Technical Design Report for LHCb RICH Detectors
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Transcript of Technical Design Report for LHCb RICH Detectors
D.Websdale: LHCb RICH TDR: LHCC 4-10-2000
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Technical Design Reportfor LHCb RICH Detectors
Presentation to LHCC4 October 2000
D.Websdale, G.Wilkinsonon behalf of LHCb RICH Group
Dedicated to Tom Ypsilantis
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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
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Requirements for Particle ID in LHCb
Momentum distributionsParticle ID required from 1 - 150 GeV/cRequires RICH system with 3 radiators
Momentum vs polar angle in B-->
RICH system divided into 2 detectors
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LHCb Spectrometer, seen from above
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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
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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 beamsPerformance studies through simulationCosts, Risks and resource requirements
Pixel HPD selected as BASELINE (performance milestones)MAPMT as BACKUP
Readout Electronics - Binary systemPrototype tests: photodetectors, radiators, mirrors, mirror supportsDetector geometry and mechanics
Structural calculations of engineering designBeam-pipe sealingPhotodetector and Mirror mounting
Software developmentFull GEANT simulation, including pattern recognitionC++ framework established
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RICH system Overview
RICH1: 5cm aerogel n = 1.03, 2-11 GeV4 m3 C4F10 n = 1.0014, 10-70 GeV
RICH2: 100 m3 CF4 n = 1.0005, 17-150 GeV
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RICH system Overview
80mm Pixel HPD (schematic)
RICH photodetector requirementsCover total area ~ 2.6 m2
Single photon sensitivityGranularity ~ 2.5mm x 2.5mmVisible and UV sensitivity25ns time resolution
Good photoelectron resolution Low occupancy
Binary Readout electronics
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RICH system Overview
RICH radiatorsRefractive index vs photon energy
HPD Photon DetectorQuantum efficiency (measured)
vs photon energy
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RICH system OverviewCharacteristics of LHCb RICH detectors:
Radiator properties
Contributions to Cherenkov angle precision
Cherenkov photon yield
Optical system alignment, mirror quality and stability ~ 0.1 mrad
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Prototype Tests
1. RICH1, RICH2 prototypes in test beamPerformance of aerogel, C4F10, CF4 radiators
Photon yieldCherenkov angle precisionChromatic propertiesScattering
Simultaneous imaging of Cherenkov rings from gas and aerogel2. HPD tests
Detecting Cherenkov rings in beam testsResponse to traversing charged particlesElectron optics, including magnetic field testsTests of prototype pixel readout chips
3. Optical system testsMirror optical qualityMirror support, precision and stability
Verify parameters assumed in RICH performance studies
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1/4-scale prototype RICH1Simultaneous imaging of Cherenkov rings from aerogel and C4F10 radiators
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Prototype RICH2
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Prototype RICH2
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Using a CEDAR Cherenkov counter upstream in the testbeam to tag kaons.
Prototype RICH2
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Photon Yields
Cherenkov Angular resolution [mrad]
Prototype performance compared with simulation
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40mm HPD - 2048 pixels 0.05mm x 0.5mm encapsulated pixel chip (LHC1)
Angular resolution in RICH2 prototype - 120 GeV/c beam
Pion /electron separation in RICH1 at 10 GeV/c
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Full-scale: 80mm prototype HPD 61 pixels 2mm x 2mm external readout
Photon yields, in low pressure runs, where ring is contained ina single HPD
Figure of Merit: N0 = Npe / ALsin2= 202 cm-1
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1980mm HPD - phosphor anode + CCDtest of electron optics
Left: Magnification vs radial position
Right: Point Spread functionvs radial position
Images of Cross with3 mT magnetic field
Left: Transverse field
Right: Axial field
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Mirror quality:analysis of image of reflected point source
40 mirrors tested (6-7 cm-thick)
R,
95% light in circle of 2 cm diameter
= 0.03 mrad
Mirror Tests: Automated optical test facility (TA2- CERN)
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Mirror Tests: Automated optical test facility (TA2- CERN)
Precision and Long-term stability of Mirror Supports < .02 mrad
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Aerogel Tests:
Samples with n ~ 1.03Matsushita - hydrophobic: C = 0.008Novosibirsk - hygroscopic: C = 0.005
Pion - proton separation at 8 GeV Photon yields: Data and simulation
I=I0 exp (-CL/4)C: Clarity coeff [m4 cm-1 ]
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Technical Design
Pixel HPD Photon detectorEncapsulated pixel readout chipReadout electronicsRICH mechanics and opticsGas systemsAlignmentMonitoring and ControlCabling, InfrastructureSafety
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Pixel HPD: Photon detector
Photocathode diameter = 75 mm: Overall diameter = 83mm (82% active)Photocathode voltage = -20kV: 5000e signal at silicon anodeElectron optics: Cross-focussed: Demagnification ~ 5Anode: Silicon pixel detector, bump-bonded to pixel readout chip
Pixel cell: 50um x 500um: 320 x 32 matrixEffective pixel size at photocathode: 2.5mm x 2.5mm: 1024 channels
Magnetic shielding: 0.9 mm Mumetal
168 HPDs in RICH1262 HPDs in RICH2
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Pixel HPDPrototype 80mm HPD
3 equipped with 61-pixel anode1 equipped with phosphor + CCD anode
Final Anode assemblyCeramic PGA carrierSilicon sensor, bump bonded to pixel chipand wire-bonded to carrier
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Pixel Chip
RequirementsDiscriminate single photoelectron hits: Threshold ~ 2000eTime-tag with LHC bunch crossing : Time resolution ~ 25 ns1 MHz Level-0 trigger, 4 us latency30 kRad radiation dose over 10 years
Characteristics of LHCb pixel chip0.25 um CMOS processCell size: 50 um x 500 um - matched to silicon sensor
Low input capacitance and reduced occupancyPre-amp RMS noise: 250e
Shaping time: 25 nsDiscriminator threshold (3-bit adjust) 2000e
Super-pixel: 10x OR: 500 um x 500 um 1024 channelsPower consumption of chip ~ 0.5 WBump-bonded to silicon sensor
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Pixel Chip
Pixel Cell
Current DevelopmentALICE-LHCb chip: 8192 cells 50 um x 425 umFabrication completed: Testing begins October
Next stepsPrepare anode assemblies: bump-bonded sensor + PGA carrierEncapsulate in 80 mm HPDDesign and fabricate final LHCb pixel chip - minor modifications
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Readout Electronics1. Pixel chip, encapsulated in HPD
Binary signals at 40 MHz, MUX 32:1
2. Level-0 adapter BoardDrive Distributes clocks, triggers via TTC to pixel chip
Controls DC power levels for pixel chipMUX 16:1Gbit optical links (100 m to counting room)
3. Level-1 BoardIn counting room (no radiation problem)Buffers data during Level-1 latency
Filters Level-1 triggersProvides zero suppressionInterfaces TTC, DCSTransports data to DAQ and event builder
430 x
Level-0On detector
220 x
Level-1Counting room
54 x
RICH not in Level-0 nor Level-1 trigger
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Readout electronics schematic
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RICH1 - Mechanics and Optics
Top view Side view
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RICH1 Mechanics and Optics
Kapton beam-pipe seals Part of HPD arrayin 1 quadrant of RICH1
Space frame supporting mirror adjustment points in RICH1
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RICH2 Mechanics and Optics
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RICH2 Mechanics and optics
Top view of one half of RICH2 HPD mounting
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RICH2 Mechanics and optics
Mirror supportFEA of RICH2 space frame
Mode 1: 1.2 Hz oscill along zMode 2: 1.4 Hz oscill along zMode 3: 2.9 Hz oscill along x
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RICH Gas Systems
Cherenkov Gas parameters
C4F10 Gas distribution system
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AlignmentCherenkov angle precision: RICH1: 1.4 mrad RICH2: 0.5 mrad
Alignment strategy:Installation and survey: precision < 1mm at photodetector planeMonitoring with laser system (ATLAS muon spectr); initial alignment ~ 0.5 mradAlignment using data: rec- = A cos(rec- 0) ; final alignment < 0.2 mrad
Monitoring and ControlGas: Flow, pressure, temperature
Purity: water, oxygen < 200 ppmnitrogen: constant, <1%
Transparency: monochromator; 200 - 800 nmMechanical stability; Lasers and semi-transparent silicon sensorsElectronics: HV monitor
Bias, leakage currents at pixel sensorDiscriminator thresholdsCalibration test pulses
Protocals: JCOP, Joint Control Project (LHC common)SCADA, Supervisor, Control and DAQ (LHC common)
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Project ManagementSchedules for:
Completion of R & D pixel chip end 2001engineering design end 2001alignment systems end 2001readout electronics mid 2002 aerogel end 2003
Construction and testing RICH vessels mid 2003completion dates HPDs end 2003
Readout electronics end 2003Gas system mid 2004
Installation / Commissioning Installation beg 2004Commissioning mid 2004 - mid 2005
MilestonesCostsDivision of Responsibilities
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Project Milestones
Date MilestoneMechanics and Optics
2002/Qtr1 Mechanical designs completed2003/Qtr4 Mechanics and Optics completed2004/Qtr1 Begin Assembly RICH1 in IP82004/Qtr3 Begin installation RICH2 in IP8
Photodetectors2000/Qtr4 Prototype HPD completed ***2001/Qtr3 Place HPD order ***2004/Qtr1 Production / testing completed
Readout electronics2002/Qtr2 Prototype chain tests completed2004/Qtr1 Production / testing completed
RICH Detectors2005/Qtr2 Commissioning completed
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Project Costs (kCHF)
Item RICH1 RICH2
Mechanics, Optics 527 1204Photodetectors 1473 2290Electronics 537 814Gas system, monitoring 365 365Aerogel 102 -
Total: 3004 4673
Total Cost (incl. spares) 7677 kCHF
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Division of responsibilities
LHCb RICH Group
Bristol UnivCambridge UnivCERNGenova UnivGlasgow UnivEdinburgh UnivMilano UnivOxford UnivImperial CollegeRutherford Appleton Lab
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MultiAnode PMTHamamatsu R7600-03-M64.
8x8 channels. Size: 26x26 mm2. Bialkali PC: Q.E. ~ 22% at max = 400 nm. Gain 106
.
Active area fraction 38%. Active area fraction Increased by lenses (78%).
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MultiAnode PMT Cluster testWithout lenses
With lenses
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MultiAnode PMT Project Schedule