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