Particle Identification in LHCb On behalf of the LHCb collaboration Participating countries to the RICH construction: CERN, ITALY, UK INSTR02 March 2002 Clara Matteuzzi

The LHCb detector Forward single-arm spectrometer p-p collisions 14 TeV at LHC Acceptance: 10-300 mrad (bending plane) 10-250 mrad (non-bending plane) INSTR02 March 2002 Clara Matteuzzi

The LHCb detector Located in Pit 8 Interaction point Local luminosity 2 x 1032 INSTR02 March 2002 Clara Matteuzzi

Physics with Particle Identification Bs K+K- Purity=84% Efficiency=79% Purity=13% INSTR02 March 2002 Clara Matteuzzi

Physics with Particle Identification Bs Ds K Purity=7.0% Purity=66% , efficiency=88% INSTR02 March 2002 Clara Matteuzzi

Physics with Particle Identification Momentum Particle ID required from 1 to 150 GeV 2 detectors with 3 radiators INSTR02 March 2002 Clara Matteuzzi

The RICH of LHCb 5 cm aerogel 4 m3 C4F10 RICH 1 RICH 2 100 m3 CF4 INSTR02 March 2002 Clara Matteuzzi

The RICH of LHCb Acceptance : 300 mrad RICH 1 120 mrad RICH 2 Mirrors: spherical (R=170 cm and 800 cm) tilted to place photodetectors outside acceptance plane mirrors necessary in RICH 2 INSTR02 March 2002 Clara Matteuzzi

Range of identification The RICH of LHCb Range of identification 2 – 11 GeV 10 –70 GeV 17 – 150 GeV INSTR02 March 2002 Clara Matteuzzi

The RICH of LHCb Characteristics of the detectors: RICH 2 RICH 1 Radiators properties Cherenkov Angle precision Photoelectron yield INSTR02 March 2002 Clara Matteuzzi

The RICH of LHCb HybridPhotoDiodes The PhotoDetectors requirements: cover an area 2.6 m2 single photoelectron sensitivity Quantum Efficiency > 20% 200 – 600 nm granularity 2.5 x 2.5 mm2 large active area 75% LHC speed read-out 40 MHz Baseline: HybridPhotoDiodes (HPD) Backup: Multianode PM (MaPMT) INSTR02 March 2002 Clara Matteuzzi

The HybridPhotoDiodes Tube and encapsulation: industry (DEP) 61 pixel HPD INSTR02 March 2002 Clara Matteuzzi

The HybridPhotoDiodes Pixel-HPD Photocathode diameter 75 mm Overall 83 mm diameter PC voltage -20 KV 5000 e signal at Si anode Electron optics: cross-focussed demagnification 5 Anode: Si pixel detector, bump bonded to pixel readout chip pixel=50 mm x 500 mm (320x32 matrix) pixel size at photocathode 2.5 x 2.5 mm2 1024 pixel 82% active area 168 HPDs in RICH1 262 HPDs in RICH2 340K electronic channels INSTR02 March 2002 Clara Matteuzzi

AEROGEL as Cerenkov radiator very light, solid quartz-like structure SiO2 low density around 0.15 g/cm3 refractive index n = 1 + 0.20 r transparent in the visible region can be hydroscopic or hydrophobic INSTR02 March 2002 Clara Matteuzzi

AEROGEL as Cerenkov radiator TRANSMITTANCE: Novosibirsk aerogel T = A e (-C t / l4) 4 cm T (%) 8 cm A is the long l transmittance C is the clarity coefficient Index of refraction: n = 1.03066 n = 1.02982 l (nm) INSTR02 March 2002 Clara Matteuzzi

AEROGEL C = 0.0045-0.0065 T = 35% for 4 cm tile at 400 nm Boreskov Inst. Catalysis (Novosibirsk) C = 0.0045-0.0065 mm4 cm-1 T = 35% for 4 cm tile at 400 nm C = 0.0096 mm4 cm-1 T = 38% for 2 cm tile at 400 nm SP30 Matsushita Electric,Japan INSTR02 March 2002 Clara Matteuzzi

AEROGEL Ageing test (g) Source of radiation: 60 Co Eg = 1.3 MeV , 1.7 MeV Dose : 420 rad/min INSTR02 March 2002 Clara Matteuzzi

Ageing test (g) Ageing test No degradation up to the dose measured INSTR02 March 2002 Clara Matteuzzi

AEROGEL Ageing test with protons -15% in the range shown 1 year LHCb operation Source of radiation: Proton beam 24 GeV Fluence : 9 109 p/cm2/s Spot : 2 x 2 cm2 INSTR02 March 2002 Clara Matteuzzi

AEROGEL Humidity test Expose tile to humid air Measure humidity absorption through weight Measure Transmittance in range 200-800 nm INSTR02 March 2002 Clara Matteuzzi

AEROGEL Humidity test Loss of 30% at 300 nm Loss of 15% at 400 nm INSTR02 March 2002 Clara Matteuzzi

AEROGEL as Cerenkov radiator Test Beam Beam from CERN-PS (T7 line) 1 – 10 GeV/c (dp/p=1%) Negative : p- Positive : p+ with protons (50 – 70%) INSTR02 March 2002 Clara Matteuzzi

AEROGEL Test Beam INSTR02 March 2002 Clara Matteuzzi

4 large Hybrid PhotoDetector AEROGEL test beam The PhotoDetectors 4 large Hybrid PhotoDetector Bialkali photocathodes (K2CsSb) 2 electrodes: fountain shape electric field 2048 Silicon pads 1x1 mm2 16 sectors = 128 pads demagnification factor 2.3 INSTR02 March 2002 Clara Matteuzzi

Quantum Efficiency of the 4 photocathodes > 20% for l=280-380 nm AEROGEL test beam The PhotoDetectors Quantum Efficiency of the 4 photocathodes > 20% for l=280-380 nm One HPD INSTR02 March 2002 Clara Matteuzzi

MONTECARLO Simulation Simulate Cherenkov radiation AEROGEL test beam MONTECARLO Simulation Simulate Cherenkov radiation in aerogel with GEANT 4 photons Rayleigh scattering Refraction on the bounderies Light absorption Light detection in photocathode Photocathode transparency etc...................... INSTR02 March 2002 Clara Matteuzzi

RESULTS (preliminary) Signal definition AEROGEL test beam RESULTS (preliminary) Signal definition Filters at exit window ADC counts INSTR02 March 2002 Clara Matteuzzi

Aerogel Novosibirsk Matsushita 4 cm 8 cm AEROGEL test beam RESULTS - resolution -- DATA -- MC Cerenkov angle in mrad DATA and MONTECARLO Aerogel Novosibirsk Matsushita 4 cm 249.6+-4.6 246.6+-3.5 252.2+-6.6 8 cm 247.0+-4.1 248.3+-3.5 247.3+-6.5 Cerenkov Radius (mm) INSTR02 March 2002 Clara Matteuzzi

beam AEROGEL test beam RESULTS - resolution 9 GeV p- Clara Matteuzzi INSTR02 March 2002 Clara Matteuzzi

No filter Filter D263 DATA 8.3 +- 0.4 5.6 +- 0.3 MONTE CARLO AEROGEL test beam RESULTS - Npe yield 4 cm thick aerogel from Novosibirsk No filter Filter D263 DATA 8.3 +- 0.4 5.6 +- 0.3 MONTE CARLO 8.9 +- 0.5 6.2 +- 0.4 INSTR02 March 2002 Clara Matteuzzi

p / p separation AEROGEL test beam RESULTS 5.8 s 3.3 s 2.8 s 6 GeV INSTR02 March 2002 Clara Matteuzzi

Conclusions RICH is essential for b-physics program of LHCb The RICH design of LHCb with 2 detectors and 3 radiators allows 3s p-k separation in 2 – 80 GeV range LHCb RICH project is progressing The design of the subsystems are advanced transition from R&D to construction is approaching The detector will be in time to take data at day 1 of LHC INSTR02 March 2002 Clara Matteuzzi