Tuning 18/18 Conclusions Construction of the LHCb tracking system well advanced  Vertex Locator: 8 ‘pre-series’ modules produced (out of 84)  Trigger Tracker: 80 half modules in production (need 128)  Outer Tracker: All modules produced  Inner Tracker: 100 modules produced & 60 are fully tested (need 336) Expected performance (for p>12 GeV) :  tracking efficiency >95%  ghost rate <7%  (B-meson decay time resolution is 37 fs !) Detectors are being shipped to CERN for installation!

19. 26 June 2006Imaging2006, Stockholm, Niels Tuning 19/18 Backup

20. 6 April 2006 20/18 Outer Tracker: Ageing? Where does it come from? Why not observed in dedicated test modules over the years (X- rays and protons) ?? Ratio of currents show signal loss Damage upstream the gas flow All production sites Irradiation with 55 Fe and 90 Sr Electron microscope show isolating layer of carbon accumulated charge ≈1.3 C/cm No effects seen Ar/CO 2 70/30 20 l/hr Gas Flow Channel Pos (cm) Recommendation from experts Try to use Ar/CO 2 /O 2 70/27/3 Try H 2 O >5000 ppm Try more conditioning with reverse bias Position 1 485cm L-wire 64 UL

21. 26 June 2006Imaging2006, Stockholm, Niels Tuning 21/18 Vertex Locator: Fast and Efficient Sufficient cluster efficiency (>99 %) Acceptable noise occupancy (<0.1 %) Low overspill (fake cluster rate from previous bunch crossing) (<25 %) Single cluster resolution: 10-20 μ m Overspill vs. S/N cut Signal/Noise Cut Noise occupancy vs. S/N cut Signal/Noise Cut TDC (ns) S/N ratio Pulse shape 25ns 0.1% 25% Radius (cm) Cluster Resolution 20μm 10μm 1cm4cm

22. 26 June 2006Imaging2006, Stockholm, Niels Tuning 22/18 Outer Tracker Beam Test Final detector modules Final prototype electronics 6 GeV electrons at DESY Efficiency Resolution Noise Cross talk HV Amplifier threshold Position along straw vs See: LHCb-2005-076LHCb-2005-076 beam