Assisi – 23 June 2005
Tito Bellunato 1
Status of the LHCb RICH detector and the
HPD
Beauty 2005
Assisi – 23 June 2005
Tito Bellunato – Università degli Studi di Milano Bicocca & INFNOn behalf of the LHCb RICH group
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The LHCb detectorDesigned to study CP violation and rare decays of B-hadrons at LHC
RICH2:17-100 GeV/c
RICH1:2-60 GeV/c
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RICH 1
Aerogel
RICH1
RICH2
aerogel
C4F10
CF4
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RICH 1 Mechanical Design - Overview
Quartz windows
Seal directly to the Vertex Locator exit window
Magnetic shields ~8 tonnes of “Armco” iron
Gas enclosure
0 G
20 GRICH 1shields
Detection plane
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Spherical beryllium mirrors
7 x 14 Hybrid Photon Detectors
Flat glass mirrors
Aerogel
Beryllium beam-pipe
C4F10 gas radiator
RICH 1 Optics
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RICH 1 Mirrors3mm thick Be base + 0.3mm glass surface
layer coated with Al.
Radius curvature: 2700mm
Beampipe hole
Beryllium blank
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Aerogel I
Transparent over a wide range: optical properties dominated by Rayleigh scattering:Transmittance T, clarity factor C, surface scattering factor A, thickness t, wavelength
linked network of SiO2 particles density = 0.15 g/cm³hygroscopic
Produced by the Boreskov Institute for Catalysis in Novosibirsk
T = Ae(- )Ct
4
A=95%C=0.0053 μm4/cm
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World-record 50 mm thickness and200 mm transverse size
n = 1.030 ± 0.001C=0.006 μm /cmtested against: radiation OK C4F10 OK?
Pre-production OK – 4 liters inside specs
4
Aerogel II
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Testbeam I
Aerogel Mirror
HPDs
Beam
Beam: PS-T9 10 GeV/c - (+, p)
Aerogel: 4 tiles 10x10x4.4 cm3 n=1.028 C=0.0052 m4/cm
Mirror curvature R= 949 mm
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1.211.091.22MC
0.861.001.19Data
HPD2HPD1HPD0Nγ
Scaling with acceptance to 2π :
9.19.311.7Data
Testbeam II
Photon yield studies: Single photon resolution (mrad):
2.42.42.4MC
3.53.23.2Data
HPD2HPD1HPD0σθ
Becomes 2.7 mrad scaled to RICH1 optics
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10 GeV/c π+, p
pion = 238.0 mrad
proton= 221.4 mrad
Testbeam III
HPD plane
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CF4 gas volume : ~100 m³Refractive index: n = 1.0005
RICH2 – software version
HPD plane:9 columns,
16 tubes each
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RICH 2 – hardware version
Superstructure
Magnetic shieldmaximum measured
field at the HPDfocal plane 6 G
Awaited in the pit by the end of A
ugust
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CCD
Laser
Lens
Single Mirror Shutter
Target
Clean room
Mirrors
Alignment I
R = 8600 mm
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Spherical Mirrors Alignment
2 mm
All mirrors from one side
Alignment and stability set a 50 μrad contribution to
the overall uncertainty inthe single photon Cherenkov
angle reconstruction
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Developed by CERN/ DEP(NL) cross-focused, 83mm Ø, encapsulated binary electronics 32 x 32 pixels (500 m x 500 m).
S20 photocathode:75 mm Ø active
The Hybrid Photon DetectorRequirements:2.6 m² coverage with 75% active area2.5 x 2.5 mm² granularitySingle photon efficiency40 MHz readout
20 kV operation
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The HPD - IIOn-detector
Off-detector
RICH2 column
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System Test I
PS beam:
10 Gev/c π- e-
Radiator vessel
HPD housing
HPD column mechanics
MirrorBeam
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System Test II
0
3500
N2 run, one HPDaccumulated rings
C4F10 run, ring on four HPDs.
single event
accumulated rings
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B┴
B║
Magnetic distortions…
0 GB║ 30 G
B┴ 50 G
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Image rotation vs radial distance on entrance plane
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
2
0 5 10 15 20 25 30 35 40 45
Entrance plane radius [mm]
Rot
atio
n an
gle
[rad
]
Delta Fi 5.0 mT [rad]
Delta Fi 3.0 mT [rad]
Delta Fi 1.0 mT [rad]
…and correctionsCalibration and distortion monitoring system in both RICHes to allow corrections
Parameterisation under control for both axial and transverse field distortions
Radial distance of hit on chip vs radial distance of LED source on entrance plane
y = -0.0016x2 + 0.2425x
y = -0,001x2 + 0,2043x
y = -0,0004x2 + 0,1772x
0
1
2
3
4
5
6
7
8
0 5 10 15 20 25 30 35 40 45
Entrance plane radius [mm]
Rad
ius
on
chip
[mm
]
Radius on chip [mm] - 5.0 mT
Radius on chip [mm] - 3.0 mT
Radius on chip [mm] - 0 mT
Poli. (Radius on chip [mm] - 0mT)
Non uniform rotation (S-distortion)
Third order polynomial fit
Non uniform radial dilatationSecond order polynomial fit
B║ 1, 3 and 5mT
Entrance plane radius (mm)Entrance plane radius (mm)
Image rotation vs radius of entrance point Radius on chip vs radius of entrance point
Radiu
s on c
hip
(m
m)
Rota
tion
ang
le (
rad)
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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
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