Particle Identification in LHCb On behalf of the

Particle Identification in LHCb On behalf of the LHCb collaboration Participating countries to the RICH construction: CERN, ITALY, UK INSTR 02 March 2002 Clara Matteuzzi

The LHCb detector Forward single-arm spectrometer Ø p-p collisions 14 Te. V at LHC ØAcceptance: 10 -300 mrad (bending plane) 10 -250 mrad (non-bending plane) INSTR 02 March 2002 Clara Matteuzzi

The LHCb detector Located in Pit 8 Interaction point Local luminosity 2 x 1032 INSTR 02 March 2002 Clara Matteuzzi

Physics with Particle Identification Bs K +K - Purity=13% INSTR 02 March 2002 Clara Matteuzzi Purity=84% Efficiency=79%

Physics with Particle Identification Bs Purity=7. 0% INSTR 02 March 2002 Ds K Purity=66% , efficiency=88% Clara Matteuzzi

Physics with Particle Identification Momentum Particle ID required from 1 to 150 Ge. V INSTR 02 March 2002 Clara Matteuzzi 2 detectors with 3 radiators

The RICH of LHCb RICH 1 INSTR 02 March 2002 5 cm aerogel 4 m 3 C 4 F 10 Clara Matteuzzi RICH 2 100 m 3 CF 4

The RICH of LHCb Ø Acceptance : 300 mrad RICH 1 120 mrad RICH 2 Ø Mirrors: spherical (R=170 cm and 800 cm) tilted to place photodetectors outside acceptance plane mirrors necessary in RICH 2 INSTR 02 March 2002 Clara Matteuzzi

The RICH of LHCb Range of identification 2 – 11 Ge. V 10 – 70 Ge. V 17 – 150 Ge. V INSTR 02 March 2002 Clara Matteuzzi

The RICH of LHCb Characteristics of the detectors: RICH 2 RICH 1 Radiators properties Cherenkov Angle precision INSTR 02 March 2002 Clara Matteuzzi Photoelectron yield

The RICH of LHCb The Photo. Detectors requirements: § cover an area 2. 6 m 2 § single photoelectron sensitivity Baseline: § Quantum Efficiency > 20% (HPD) 200 – 600 nm § granularity 2. 5 x 2. 5 mm 2 § large active area § LHC speed 75% read-out INSTR 02 March 2002 40 MHz Clara Matteuzzi Hybrid. Photo. Diodes Backup: Multianode PM (Ma. PMT)

The Hybrid. Photo. Diodes Tube and encapsulation: industry (DEP) 61 pixel HPD INSTR 02 March 2002 Clara Matteuzzi

Pixel-HPD The Hybrid. Photo. Diodes ØPhotocathode diameter 75 mm ØOverall 83 mm diameter ØPC voltage -20 KV 82% active area 5000 e signal at Si anode ØElectron optics: cross-focussed demagnification 5 ØAnode: Si pixel detector, bump bonded to pixel readout chip pixel=50 mm x 500 mm (320 x 32 matrix) pixel size at photocathode 2. 5 x 2. 5 mm 2 1024 pixel 168 HPDs in RICH 1 262 HPDs in RICH 2 INSTR 02 March 2002 340 K electronic channels Clara Matteuzzi

AEROGEL as Cerenkov radiator v very light, solid quartz-like structure Si. O 2 v low density around 0. 15 g/cm 3 v refractive index n = 1 + 0. 20 r v transparent in the visible region v can be hydroscopic or hydrophobic INSTR 02 March 2002 Clara Matteuzzi

AEROGEL as Cerenkov radiator TRANSMITTANCE: Novosibirsk aerogel T=Ae (-C t / l 4) 4 cm T (%) 8 cm A is the long l transmittance C is the clarity coefficient l (nm) INSTR 02 March 2002 Index of refraction: n = 1. 03066 n = 1. 02982 Clara Matteuzzi

AEROGEL Boreskov Inst. Catalysis (Novosibirsk) C = 0. 0045 -0. 0065 mm 4 cm-1 T = 35% for 4 cm tile at 400 nm C = 0. 0096 mm 4 cm-1 T = 38% for 2 cm tile at 400 nm INSTR 02 March 2002 SP 30 Matsushita Electric, Japan Clara Matteuzzi

AEROGEL Ageing test (g) Source of radiation: 60 Co Eg = 1. 3 Me. V , 1. 7 Me. V INSTR 02 March 2002 Dose : 420 rad/min Clara Matteuzzi

Ageing test (g) Ageing test No degradation up to the dose measured Clara Matteuzzi INSTR 02 March 2002

AEROGEL Ageing test with protons -15% in the range shown 1 year LHCb operation Source of radiation: Proton beam 24 Ge. V INSTR 02 March 2002 Fluence : 9 109 p/cm 2/s Spot : 2 x 2 cm 2 Clara Matteuzzi

Humidity test AEROGEL v Expose tile to humid air v Measure humidity absorption through weight v Measure Transmittance in range 200 -800 nm INSTR 02 March 2002 Clara Matteuzzi

Humidity test INSTR 02 March 2002 AEROGEL Loss of 30% at 300 nm Loss of 15% at 400 nm Loss of 8% at 500 nm Clara Matteuzzi

AEROGEL as Cerenkov radiator Test Beam from CERN-PS (T 7 line) 1 – 10 Ge. V/c (dp/p=1%) Negative : Positive : INSTR 02 March 2002 pp+ with protons (50 – 70%) Clara Matteuzzi

AEROGEL INSTR 02 March 2002 Clara Matteuzzi Test Beam

AEROGEL test beam The Photo. Detectors 4 large Hybrid Photo. Detector Ø Bialkali photocathodes (K 2 Cs. Sb) Ø 2 electrodes: fountain shape electric field Ø 2048 Silicon pads 1 x 1 mm 2 16 sectors = 128 pads Ø demagnification factor 2. 3 INSTR 02 March 2002 Clara Matteuzzi

AEROGEL test beam The Photo. Detectors One HPD INSTR 02 March 2002 Quantum Efficiency of the 4 photocathodes > 20% for l=280 -380 nm Clara Matteuzzi

AEROGEL test beam Simulate Cherenkov radiation in aerogel with GEANT 4 MONTECARLO Simulation §Rayleigh scattering §Refraction on the bounderies §Light absorption §Light detection in photocathode §Photocathode transparency etc. . . . . INSTR 02 March 2002 Clara Matteuzzi photons

AEROGEL test beam RESULTS (preliminary) Signal definition Filters at exit window ADC counts INSTR 02 March 2002 Clara Matteuzzi

AEROGEL test beam RESULTS - resolution -- DATA -- MC Cerenkov angle in mrad DATA and MONTECARLO Aerogel Novosibirs Matsushit k a Cerenkov Radius (mm) 4 cm 8 cm INSTR 02 March 2002 249. 6+-4. 6 246. 6+-3. 5 247. 0+-4. 1 248. 3+-3. 5 Clara Matteuzzi 252. 2+-6. 6 247. 3+-6. 5

AEROGEL test beam RESULTS - resolution 9 Ge. V beam INSTR 02 March 2002 Clara Matteuzzi p-

AEROGEL test beam RESULTS - Npe yield 4 cm thick aerogel from Novosibirsk No filter DATA MONTE CARLO INSTR 02 March 2002 Filter D 263 8. 3 +- 0. 4 5. 6 +- 0. 3 8. 9 +- 0. 5 Clara Matteuzzi 6. 2 +- 0. 4

AEROGEL test beam 6 Ge. V 5. 8 s p /p 8 Ge. V 3. 3 s 2. 8 s INSTR 02 March 2002 RESULTS 10 Ge. V Clara Matteuzzi separation

Conclusions v RICH is essential for b-physics program of LHCb v The RICH design of LHCb with 2 detectors and 3 radiators allows 3 s p-k separation in 2 – 80 Ge. V range v LHCb RICH project is progressing § The design of the subsystems are advanced § transition from R&D to construction is approachi v The detector will be in time to take data at day 1 of LHC INSTR 02 March 2002 Clara Matteuzzi