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Technical Design Report for LHCb RICH Detectors

Technical Design Report for LHCb RICH Detectors. Presentation to LHCC 4 October 2000. D.Websdale, G.Wilkinson on behalf of LHCb RICH Group. Dedicated to Tom Ypsilantis. Requirements for Particle ID in LHCb. Selection of specific B-decay channels for CP-violation measurements

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Technical Design Report for LHCb RICH Detectors

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  1. Technical Design Report for LHCb RICH Detectors Presentation to LHCC 4 October 2000 D.Websdale, G.Wilkinson on behalf of LHCb RICH Group Dedicated to Tom Ypsilantis

  2. Requirements for Particle ID in LHCb • Selection of specific B-decay channels for CP-violation measurements • Kaon tagging of B-flavour via b-c-s cascade

  3. Requirements for Particle ID in LHCb Momentum distributions Particle ID required from1 - 150 GeV/c RequiresRICH system with 3 radiators Momentum vs polar angle in B--> pp RICH system divided into 2 detectors

  4. LHCb Spectrometer, seen from above

  5. Content of RICH TDR presentation • Evolution since Technical Proposal • RICH system overview • Prototype tests • Physics performance through simulation • Technical design • Project organisation, schedules, costs Guy Wilkinson

  6. Evolution since Technical Proposal (20.2.98) • Photodetector Choice: • 3 options studied: PAD HPD - 2048 pads, 1mm x 1mm, analogue readout (M x 2.3) • Pixel HPD - 1024 pixels 0.5mm x 0.5mm, binary readout (M x 5) • Hamamatsu MAPMT - 64 anodes, 2mm x 2mm, analogue readout • Prototype measurements in Lab and as Cherenkov detector in test beams • Performance studies through simulation • Costs, Risks and resource requirements • Pixel HPD selected as BASELINE (performance milestones) • MAPMT as BACKUP • Readout Electronics - Binary system • Prototype tests:photodetectors, radiators, mirrors, mirror supports • Detector geometry and mechanics • Structural calculations of engineering design • Beam-pipe sealing • Photodetector and Mirror mounting • Software development • Full GEANT simulation, including pattern recognition • C++ framework established

  7. RICH system Overview RICH1: 5cm aerogel n = 1.03, 2-11 GeV 4 m3 C4F10 n = 1.0014, 10-70 GeV RICH2: 100 m3 CF4 n = 1.0005, 17-150 GeV

  8. RICH system Overview • RICH photodetector requirements • Cover total area ~ 2.6 m2 • Single photon sensitivity • Granularity ~ 2.5mm x 2.5mm • Visible and UV sensitivity • 25ns time resolution 80mm Pixel HPD (schematic) • Good photoelectron resolution • Low occupancy • Binary Readout electronics

  9. RICH system Overview • RICH radiators • Refractive index vs photon energy • HPD Photon Detector • Quantum efficiency (measured) • vs photon energy

  10. RICH system Overview Characteristics of LHCb RICH detectors: Radiator properties Contributions to Cherenkov angle precision Cherenkov photon yield Optical system alignment, mirror quality and stability ~ 0.1 mrad

  11. Prototype Tests • 1. RICH1, RICH2 prototypes in test beam • Performance of aerogel, C4F10, CF4 radiators • Photon yield • Cherenkov angle precision • Chromatic properties • Scattering • Simultaneous imaging of Cherenkov rings from gas and aerogel • 2. HPD tests • Detecting Cherenkov rings in beam tests • Response to traversing charged particles • Electron optics, including magnetic field tests • Tests of prototype pixel readout chips • 3. Optical system tests • Mirror optical quality • Mirror support, precision and stability • Verify parameters assumed in RICH performance studies

  12. 1/4-scale prototype RICH1 Simultaneous imaging of Cherenkov rings from aerogel and C4F10 radiators

  13. Prototype RICH2

  14. Prototype RICH2

  15. Prototype RICH2 Using a CEDAR Cherenkov counter upstream in the testbeam to tag kaons.

  16. Prototype performance compared with simulation Photon Yields Cherenkov Angular resolution [mrad]

  17. 40mm HPD - 2048 pixels 0.05mm x 0.5mm encapsulated pixel chip (LHC1) Pion /electron separation in RICH1 at 10 GeV/c Angular resolution in RICH2 prototype - 120 GeV/c p beam

  18. Full-scale: 80mm prototype HPD 61 pixels 2mm x 2mm external readout Photon yields, in low pressure runs, where ring is contained in a single HPD Figure of Merit: N0 = Npe / eALsin2q = 202 cm-1

  19. 80mm HPD - phosphor anode + CCD test of electron optics Left: Magnification vs radial position Right: Point Spread function vs radial position Images of Cross with 3 mT magnetic field Left: Transverse field Right: Axial field

  20. Mirror Tests: Automated optical test facility (TA2- CERN) Mirror quality: analysis of image of reflected point source 40 mirrors tested (6-7 cm-thick) R, s q 95% light in circle of 2 cm diameter s q = 0.03 mrad

  21. Mirror Tests: Automated optical test facility (TA2- CERN) Precision and Long-term stability of Mirror Supports < .02 mrad

  22. Aerogel Tests: Samples with n ~ 1.03 Matsushita - hydrophobic: C = 0.008 Novosibirsk - hygroscopic: C = 0.005 I=I0 exp (-CL/l4) C: Clarity coeff [mm4 cm-1 ] Photon yields: Data and simulation Pion - proton separation at 8 GeV

  23. Technical Design Pixel HPD Photon detector Encapsulated pixel readout chip Readout electronics RICH mechanics and optics Gas systems Alignment Monitoring and Control Cabling, Infrastructure Safety

  24. Pixel HPD: Photon detector 168 HPDs in RICH1 262 HPDs in RICH2 Photocathode diameter = 75 mm: Overall diameter = 83mm (82% active) Photocathode voltage = -20kV: 5000e signal at silicon anode Electron optics: Cross-focussed: Demagnification ~ 5 Anode: Silicon pixel detector, bump-bonded to pixel readout chip Pixel cell: 50um x 500um: 320 x 32 matrix Effective pixel size at photocathode: 2.5mm x 2.5mm: 1024 channels Magnetic shielding: 0.9 mm Mumetal

  25. Pixel HPD • Prototype 80mm HPD • 3 equipped with 61-pixel anode • 1 equipped with phosphor + CCD anode • Final Anode assembly • Ceramic PGA carrier • Silicon sensor, bump bonded to pixel chip • and wire-bonded to carrier

  26. Pixel Chip • Requirements • Discriminate single photoelectron hits: Threshold ~ 2000e • Time-tag with LHC bunch crossing : Time resolution ~ 25 ns • 1 MHz Level-0 trigger, 4 us latency • 30 kRad radiation dose over 10 years • Characteristics of LHCb pixel chip • 0.25 um CMOS process • Cell size: 50 um x 500 um - matched to silicon sensor • Low input capacitance and reduced occupancy • Pre-amp RMS noise: 250e • Shaping time: 25 ns • Discriminator threshold (3-bit adjust) 2000e • Super-pixel: 10x OR: 500 um x 500 um 1024 channels • Power consumption of chip ~ 0.5 W • Bump-bonded to silicon sensor

  27. Pixel Chip Pixel Cell • Current Development • ALICE-LHCb chip: 8192 cells 50 um x 425 um • Fabrication completed: Testing begins October • Next steps • Prepare anode assemblies: bump-bonded sensor + PGA carrier • Encapsulate in 80 mm HPD • Design and fabricate final LHCb pixel chip - minor modifications

  28. Readout Electronics • 1. Pixel chip, encapsulated in HPD • Binary signals at 40 MHz, MUX 32:1 • 2. Level-0 adapter Board • Drive Distributes clocks, triggers via TTC to pixel chip • Controls DC power levels for pixel chip • MUX 16:1 • Gbit optical links (100 m to counting room) • 3. Level-1 Board • In counting room (no radiation problem) • Buffers data during Level-1 latency • Filters Level-1 triggers • Provides zero suppression • Interfaces TTC, DCS • Transports data to DAQ and event builder 430 x Level-0 On detector 220 x Level-1 Counting room 54 x RICH not in Level-0 nor Level-1 trigger

  29. Readout electronics schematic

  30. RICH1 - Mechanics and Optics Side view Top view

  31. RICH1 Mechanics and Optics Kapton beam-pipe seals Part of HPD array in 1 quadrant of RICH1 Space frame supporting mirror adjustment points in RICH1

  32. RICH2 Mechanics and Optics

  33. RICH2 Mechanics and optics HPD mounting Top view of one half of RICH2

  34. RICH2 Mechanics and optics • FEA of RICH2 space frame • Mode 1: 1.2 Hz oscill along z • Mode 2: 1.4 Hz oscill along z • Mode 3: 2.9 Hz oscill along x Mirror support

  35. RICH Gas Systems Cherenkov Gas parameters C4F10 Gas distribution system

  36. Alignment • Cherenkov angle precision: RICH1: 1.4 mrad RICH2: 0.5 mrad • Alignment strategy: • Installation and survey: precision < 1mm at photodetector plane • Monitoring with laser system (ATLAS muon spectr); initial alignment ~ 0.5 mrad • Alignment using data: qrec- qp= A cos(frec- f0) ; final alignment < 0.2 mrad Monitoring and Control Gas: Flow, pressure, temperature Purity: water, oxygen < 200 ppm nitrogen: constant, <1% Transparency: monochromator; 200 - 800 nm Mechanical stability; Lasers and semi-transparent silicon sensors Electronics: HV monitor Bias, leakage currents at pixel sensor Discriminator thresholds Calibration test pulses Protocals: JCOP, Joint Control Project (LHC common) SCADA, Supervisor, Control and DAQ (LHC common)

  37. Project Management • Schedules for: • Completion of R & D pixel chip end 2001 • engineering design end 2001 • alignment systems end 2001 • readout electronics mid 2002 • aerogel end 2003 • Construction and testing RICH vessels mid 2003 • completion dates HPDs end 2003 • Readout electronics end 2003 • Gas system mid 2004 • Installation / Commissioning Installation beg 2004 • Commissioning mid 2004 - mid 2005 • Milestones • Costs • Division of Responsibilities

  38. Project Management

  39. Project Milestones Date Milestone Mechanics and Optics 2002/Qtr1 Mechanical designs completed 2003/Qtr4 Mechanics and Optics completed 2004/Qtr1 Begin Assembly RICH1 in IP8 2004/Qtr3 Begin installation RICH2 in IP8 Photodetectors 2000/Qtr4 Prototype HPD completed *** 2001/Qtr3 Place HPD order *** 2004/Qtr1 Production / testing completed Readout electronics 2002/Qtr2 Prototype chain tests completed 2004/Qtr1 Production / testing completed RICH Detectors 2005/Qtr2 Commissioning completed

  40. Project Costs (kCHF) Item RICH1 RICH2 Mechanics, Optics 527 1204 Photodetectors 1473 2290 Electronics 537 814 Gas system, monitoring 365 365 Aerogel 102 - Total: 3004 4673 Total Cost (incl. spares) 7677 kCHF

  41. Division of responsibilities LHCb RICH Group Bristol Univ Cambridge Univ CERN Genova Univ Glasgow Univ Edinburgh Univ Milano Univ Oxford Univ Imperial College Rutherford Appleton Lab

  42. MultiAnode PMT Hamamatsu R7600-03-M64. 8x8 channels. Size: 26x26 mm2. Bialkali PC: Q.E. ~ 22% at lmax = 400 nm. Gain  106. Active area fraction 38%. Active area fraction Increased by lenses (78%).

  43. MultiAnode PMT Cluster test Without lenses With lenses

  44. MultiAnode PMT Project Schedule

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