gas micro pattern detectors for tracking
Post on 07-Oct-2014
38 Views
Preview:
TRANSCRIPT
Gas Micropattern Detectors for TrackingGas Micropattern Detectors for Tracking
L. Ropelewski CERN PH/DT2/STL. Ropelewski CERN PH/DT2/ST
HistoryHistory
TechnologyTechnology
PerformancePerformance
LimitationsLimitations
PerspectivesPerspectives
Compass APV hybrids
OutlookOutlook
(GEM biased)
Single (Multi) Wire Proportional ChamberSingle (Multi) Wire Proportional Chamber
Cylindrical geometry is not the only one able to generate strong electric field:
parallel plate strip hole groove
( )
arCVrV
rCVrE
ln2
)(
12
0
0
0
0
⋅=
⋅=
πε
πε
anode
e-
primary electron
MicroStrip Gas ChamberMicroStrip Gas Chamber
Typical distance betweenwires limited to 1 mmdue to mechanical andelectrostatic forces
Typical distancebetween anodes 200 μmthanks to semiconductoretching technology
MWPC MSGC
anode cathodecathode
A. OedNucl. Instr. and Meth. A263 (1988) 351.
Rate capability limit due to spacecharge overcome by increased amplifying cell granularity
MicroStrip Gas ChamberMicroStrip Gas Chamber
A. OedNucl. Instr. and Meth. A263 (1988) 351.
Lift-off technique
Semiconductor industry technology:
PhotolithographyEtchingCoatingDoping
Light construction2D readout – anodes, cathodes, backplane
MicroStrip Gas ChamberMicroStrip Gas Chamber
Thin cathode and anode strips on insulatingsupport: glass, silicon, kapton, tedlar …
24 cm
MicroStrip Gas ChamberMicroStrip Gas Chamber
-30
-25
-20
-15
-10
-5
0
5
10
0 10 20 30 40 50 60Strip number (200 µm pitch)
MSGC Beam Event BW
fwhm~350µm
1.1
1.0
0.9
0.8
0.7
0.6
Rel
ativ
e ga
in
6 7 8 90.1
2 3 4 5 6 7 8 91
2 3 4 5
Rate (MHz/mm 2 )
V d= -3000V, V c= -460VPestov glass coating
ρbulk =10 10 Ωcm
ρbulk =10 11 Ωcm
MSGC
INFN - Pisa
Source: 5.4 KeV Cr X-raysNe-DME (50/50)
V d= -1000V, V c= -564VD263 uncoatedρsurface =510 17 Ω/square
Single event wire map
Surface resistivity !!
Spatial resolution = 34.5 ± 0.4 μm2-track resolution ~400 μm
Ne(25)-DME(75)Vcath= -530 VVdrift= -3000 V
Rate capability > 1 MHz/mm2
Energy resolution ~11% for 5.9 keV
MicroStrip Gas ChamberMicroStrip Gas ChamberCMS (rejceted)Advanced passivated MSGCTelescope of 32 MSGCs tested at PSI in Nov99 (CMS Milestone)
HERA-B Inner TrackerMSGC-GEM detectorsRmin ~ 6 cm 106 particles/cm2•s
300 μm pitch184 chambers: max 25x25 cm2
~ 10 m2; 140.000 channels D20 diffractometer at ILLfor neutron detection1D localisation48 MSGC plates (8 cm x 15 cm)Substrate: Schott S8900Angular coverage : 160° x 5,8°Position resolution : 2.57 mm ( 0,1°)5 cm gap; 1.2 bar CF4 + 2.8 bars 3HeEfficiency 60% @ 0.8 ÅDIRAC
MSGC-GEM detectorsHadron beam3 105 particles/cm2.s4 planes; 10x10 cm2
MicroStrip Gas ChamberMicroStrip Gas ChamberSurface chargingBulk resistivity of the support materialSurface modification by doping or deposition
AgeingGas, Gas system, MSGC support, Construction material
Discharges
Charge pre-amplification for ionization released in high field close to cathode
MSGC: Discharge mechanisms
Field emission from the cathode edge
Very high ionization release:avalanche size exceeds Reather’s limit
Q ~ 107
MicroStrip Gas ChamberMicroStrip Gas Chamber
Uncoated MSGCCoated MSGC
Electric field strength close to support plane in MSGC
Surface resistivity modification
MicroStrip Gas ChamberMicroStrip Gas Chamber
Advanced passivation
Standard passivation
Cathode edge passivation
Bellazzini et al.
Micropattern Gas DetectorsMicropattern Gas Detectors
Pre-amplification: parallel plate, preamplifier …
MicroGap Chamber MicroGroove Chamber
R. Bellazzini et alNucl. Instr. and Meth. A424(1999)444
R. Bellazzini et alNucl. Instr. and Meth. A335(1993)69
Micropattern Gas DetectorsMicropattern Gas DetectorsNonplanar anode – cathode
Compteur A Trous (CAT)
F. Bartol et al, J. Phys.III France 6 (1996)337
Single hole proportional counter
Micropattern Gas DetectorsMicropattern Gas Detectors
R. Bellazzini et alNucl. Instr. and Meth. A423(1999)125
The Well Detector
Multi hole proportional counter
Nonplanar anode – cathode
MicroPin Array (MIPA)
Matrix of individual needle proportional counters
MicroDot
Metal electrodes on silicon
S. Biagi et alNucl. Instr. and Meth. A361(1995)72 P. Rehak et al, IEEE Trans. Nucl. Sci. NS-47(2000)1426
Micropattern Gas DetectorsMicropattern Gas DetectorsGuard ring
MicroWire chamber
B. Adeva et al., Nucl. Instr. And Meth. A435 (1999) 402
Field Gradient Lattice Detector FGLD
L. Dick, R. de Oliveira, D. WattsNucl. Instr. And Meth. A535 (2004) 347
Micropattern Gas DetectorsMicropattern Gas DetectorsNonplanar anode-cathode
MicroMEGAS
Thin-gap parallel plate chamber
Y. Giomataris et alNucl. Instr. and Meth. A376(1996)29
Micropattern Gas DetectorsMicropattern Gas Detectors
A. Sarvestani et al., Nucl. Instr. And Meth. A410 (1998) 238
MicroCAT
Thin-gap parallel plate chamber variation
MicroParallel plate
50-100μm
50 -100μm
Y.Giomataris et al, NIM A 376 (1996) 29
800μm50μm
MicromegasMicromegas
MicromegasMicromegas
D.Thers et al NIM A 469 (2001) 133
energy resolution ~ 10%
55 FeAr + 10% C4H10
High voltage [V]350 450400 500 550 600 650
103
102
104
105105
gain
gain
1000 10000 20000 30000 time[min]
ageing:Ar-iC4H10 94-6% up to 24.3mC/mm2
10 years LHC
1
0.8
0.6
0.4
0.2
1.8*1012 particles/mm2
1
0.9
0.8
0.7
0.6
10-4
10-5
10-6
10-7
10-8
discharge probability
effici
ency
efficiency & discharge probability
High Voltage [V]
MicromegasMicromegas
300mm
420 V operating point~3-4.103 Gain
σ = 9 ns
σ =70 µm
Spatial resolution < 70 µm
MicromegasMicromegas
Large efficiency plateau > 40 V
Time resolution : 9 nsD.Thers et al NIM A 469 (2001) 133
Discharge point in micropattern gas detectors isalmost the same in all tested devices
A. Bressan et alNucl. Instr. and Meth. A424(1999)321
Micropattern Gas DetectorsMicropattern Gas Detectors
Micropattern Gas DetectorsMicropattern Gas Detectors
Addition of GEM over the MSGC allows to largely increase the gain before discharge
GEM: Gas Electron MultiplierGEM: Gas Electron MultiplierThin metal-coated polymer foil pierced by a high density of holes (50-100/mm2)Typical geometry: 5 μm Cu on 50 μm Kapton, 70 μm holes at 140 μm pitch
F. Sauli, Nucl. Instrum. Methods A386(1997)531
70 µm
140 µm
GEM PrincipleGEM Principle
70 µm
55 µm
5 µm
50 µm
ElectronsElectrons
IonsIons
GEM hole cross section Avalanche simulation
60 %
40 %
50 μm Kapton5 μm Cu both sides
Photoresist coating, masking and exposureto UV light
Metal etching
Kapton etching
Second masking
Metal etching and cleaning
Rui De OliveiraCERN-EST-DEM
GEM ManufacturingGEM Manufacturing
GEM ManufacturingGEM Manufacturing
Art of Kapton EtchingArt of Kapton Etching
Single GEM PerformancesSingle GEM Performances
0
50
100
150
200
250
0 100 200 300 400 500 600 700 800Pulse Height (ADC channels)
Cou
nts
GEM H2+PCAr-DME 80-20ΔV
GEM= 520 V (Gain ~5000)
GEM H2+PC X Pulse Height
102
103
104
200 300 400 500 600 700ΔVGEM
(V)
SINGLE GEM+PCB
Eff. Gain-Vgem Ar-CO2-DME
Ar-DME 70-30
Ar-CO2 70-30
Effe
ctiv
e G
ain
Gain
R. Bouclier et al NIM A 396 (1997) 50
Energy resolution5.9 keV Fe55~20% fwhm
Very good multi-track resolutionRequires high density of readout channels
S1 S2 S3 S4
Induction gape-
e-
I+Ar-CO2 70-30
Signal ReadoutSignal Readout
Electrons are collected on patterned readout boards.A fast signal can be detected on the lower GEM electrode for triggering or energy discrimination. All readout electrodes are at ground potential.
A. Bressan et al, Nucl. Instr. and Meth. A425(1999)254
CartesianCompass, LHCb
Small angle
Hexaboard, padsMICE
MixedTotem
Full decoupling of the charge ampification structure from thecharge collection and readoutstructure.
Both structures can be optimizedindependently !
GEM 1
GEM 2
ED
ET
EI
DRIFT
READOUT
DRIFT
TRANSFER
INDUCTION
Double GEM
MultiMulti--GEM DetectorsGEM Detectors
Cascaded GEMs achieve larger gains and safer operation in harsh environmentsTriple GEM
C. Buttner et al, Nucl. Instr. and Meth. A 409(1998)79S. Bachmann et al, Nucl. Instr. and Meth. A 443(1999)464
Single GEM
exposed to heavily ionizing tracks (alpha particles) all micro-pattern detectors discharge at low gains
MultiMulti--GEM DetectorsGEM DetectorsDischarge Probability on Exposure to 5 MeV Alphas
Multiple structures provide equal gain at lower voltage.Discharge probability on exposure to α particles is strongly reduced.
S. Bachmann et al Nucl. Instr. and Meth. A479(2002)294
High Intensity Runs at PSI High Intensity Runs at PSI ππM1 BeamM1 Beam
107 s-1 215 MeV/c π-
5.107s-1 350 MeV/c π+
S. Bachmann et al, Nucl. Instr. and Meth. A 470 (2001)548
Efficiency for minimum ionizing particles with 3 mm gap
Space resolution ~ 40 μm rmsCluster size ~ 500 μm FWHM
A. B
ress
anet
al,
Nuc
l. In
str.
And
Met
h. A
425(
1999
)262
Rate capability > 106 Hz mm-2
GAIN ~ 104
Ar-CO2 70-30
C. Altunbas et al, DESY Aging Workshop (Nov. 2001) Nucl. Instr. and Meth. A
1 mC~2.1010 min.ion. particles
J. Benlloch et al, IEEE NS-45(1998)234
MultiMulti--GEM DetectorsGEM Detectors
3.106 particles/mm2
COMPASSCOMPASS
High rate forward spectrometer: ~ 5.107 polarized 160 GeV µ+/s on polarized 6LiD target
22 Triple-GEM detectors, mounted in pairs on 11 stationsData taking since 2001
Triple GEM Tracker for COMPASS at CERN (NA58)
http://wwwcompass.cern.ch/
COMPASS Triple GEMCOMPASS Triple GEM
• Active Area 30.7 x 30.7 cm2
• 2-Dimensional Read-out with2 x 768 Strips @ 400 µm pitch
• 12+1 sectors GEM foils• Central Beam Killer 5 cm Ø
(remotely controlled)• Total Thickness: 15 mm• Honeycomb support plates• Thickness in active area 0.7% X0
B. Ketzer et al, IEEE Trans. Nucl. Sci. NS-48(2001)1065C. Altumbas et al, NIM A490(2002)177
GEM foils for COMPASS (31x31 cm2), 12-sectors + beam killer
~ 100 foils produced22 Triple-GEM detectors running
Sector separation
Voltage-controlled Central disk
COMPASS Triple GEMCOMPASS Triple GEM
HV test of the foil after every step Final detector module
Spacer Grid: 2 mm thick fibreglass plate with thin (~300 μm) gap-restoring strips
COMPASS Triple GEMCOMPASS Triple GEM
31 cm
Beam KillerBeam Killer
The central beam area can be remotely activated for calibrations and alignments, and disabled during high intensity runs.
TwoTwo--Dimensional ReadoutDimensional Readout
Two orthogonal sets of parallel strips at 400 µm pitchengraved on 50 µm Kapton80 µm wide on upper side,350 µm wide on lower side(for equal charge sharing)
350 µm
80 µm
400 µm
400 µm
C. Altumbas et al, NIM A490(2002)177
The detected charge is equally shared by the two projections: correlation width 10% rms. Excellent multi-track ambiguity resolution power.
80 µm stripss = 69.6 µm
350 µm stripss = 71.3 µm
Position resolution
Efficiency Efficiency –– High Rate RunsHigh Rate RunsB.
Ket
zer a
nd Q
. Wei
tzel
(CO
MPA
SS)
Efficiency distribution of reconstructed tracks
Beam: 4x107 muons / s
90
92
94
96
98
100
0 5 10 15
2-D
Effi
cien
cy
Track Multiplicity
multeff
0
500
1000
1500
0 2 4 6 8 10 12
Even
ts
Track Multiplicity
track multiplicity
u (mm)-150 -100 -50 0 50 100 150
0.7
0.75
0.8
0.85
0.9
0.95
1
GM06U
Effi
cien
cy
Efficiency vs positionAverage, all tracks:ε=97.5 %Average,spacers removed:ε=98.7 %
2D reconstruction efficiency vs track multiplicity
LHCb Muon TriggerLHCb Muon Trigger
Fast TripleGEM Detectors for LHCb Muon Trigger12 double TGEM detectors operated with fast gas mixture (Ar-CO2-CF4)
Rate - 5 kHz mm-2
Time resolution 4.5 ns rmsRadiation hard up to integrated charge of 18 mC mm-2 (10 LHCb years)
M. Alfonsi et al, Nucl. Instr. and Meth. A535(2004)319
Pad readout plane
20x24 cm2 GEM modules
Considerable improvement with respect to the Ar/CO2=70/30 gas mixture
Best Choice:
Ar/CO2/CF4 45/15/40Fast & Non-flammable
9.7 ns 5.3 ns
4.5 ns 4.5 ns
Single Chamber Time Spectra
LHCb GEM Time ResolutionLHCb GEM Time Resolution
A. Cardini et al., IEEE NSS, Portland, Oct.21 2003
The fluorine strongly etched the third GEM, not only widening the copper holesbut also etching the kapton inside hole (from the bottom to the top), changing the hole shape. The effective inner hole diameter, from the standard 45-50 μm becomes 60-65 μm.
Stability of GEM foils operated with CFStability of GEM foils operated with CF44
TOTEM DetectorsTOTEM Detectors
RP1RP1 (RP2)(RP2) RP3RP3
220 m220 m(180 m)(180 m)147 m147 m
Roman Pots:Roman Pots:
~14 m
CMSCMST1: 3.1 < |η| < 4.7
T2: 5.3 < |η| < 6.5
10.5 m T1T1 T2T2
HF
Inelastic Telescopes:Inelastic Telescopes:
TOTEM Experiment at CERN LHC:Total Cross Section, Elastic Scattering and Diffraction Dissociation
T2 TelescopeT2 Telescope
2x10 half moon detector planes on each side of IP
TOTEM GEM : Concept and DesignTOTEM GEM : Concept and Design
Analogue readout of the stripsvia APV25
PadsTrigger: VFAT Digital readout
65(ϕ) x 24(η) = 1560 padsPads: 2x2 mm2 __ 7x7 mm2
Strips: 256 equidistant (80 μm wide, 400 μm pitch)
HV services
frame spacer
GEM sector border
TOTEM GEM TOTEM GEM -- Readout BoardReadout Board
Quality test forcontinuity and shorts –Capacitance measurementbetween channels forstrips and pads
50 μm Polyimide
25 μm PolyimideEpoxy glue
5 μm Cu10 μm CuEpoxy glue
2004 prototype
bonding contactfor pads
125 μm FR4
15 μm Cu
Ni Au15 μm Cu
radial stripspads
TOTEM GEM TOTEM GEM -- Readout BoardReadout Board
Laboratory and Beam TestsLaboratory and Beam Tests
Lab performance as expected:
Gas gain 104
Charge sharingpad signal 10% higher – advantage for higher S/N for trigger electronics
Good charge correlation
Good energy resolution
Compass APV hybrids
X5 Beam test:
All strips and one (out of four ) sectors of pads connected to COMPASS APV hybrids
Readout chain from COMPASS
All channels readout
Latency and HV scan
Good noise-signal peak separation
TOTEM GEM Final Detector ModuleTOTEM GEM Final Detector Module
Gas in/outHV cables
HV divider
Cooling
Support
Mother board
VFAT card
APV card
TOTEM GEM TOTEM GEM –– AssemblyAssembly
TOTEM GEM TOTEM GEM –– assemblyassembly
Production on semi-industrial scalein Helsinki
28 cm
PerspectivesPerspectives
TPC end cap readout (ion feedback reduction)TPC end cap readout (ion feedback reduction)
Non planar large acceptance detectorsNon planar large acceptance detectors
Light detectors Light detectors –– mass reductionmass reduction
New readout structures adopted to experimental needsNew readout structures adopted to experimental needs
Large detectors Large detectors –– new technologies (thick GEM)new technologies (thick GEM)
High resolution detectors integrated with pixel CMOS chipsHigh resolution detectors integrated with pixel CMOS chips
UV light detectionUV light detection
Hadron blindHadron blind
Industrialization of the mass productionIndustrialization of the mass production
GEM TPCGEM TPC
GEM TPCVERTEX
GEM readout for the Time Projection Chamber (GEM-TPC)
International Linear Collider Detector
ILC TPC R&D groups (~ 40)
http://alephwww.mppmu.mpg.de/~settles/tpc/welcome3.html
Narrow pad response function: Δs ~ 1 mmFast signals (no ion tail): ΔT~20 nsVery good multi-track resolution: ΔV ~ 1 mm3
(Standard MWPC TPC ~ 1 cm3)Strong ion feedback suppressionNo ExB distortionsFreedom in end-cap shapesRobustness
LEGS GEMLEGS GEM--TPCTPCGEM-TPC for LEGS (Laser Electron Gamma Source, Brookhaven)
Bo Yu, personal communication
Ion feedback reduction
HV plane with dual layer wire mesh allows laser calibration
Double GEM planes
Interpolating anode pad plane with ASICs on the back
GEM-TPC studies in high magnetic field at DESY:
80 cm drift - Triple GEM detector
P. Wienemann, Int. Linear Collider Workshop, SLAC March 18-22, 2005
2.2x6.2 mm2 pads readout
GEM TPCGEM TPC
M. Killenberg et al, Nucl. Instr. and Meth. A530(2004)251
GEM TPC StudiesCharge transport in high magnetic fields:
Ion feedback:
Electron signal:
GEM TPCGEM TPC
• A MSGC and GEM combination in a single plate
– hole / strip pitch ~ 200 µm• 2 multiplication stages
– High gain• 2D capability
– 2 sided patterns on MHSP– Patterned cathode plane
Veloso et al, RSI, 71(2000)2371Maia et al., NIM A 504 (2003)364Veloso et al, NIM A 524(2004)124Breskin et al, to be published in NIM A
The MicroThe Micro--Hole & Strip Plate gas detectorHole & Strip Plate gas detector
1E-4
1E-3
1E-2
1E-1
1E+0
1E+1
1E+01 1E+02 1E+03 1E+04 1E+05 1E+06
Effective Gain
Drif
t IB
F
250 V
300 V
320 V
VGEM = 300 V
VGEM = 350 V
VGEM = 400 V
VC-T1,2 =
TACTIC and TACTIC and BoNuSBoNuSTRIUMF Annular Chamber for Tracking and Identification of Charged particlesMeasurement of nuclear cross sections for astrophysics
http://tactic.triumf.ca/about.html
8Li(α,n) 11B
8Li ions (90-220 keV/u) interacting in He gas
Cylindrical GEM detector with pad readout:
H. Fenker, The BoNuS Detector
BoNuS Radial Time Projection Chamber in JLAB
GEM Foil Material Budget ReductionGEM Foil Material Budget Reduction
Detector element (material)
Rad. length [cm]
x/X0
Si 300 μm 9.4 3.2 10-3
Cu 5 μm 1.44 3.5 10-4
Kapton 50 μm 8.57 1.8 10-4
Argon 1 cm 11762 0.85 10-4
Triple GEM standard:5 x Kapton 50 μm7 x Cu 5 μmArgon 7 mm
3.4 10-3
Triple GEM light:5 x Kapton 50 μm7 x Cu 1 μmArgon 7 mm
1.5 10-3
standard
light
Hexaboard readout:matrix of hexagonal pads interconnected along three projections at 120º
U
V
W
S. Bachmann et al Nucl. Instr. and Meth. A 478 (2002) 104F. Sauli, RICH04 (Playa del Carmen, Nov. 30-Dec. 5, 2004 Subm. Nucl. Instr. And Meth.
1.1 mm
2.4 mm
1.3 mm
Hexaboard Readout
Two-photon event
31 cm
Large GEM DetectorsLarge GEM DetectorsGEM foil size is limited by :Starting raw material dimensions2 masks alignment
mean pad size ~ 2 cm216x64 7x7 mm2 —› 38x38 mm2
180 cm !
Thick GEMThick GEM
• PCB tech - etching + drilling • Simple and robust• VTGEM~2KV (at atmospheric pressure)• 105 gain in single- & 107 double-TGEM• Sub-mm to mm special resolution• Fast (ns)• Low pressure (<1Torr) gain 104
• Microlithography + etching• High Spatial resolution (tens of
microns); VGEM~400V• >103 gain in single GEM• 106 gain in cascaded GEMs• Fast (ns)• Low pressure – gain~30
1mm1mm
TGEM*Standard GEM
*Similar approach to Peskov’s “optimized GEM”R. Chechik, A. Breskin and C. Shalem, Thick GEM-like multipliers—a simple solution for large area UV-RICH detectors, to be published in NIMA
Thick GEMThick GEM
0 500 1000 1500 2000 2500 300010-3
10-2
10-1
100
101
102
103
104
105
106
0 500 1000 1500 2000 2500 300010-3
10-2
10-1
100
101
102
103
104
105
106
0 500 1000 1500 2000 2500 300010-3
10-2
10-1
100
101
102
103
104
105
106
0 500 1000 1500 2000 2500 300010-310-210-1100101102103104105106
0.4mm thickness
Ar/CO2(30%)Ar/CH4(5%)
CH4 CF4
single TGEMAtmospheric pressure
Effe
ctiv
e G
ain
ΔVTGEM [v]105 106 107 108 109
102
103
104
105
Atmospheric pressure Ar/CH4 (95:5)UV photons (185nm) - CsI photocathode
Double TGEM Single TGEM
Effe
ctiv
e G
ain
Rate [electrons/mm2sec]
R. Chechik, A. Breskin and C. Shalem, Thick GEM-like multipliers—a simple solution for large area UV-RICH detectors, to be published in NIMA
Integrated DetectorsIntegrated DetectorsE. C
osta et al, Nature 411(2001)662
R. Bellazziniet al, N
ucl. Instr. Methods A535(2004)477
X-Ray Polarimeter
Micro-GEM detector with pad readout: tracking the direction of the photoelectrons
CMOS ASIC readout with 2101 hexagonal pixels at 80 µm pitch
1 mm
Reconstruction of a 5 keV photoelectron
UV Light Detection (RICH)UV Light Detection (RICH)
UV transparent Quartz window
200 µm
D. Mormann et al, Nucl. Instr. and Meth. A478(2002)230
T. Meinschad, L. Ropelewski and F. Sauli, Nucl. Instr. and Meth. A535(2004)324
Single photelectron p.h. spectrum
Hadron BlindHadron Blind
C. Aidala et al, Nucl. Instr. and Methods A502(2003)200A. Kozlov et al, Nucl. Instr. and Meth. A523(2004)344
Windowless Cherenkov detector(inverted field TPC)CF4 gas radiatorTriple-GEM chamberCsI photocathode on first GEM
PHENIX Upgrade at BNLHadron-blind GEM-TPC-RICH
e+ e-
E
hadron
drift
Charge
Photoelectrons
Electron pairs produce Cherenkov light, but hadrons with P < 4 GeV/c do not
Other ApplicationsOther Applications
XX--ray radiographyray radiography
Neutron detectionNeutron detection
Optical GEMOptical GEM
Cryogenic detectorsCryogenic detectors
TwoTwo--phase detectorsphase detectors
Parallax free detectorParallax free detector
Absorption radiography with GEM (8 keVX-rays)
Trigger from the bottom electrode of GEM.
S. Bachmann et al, Nucl. Instr. and Meth. A471(2001)115
top related