Transcript Slide 1

Highlights from RICH2007
PPD Seminar
S.Easo, A.Papanestis, S.Ricciardi
Contribution from S.Easo
28-11-2007
1
Outline
 RICH
detectors in accelerator based experiments:
 Review of Advantages and Limitations of RICH for PID
 R&D
for new RICH systems
 Historical Overview:
1900
1934-44
1960
1976
(Marie & Pierre Curie)
P.Cherenkov + Frank + Tamm
Arthur Roberts : First Proposal for RICH
T. Ypsilantis + J. Seguinot :
Pioneering the construction of the first RICH
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RICH design: Basics
N 
2 p
m
2
1
 m22


n 2  1 [  c (tot)]
2
.
For momenta well above threshold
p/K separation-limiting case
Refractive Indices
n=1.474 (Fused Silica)
10000
n=1.27 (C6F14 CRID)
n=1.02 (Typical Silica Aerogel)
p /K Separation ()
1000
  (tot ) 
100
c
  i 
N pe
n=1.001665 (C5F12/N2 CRID Mix)
C
n=1.0000349 (He)
[c(tot)]
10
1
1
10
100
Momentum (GeV/c)
1000
u
2 mrad
l
1 mrad
n
0.5 mrad
▲
0.1 mrad
 N  optimization is not the whole story: One needs to minimize the misID rate
and maximize the Positive ID efficiency.
 Sources of misID includes interactions, particle decays, physics effects
in other parts of the detector etc.
B.Ratcliff
3
Detectors-Photon Detection and Radiator Thresholds
 Aerogel: Rayleigh scattering  Low effective transmission at low wavelengths
B.Ratcliff
4
RICH Imaging-Limits to Performance
  (tot ) 
c
•
  i 
N pe
C
N pe : More Photons are better, but limited by the technology available.
Larger bandwidth rapid increase in chromatic error
•C
: Need excellent tracking detector and control of alignment systematics
• Physics Limits: overall performance for the event limited by decays and interactions.
• Single photon resolution:
[c ]i  [Pr oduction ]2  [Transport ]2  ([Im aging ]2+[Detection]2 )
• Examples of performances shown in the following slides.
• Many choices available for tuning the performance.
B.Ratcliff
5
Types of RICH Detectors: Current/Near Future
D.Websdale
6
 Discussion: Why RICH is not used in General Purpose Detectors at LHC, ILC:
Large Momenta Low Refractive Index Gas Radiators of Length 1 to 2 meters.
Increase the size and hence cost, of calorimeter & muon detectors, downstream of a RICH
D.Websdale 7
 RICH covers the large Momentum range 1-100 GeV/c : using three radiators: Aerogel, C4F10 and CF4.
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LHCb-RICH
 Pioneered the use of HPDs: 1024 pixels per tube bump bonded to readout chip and
encapsulated in the vacuum tube.
HPDs in RICH2
 RICH2 installed and ready for global commissioning.
 RICH1: Major parts installed. Photodetectors ready to mount on RICH1.
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Example of LHCb-RICH PERFORMANCE
• Performance as seen in Simulated Data in 2006
• Yield: Mean Number of hits per isolated
saturated track (Beta ~1).
Aerogel
C4F10
CF4
5.3
24.0
18.4
Single Photon Cherenkov
Angle Resolutions in mrad.
Components
and Overall (mrad)
Aerogel C4F10 CF4
Chromatic
2.36
0.90
0.46
Emission Point
0.38
0.82
0.36
Pixel Size
0.52
0.52
0.17
PSF
0.54
0.53
0.17
Overall RICH
2.53
1.44
0.66
Overall
RICH+Tracks
2.60
1.60
0.70
• Chromatic: From the variation in
refractive index.
• Emission Point: Essentially from the
tilt of the mirrors.
• Pixel Size: From the granularity of the
Silicon detector pixels in HPD
• PSF ( Point Spread Function):
From the spread of the Photoelectron direction
as it travels inside the HPD
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LHCb RICH
LHCb RICH PID Performance
B0sDs-K+
B0sDs- p+
(signal)
(background)
After using RICH, background at 10%
level from 10 times level
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BABAR DIRC: PERFORMANCE
• DIRC measures
 DIRC Performs as per design: p/K separation in 0.54 GeV/c
J. Schwiening
12
DIRC Upgrade: Focusing DIRC for Super B Factory
 Prototype tests made with 6 X 6 mm Hamamatsu H8500 flat panel MAPMT (TTS=140 ps ),
Burle 85011 MCP-PMT( TTS = 50-70 ps),
3 X 12 mm Hamamatsu H9500 Flat panel PMT   TTS =220ps).
J. Schwiening
13
DIRC Upgrade: Expected Performance
/
/
Lpath=10 m
Npe = 28 for 1.7 cm quartz
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J. Schwiening
BELLE Upgrade: Super B Factory
P.Krizan
 Beam Tests done with 2cm thick Aerogel tiles and H-8500 Flat panel MAPMT:
• Details in NIMA 553 (2005) 58
• Single photon resolution: 15 mrad, Npe = 6. This yields a 4  K/p separation
• The photon detector does not work in Magnetic field
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BELLE Upgrade: Proximity Focusing RICH
T.Iijima, P.Krizan
 Other Photon detector options for 1.5 T field:
 To increase the yield: increase the thickness of aerogel or use aerogel tiles as multiple radiators.
Conventional
c=22.1mrad
Npe=10.7
4cm thick aerogel
n=1.047
Multiple
Radiator
s layers of 2cm thick
2
c=14.4mrad
Npe=9.6
n1=1.047, n2=1.057
p/K separation with focusing configuration ~ 4.8 @4GeV/c
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BELLE Upgrade: Super B factory
H.Haba, S.Korpar
 Tests done with aerogel radiator
producing Cherenkov photons from
a cosmic ray setup and Hamamatsu SiPM
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RICH with Gas based photodetectors
 CLEO-c Experiment : Charm Physics at CESR : p /K separation up to 3 GeV/c .
LiF radiator with 20 m 2 of CH4+TEA in MWPC.
 ALICE experiment:
• Physics of Strongly interacting matter, QGP
in nucleus-nucleus collisions at LHC.
• p /K separation in 1 5 GeV/c
• 11 m2 of CSI photocathode
• gain < 10 5
 Ready to take data
 At high event rates the gain is limited by the photon and ion feed
back problems.
L.Molnar
18
ALICE Upgrade: Simulation
 New version of gas based detectors are being developed:
GEM detectors : 0.31.6 ns readout time.
 ALICE:
 Simulation: Mirror ROC 240 cm, Photons
focusing on a plane at ROC/2.
p
K
p
G.Volpe
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Result of ALICE upgrade simulation
Gas based Detectors
R.Chechik
GEM
• PHENIX: Identify electron pairs coming from relativistic heavy ion
collisions at sqrt(s)= 200 GeV for Au-Au.
Background from charged hadrons, electron-positron pairs from
g conversions and p 0 Dalitz decays in the invariant mass
range < 1GeV/c2
• HBD features: No windows: Photons create blobs of hits in the GEM
Hadron Blind: Hadrons produce only ionization signal which
are then suppressed.
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Summary
• The field of RICH detectors is still evolving. Several new detectors are ready to
take data or are planned to be constructed.
• New types of photodetectors: Flat Panel PMTS, Silicon photomultipliers and GEMs
have the potential to improve the performance of the next generation of RICH detectors.
• Novel Detector configurations like Focusing DIRC, Focusing Aerogel tiles
can also enhance the performance of the RICH systems.
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EXTRA
SLIDES
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COMPASS UPGRADE
F.Tessarotto
 Spin structure of the nucleon,
gluon polarization
 Open charm produciton leading to D mesons.
D0  K - p +
• At high rates, lot of background hits seen
in the very forward region in MWPC.
Expected increase in trigger rate 20100 kHz
• Replace the central region with MAPMT
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COMPASS Upgrade
F.Tessarotto
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