Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009 The THGEM: a THick robust Gaseous...

Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009

The THGEM: The THGEM: a THick robust Gaseous Electron a THick robust Gaseous Electron Multiplier for radiation detectorsMultiplier for radiation detectors

A. Breskin, M. Cortesi, R. Alon, J. Miyamoto, V. Peskov, G.Bartesaghi, R. Chechik

Weizmann Institute of Science, Rehovot, IsraelV. Dangendorf

PTB, Braunschweig, Germany J. Maia and J.M.F. dos Santos

University of Coimbra, Portugal

MOTIVATIONMOTIVATION:: Robust, economic, large-area radiation imaging detectorsFAST, HIGH-RATE, MODERATE LOCALIZATION RESOLUTION


THGEM – a family of hole gas multipliers:THGEM – a family of hole gas multipliers:

ECONOMIC & ROBUST ECONOMIC & ROBUST !!

Avalanche “confined” inside a hole in an insulating plate ->Avalanche “confined” inside a hole in an insulating plate ->Reduced secondary effects, independent holes

h=0.1 mm rim: prevents discharges high gains !

Cu G-10

1mm

Typical dimensions:Hole diameter d = 0.3 - 1mmPitch a = 0.7- 7mmThickness t = 0.4 - 3mm

Manufactured by standard PCB techniques of precise drilling in G-10 (and other materials) and Cu etching.

Other groups independently developed similar structures: Optimized GEM: L. Periale et al., NIM A478 (2002) 377. LEM: P. Jeanneret, PhD thesis, 2001. P.S.Barbeau et al, IEEE NS50 (2003) 1285.

First publication: R.Chechik et al. NIM A535 (2004) 303 Recent review: A.Breskin et al. NIM A598 (2009) 107


THGEM – Operation principle THGEM – Operation principle (like GEM, similar voltages and fields)(like GEM, similar voltages and fields)

Advantages of large hole dimensions:Hole dimensions >> mean free path High gains within the hole

Hole dimensions >> e- diffusion Easy electron transport into and out of the holesEfficient cascading of elements: 10-100 times higher gain

E~40kV/cm

Upon application of voltage across the plate (V=400-1200V function of gas and thickness): a dipole field dipole field in the holes focusesfocuses e- into the holes defocusesdefocuses e- out the hole

1e- in

104- 105 e- out


THGEM – Operation THGEM – Operation principle principle Multiplication of e- induced by

radiation in gas or from solid converters (e.g. a photocathode)

Detector properties governed by:e- transport (e.g. efficiency to single e-)multiplicationcharge induction on readout electrodesion-backflow

Reflectivephotocathode

Semi-transparent photocathode

e- focusedfocused into the holes by the hole dipole field


THGEM production methodsTHGEM production methodsNo mask, Weizmann

Drill + etch under the CuSmall and zero rim

Surface damaged

Cu

RIM

Cu

Nice edge RIM

With mask, WeizmannEtch w mask + drill

Large rim

displacement

With mask, Eltos, ItalyDrill +etch w mask

Large rim

No displacementDetached Cu

CERN, Zero rim: drill + short etching to remove sharp edges from drilling.


3x3 cm: basic studies, many geometries

10x10 cm: 2D imaging

30x30 cm: n detector

All produced with mask Rim=0.1mm

The THGEMsThe THGEMs at Weizmannat Weizmann

2003

2008

THGEM efficiency for single THGEM efficiency for single photoelectronsphotoelectrons


Hole dimensions >> e- diffusion efficient transport from the conversion gap

e- focused into the holes by the dipole field

Full efficiency: at THGEM gain = 10-30 !!

Edrift = 1kV/cm

VHOLE [Volt]

Gain=100

Semitransparentphotocathode

e- extraction requires Edrift >0.5kV/cm

Edrift =0

Reflectivephotocathode

e- extraction optimal @ Edrift =0kV/cm

In GEM: 500-1000

Full efficiency: at THGEM gain = 30-100 !!

Under study in Ne and Ne/CH4 mixtures

Single THGEM gainSingle THGEM gain

x100 higher gain compared to single

GEM


Very high gain in 100% Ne and Ne mixtures

At very low voltages !!100% Ne: Gain 105 @ <500VVoltage increases w increased

CH4 %

General:Gain limit (x-ray) << Gain limit (UV) (charge density!)in Ne mixtures on x3 lower (diffusion)

104-105105-106

With single photoelectronsWith single photoelectrons


double THGEM gaindouble THGEM gainHole dimensions >> e- diffusion efficient transport in the transfer gap efficient cascading of THGEMsMuch higher gain at lower voltages

>106

Ar mixtures,Ar mixtures,single photoelectronssingle photoelectrons

Etrans=3kV/cm

Very high gain even with x-rayAt very low voltages

!!100% Ne: Gain 106 @ ~300V

>106

Edrift=0.2kV/cmEtrans=3kV/cm

Ne mixtures, x-raysNe mixtures, x-rays

Efficient cascading Total gain = Gain1 x gain2


THGEM - rim effect and stabilization THGEM - rim effect and stabilization timetime

From: Trieste group (RD51): larger rim -> longer stabilization time

Old data: Chechik et al. Proceedings of SNIC2006, eConf C0604032, 0025 (2006)

Larger rim Insulator Charging up few hours of stabilization gain variation ~ x2. Stabilization time depends on:voltages, currents, gas type and purity, materials, geometry, production method

Rim=0.12mmFurther R&D in progress @ CERN-RD51

gain = 104, UV light, e- flux ≈ 104 Hz/mm2

Larger rim higher voltages Higher gains

>104

THGEMs produced by chemical etching (no mask) @ PE, Israel

Single THGEM, 6 keV x-rays


THGEM counting rate and pulsesTHGEM counting rate and pulses

Rate capability = 10MHz/mm2

@ GAIN ~104 Ar/CH4 (1 atm)

single photoelectronssingle photoelectrons

Fast signals in atm. pressure Ar/30%CO2 Double THGEM ( t=1.6 d=1, a=1.5 mm)

gain=~106

rise time < 10 ns

9 keV x-rays9 keV x-rays

100% Ne ~X10 slower gasMore CH4 faster pulses,Higher voltages75 ns 30 ns


THGEM timing (UV photons and THGEM timing (UV photons and particles) particles)

Similar resolution with semitransparent PCCompatible with e- transport

*Breskin et al NIM A483 (2002) 670

pulsed UV lamp

Reflective CsI PC

0.3 mm

0.4 mm

0.7 mm

MIPS

Double-THGEM: particles & cosmics: =10-13 nsTriple-GEM (same setup): 7-9 ns

Multi-GEM: 5-12 ns depending on gas-faster with Ar/CF4

-slower with Ar/CO2 mixtures)

1 10 100 10000

2

4

6

8

10

12

[n

s]

# of Photoelectrons

Reflective CsI PC Ar/CH4 (95:5) 1 atm

double THGEM

triple GEM w CF4

**UV photonsUV photons

EHole

EHole

ETrans

EInd

EDrift

Induced-signal width matched to readout-pixel size.

8 keV X-Ray • 10x10cm2 THGEMs t=0.4, d=0.5, a=1 mm

C-paint Resistive anode (match induced signal size)• 2-sided pad-string readout 2mm pitch • Delay-line readout (SMD)

2D imaging-detector w/economic readout2D imaging-detector w/economic readout



Gain uniformity FWHM ± 10%

55Fe

Gain ~ 6x10Gain ~ 6x1033

21%

1 mm pitch THGEM + 2 mm pitch Readout + DL interpolation -->

2D imaging: results with 6-8 keV x-ray2D imaging: results with 6-8 keV x-ray Ar/CHAr/CH4 4 (95/5)(95/5)

Localization Resolution ~0.7 mm FWHM

35 40 45 50-5

0

5

10

15

20

PS

F

X Coordinate (mm)

~0.7 mm FWHMMask: Raw Data

10 lp/cm

From edge analysis


2D imaging: results with 5-9 keV x-ray2D imaging: results with 5-9 keV x-ray Ne/5%CHNe/5%CH44

preliminary

x-rays < 5keVFlat-field illumination: hole pattern is visible/ Resolution ~0.3mm FWHM

The THGEM electrode

The 2D image

Recently numerous proposed solutions to charge and light detection in the gas

phase of noble liquids“TWO-PHASE DETECTORS”

Possible applications of noble liquids:- Noble liquid ionization calorimeters - Liquid argon TPC (solar neutrinos) - Scintillation detectors and two-phase emission

detectors exotic particles searches (WIMP …)

- Development of γ-cameras for nuclear medicine imaging e.g. PET, Compton… cathod

e

WIMP

Gas

Liquid

e-E

Ar/Xe


THGEM Operation in Noble gases: Ar, THGEM Operation in Noble gases: Ar, XeXefor LARGE-VOLUME Noble-gas detectors for rare

eventsand others.

Advantages for THGEM vs. GEM: reduced effect of condensation on surfaces


THGEM Operation in Noble gasesTHGEM Operation in Noble gasesAvalanche confinement in holes is notnot hermetic -> Field extends out by ~hole diameter ->Photon secondary effects might be important depending on geometry and gas.

-2 -1 0 1 20

5

10

15

20

Eho

le k

V/c

m

Z [mm]

THGEMthickness

d=0.3 mmd=1.0 mm

VTHGEM

=1kV

Avalanche & photonsOutside the hole. Ne, Ar have energetic photonsNeed to optimize sizes and fields according to the gas.

E

THGEM in Ar, XeTHGEM in Ar, Xe

Ar/Xe =Penning mixt. x20 higher gain, lower voltages.The lower gain in “purified” Ar secondary effects due to “energetic” UV-photon feedback Under investigations

6keV x-rays

R. Alon et al. 2008_JINST_3_P01005

105

0 400 800 1200 1600100

101

102

103

104

105

106

6

5

4

32

1

Ne

Ar

Ar/5%Xe

Gai

n

VTHGEM

[V]

1 bar

XeAr

Double THGEM

Kr

Not purified

Purified gases



THGEM in Xe,Ar/XeTHGEM in Xe,Ar/Xe R. Alon et al. 2008_JINST_3_P01005

1000 2000 3000100

101

102

103

104

105

2.9 bar2 bar1 bar

0.5 bar

open: Single THGEMclosed: Double THGEM

Gain

VTHGEM

[V]

Xe

THGEM: t=0.4mm, d=0.3mm, a=1mm, rim=0.1mm Double-THGEM, t=0.4mm, d=0.5mm, a=0.9mm

0 500 1000 1500101

102

103

104

105

106

2 bar10.7

0.50.3

0.2

Gain

VTHGEM

[V]

Ar:Xe (95:5)

0.1

Ar/Xe (95/5) Penning mixture,Good energy resolutionGain > 10Gain > 1044 at all pressuresLow voltages

Xe Ar/Xe (95/5)

200 400 600 800 1000 12000

10

20

30

40

50Co

unts

/Cha

nnel

Double THGEM, t=0.4mm, d=0.5mm, a=0.9mm

FWHM = 19%

Ar:Xe (95:5) 1 bar

Channel

THGEM in liquid-Ar temperaturesTHGEM in liquid-Ar temperatures

Stable operation in two-phase Ar, T=84KDouble-THGEM Gains: 8x103

Experimental setup

BINP/Weizmann: Bondar et al, 2008 JINST 3 P07001

2-THGEMG-10

1-THGEMG-10

2-THGEMKEVLAR

3-GEM

GOOD PROSPECTS FOR CRYOGENIC-PHOTOMULTIPLIER OPERATION IN THE LXe-CAMERA


Radio-clean THGEM for rare-event Radio-clean THGEM for rare-event physicsphysics

• Motivation: need charge and scintillation-light readout elements for noble-liquid detectors with very low natural radioactivity.

• E.g. Cirlex (a polyimide like Kapton) is 30 times radio-cleaner compared to PMT-glass

• Cirlex-THGEM preliminary tests: M. Gai et al. arXiv:0706.1106

•

The Cirlex-THGEM

WIMPinteractio

nLXe

e-

THGEM photon Detector

Photon

e-

CsI Photo-Cathode

EG

EL

The 2-phase THGEM LXe Dark-Matter detector

concept

(M.Gai-UCONN / D.McKinsey-YALE / A.Breskin-WEIZMANN)

THGEM

Segmented

Anode

MgF2 window

LXe conversion volume

CsIphotocathode

THGEM-GPM for LXe Gamma CameraTHGEM-GPM for LXe Gamma CameraSubatech-Nantes/Weizmann

Gas photomultiplier



Photon detectors for RICH: Photon detectors for RICH: reflective CsI PC deposited on the THGEMreflective CsI PC deposited on the THGEMphotoelectron extraction into gas, surface electric field by the hole dipoleRICH RICH Requires: • High field on the PC surface (for high QE). • Good e- focusing into the holes (for high detection

efficiency). • Low sensitivity for MIPS background radiation (e.g. in

RICH).

Immediate interest: COMPASS & ALICE, R&D in RD51

efficient photoelectron extraction over the entire PC area: pitch 0.7mm, d=0.3mm: any voltage > 400V any gas, including Ne, Ne/CH4

pitch 1mm, d=0.5mm: similar results

Distance = 0

Min. field

-0.30 -0.15 0.00 0.15 0.300

2

4

6

8

10d = 0.3 mm, h = 0.1 mm, a = 0.7 mm, t=0.4mm

Ele

ctric

Fie

ld (

kV/c

m)

Distance form the center between hole (mm)

VTHGEM

= 400 V

VTHGEM

= 800 V

VTHGEM

= 1200 V

VTHGEM

= 1600 V

EDrift

= ETran

= 0 kV/cm

EfficientExtractionFrom PC

e-Ref PC


Maximum efficiency at Edrift =0.

• Slightly reversed Edrift (50-100V/cm) =>

good photoelectron collection & low sensitivity to MIPS (~5-10%) !

-0.6 -0.4 -0.2 0.0 0.2 0.4 0.60.0

0.5

1.0

1.5

2.0

0

Gain~103

1 Atm. Ar/CH4(95:5)

40

20

80

60

100

e- tra

nsf

er

effic

iency

[%

]

Edrift [kv/cm]

Re

lativ

e

Photon detectors for RICH: Photon detectors for RICH: reflective CsI PC deposited on the THGEMreflective CsI PC deposited on the THGEM

Photoelectron collection into the holes by the dipole field

Currently R&D for upgrade of COMPASS & ALICE RICH

Reduced sensitivity to MIPS proved with multi-GEM detectors of PHENIX

e

MIP

EE E=0

Edrift

Ref. PC

New concept: Digital sampling calorimetry New concept: Digital sampling calorimetry for ILCfor ILC with A. White with A. White Univ. Texas Arlington/Weizmann


Sampling the jet + advanced pattern recognition algorithms -> Very high precision jet energy measurement.

Simulated event with 2 hadronic jets

Reconstructed jet:Simulated energy resolution

General scheme of a detector

HCal

2 sampling layers with THGEM-based elements


Fast-neutron Imaging-detectorFast-neutron Imaging-detector

• neutrons scatter on H in plastic-radiator foil, p escape the foil.

• p induce electrons in gaseous conversion gap.

• electrons are multiplied and localized in cascaded-THGEMs imaging detector.

• require high gain and large dynamic range (p spectrum)

• efficiency 1 layer: 0.1-0.2%

• High multiplication factors• High stability• w Ne mixtures: high gain and dynamic range.

Weizmann/PTB/Soreq

THGEM 1

THGEM 2

gas

B, Li, Gd…converter: thermal neutron detectore.g. position sensitive n-dosimetry for BNCT (with Univ.& INFN, Milano)

Double THGEMs:


Operation principle:

• n energy selected by TOF• Image “on” ad “off” resonance• Ratio of images => element selection

Fast Neutron Resonant Radiography Fast Neutron Resonant Radiography (FNRR)(FNRR)forfor element-resolved radiography element-resolved radiography

Detector requirements • area: >30x30 cm2 • detection eff. @ 2-10 MeV : ~ 5-10%• Insensitivity to gamma• counting rate : > MHz cm-2

• Time Resolution ~ few ns• Position resolution: ~ 0.5 mm• 25-50 layers. => THGEM will reduce THGEM will reduce costcost

Weizmann/PTB/Soreq

Dangendorf et al. NIM A542(2005)197

C rodsC rods

Triple-GEM 10 x 10 cm 2

AllAll

SteelSteel

C onlyC only

Be target

pulsed, white

neutron beam

Neutron imaging detector with fast timing capability !

nsec-pulsed broad energy deuteron

beam

neutron source: sample

• Single-photonSingle-photon imaging.

e.g. Ring Imaging Cherenkov (RICH) detectors.

• Fast ParticleParticle tracking at moderate (sub-mm) resolutions + high

rates.

• Moderate-resolution TPC (Time Projection Chamber) readout

elements.

• Sampling elements in calorimetry.

• Ionization & scintillation recording from Noble-Liquid & High-

pressure

detectors, including 2-phase detectors

(Dark-Matter, neutrino, double-beta decay, Gamma Cam…)

• Moderate-resolution (sub-mm), fast (ns) X-rayX-ray and nn imaging.

• Possible low-pressure operation: Possible low-pressure operation: Nuclear Physics applicationsNuclear Physics applications

SummarySummary

Robust, economic, large-area radiation imaging detectorsHIGH-GAIN, FAST, HIGH-RATE, MODERATE 2D- RESOLUTION



Weizmann Group THGEM papers:

R.Chechik et al. NIM A535 (2004) 303 (first idea)

R.Chechik et al. NIM A553 (2005) 35 (application to photon detectors)

C.Shalem et al. NIM A558 (2006) 475 & NIM A558 (2006) 468 (atm. And

low-p)

M.Cortesi et al. 2007_JINST_2_P09002 (imaging)

M.Cortesi et al. NIM A572 (2007) 175 (2D imaging)

R.Alon et al. 2008_JINST_3_P01005 (Ar, Xe)

R.Alon et al. 2008 JINST 3 P11001 (timing)

R.Chechik and A.Breskin NIM A595 (2008) 116 (application to photon

detectors)

A.Breskin et al. NIM A598 (2009) 107 (a concise review)

R.Chechik,et al. /http://www.slac.stanford.edu/econf/C0604032/papers/

0025.PDFS. (including long term stability)

C. Shalem MSc 2005 JINST TH 001

R. Alon MSc 2008 JINST TH 001

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Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009 The THGEM: a THick robust Gaseous...

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