Status of the LHCb RICH detector and the HPD

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1 Beauty 2005 Status of the LHCb RICH detector and the HPD Tito Bellunato Università degli Studi di Milano Bicocca & INFN On behalf of the LHCb RICH group Assisi 23 June Assisi June Tito Bellunato

2 The LHCb detector Designed to study CP violation and rare decays of B-hadrons at LHC RICH1: 2-60 GeV/c RICH2: GeV/c Assisi 23 June 2005 Tito Bellunato 2

3 RICH aerogel RICH1 RICH-1 C4F10 Aerogel θ [mrad] 200 CF4 RICH2 RICH Momentum [GeV/c ] Assisi 23 June 2005 Tito Bellunato 3

4 RICH 1 shields 20 G Detection plane 0 G

5 RICH 1 Optics 7 x 14 Hybrid Photon Detectors Flat glass mirrors Spherical beryllium mirrors Aerogel Beryllium beam-pipe C4F10 gas radiator Assisi 23 June 2005 Tito Bellunato 5

6 RICH 1 Mirrors 3mm thick Be base + 0.3mm glass surface layer coated with Al. Radius curvature: 2700mm Beryllium blank Beampipe hole Assisi 23 June 2005 Tito Bellunato 6

7 Aerogel I linked network of SiO2 particles density = 0.15 g/cm³ hygroscopic A=95% C= µm 4 /cm Transparent over a wide range: optical properties dominated by Rayleigh scattering: Transmittance T, clarity factor C, surface scattering factor A, thickness t, wavelength λ Ct T = Ae (- λ 4 ) Produced by the Boreskov Institute for Catalysis in Novosibirsk Assisi 23 June 2005 Tito Bellunato 7

8 Aerogel II World-record 50 mm thickness and 200 mm transverse size n = ± C=0.006 µm /cm tested against: radiation OK C4F10 OK? Pre-production OK 4 liters inside specs Assisi 23 June 2005 Tito Bellunato 8

9 Testbeam I HPDs Beam Mirror curvature R= 949 mm Aerogel Beam: PS-T9 10 GeV/c π - (π +, p) Aerogel: 4 tiles 10x10x4.4 cm 3 Mirror n=1.028 C= µm 4 /cm Assisi 23 June 2005 Tito Bellunato 9

10 Testbeam II Photon yield studies: Single photon resolution (mrad): Nγ HPD0 HPD1 HPD2 σ θ HPD0 HPD1 HPD2 Data Data MC MC Scaling with acceptance to 2π : Data Becomes 2.7 mrad scaled to RICH1 optics Assisi 23 June 2005 Tito Bellunato 10

11 Testbeam III 10 GeV/c π +, p HPD plane θ pion = mrad θ proton = mrad Assisi 23 June 2005 Tito Bellunato 11

12 RICH2 software version CF4 gas volume : ~100 m³ Refractive index: n = HPD plane: 9 columns, 16 tubes each Assisi 23 June 2005 Tito Bellunato 12

13 RICH 2 hardware version Superstructure Magnetic shield maximum measured field at the HPD focal plane 6 G Awaited in the pit by the end of August Assisi 23 June 2005 Tito Bellunato 13

14 Assisi 23 June 2005 Tito Bellunato 14

15 Alignment I Clean room CCD Target Lens Laser Mirrors Single Mirror Shutter R = 8600 mm Assisi 23 June 2005 Tito Bellunato 15

16 Spherical Mirrors Alignment All mirrors from one side 2 mm Alignment and stability set a 50 µrad contribution to the overall uncertainty in the single photon Cherenkov angle reconstruction Assisi 23 June 2005 Tito Bellunato 16

17 The Hybrid Photon Detector Requirements: 2.6 m² coverage with 75% active area 2.5 x 2.5 mm² granularity Single photon efficiency 40 MHz readout S20 photocathode: 75 mm Ø active 20 kv operation Developed by CERN/ DEP(NL) cross-focused, 83mm Ø, encapsulated binary electronics 32 x 32 pixels (500 µm x 500 µm). Assisi 23 June 2005 Tito Bellunato 17

18 The HPD - II On-detector Off-detector RICH2 column Assisi 23 June 2005 Tito Bellunato 18

19 System Test I HPD column mechanics Mirror Beam HPD housing Radiator vessel PS beam: 10 Gev/c π - e - Assisi 23 June 2005 Tito Bellunato 19

20 System Test II 3500 N2 run, one HPD accumulated rings 0 C4F10 run, ring on four HPDs. single event accumulated rings Assisi 23 June 2005 Tito Bellunato 20

21 Magnetic distortions B B B 50 G B 30 G 0 G Assisi 23 June 2005 Tito Bellunato 21

22 and corrections Calibration and distortion monitoring system in both RICHes to allow corrections [rad] Rotation angle (rad) 2 1,8 1,6 1,4 1,2 1 0,8 0,6 0,4 Non uniform rotation (S-distortion) Non uniform radial dilatation Third order polynomial fit Second order polynomial fit Image rotation vs radius of entrance point Image rotation vs radial distance on entrance plane B 1, 3 and 5mT Delta Fi 5.0 mt [rad] Delta Fi 3.0 mt [rad] Delta Fi 1.0 mt [rad] Radius on chip (mm) Radius on chip [mm] 8 7 Radius Radial on distance chip of hit vs on chip radius vs radial distance of of entrance LED source on entrance point plane Radius on chip [mm] mt Radius on chip [mm] mt Radius on chip [mm] - 0 mt 6 Pli(Rdi hi [ ] 0 5 y = x x 4 y = -0,001x 2 + 0,2043x 3 y = -0,0004x 2 + 0,1772x 2 0, Entrance plane radius [mm] Entrance plane radius (mm) Entrance plane radius [mm] Entrance plane radius (mm) Parameterisation under control for both axial and transverse field distortions Assisi 23 June 2005 Tito Bellunato 22

23 Conclusions The RICH project is healthy and advanced Construction is under way - almost over for RICH2 The photon detector is understood in both detection issues and data-flow Eager for first collisions in 2007 Assisi 23 June 2005 Tito Bellunato 23