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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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 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


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


38Project Management


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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

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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

technical design report for lhcb rich detectors

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