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An overview of the LHCb RICH detectors. Neville Harnew University of Oxford On behalf of the LHCb RICH Collaboration. RICH 2007 Trieste 15-20 Oct 2007. Outline of the talk. The LHCb Experiment The RICH status RICH1 RICH2 The Hybrid Photon Detector (HPD) project - PowerPoint PPT Presentation
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An overview of the LHCb RICH detectors
An overview of the LHCb RICH detectors
RICH 2007Trieste
15-20 Oct 2007
Neville HarnewUniversity of Oxford
On behalf of the LHCb RICH Collaboration
2 RICH 2007 15-20 October, Trieste N. Harnew
Outline of the talk
The LHCb Experiment The RICH status
RICH1 RICH2
The Hybrid Photon Detector (HPD) project RICH2 commissioning RICH calibration Performance Summary
3 RICH 2007 15-20 October, Trieste N. Harnew
The LHCb Detector
AcceptanceVertical 250mradHorizontal 300mradto 10 mrad
Two RICH detectors provide/K/p identification
Forward spectrometer (running in pp collider mode). A dedicated B-physics experiment at the LHC
4 RICH 2007 15-20 October, Trieste N. Harnew
LHCb detector in place,commissioning is well underway….
RICH1RICH2
5 RICH 2007 15-20 October, Trieste N. Harnew
C4F10 gasn=1.0014 Up to ~70 GeV/c
CF4 gasn=1.0005 Beyond ~100 GeV/c
Silica Aerogeln=1.03 1-10 GeV/c
The RICH Radiators
Aerogel C4F10 CF4
5.3 24.0 18.4RICH1:
25250 mrad vertical25 300 mrad horizontal
RICH2: 15100 mrad vertical,
15 120 mrad horizontal
Expected photon yields – for isolated saturated particles
6 RICH 2007 15-20 October, Trieste N. Harnew
The LHCb RICH Detectors
1m
4m
7 RICH 2007 15-20 October, Trieste N. Harnew
RICH1 schematic : “vertical” geometry
4m
Upper Magnetic Shielding Protects HPDs from B field, supports upper HPDs
Spherical Mirrors Lightweight carbon fibre mirrors 1.5% radiation length
Glass Planar Mirrors
Beryllium beampipe
(defines RICH1 inner acceptance)
VELO Exit Window 2mm aluminium.. Sealed to gas enclosure. No RICH entrance window.
Photon detector plane 14 by 7 Hybrid Photon Detectors (HPDs)
Quartz Window
Gas Enclosure supports mirrors and aerogel, contains C4F10
RICH1 Exit Window Carbon fibre & PMMI foam
Sealed direct to the beampipe.
Lower Photon detector plane Mounted on lower shield
Lower Magnetic Shielding mounted on cavern floor, supports lower HPDs and Gas Enclosure
8 RICH 2007 15-20 October, Trieste N. Harnew
RICH1 Magnetic shielding RICH1 picture gallary
Gas Enclosure before installation
Trial installation of the HPD box
Gas enclosure and mirrors installed in LHCb pit
Beryllium beampipe, VELO exit window and seal and planar mirrors
9 RICH 2007 15-20 October, Trieste N. Harnew
The RICH1 Mirrors
Carbon Fibre Mirrors: 1.5% radiation lengthGlass planar mirrors
Spherical mirrors
See talk by Fabio Metlica
10 RICH 2007 15-20 October, Trieste N. Harnew
16 aerogel tiles for RICH1. Produced by Boreskov Institute of Catalysis Novisibirsk
200x200x50 mm tiles – the largest ever
n=1.03 ; gives /K separation up to ~10 GeV/c
Exceptional clarity C ~ 0.005 m4cm-1
[I/I0 = A exp –(Ct/4) for thickness t]
Excellent homogeneity (n-1)/(n-1) <1%
Tiles have undergone extensive ageing studies
The RICH1 Aerogel Radiator
Test installation into RICH1
See talk by Tito Bellunato and poster by Davide Perego
11 RICH 2007 15-20 October, Trieste N. Harnew
RICH2 schematic : “horizontal” geometry
8m
Magnetic Shields protect the HPD planes
Flat Mirrors each made from 20 square glass segments
HPD planes of 9 by 16 HPDs
Gas Enclosure Contains CF4 gas radiator and the optical system
Spherical Mirrors each made from 21 glass hexagonal segments
RICH2 entrance / exit windows carbon fibre and foam sandwich
12 RICH 2007 15-20 October, Trieste N. Harnew
RICH2 to the pit-Nov 2005 Mirrors aligned to 150
rad before move After move, mirror
movement ~100 rad Stability & alignment
verified. No need to re-align in situ
cf. RICH-2 Cherenkov angle resolution ~ 700 rad
13 RICH 2007 15-20 October, Trieste N. Harnew
Pixel Hybrid Photon Detectors
Pixel HPDs developed in collaboration
with industry (Photonis-DEP lead
partner)
Combines vacuum technology with
silicon pixel readout ( Quartz window
with S20 photocathode).
484 HPDs occupy a total area of 3.3m2
with 2.5 x 2.5 mm granularity
Factor 5 demagnification @ 20kV.
Operates at the LHC bunch crossing
frequency (40MHz)
Encapsulated 32x32 pixel silicon
sensor Bump-bonded binary readout
chip
200-600 nm wavelength coverage
14 RICH 2007 15-20 October, Trieste N. Harnew
HPD qualification
Two Photon Detector Test Facilities (PDTFs) have qualified all 550 HPDs produced by Photonis/DEP.
98% of tubes have passed the selection criteria.
Excellent response, QE, dark counts, ion feedback etc.
See talk by Stephan Eisenhardt
15 RICH 2007 15-20 October, Trieste N. Harnew
The HPD readout chain
All HPDs arranged in columns with ancillary front-end electronics
LV & HV boards power the HPDs
Level-0 boards pass triggered data to the Level-1 off-detector board via an ~100m optical link
Level-1 off-detector receives and zero-suppresses the data and passes to the DAQ
HPD column assembly
16 RICH 2007 15-20 October, Trieste N. Harnew
RICH2 Commissioning
Laser photon source. Hit
map of 2.4M channels.
RICH2 is complete and
running
10kV applied.
See talk by Carmelo D’Ambrosio
Most of columns have been up to 20kV. Operating RICH2 has now become a routine and safe task.
10 failed HPDs disconnected (out of 288) – these will be replaced The detector control/safety systems (DCS and DSS) are operational RICH2 is ready for global commissioning.
17 RICH 2007 15-20 October, Trieste N. Harnew
Detector control system in place
HPD boxtemperature
HPD boxhumidity
<- 5 days ->
Cooling pressure over 60 days
Light level
<- 5 days ->
See talk by Mario Sannino
University Genoa
18 RICH 2007 15-20 October, Trieste N. Harnew
RICH calibration procedures in place
Calibration & alignment systems use projected test patterns: Corrections to HPD
trajectories for magnetic field.
RICH alignment monitoring.
Calibration & alignment also with tracks (data): Alignment with tracks. Refractive index monitoring. Cherenkov angle resolution
from isolated rings. Particle ID calibration with
D*’sSee talk by Antonis Papanestis
Test pattern
with B=0
B=0 and B=30G
19 RICH 2007 15-20 October, Trieste N. Harnew
RICH performance (testbeam)
Pixel map of a C4F10 ring integrated with ~50k events over 3 HPDs (preliminary)
Performance of the RICH system has been verified in a 80 GeV/c charged particle beam at CERN SPS. C4F10 ~1m radiator length.
Realistic 25 ns beam structure
Final RICH hardware and DAQ
RICH specifications for photon yield and θc resolution have been verified.
C4F10 run
See talk by Sean Brisbane
20 RICH 2007 15-20 October, Trieste N. Harnew
PID Performance Ring finding
- The algorithm uses tracks, and performs a global likelihood fit to particle hypotheses across both RICH detectors.
– K separation
- Excellent efficiency and low mis-ID rate
See talk by Claus Buszello
21 RICH 2007 15-20 October, Trieste N. Harnew
Summary and prospects
LHCb RICH has excellent particle ID - crucial for the B physics programme of LHCb
RICH1 installation almost complete
Ready for commissioning at end of year
Innovative carbon fibre mirror and aerogel technology
RICH2 is almost commissioned
Ready for global commissioning
Hybrid Photon Detectors provide excellent single photon sensitivity. Performance is excellent
LHCb expects its first physics data in 2008, with stable running in 2009. We look forward to data-taking with a completed RICH system !
22 RICH 2007 15-20 October, Trieste N. Harnew
Spare slides
23 RICH 2007 15-20 October, Trieste N. Harnew
RICH Performance
Aerogel C4F10 CF4
Chromatic 2.4 0.9 0.5
Emission Point
0.4 0.8 0.4
Pixel 0.5 0.5 0.2
Track 0.5 0.5 0.2
Overall 2.5 1.4 0.7
Single Cherenkov photon angle resolution (mrad)
number of photoelectrons
Aerogel C4F10 CF4
5.3 24.0 18.4
Chromatic Uncertainty
The uncertainty due to the dependence of the refractive index on the wavelength of the photon Emission point Error
The uncertainty due to the assumption the photon was emitted at the centre of the track
Pixel Uncertainty
The uncertainty due to the limited resolution of the pixel detectors
Tracking Uncertainty
The uncertainty due to the limited accuracy of the tracking stations
Combining Uncertainty
The CU, EPE and PE are independent but the TU is not and so does not reduce with higher statistics
24 RICH 2007 15-20 October, Trieste N. Harnew
HPD test results
25 RICH 2007 15-20 October, Trieste N. Harnew
Magnetic Distortion calibration
B┴
B║
Magnetic fields distort the electron trajectories of the HPDs.
We should expect significant distortions in the LHCb RICHes (max 24 Gauss in RICH1) .
Tubes are individually shielded in mumetal cylinders to mitigate these effects.
Below: RICH2 projection system
Axial Transverse
26 RICH 2007 15-20 October, Trieste N. Harnew
LHC “approved” schedule - Aug 2007
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