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The Ring Imaging Cherenkov Detectors for LHCb

The Ring Imaging Cherenkov Detectors for LHCb. Antonis Papanestis CCLRC – RAL On behalf of the LHCb RICH group. The LHCb Detector A forward single arm spectrometer. Calorimeter. RICH2. Muon. Tracker. RICH1. VELO. Magnet. production favours small polar angles and same hemisphere.

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The Ring Imaging Cherenkov Detectors for LHCb

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  1. The Ring Imaging Cherenkov Detectors for LHCb Antonis Papanestis CCLRC – RAL On behalf of the LHCb RICH group

  2. The LHCb DetectorA forward single arm spectrometer Calorimeter RICH2 Muon Tracker RICH1 VELO Magnet HEP 2005 Lisbon

  3. production favours small polar angles and same hemisphere b production at the LHC LHCb luminosity: 2×1032 cm-2 s-1 to avoid multiple interactions LHCb acceptance: 300 mrad horizontal 250 mrad vertical HEP 2005 Lisbon

  4. LHCb RICH SystemTwo detectors, three radiators RICH1: Aerogel 2→10 GeV/c n=1.03 (nominal at 540 nm) C4F10 up to 70 GeV/c n=1.0014 (nominal at 400 nm) Acceptance: 25→250 mrad (vertical) 300 mrad (horizontal) RICH2: CF4 up to 100 GeV/c n =1.0005 (nominal at 400 nm) Acceptance: 15→100 mrad (vertical) 120 mrad (horizontal) HEP 2005 Lisbon

  5. RICH1 (1) Magnetic shield box VerticalX-section HPD plane: 7 columns, 14 tubes each HEP 2005 Lisbon

  6. RICH1 (2) Optimised for: • Low material budget • Beryllium mirrors • 4 mm Be, 0.5 mm glass • Exit window: • PMI (polymethacryli-mide) foam between carbon fibre epoxy skins • High (60 mT) magnetic fields • Magnetic shields • 8 tonnes of “Armco” iron each HEP 2005 Lisbon

  7. Aerogel Silica Aerogel: • fragile linked network of SiO2 nanocrystals • Density = 0.15 g/cm3 • Nominal n=1.03 at 540 nm • Transparency 35% at 400 nm (4 cm tile) • Hygroscopic HEP 2005 Lisbon

  8. Aerogel testbeam with 4 pad-HPD DATAand MONTECARLO Published in NIMA 519(2004) 493 HEP 2005 Lisbon

  9. RICH2 Optics Top View Beam Axis- Z RICH2 schematic Mirror Support Panel Spherical Mirror Support Structure Y X Z X Flat Mirror Central Tube HEP 2005 Lisbon Photon funnel+Shielding

  10. RICH2 under construction • Spherical mirrors (56) in place and aligned. • Flat mirrors (40) delivered, installation almost complete. • Final leakage test after the windows are placed back. • To be installed at the end of August. HEP 2005 Lisbon

  11. 2 mm RICH2 mirror alignment All mirrors from one side Alignment and stability set a 50 μrad contribution to the overall uncertainty in the single photon Cherenkov angle reconstruction HEP 2005 Lisbon

  12. Hybrid Photon Detectors • Main features: • Total coverage 2.6 m2 (active 65%) • Granularity of 2.5 X 2.5 mm2 • Sensitive in 200600 nm • 40 MHz readout • Tolerant well beyond 3 kRad/year • Binary output Tube Ø: 83 mm S20 photocathode: 75mm Ø active HEP 2005 Lisbon

  13. HPD testing Production rate: 30 HPDs per month over production period of ~18 months Thorough HPD testing LHCb quality assurance: 2 photon detector test facilities 1 HPD per work day per facility over production period of ~18 months ←100 mm → HEP 2005 Lisbon

  14. System test Mirror HPD column mechanics Beam HPD housing Accumulated rings in C4F10 Beam Pipe Radiator vessel HEP 2005 Lisbon

  15. Digitisation Geometry DB (xml) Geant4 simulation Simulated data PYTHIA EVTGEN Data (real or simulated) Reconstruction Physics Analysis Software • Custom simulation of Cherenkov light production allowed the study and optimisation of the various system parameters. • LHCb now use a C++ OO framework (Gaudi) and have incorporated Geant 4 in the framework Gaudi is a very flexible framework that simplifies the introduction and testing of new pattern recognition algorithms. Currently testing the use of RICH information in High Level Trigger HEP 2005 Lisbon

  16. 100 100 80 80 60 60 40 40 20 20 0 0 RICH performance(in full detector realistic simulation) Efficiency (in %) of pion and kaon identification and Probability (in %) of misidentifying pion and kaon pe, m or p K  K or P Ke, m, or p pK or P Particle Momentum (GeV/c) Particle Momentum (GeV/c) HEP 2005 Lisbon

  17. Conclusions • RICH is an essential part of LHCb • RICH2 almost ready for installation, RICH1 under construction • Production of HPDs started • Pre-series OK • LHCb will produce physics from day one of LHC running HEP 2005 Lisbon

  18. Spare slides HEP 2005 Lisbon

  19. HPD anode Wire-bonding High T cure Chip+sensor Glue Ceramic carrier HEP 2005 Lisbon

  20. HPD flowchart Tube body assembly Photo-cathode deposition and vacuum sealing HPD cabling and potting Vacuum bake-out@ 300°C Final HPD testing Anode incoming inspectionand testing Anode testing QE measurement and anode testing HEP 2005 Lisbon

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