Introduction B-physics at LHCb The LHCb experiment The LHCb Outer Tracker Design and construction

1. Construction, Installation and Commissioning of a High-Efficiency and High-Resolution Straw Tube Tracker for the Experiment • Introduction • B-physics at LHCb • The LHCb experiment • The LHCb Outer Tracker • Design and construction • Installation and commissioning Fabian Jansen (Nikhef) On behalf of the LHCb Outer Tracker group 11th Pisa meeting on advanced detectors La Biodola, Isola d’Elba (Italy), May 24-30 2009

2. B-physics Vtb Vtb rare decay B0 → K* μ+μ- B0 K* b s new physics? μ+ μ- • The physics of hadrons containing b-quarks • CP-violation (Charge-Parity asymmetry) with B-mesons • measurable through B/anti-B mixing and decay • New physics with rare B decays • B decays with small conventional branching fractions involving loop diagrams • New physics may contribute at the same scale as conventional physics • Nobel prize 2008: • spontaneous symmetry breaking + • at least three families of quarks = possible CP violation B mixing 11th Pisa Meeting on Advanced Detectors

3. B-physics at LHCb b • The LHC will act as a B factory with large b-quark production rate • σbb ~ 500μb for pp collisions at s = 14TeV • B hadrons are produced predominantly forward/backward • LHCb • forward spectrometer (10-300 mrad) • dedicated to B physics • “modest” luminosity L~ 2 1032cm-2s-1 • expected 1012 bb/year (107 sec) b p p 250mrad collision 100 mb 230 mb p p 11th Pisa Meeting on Advanced Detectors

4. LHCb detector: overview • One-arm forward spectrometer: subdetectors cascade in beam direction proton beam proton beam collision point ~1 cm B 11th Pisa Meeting on Advanced Detectors

5. LHCb detector: vertexlocater • contains the pp-collision point • precise determination of primary and secondary vertices (B lifetime) ~1 cm B 11th Pisa Meeting on Advanced Detectors

6. LHCb detector: RICH1,RICH2 • Particle IDentification; kaon-pion separation 11th Pisa Meeting on Advanced Detectors

7. LHCb detector: calorimeter system • particle identification; electron, photon, hadron • trigger (at 40MHz) 11th Pisa Meeting on Advanced Detectors

8. LHCb detector: muon system • muon tracking • trigger (at 40MHz) 11th Pisa Meeting on Advanced Detectors

9. LHCb detector: tracking stations • charged particle momentum determination • TT before magnet, Inner and Outer Tracker after magnet 11th Pisa Meeting on Advanced Detectors

10. Outer tracker performance requirements • High speed • 25ns bunch crossing cycle • Momentum resolution (Δp/p) better than 0.5% (2-100GeV tracks) • precise (B-)mass reconstruction • =► spatial resolution less than 200μm • Occupancy below 10% • efficient track reconstruction • High efficiency • efficient B reconstruction beam pipe and Inner Tracker expected J/ψ mass distribution OT expected occupancy: Average = 4.5% Hottest region = 9% σ=11MeV! 11th Pisa Meeting on Advanced Detectors

11. Outer Tracker module design and production 00 -50 +50 00 The Outer Tracker consists of 3 stations ~0.5m apart • Station • 2 support frames (C-frames) mounted vertically with 2 layers of detector modules • =► 4 layers of modules with orientation 00,+50,-50,00 • Every C-frame is in two halves that can be moved horizontally in and out around the beam pipe • Layer • 14 type F modules; full height • 4 type S modules; half height outside the hot region Type F S2 S3 S1 Inner Tracker 2400 mm 2900 mm 3070 mm 11th Pisa Meeting on Advanced Detectors

12. Outer Tracker module design and production • Module • 2 staggered layers of 64 straw tubes • split in electrically independent upper and lower sections with Front End electronics on both sections • 1module: X/X0 = 0.37%! • Straw • 5mm radius • 25μm anode wire at 1550V • Ar(70%)/CO2(30%) 4800 mm 340 mm module top view aluminum laminated kapton wound on carbon doped kapton-XC 11th Pisa Meeting on Advanced Detectors

13. Outer Tracker module design and production • Detector Module mass • construction ~ assembly of: • - 56,000 straws • 56,000 wires • 200,000 soldered joints • 620 panels • 185 F and 124 S Modules • 2004-2005: OT module production • Quality assurance during production • wire tension (<7%) • wire position (<100μm) • dark current (<10nA at 1600V) • Quality assurance after production • gas tightness (<1mbar/minute) • dark current (<10nA at 1600V and Ar(70%)/CO2(30%) ) • Detector response to 90Sr source; full scan (every cm) of all OT modules • Module production summary • dead channels: disconnected shorts (0.6‰) • “noisy” channels: high dark current (0.7‰), often cured after HV training • Cracow: all straw-support panels • Warsaw: 124 type S modules • Heidelberg: 62 type F modules • Nikhef: 130 type F modules LHCb note: lhcb-2004-078 11th Pisa Meeting on Advanced Detectors

14. OT Front End electronics design and production • HV circuit board • 330 pF capacitors decouple signal from HV • embedded capacitors reduce leakage currents • ASDBLR amplifier • discriminate signal against threshold • high speed through elimination of long ion tail by shaping and baseline restoring of signal; dead time ~20ns • low noise through differential logic swing • low threshold =► good efficiency & resolution • OTIS time-to-digital converter • 25ns LHC bunch clock into 64 TDC bins • incorporate up to three BX drift time • GOL • Transfer of data of 128 channels (+headers) via optical fiber at 1.6Gb/s See poster: The FE Electronics of the LHCb Straw Tube Tracker 11th Pisa Meeting on Advanced Detectors

15. OT Front End electronics design and production • 2005-2008 OT FE electronics production • All components tested and selected individually before assembly • All FE boxes tested after assembly on • threshold characteristics • timing behavior • noise and cross talk • trigger latency response threshold scan rejected components insensitive channels ASDBLR’s replaced linearity scan All Front End electronics components with bad characteristics/behavior/response were replaced! nonlinear channel OTIS replaced LHCb note: lhcb-2007-122 11th Pisa Meeting on Advanced Detectors

16. Test beam at Desy • Beginning of 2005: beam test at Desy • First four half-length OT modules • Final prototype FE electronics • Efficiency • Resolution • Noise & Cross Talk • High Voltage • Amplifier threshold • Position along straw VS LHCb Note: lhcb-2005-076 11th Pisa Meeting on Advanced Detectors

17. Test beam results (1) 2.45 mm 2.45 mm RT-relation efficiency profile Drift time (ns) Efficiency r (mm) results for 1550V HV, 800mV threshold r (mm) next slide  resolution and efficiency for different HV and amplifier threshold 11th Pisa Meeting on Advanced Detectors

18. Test beam results (2) Good efficiency and resolution for HV > 1550V ε 98% σ 200 µm • Corresponds to Gain > 50,000 0.6 Resolution (mm) 0.2 0 1400 100 Efficiency 0 1200 1400 1550 HV(V) 11th Pisa Meeting on Advanced Detectors

19. Outer tracker module installation (1) bridge beam pipe • module support frame (C-frame) • 2x9 detector modules • 4x9 FE boxes • cooling, gas • Low Voltage, High Voltage, etc. 11th Pisa Meeting on Advanced Detectors

20. Outer Tracker module installation (2) • 2006-2007: Assembly of modules into C-frames and installation of C-frames in detector • Before assembly of modules, C-frames tested for • gas tightness of gas distribution system <1mbar/minute at 10mbar CO2 • High Voltage leakage currents <10nA/RMS<1nA • Low Voltage connections OK • optical fiber attenuation <30dBm • After assembly of modules into C-frame, modules tested for • gas tightness: <1mbar/minute & matching production • High Voltage leakage currents <100nA/channel at 3 minutes 1.8kV-CO2 • Functionality test with 55Fe source • >2700 straws (~½OT) individually tested • 13 dead channels; 11 known at production • 2008: Installation of FE electronics LHCb note lhcb-2008-033 11th Pisa Meeting on Advanced Detectors

21. Outer Tracker commissioning overview this is a snap shot, work is ongoing! ok FE not installed I2C problem BxID mismatch QPLL not locked other problem optical link problem desynchronisation all TELL1 OK 11th Pisa Meeting on Advanced Detectors

22. Data taking (1) • During the last months OT was taking data in global LHCb commissioning • random and calibration triggers (test pulse possibility) • cosmic muons triggered by CALO/MUON • “media day” (beam!) media day 11th Pisa Meeting on Advanced Detectors

23. Data taking (2) • Look at various type of data with various goals • Random trigger for noise, FE debugging, … • Calibration test pulse trigger for threshold characteristics, timing behavior,… • Cosmics trigger for • t0 calibration/time alignment • RT calibration • Alignment • track reconstr. • … cosmics event Next slides: first t0 & RT calibrations with cosmics 11th Pisa Meeting on Advanced Detectors

24. Cosmics data (1) • Use calorimeter to trigger cosmic muons • Correct for downstream (early OT hits) or upstream (late OT hits) • Correct for Time Of Flight and wire propagation time TDC = tcosmic + tTOF + tdrift + tprop + t0 11th Pisa Meeting on Advanced Detectors

25. Cosmic data (2) • t0 calibration with cosmics: a first analysis Faulty CLK fan-outs, now replaced! module t0 (ns) module <3ns variation in t0’s! module average t0 (ns) 11th Pisa Meeting on Advanced Detectors

26. Cosmic data (3) • RT relation with cosmics: a first analysis RT-relation in beam test RT-relation from cosmics calibration with cosmics ongoing work! 11th Pisa Meeting on Advanced Detectors

27. Summary • LHCb will be ready to collect data with its full detector as LHC turns on: • Test of Charge-Parity asymmetry • probe rare B decays • Tracking system performance of crucial importance • Outer Tracker consisting of straw-tubes modules • All OT modules and electronics built and tested • Quality Assurance during production • Beam tests • All OT modules and electronics installed and re-tested in situ • Commissioning well advanced • Electronics debugging • Cosmic trigger for OT commissioning: track reconstruction, T0 and RT calibration, alignment, etc Beam for B physics 11th Pisa Meeting on Advanced Detectors

28. 11th Pisa Meeting on Advanced Detectors