The THGEM: a THick robust Gaseous Electron Multiplier for radiation 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: Robust, economic, large-area radiation imaging detectors FAST, HIGH-RATE, MODERATE LOCALIZATION RESOLUTION Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
THGEM – a family of hole gas multipliers: Avalanche “confined” inside a hole in an insulating plate -> Reduced secondary effects, independent holes Typical dimensions: Hole diameter d = 0. 3 - 1 mm Pitch a = 0. 7 - 7 mm Thickness t = 0. 4 - 3 mm 1 mm Cu G-10 h=0. 1 mm rim: prevents discharges high gains ! Manufactured by standard PCB techniques of precise drilling in G-10 (and other materials) and Cu etching. ECONOMIC & ROBUST ! First publication: R. Chechik et al. NIM A 535 (2004) 303 Recent review: A. Breskin et al. NIM A 598 (2009) 107 Other groups independently developed similar structures: Optimized GEM: L. Periale et al. , NIM A 478 (2002) 377. LEM: P. Jeanneret, Ph. D thesis, 2001. P. S. Barbeau et al, IEEE NS 50 (2003) 1285. Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
THGEM – Operation principle (like GEM, similar voltages and fields) Upon application of voltage across the plate (V=400 -1200 V function of gas and thickness): a dipole field in the holes focuses e- into the holes defocuses e- out the hole 1 e- in E~40 k. V/cm 104 - 105 e- out 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 holes Efficient cascading of elements: 10 -100 times higher gain Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
THGEM – Operation principle Multiplication of e- induced by radiation in gas or from solid converters (e. g. a photocathode) Reflective photocathode Semitransparent photocathode e- focused into the holes by the hole dipole field Detector properties governed by: e- transport (e. g. efficiency to single e-) multiplication charge induction on readout electrodes ion-backflow Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
THGEM production methods With mask, Weizmann Etch w mask + drill Large rim No mask, Weizmann With mask, Eltos, Italy Drill + etch under the Cu Drill +etch w mask Small and zero rim Large rim displacement Cu Nice edge RIM Cu Surface damaged RIM No displacement Detached Cu CERN, Zero rim: drill + short etching to remove sharp edges from drilling. Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
The THGEMs at Weizmann 2003 3 x 3 cm: basic studies, many geometries 10 x 10 cm: 2 D imaging 30 x 30 cm: n detector 2008 All produced with mask Rim=0. 1 mm Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
THGEM efficiency for single photoelectrons Hole dimensions >> e- diffusion efficient transport from the conversion gap e- focused into the holes by the dipole field Reflective photocathode Semitransparent photocathode e- extraction requires Edrift >0. 5 k. V/cm e- extraction optimal @ Edrift =0 k. V/cm Gain=100 Edrift = 1 k. V/cm Edrift =0 VHOLE [Volt] Full efficiency: at THGEM gain = 30 -100 !! Full efficiency: at THGEM gain = 10 -30 !! Under study in Ne and Ne/CH 4 mixtures Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009 In GEM: 500 -1000
Single THGEM gain With single photoelectrons 105 -106 104 -105 x 100 higher gain compared to single GEM General: Gain limit (x-ray) << Gain limit (UV) (charge density!) in Ne mixtures on x 3 lower (diffusion) Rachel Chechik Weizmann Institute Very high gain in 100% Ne and Ne mixtures At very low voltages !! 100% Ne: Gain 105 @ <500 V Voltage increases w increased CH 4 % TIIPP 09 Tsukuba March 2009
double THGEM gain Hole dimensions >> e- diffusion efficient transport in the transfer gap efficient cascading of THGEMs ÄMuch higher gain at lower voltages Ar mixtures, single photoelectrons >106 Ne mixtures, x-rays >106 Etrans=3 k. V/cm Efficient cascading Total gain = Gain 1 x gain 2 Rachel Chechik Weizmann Institute Edrift=0. 2 k. V/cm Etrans=3 k. V/cm Very high gain even with x-ray At very low voltages !! 100% Ne: Gain 106 @ ~300 V TIIPP 09 Tsukuba March 2009
THGEM - rim effect and stabilization time Single THGEM, 6 ke. V x-rays THGEMs produced by chemical etching (no mask) @ PE, Israel >104 Larger rim higher voltages Higher gains gain = 104, UV light, e- flux ≈ 104 Hz/mm 2 Rim=0. 12 mm Old. Rachel : Chechik Weizmann Instituteof data Chechik et al. Proceedings Larger rim Insulator Charging up few hours of stabilization gain variation ~ x 2. Stabilization time depends on: voltages, currents, gas type and purity, materials, geometry, production method From: Trieste group (RD 51): larger rim -> longer stabilization time Further R&D in progress @ CERN-RD 51 TIIPP 09 Tsukuba March 2009 SNIC 2006, e. Conf C 0604032, 0025 (2006)
THGEM counting rate and pulses single photoelectrons rise time < 10 ns gain=~106 Fast signals in atm. pressure Ar/30%CO 2 Double THGEM ( t=1. 6 d=1, a=1. 5 mm) 9 ke. V x-rays 75 ns 30 ns Rachel Chechik Weizmann Institute Rate capability = 10 MHz/mm 2 @ GAIN ~104 Ar/CH 4 (1 atm) 100% Ne ~X 10 slower gas More CH 4 faster pulses, Higher voltages TIIPP 09 Tsukuba March 2009
THGEM timing (UV photons and b particles) Reflective Cs. I PC pulsed UV lamp * 0. 3 mm 0. 4 mm UV photons 0. 7 mm Similar resolution with semitransparent PC Compatible with e- transport MIPS Multi-GEM: 5 -12 ns depending on gas -faster with Ar/CF 4 -slower with Ar/CO 2 mixtures) Double-THGEM: b particles & cosmics: s=10 -13 ns Triple-GEM (same setup): s=7 -9 ns *Breskin et al NIM A 483 (2002) 670 Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
2 D imaging-detector w/economic readout 8 ke. V X-Ray EDrift • 10 x 10 cm 2 THGEMs t=0. 4, d=0. 5, a=1 mm C-paint Resistive anode (match induced signal size) • 2 -sided pad-string readout 2 mm pitch EHole • Delay-line readout (SMD) ETrans EHole EInd Induced-signal width matched to readout-pixel size. Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
2 D imaging: results with 6 -8 ke. V x-ray Ar/CH 4 (95/5) Gain ~ 6 x 103 Gain uniformity FWHM ± 10% 21% 55 Fe From edge analysis Mask: Raw Data 1 mm pitch THGEM + 2 mm pitch Readout + DL interpolation --> 10 lp/cm Localization Resolution ~0. 7 mm FWHM Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
2 D imaging: results with 5 -9 ke. V x-ray Ne/5%CH 4 preliminary The THGEM electrode The 2 D image x-rays < 5 ke. V Flat-field illumination: hole pattern is visible/ Resolution ~0. 3 mm FWHM Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
THGEM Operation in Noble gases: Ar, Xe for LARGE-VOLUME Noble-gas detectors for rare events and others. Ar/Xe Recently numerous proposed solutions to charge and light detection in the gas phase of noble liquids “TWO-PHASE DETECTORS” Gas 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 …) e- Liquid - Development of γ-cameras for nuclear medicine imaging e. g. PET, Compton… cathode Advantages for THGEM vs. GEM: reduced effect of condensation on surfaces Rachel Chechik Weizmann Institute WIMP TIIPP 09 Tsukuba March 2009 E
THGEM Operation in Noble gases Avalanche confinement in holes is not hermetic -> Field extends out by ~hole diameter -> Photon secondary effects might be important depending on geometry and gas. E Avalanche & photons Outside the hole. Ne, Ar have energetic photons Need to optimize sizes and fields according to the gas. Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
THGEM in Ar, Xe R. Alon et al. 2008_JINST_3_P 01005 Not purified 6 ke. V x-rays 105 Purified gases Ar/Xe =Penning mixt. x 20 higher gain, lower voltages. The lower gain in “purified” Ar secondary effects due to “energetic” UV-photon feedback Under investigations Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
THGEM in Xe, Ar/Xe THGEM: t=0. 4 mm, d=0. 3 mm, a=1 mm, rim=0. 1 mm Xe R. Alon et al. 2008_JINST_3_P 01005 Double-THGEM, t=0. 4 mm, d=0. 5 mm, a=0. 9 mm Ar/Xe (95/5) Penning mixture, Good energy resolution Gain > 104 at all pressures Low voltages Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
THGEM in liquid-Ar temperatures BINP/Weizmann: Bondar et al, 2008 JINST 3 P 07001 2 -THGEM KEVLAR 2 -THGEM G-10 3 -GEM 1 -THGEM G-10 Stable operation in two-phase Ar, T=84 K Double-THGEM Gains: 8 x 103 Experimental setup GOOD PROSPECTS FOR CRYOGENIC-PHOTOMULTIPLIER OPERATION IN THE LXe-CAMERA
Radio-clean THGEM for rare-event physics (M. Gai-UCONN / D. Mc. Kinsey-YALE / A. Breskin-WEIZMANN) • 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. ar. Xiv: 0706. 1106 • The 2 -phase THGEM LXe Dark-Matter detector concept THGEM photon Detector WIMP interaction The Cirlex-THGEM e- e. LXe Photon Cs. I Photo-Cathode Rachel Chechik Weizmann Institute EG TIIPP 09 Tsukuba March 2009 EL
THGEM-GPM for LXe Gamma Camera Subatech-Nantes/Weizmann THGEM Cs. I photocathode g LXe conversion volume Segmented Gas photomultiplier Anode Mg. F 2 window Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
Photon detectors for RICH: reflective Cs. I PC deposited on the THGEM photoelectron extraction into gas, surface electric field by the hole dipole 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). Ref PC e- Distance = 0 Efficient Extraction From PC Min. field efficient photoelectron extraction over the entire PC area: pitch 0. 7 mm, d=0. 3 mm: any voltage > 400 V any gas, including Ne, Ne/CH 4 pitch 1 mm, d=0. 5 mm: similar results Rachel Chechik Weizmann Institute Immediate interest: COMPASS & ALICE, R&D in RD 51 TIIPP 09 Tsukuba March 2009
Photon detectors for RICH: reflective Cs. I PC deposited on the THGEM Photoelectron collection into the holes by the dipole field MIP e E Edrift E=0 Relative Ref. PC E Maximum efficiency at Edrift =0. • Slightly reversed Edrift (50 -100 V/cm) => good photoelectron collection & low sensitivity to MIPS (~5 -10%) ! Reduced sensitivity to MIPS proved with multi-GEM detectors of PHENIX Currently R&D for upgrade of COMPASS & ALICE RICH Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
New concept: Digital sampling calorimetry for ILC with A. White Univ. Texas Arlington/Weizmann General scheme of a detector HCal 2 sampling layers with THGEM-based elements Sampling the jet + advanced pattern recognition algorithms -> Very high precision jet energy measurement. Reconstructed jet: Simulated energy resolution Simulated event with 2 hadronic jets Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
Fast-neutron Imaging-detector Weizmann/PTB/Soreq gas • p induce electrons in gaseous conversion gap. THGEM 1 • electrons are multiplied and localized in cascaded-THGEMs imaging detector. THGEM 2 Double THGEMs: • neutrons scatter on H in plastic-radiator foil, p escape the foil. • 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. B, Li, Gd…converter: thermal neutron detector e. g. position sensitive n-dosimetry for BNCT (with Rachel Chechik Weizmann Institute Univ. & INFN, Milano) TIIPP 09 Tsukuba March 2009
Fast Neutron Resonant Radiography (FNRR) for element-resolved radiography Weizmann/PTB/Soreq sample neutron source: nsec-pulsed broad energy deuteron beam Steel All Be target C rods Operation principle: • n energy selected by TOF • Image “on” ad “off” resonance • Ratio of images => element selection C only Triple-GEM 10 x 10 cm pulsed, white neutron beam Neutron imaging detector with fast timing capability ! 2 Dangendorf et al. NIM A 542(2005)197 Detector requirements • area: >30 x 30 cm 2 • detection eff. @ 2 -10 Me. V : ~ 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 cost Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
Summary Robust, economic, large-area radiation imaging detectors HIGH-GAIN, FAST, HIGH-RATE, MODERATE 2 D- RESOLUTION • Single-photon imaging. e. g. Ring Imaging Cherenkov (RICH) detectors. • Fast Particle 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-ray and n imaging. • Possible low-pressure operation: Nuclear Physics applications Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
Weizmann Group THGEM papers: R. Chechik et al. NIM A 535 (2004) 303 (first idea) R. Chechik et al. NIM A 553 (2005) 35 (application to photon detectors) C. Shalem et al. NIM A 558 (2006) 475 & NIM A 558 (2006) 468 (atm. And low-p) M. Cortesi et al. 2007_JINST_2_P 09002 (imaging) M. Cortesi et al. NIM A 572 (2007) 175 (2 D imaging) R. Alon et al. 2008_JINST_3_P 01005 (Ar, Xe) R. Alon et al. 2008 JINST 3 P 11001 (timing) R. Chechik and A. Breskin NIM A 595 (2008) 116 (application to photon detectors) A. Breskin et al. NIM A 598 (2009) 107 (a concise review) R. Chechik, et al. /http: //www. slac. stanford. edu/econf/C 0604032/papers/ 0025. PDFS. (including long term stability) C. Shalem MSc 2005 JINST TH 001 R. Alon MSc 2008 JINST TH 001 Rachel Chechik Weizmann Institute TIIPP 09 Tsukuba March 2009
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