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 Multiplier for radiation detectors detectors A. Breskin, M. Cortesi, R. Alon, J. Miyamoto, V. Peskov, G.Bartesaghi, R. Chechik Weizmann Institute of Science, Rehovot, Israel V. Dangendorf PTB, Braunschweig, Germany J. Maia and J.M.F. dos Santos University of Coimbra, Portugal MOTIVATION MOTIVATION : : Robust, economic, large-area radiation imaging detectors FAST, HIGH-RATE, MODERATE LOCALIZATION RESOLUTION
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Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009 The THGEM: a THick robust Gaseous Electron Multiplier for radiation detectors A.Breskin, M.
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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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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.
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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)
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
THGEM in Xe,Ar/XeTHGEM in Xe,Ar/Xe R. Alon et al. 2008_JINST_3_P01005
THGEM-GPM for LXe Gamma CameraTHGEM-GPM for LXe Gamma CameraSubatech-Nantes/Weizmann
Gas photomultiplier
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009
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
Rachel Chechik Weizmann Institute TIIPP09 Tsukuba March 2009