RICH options for PID

RICH OPTION FOR PID
• Fundamentals
• State of the art in HEP
• Future applications
ANTONELLO DI MAURO (CERN, GENEVA, SWITZERLAND)
TAU-CHARM WORKSHOP, LA BIODOLA, ELBA, ITALY – 28/05/2013
PID BY CHERENKOV RING
IMAGING
Particle Identification:
Cherenkov angle qc
cos c 
1
n ( ) b
particle velocity b
+
momentum p known
A. Di Mauro - CERN
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Roberts never built a practical device…
p
m
 p n 2 cos 2c  1
βγ
PID BY CHERENKOV RING
IMAGING
Particle Identification:
Cherenkov angle qc
cos c 
1
n ( ) b
particle velocity b
+
momentum p known
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p
m
 p n 2 cos 2c  1
βγ
EXAMPLES OF CHERENKOV
ANGLES AND PHOTON YIELD
N ph
2

 d


b
(

)
2
t


 2LZ   1  
  2
b


 
bn 1 
1

N ph [cm 1eV 1 ]b 1  370 Z 2 1  2 
 n 
L = radiator length
ei = photon detector efficiencies
Np.e. : number of photoelectrons
•
•
N p.e.  370 L  sin 2c (E)   e i E dE  LN o sin 2c
i
The figure of merit N o  370  eV 1  cm 1  e total E is a measure of quality of the
optical system and detector performance, limited mainly by photon detection
efficiency (PDE), which is usually 10-20%
N0 ~ 20 -100 cm-1 typically
Refractive
index
gt
qmax
qc = qc()-qc(K)
[mrad]
Nph/(cm eV)
Npe/(cm eV)
(N0=50 & b=1)
Solid Quartz (SiO2)
1.47
1.37
47.1o (823 mrad)
6.5 @ 4 GeV/c
199
27
Liquid C6F14
1.3
1.56
39.7o (693 mrad)
8.4 @ 4 GeV/c
151
20
Aerogel (SiO2)
1.05
3.3
17.8o (309 mrad)
22.8 @ 4 GeV/c
34.4
4.7
C4F10 gas at 1 bar
1.0015
18.3
3.13o (55 mrad)
29 @ 10 GeV/c
1.1
0.15
He gas at 1 bar
1.00004
111
0.5o (8.9 mrad)
1.4 @ 100 GeV/c
0.03
0.004
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Radiator
RESOLUTION OF RICH
DETECTORS
J. Seguinot and T. Ypsilantis, Nucl. Instr. & Meth. A343(1994), 1-29 and 30-51
E. Nappi and J. Seguinot, Rivista del Nuovo Cimento, Vol 28. N. 8-9 (2005)
Error on particle’s b
b
1
cos c 

  c (tot ) tan c
n ( ) b
b
  (tot ) 
  ( p.e.)
c
c
N p .e .
  c (track )
  ( p.e.)   2 (chromatic)   2 ( pixel )   2 (imaging )
c
c
c
c
goal:
detect the maximum number of photons with the best angular resolution
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qc (chromatic) : resolution broadening because of radiator dispersion n=n()
qc (pixel) : resolution broadening due to final detector pixel size (spatial resolution)
qc (imaging) : effect of imaging method (lens, mirrors,…)
IDEAL PARTICLE
SEPARATION
J. Seguinot and T. Ypsilantis, Nucl. Instr. & Meth. A343(1994), 1-29 and 30-51
E. Nappi and J. Seguinot, Rivista del Nuovo Cimento, Vol 28. N. 8-9 (2005)
 (m )  c (m1 )
Separation in number of sigmas n  c 2
  (tot )
c
b~1
m2  m1
n 
2 p 2 c (tot ) tan c
2
2
J. Va’vra, Fermilab 10.8.2010
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In practical counters
qc(tot) is typically
between 0.1 and 4 mrad
RICH COUNTER DESIGN
PHYSICS / PID
separation
power
photon detector
momentum
range
radiator
configuration
low momenta:
proximity focusing
photon detector
photon detector
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DIRC
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high momenta:
mirror focusing
Refractive
index
@ 600 nm

K
p
 cutoff
[nm]
He
1.000035
16.68
59.01
112.14
112
Ar
1.000283
5.87
20.75
39.44
124
CO2
1.000449
4.66
16.47
21.48
175
C4F10
1.0015
2.5
9.0
17
136
Aerogel
1.03
0.6
2.0
3.8
300
C6F14
1.3
(@170nm)
0.174
0.614
1.168
165
H2O
1.33
0.158
0.56
1.065
190
NaF
1.33
0.161
0.567
1.079
125
LiF
1.39
0.144
0.509
0.969
105
quartz
1.46
0.132
0.465
0.884
158
solids
liquids
gases
Material
pthreshold [GeV/c]
(limit for total internal reflection ~ 1.41)
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EXAMPLES OF
CHERENKOV RADIATORS
PHOTON DETECTOR
REQUIREMENTS
• Single photon (VUV
visible) sensitivity
• High photoconverter QE + ese (low noise)
• Large packing factor (active area %) egeom
• High granularity
maximize Npe
minimize q
• Depending on experimental conditions:
rate capability and ageing properties
•
large area coverage (cost)
•
sensitivity to B
Gaseous
(UV)
Vacuum based
(UV, visible)
TEA,TMAE,EF/MWPC, PMT, MaPMT, MCPCsI/MWPC,
PMT, HPD
CsI/THGEM A. Di Mauro - CERN
Solid state
(visible)
G-APD, SiPM
9/30
•
PERFORMANCE LIMIT
N p.e.  E  E2 -E1
 c (chromatic)  E; E
For any combination of radiator and detection bandwidth
there is an intrinsic (chromaticity) performance limit
Evolution of RICH technique in
last ~15 years:
•
A. Di Mauro - CERN
shift of detector bandwidth
from UV to visible (larger N0,
higher rate capability,…)
development of CsI-based
gaseous UV photo-detectors for
large systems to overcome
operational issues related to
photosensitive vapors used in
the past (e.g. DELPHI, SLD)
10/30
•
Experiment
Type
Radiator (n)/L
Photon detector
(photosensitive area)
ALICE @ CERN/LHC
Proximity focusing
C6F14 (1.029)/1.5 cm
CsI-MWPC
(11 m2)
COMPASS @ CERN/SPS
Mirror focusing
C4F10 (1.0014)/3 m
CsI-MWPC + MAPMT
(6 m2)
CLEOIII @ CESR
Proximity focusing
LiF (1.46) / 1 cm
MWPC (TEA+CH4)
( 16 m2)
PHENIX @ RHIC
Proximity focusing
CF4 (1.0005) / 50 cm
CsI-GEM
(1.5 m2)
LHCb @ CERN/LHC
Mirror focusing
Aerogel (1.03)/ 5 cm C4F10
(1.0014)/ 80 cm
CF4 (1.0005) / 200 cm
HPD
(3.3 m2)
NA62 @ CERN/SPS
Mirror focusing
Ne (1.000063) / 18 m
PMT
( 0.4 m2)
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SOME RICH COUNTERS IN
NP AND HEP EXPERIMENTS
LIF RADIATOR FOR CLEO III
• /K separation from 470 MeV/c to
2.65 GeV/c with 4σ significance
• LiF radiator, photon detector
MWPC with TEA/CH4
nLiF (7 eV)= 1.46
“sawtooth” radiator
(@ track angles < 22 o)
M. Artuso et al., NIMA 554 (2005) 147
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total internal reflection
CSI: A BREAKTHROUGH IN
CHERENKOV PHOTODETECTION
gold front
surface (0.4
mm)
nickel barrier layer
(7mm)
multilayer
pcb with
metalized
holes
60 cm
H. Hoedlmoser et al., NIM A 574 (2007) A.
28.Di Mauro - CERN
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RD26@CERN (F. Piuz et al., R&D for the
development of large area CsI photocathodes,
1992):
- CsI processing, QE enhancement (substrate
layout and cleaning, slow deposition rate 1
nm/s, thermal treatment at 60 oC for 8 h, in situ
encapsulation and dry Ar, in situ measurement
of PC response, mounting in glove-box)
- Stable operation under gas (read-out
electronics with long integration time (1 ms) 
low gas gain ~5 x 104)
CSI DEPOSITION PLANT AT
CERN
0.45
PC32 (STAR-RICH)
ALICE/HMPID
W.I.S.- RD-26 ref.
TUM-HADES
0.4
0.35
0.25
0.2
0.15
0.1
0.05
0
150
160
170
180
190
200
210
220
wavelength [nm]
Mass production of ALICE
RICH CsI photocathodes
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H. Hoedlmoser et al., NIM A 566 (2006) 338.
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CsI QE
0.3
ALICE HMPID AT LHC
High Momentum Particle Identification Detector
/K: 1-3 GeV/c
K/p: 1.5-5 GeV/c
A. Di Mauro - CERN
Pb-Pb
collisions
• 7 proximity focusing RICH modules,
~ 11 m2 of CsI photosensitive area,
5 m from IP
• 6 CsI photocathodes of 0.64m x
0.40m per module
• Charged particles multiplicity
~10000/evt, trigger rates ~ 5kHz
15/30
1.4m
ALICE HMPID AT LHC
Radiator:
15 mm C6F14 – n=1.3 @ 170 nm
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Photon detector:
• MWPC, CH4 at atm. P, 8x8.4 mm2 pad
segmented cathode coated with 300 nm
CsI layer
• multiplexed analogue pad readout,
~161000 channels
HIGH RATES: THE CASE OF
COMPASS AT CERN/SPS
•
Hadron PID from 3 to 60 GeV/c
Photosensitive area ~ 6 m2
Trigger rates: up to ~30 kHz,
beam rates up to ~40 MHz
RICH in operation since 2002,
upgraded in 2006 with
Hamamatsu R7600-03-M16
MaPMTs on 25% of active area
Al vessel
MWPC’s +
CsI
1.6 mC/cm2
5m
MWPC+CsI
operation at large
rates induces PC
ageing due to ion
bombardment
and/or instability
owing to space
charge build up
UV mirror
wall
PMT’s
6.3 mC/cm2
6.8 mC/cm2
H. Hoedlmoser et al., NIM A 574 (2007) 28.
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radiator gas:
C4F10
17/30
•
•
•
R. Chechik and A. Breskin
NIM A 595 (2008) 116
semi-transparent
photocathode
• fast signals [1-10 ns]
• high gain [>105]
• operation in noble gases(mixtures)
• high 2D precision
• largely reduced photon feedback
compared to “open” geometry
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• no ion feedback
• high rate capability
(> 106 particles/mm2)
18/30
CSI + GEMS
Micro-hole + Flipped reversebias strip plates:
ions are trapped by
negatively biased cathode
strips
PHENIX HBD AT RHIC
mesh
El. Field
photo
electron
qpair
Cherenkov
blobs
primary
ionization from
dE/dx CsI (350 nm)
e-
opening
angle
e+
GEMs
B≈0
•
•
Hadron Blind Detector, 50 cm CF4 gas
radiator, proximity focusing, photon blobs
imaging by CsI/3-GEM operated with same
CF4 (windowless detector, record N0 ~ 300
cm-1)
Reverse bias in drift region for “hadron
blindness”, detect only e+/e-
NIMA (2011) doi:10.1016/j.nima.2011.04.015
Talks @ QM2011
A. Di Mauro - CERN
Distinguish open Dalitz (2 singles) from close
conversion (one double) e+e- pair
19/30
pads
THGEM & RETGEMStandard GEM
Thick-GEMs (TGEMs) were
introduced later in the last
decade as evolution of GEMs
towards a simpler and more
robust detector (holes are
drilled in standard PCB, Cu
etching of hole’s rims)
THGEM
1mm
103-104 gain in single GEM
105 gain in single-TGEM
100 mm
Resistive TGEMs (RETGEM) have
resistive instead of metallic
electrodes, providing additional
protection against sparks
IBF <10%
time resolution of 8 ns RMS
V. Peskov et al., Nucl. Instrum. Methods A576(2007), 362
Thick GEM and RETGEM are robust and cost
effective solution for large area RICH applications
V. Peskov et al., Nucl. Instrum. Methods
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A478(2002), 377
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Hole diameter d = 0.3 - 1 mm
Pitch
a = 0.7- 7 mm
Thickness
t = 0.4 - 3 mm
ALICE & COMPASS R&D
ON CSI-THGEM COUNTERS
COMPASS
ALICE VHMPID
Ar/CH4: 50/50
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Effective gain:
0.91 · 106
-
Integration RICH+EMCAL to address jet
physics → limited space, reduce
radiator L
Lower PID range (/K: 5-16 GeV/c, K
thresh. 1 bar ~ 9 GeV/c)
DCAL
C4F8O radiator gas pressurization: tune
refractive index + increase photon
yield to compensate shorter L
CERN PS/T10, C4F8O @ 3.5 bar
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-
VHMPID
A. Di Mauro et al, VCI 2013 proceedings
ALICE VHMPID
UPGRADE
AEROGEL AS CHERENKOV
RADIATOR
•
•
Silica SiO2 colloid, the lightest
“solid”, : 3-350 mg/cc
Fills the gap between
gaseous and liquid radiators,
n: 1.008-1.08
Production of hydrophobic
aerogel of outstanding
quality driven by BELLE
n=1+0.26*
most of the
photons experience
Rayleigh scattering
T=A*exp(-Ct/4)
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visible light detection
23/30
•
LHCb RICHs
Two RICHs for /K separation from 1 to 100 GeV/c
4m
1m
- quartz window with S20 photocathode;
- cross-focusing optics;
- space resolution 2.5 x 2.5 mm2;
- low noise (dark count rate < 5 kHz/cm2);
- 0.5 Mchannels
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Photon detectors: 484 HPDs developed in
collaboration with industry (Photonis:)
LHCb RICHs
RICH1
RICH2
C4F10
(small rings)
Aerogel
(large rings)
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CF4
- huge yields of charmed hadrons 10 x B-factories
- very low background
- first evidence for charm CP-violation
•
HPD issues: constantly increasing rate of ion feedback (residual gas
ionization) + 1 MHz readout of encapsulated FEE not compatible with future
high luminosity (2x1033 cm-2 s-1)
replace photodetectors (MaPMT, MCPPMT under consideration)
•
RICH1 aerogel radiator, compromised /K separation at high luminosity (low
photon yield wrt background)
DIRC type TOF detector called TORCH
(Time Of internally Reflected Cherenkov light) with MCP-PMT behind RICH2
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LHCb RICHs UPGRADE
FDIRC, TOP, TORCH
Focusing-DIRC: add focusing mirror to correct
emission point uncertainty+ arrival time of photons
to correct chromatic error
/K separation > 2.5  up to 4.2 GeV/c
Needs ~ 200 ps time resolution (Photonis MCP)
Time Of Propagation @ BELLE II
Measure (TOF+TOP) to identify /K < 4 GeV/c
Needs ~ 40 ps time resolution (Hamamatsu MCP)
NIMA 639 (2011), 282
TORCH
Measure (TOF+TOP) to
identify /K < 10 GeV/c
L~ 10 m, TOF (-K) = 35
ps at 10 GeV → aim for
~15 ps resolution per
track
Need ~ 40 ps time
resolution (Photonis MCP)
NIMA 639 (2011), 173
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K. Matsuoka, proceedings of VCI 2013
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In PANDA FDIRC: chromaticity corrected by LiF block
MCP-PMT
Commercial devices (Photonis, Hamamtsu, …) still very
expensive due to Pb-glass processing.
LAPPD (Large Area Picosecond Photon Detectors)
collaboration at Argonne and Chicago uses atomic layer
deposition on Incom glass, aim at cheap large area MCP
production.
A. Elagin, VCI 2013 Proceedings
A. Di Mauro - CERN
concern: limited
photocathode
life-time due to ion
feedback, Al layer
blocks almost all ions
8” x 8” plate
28/30
MCP-PMTs (1960s) are based on
the concept of continuous
dynode electron multiplier
(Farnsworth, 1930)
FARICH
•
•
•
Proximity focusing RICH with aerogel and
NaF radiator+ MCPPMT, proposed for
SuperB and Tau-Charm factory at
Novosibirsk.
NaF radiator has the lowest n among solids
(1.33 @ 600 nm), no internal reflection down
to ~ 170 nm
/K separation > 3  up to ~ 7 GeV/c
X0 ~ 26% :
• Aerogel, 3 layers, 40 mm in total ~ 4%
• Naf, 5 mm ~ 4%
• MCP-PMT ~ 8%
• Cables, mechanics ~ 10 %
NIM A 639(2011), 290
NIM A 595(2008), 100
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•
SUMMARY
Reach of present PID techniques
•
TOF& dE/dx cover the lowest momentum range, “the RICH technique is clearly superior
to all other methods” (J. Va’vra)
•
For a given Cherenkov radiator several options exist for the photon detector and the
choice will depend mainly from experimental conditions (and cost…)
•
Availability of commercial devices with time resolution of a few10 ps is pushing the
mixing of TOF and RICH techniques (FDIRC, TOP, TORCH,…) for all high luminosity future
systems
•
Interesting developments are ongoing in the field of micropattern gaseous photon
counters (CsI+GEM, TGEM, …) which represent still the most cost-effective solution for
large photosensitive surface (> 1 m2)
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J. Va’vra, Fermilab 10.8.2010
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backup
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BABAR DIRC
33/30
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