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

Assisi – 23 June 2005

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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