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UK Participation in the LHCb Experiment

UK Participation in the LHCb Experiment. Motivation Experiment RICH Vertex Detector UK Role Conclusions. PPC meeting Coseners 2. 11. 2000. Franz Muheim University of Edinburgh. UK Institutes. LOI. TP. University of Edinburgh 1999. University of Glasgow LOI.

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UK Participation in the LHCb Experiment

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  1. UK Participation in the LHCb Experiment Motivation Experiment RICH Vertex Detector UK Role Conclusions PPC meeting Coseners 2. 11. 2000 Franz Muheim University of Edinburgh

  2. UK Institutes LOI TP University of Edinburgh 1999 University of Glasgow LOI Imperial College LOI Rutherford Appleton Laboratory 1999 University of Oxford LOI University of Bristol 2000 PPC meeting

  3. Introduction • CPV only observed in neutral kaon system • theoretical uncertainties • Standard Model • 3 generation CKM matrix allows for CPV • predicts large CPV asymmetries for B mesons • No real understanding • Baryogenesis: additional source of CPV needed • why is strong CPV small? • New physics around the corner? UnitarityTriangles PPC meeting

  4. in B Meson System • Standard Model makes accurate predictions • precision tests of CKM elements and CPV phases, of the 3 sides and 3 angles need to measure 5 directly • CPV predicted in many decays • consistency checks • need larges samples of Bd, Bu, Bs, Bc mesons • Ideal to search for new physics • Can extract parameters of SM and new physics PPC meeting

  5. Large Hadron Collider • By 2005: BABAR, BELLE, CLEO-III, CDF, D0, HERA-B • 1st test of CKM matrix , 3 sides vs sin 2b • LHCb is a 2nd generation experiment • precision measurements of CP overconstrain CKM elements • large statistics, Bs mesons • LHC is the most intensive source of B mesons (Bd, Bu, Bs, Bc) • bb = 500 b inelastic = 80 mb • Luminosity <L>LHCb = 2 x1032 cm-2 s-1<L>LHC = 1034 cm-2 s-1 • 1012 bb / 107 s LHC PPC meeting

  6. LHCb Experiment • LHCb Detector • forward single arm spectrometer • Challenges • Trigger: leptonic and hadronic final states (eg Bd -> pp) • Particle Identification:-K separation 1 GeV < p < 150 GeV • Vertexing: proper time resolution 43 fs Bs -> Dsp(K) 30 fs Bs -> J/y f bb angular production PPC meeting

  7. LHCb Experiment • Acceptance 10 - 300 (250) mrad (non)-bending plane • Open geometry easy access Vertex RICH1 RICH2 PPC meeting

  8. Particle Identification • Excellent charged particle Identification required from1 - 150 GeV/c Momentum vs polar angle Momentum • RequiresRICH system with 3 radiators • RICH system divided into 2 detectors PPC meeting

  9. RICH System Overview Ring Imaging Cherenkov Detectors RICH1 RICH2 • Acceptance • 300 mrad RICH 1 • 120 mrad RICH 2 • Radiators: thickness L, refractive index n, angle , /K threshold Aerogel C4F10 CF4 • 5 85 167 cm • 1.03 1.0014 1.0005 • 242 53 32 mrad • 0.6 2.6 4.4 GeV • 2.0 9.3 15.6 GeV Photo detectors PPC meeting

  10. Photo Detectors C4F10 small rings Aerogel large rings • Photo detector area: 2.6 m2 • Single photon sensitivity: 200 - 600 nm, quantum efficiency > 20% • Good granularity: ~ 2.5 x 2.5 mm2 • Large active area fraction:  73% • LHC speed read-out electronics: 40 MHz • LHCb environment: magnetic fields, charged particles • Photodetector choice 12/99 • Pixel HPD is baseline, MaPMT is backup CF4 HPD or MAPMT PPC meeting

  11. Hybrid Photo Diodes Pixel HPD (baseline) • Quartz window, thin S20 photocathodeQE dE = 0.77 eV • 32 x 32 Si pixel array: 500 m • Cross-focusing optics • demagnification ~ 5 • 50 m point-spread function • 20 kV operating voltage • Encapsulated binary electronics • Tube, encapsulation: industry • Pixel sensor -20 kV 61 pixel HPD • Existing prototype external read-out  = 80 mm PPC meeting

  12. HPD R&D Results • Simultaneous detection of Cherenkov rings from aerogel and C4F10 radiators RICH 1 1/4-scale prototype PPC meeting

  13. HPD R&D Results II Testbeam • Testbeam Setup • RICH 1 prototype • 3 HPDs • Figure of merit • N0  202 cm-1 LED Spectrum PPC meeting

  14. HPD Electronics • ALICE / LHCb • pixel size 50 m x 425 m • 8 pixels = 1 LHCb unit • 40 MHz read-out clock • tests are currently ongoing • Bump bonding: chip-sensor Pixel chip Occupancy ~3 % RICH 1 < 1% RICH 2 50 mm PPC meeting

  15. MAPMT (backup) Multianode Photo Multiplier Tube • 8x8 dynode chains, pixel 2x2 mm2 • Gain: 3.105 at 800 V • UV glass window Bialkali photo cathode, QE = 22% at  = 380 nm • MAPMT active area fraction: 38% (includes pixel gap) • Increase with quartz lens with one flat and one curved surface to 85% PPC meeting

  16. MAPMT R&D Results 3x3 Cluster Test • Beam test • RICH 1 Prototype • CF4 @ 700 mbar • 40 MHz Read-out: APVm chip • Observe in data6.51  0.34 p.e. • Expect from simulation6.21 p.e. PPC meeting

  17. RICH Performance • Simulation • based on measured test beam HPD data • global pattern recognition • background photons included • # of detected photons • 7 Aerogel 33 C4F10 18 CF4 • Angular resolution[mrad] • 2.00 Aerogel 1.45 C4F10 0.58 CF4 -K separation PPC meeting

  18. Bd ->  + • sensitive to CKM angle  • Adir and Amix depend also on |P/T| and strong phase  •  ~ 20 - 50in 1 year •  dependent • if |P/T| from elsewhere • Backgrounds have Tree T Penguin P PPC meeting

  19. Bs -> DsK • Both diagrams of O(3) • expect large • Rate asymmetries measure angleg-2dg • Expect 2400 events in 1 year of data taking • s(g-2dg) = 60 .. 140 PPC meeting

  20. RICH Construction Photo detectors RICH 1 Beam-pipe 14% X0 Kapton beam-pipe seal Mirrors PPC meeting

  21. RICH Construction II RICH 2 12.4% X0 Finite Element Analysis Static deflections Natural frequencies Mirrors Side view Top view Photo detectors PPC meeting

  22. RICH Electronics • Pixel chip • encapsulated, binary, 40 MHz, 32:1 MUX • Level 0 • on detector • Gbit optical links • clocks, triggers - TTC • Level 1 • in counting room • buffers data L1 latency, transports to DAQ • zero suppression • TTC, DCS interface PPC meeting

  23. Technical Design Report • Submitted 7.9.2000 • other institutes • CERN • Genova, Milano Division of responsibilities PPC meeting

  24. RICH Project Schedule PPC meeting

  25. Vertex Detector VErtex LOcator Design • Si strip detectors p-n, n-n, single sided, double metal read-out 220 m thick, 1800 wedges • Optimized for Level 1 trigger (L1) • Alternate r and phi strip detectors varying strip pitch 20 - 40 m in r • Detector halves retracted by  30 mm in y during injection • 8 mm from beam during physics • Radiation damage • may replace detectors after a few years Si detectors Si Strip Layout radial phi PPC meeting

  26. VELO Design Optimisation • Use Liverpool MAP farm (300 Linux PCs) • 3.5 Million events • optimize # of stations, positions, outer & inner radii • 25 stations, mounted in “toblerone” RF shields • 220 k channels • 9.5 hits/ track • Proper time resolution • st = 43 fs Bs -> Dsp • sensitive up to xs ~ 75 (1 year) Toblerone RF shield PPC meeting

  27. VELO R&D Tests • irradiated prototypes • cluster finding efficiency • resolution • signal shape Testbeam Setup 200 mm p-n “Micron” • Analogue read-out • Front-end chip design • sub micron - BEETLE • DMILL - SCTA128_VELO PPC meeting

  28. VELO Summary • Geometry • smallest pitch where most important for impact parameter resolution, at inner radius: “pixels” of 20 x 6300 m2 • optimum for L1 trigger • constant occupancy < 5 x 10-3 • Thin detectors • read out at outer rim • minimize multiple scattering • S/N ~ 15 sufficient for L1 trigger • Number of readout channels • 220 k reflects in cost • Technical Design Report expected by April 2001 • UK responsibilities • Silicon detectors, hybrids, and assembly PPC meeting

  29. UK Costs PPC meeting

  30. Conclusions • LHCb is progressing rapidly since Technical Proposal • Major technology choices made, e.g. pixel HPD baseline for RICH photo detectors • Technical Design Reports • Magnet approved, • RICH & ECAL submitted • other subsystems on track • UK groups havelarge responsibilities for • RICH • Vertex detector • Software / Computing • Construction starts soon PPC meeting

  31. New Methods • New strategies for measuring CKM angles - direct • combine Bd -> K - charged and neutral B to extract g •  ~ 20 - 70ambiguous solutions • combine Bs ->KKand Bd ->  •  ~ 40 known, U-spin • LHCb RICH at its best • combine Bd,s ->D+d,s D-d,s • O(100k) events per year •  ~ a few 0 • Overconstrain CP angles a, b,g,and dg PPC meeting

  32. Rare Decays • Bs -> m+m- • Standard Model branching ratio: 3.7 x 10-9 ideal to search for new physics - FCNC • Expected signal (bkgd) : 11 (3.3) 1 year • Bd -> K*m+m- • Standard Model branching ratio: 1.5 x 10-6 dimuon mass spectrum, forward-backward asymmetry • combine with Bd -> r m+m-|Vts/Vtd| • Expected signal (bkgd): 22400 (1400) 1 year • Bd -> K*g • Standard Model branching ratio: 5 x 10-5 search for new physics in CPV asymmetry O(1%) in SM • Expected signal: 26000 1 year PPC meeting

  33. LHCb CP Sensitivities Parameter Channels Evts/year (1 year) LHCb feature 2(+) Bd 4900 |P/T| = 0 2-5 PID, hadron trigger Bdr ~1300 3-6 PID, hadron trigger 2+ Bd  D* 340000 > 11 PID, hadron trigger  BdJ/Ks 37000 0.6 -2 Bs DsK 2400 6-14 PID, hadron trigger, t  Bd  DK* 400 10 PID, hadron trigger  Bs  J/yf 44000 0.6 t Bs oscillations xs Bs  Ds 120000 up to 75 hadron trigger, t Rare Decays BR Bs   <210-9 t Bd  K*mm 22400 PID PPC meeting

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