1. THGEM in Ne-mixtures UV-photon detection in RICH & more Weizmann: M. Cortesi, R. Chechik, R. Budnik, CERN: V. Peskov Coimbra & Aveiro: J. Veloso, C. Azevedo, J. dos Santos, Nantes: S. Duval, D. Thers, Work within CERN-RD51 Amos Breskin Weizmann Institute of Science THGEM Recent works: Review NIM A 598 (2009) 107 2010 JINST 5 P01002 2009 JINST 4 P08001 Amos Breskin RICH2010 Cassis

2. Amos Breskin Thick Gas Electron Multiplier (THGEM) SIMPLE, ROBUST, LARGE-AREA Printed-circuit technology  Intensive R&D  Many applications 1 e - in 10 4 - 10 5 e - s out ~40kV/cm THGEM Double-THGEM: 10-100 higher gains ~ 10-fold expanded GEM Weizmann 2003 Effective single-electron detection Few-ns RMS time resolution Sub-mm position resolution MHz/mm 2 rate capability Cryogenic operation: OK Gas: molecular and noble gases Pressure: 1mbar - few bar Magnetic fields Thickness 0.5-1mm small rim prevents discharges Similar hole-multipliers: - Optimized GEM: L. Periale et al., NIM A478 (2002) 377. - LEM: P. Jeanneret, PhD thesis, 2001. RICH2010 Cassis

3. Comparatively low operation voltages  reduced discharge probability, discharge energy and charging-up effects High gains, even with single-THGEM High single-photoelectron gains even in the presence of ionizing background (higher dynamic range compared to Ar-mixtures) Important for RICH: Ne yields ~ 2.5 fold less MIP- induced electrons than Ar Photon detection efficiency? Ne-based mixtures Amos Breskin RICH2010 Cassis

4. Gain: Single/Double THGEM in Ne-mixtures Very high gain in Ne and Ne mixtures, even with X-rays At very low voltages !! X-rays: 2-THGEM 100% Ne: Gain 10 6 @ ~300V UV: 1-THGEM Ne/CF 4 (10%): Gain > 10 6 @ ~800V 10 6 Double-THGEM 9 keV X-rays Single-THGEM CsI PC + UV-light (180 nm) 10 6 Amos Breskin RICH2010 Cassis 2009 JINST 4 P08001

5. Amos Breskin A VERY FLAT UV-IMAGING DETECTOR ~10-12 mm h Photocathode THGEMs readout 100x100mm 2 THGEM With 2D delay-line readout  0.3mm holes Cortesi et al. 2007 JINST 2 P09002 window Resistive anode Spatial Resolution (FWHM) Ar/5%CH 4  0.7 mm with 9 keV X-rays Ne  1.4 mm with 9 keV X-rays Ne/5%CH 4  0.3 mm with 4 keV X-rays RICH2010 Cassis

6. THGEM/Ne-mixtures: Pulse shape THGEM signals w fast amp Increasing %CH 4 -> higher voltages & faster avalanches Amos Breskin RICH2010 Cassis

7. Gain Stability Single THGEM (t=0.4mm, d=0.5mm, a=1mm, rim=0.12mm) Gain = 10 4, UV light, e - flux ≈ 10 kHz/mm 2 CsI UV Amos Breskin RICH2010 Cassis GAIN-STABILTY (charging up, substrate polarization) function of : substrate material, rim size around hole, HV value, gain, radiation flux, surface resistivity, mode of operation etc. Good stability (Trieste): Holes with no rim – but no-rim: 10-100 times lower gain New results in Ne-mixtures (much lower HV): ~stability with rim

8. UV-photon detectors UV-photon detectors RICH Noble-liquids Amos Breskin RICH needs: high efficiency for photons low sensitivity to MIPs & background Stability (CsI, gain) low discharge rate RICH2010 Cassis

9. R&D activity for upgrades of ALICE & COMPASS RICH EXEMPLE: ALICE Amos Breskin Recent beam-tests @ CERN of THGEM/CsI UV-RICH protos: Peskov, Levorato talks RICH2010 Cassis Very High Momentum Particle Identification Detector (VHMPID)

10. Two UV-photon options considered for ALICE & COMPASS RICH THGEM (RETGEM) ? ?  MWPC Amos Breskin Open geometry: Photon & ion feedback  gain limit  PC aging PC excitation effects MIP sensitivity Closed geometry: No photon feedback Reduced ion feedback More robust, simpler Reduced MIP sensitivity  high gains  Lower PC aging RICH2010 Cassis Extensive Comparative study: THGEM/CsI vs MWPC/CsI: Talk by Peskov

11. Double-THGEM photon-imaging detector  RICH UV photon e-e- Segmented readout electrode CsI photocathode THGEM pe photocathode E drift MIP e THGEM Reflective CsI PC on top of THGEM: - Photoelectron extraction efficiency (QE eff ) - collection efficiency into holes - Photon detection above threshold Unique: Slightly reversed E drift (50-100V/cm)  Good photoelectron collection  low sensitivity to MIPS *  background reduction & higher gain! Amos Breskin Chechik NIM A553(2005)35 RICH2010 Cassis _______ * Phenix GEM/CsI HBD Talk by Tserruya

12. Gain in 1-, 2-, 3-THGEM Amos Breskin 10 5 Ne/5%CH 4 Ne/5%CF 4 THGEM: thickness t=0.4 mm, holes d=0.3 mm, rim h=0.1 mm, pitch a = 1 mm. Conversion gap 10 mm, transfers and induction gaps 2 mm X-ray rate: 1kHz/mm 2 Similar HV for similar gains RICH2010 Cassis 9 keV x-rays @ 1KHz/mm 2

13. 1-, 2-, 3-THGEM:Gain limit vs rate: x-rays Amos Breskin MAX-gain decrease with rate observed, similarly to other gas-detectors  Rather limit In this geometry, with 3-THGEM: Ne/5%CH 4 & Ne/5%CF 4 @ 10 4 Hz/mm 2 (x-rays)  max-gain of ~6x10 4  1.5 x 10 7 electrons (~250 electrons) 10 5 Hz/mm 2 UV photons  5 x 10 6 electrons (gain 5 x 10 6 ) 10 5 Ne/5%CH 4 Ne/5%CF 4  PESKOV talk

14. Normal drift field Reversed drift filed @ gain 5x10 5 the breakdown rate with reversed drift field is almost 10 times lower With ~same pe collection efficiency Ru+UV Fe+UV UV only Ru+UV Fe+UV UV only pe photocathode E drift MIP e THGEM THGEM: Discharge rate Gain 5 10 5 Counting-RATES: Ru ~100 Hz/ cm2 Fe ~10KHz/cm2 Triple THGEM, Ne+10%CH 4 10 -2 sparks/min 10 -1 sparks/min Amos Breskin RICH2010 Cassis

15. To prove that Ne-based mixtures can be beneficial for RICH  R&D to demonstrate, as a first step, that in Ne-mixtures one can reach: - good photoelectron extraction from CsI photocathode  extr - good photoelectron collection efficiency  coll QE in vacuum Effective area Extraction efficiency Backscattering in gas Collection into holes threshold photocathode pe THGEM Photon detection efficiency - high gain: high electron detection efficiency above threshold  photon Amos Breskin RICH2010 Cassis EFFECTIVE PHOTON DETECTION EFFICIENCY: Absolute Detection Efficiency:

16. Electric field at THGEM electrode surface Photoelectron extraction from CsI Ne/10%CF 4 ~as good as CF 4  e.g. value for Ne/10%CF 4 Amos Breskin feedback d=0.3mm, a=0.7mm, t=0.4mm Thicker THGEM  higher fields 2010 JINST 5 P01002 CH 4 CF 4

17. Photoelectron collection into THGEM holes Even at low gain  100% collection efficiency in Ne-mixtures 2010 JINST 5 P01002 Amos Breskin RICH2010 Cassis

18. Gas∆V THGEM (V) Gain (UV) QE 170nm A eff This THGEM A eff [1] Optimal THGEM ε extr ε coll ε effph This THGEM ε effph 2 Optimal THGEM Ne/CH 4 (95/5)8005.4E4 0.30.54 0.910.73 [2] 10.120.20 Ne/CH 4 (90/10)9001.3E5 0.30.54 0.910.79 [3] 10.130.22 Ne/CF 4 (95/5)7506.0E5 0.30.54 0.910.76 3 10.120.21 Ne/CF 4 (90/10)8501.2E6 0.30.54 0.91 0.83 4 10.14 0.23 [1] [1] Optimal THGEM: t = 0.4 mm, d = 0.3 mm, a = 1 mm; h = 0.01 mm, [2] [2] Value for 1.5 kV/cm photocathode electric field [3] [3] Values for 2kV/cm photocathode electric field Wire chamber: fp th ~0.70 in COMPASS  ε photon ~0.21 @170nm ~0.90 in ALICE  ε photon ~0.27 @170nm @ 170nm Expected THGEM UV detector performance 2010 JINST 5 P01002 Amos Breskin Need RICH-THGEM-proto beam studies~ expected ~0.2 for fp th ~0.9 RICH2010 Cassis

19. Avalanche-ion blocking Avalanche ions impinging the photocathode - damage the photocathode - lifetime limit, - secondary effects – gain limits Damage: Long understood issue In present MWPC/CsI photon detectors: 100% ions hit the photocathode In cascaded-THGEM: few% Patterned hole multipliers: 10 -3 to 10 -4 Efforts to pattern THGEM electrodes

20. The Micro-hole & Strip plate (MHSP) Weizmann/Coimbra/Aveiro With MHSP/GEM cascade: BEST ION TRAPPING : ~10 -4 100 X better than 3-GEM 20 X better than Micromegas ION BLOCKING with PATTERNED HOLE MULTIPLIERS IBF=3*10 -4 @ Gain=10 5 Like GEM, but with additional patterned strip-electrodes: extra gain OR ion blocking. Ion deflection by strips between holes  efficient ion trapping 2007 JINST 2 P08004 RICH2010 Cassis Amos Breskin

21. CHALLENGE: visible-light Gas Photomultipliers! Cascaded patterned hole-multipliers with K-Cs-Sb photocathodes Gain ~10 5 + full photoelectron collection efficiency Works uniquely due to efficient ion blocking 10 5  “flat-panel” large-area photon-imaging detectors insensitive to B  numerous applications: RICH, large Astro experiments… Cascaded GEM: gain limit was <100 2009 JINST 4 P07005 Bialkali PC Visible photon K-Cs-Sb QE~27% @ 375nm CsI Sealed vis-GPM RICH2010 Cassis Amos Breskin

22. THCOBRA: a patterned THGEM for ion blocking Pitch = 1 mm Hole diameter = 0.3 mm Rim = 0.1 mm Thickness = 0.4 mm Aveiro/Coimbra/Weizmann Veloso POSTER THGEM-FTHCOBRA THGEM-THCOBRA Need to block ions without loosing primary photoelectrons So far: good ion blocking but loss of photoelectrons Previous success: FRMHSP/GEM/MHSP Ion blocking factor 10 4 & full electron collection Ion blocking electrodes Ion reduction: less feedback, less PC aging RICH2010 Cassis Amos Breskin

23. Cryo-THGEM applications RICH2010 Cassis Amos Breskin

24. Noble-gas detectors WIMP Gas Liquid e- E Ar, Xe… Primary scintillation Secondary scintillation Electron multiplier &/or photomultiplier photomultiplier Amos Breskin Charge &/or scintillation-light detection in liquid phase or Charge &/or scintillation-light detection In gas phase of noble liquids: “TWO-PHASE DETECTORS” Possible applications: Noble liquid ionization calorimeters Noble-Liquid TPCs (solar neutrinos) Two-phase detectors for Rare Events (WIMPs,  -decay, …) Noble-liquid  -camera for medical imaging Gamma astronomy Gamma inspection..... RICH2010 Cassis Use THGEM electron multipliers & THGEM/CsI photomultipliers ?

25. Experimental setup at Budker-Novosibirsk First results with double-THGEM in 2-phase LAr @ 84K Bondar 2008 JINST 3 P07001 Good prospects for CRYOGENIC GAS-PHOTOMULTIPLIERS operation in gas phase of noble liquids! Amos Breskin RICH2010 Cassis Double-THGEM in two-phase Xe at T=164K Max. gain limit due to connector… 2-THGEM G-10 1-THGEM G-10 2-THGEM KEVLAR 3-GEM Stable operation in two-phase Ar, T=84K Double-THGEM  Gains: 8x10 3 2-THGEM G-10 two-phase Xe Buzulutskov VCI 2010; in preparation for JINST

26. THGEM and THGEM/G-APD @ Cryo temperatures G-APD bipolar G-APD unipolar 2-THGEM Buzulutskov et al. (Budker/ITEP/Weizmann) 60 keV X-ray at 2THGEM gain=400  SiPM ~1000e before amplification! Two-phase detectors with THGEM+SiPM  ~0.6pe/initial e at THGEM gain=400 in Ar  SiPM signal: N pe ~ 0.6N initial e’s x SiPM gain Efficient readout of noble-liquid detectors? 2-phase LAr detector THGEM G-APD (SiPM) VCI 2010 & paper submitted to JINST Idea: Good S/N @ low THGEM-gain, recording avalanche photons with Geiger APDs (G-APD) SiPM RICH2010 Cassis Amos Breskin

27. Cryo-GPM with windows Cryo-GPM with windows 2-phase or liquid scintillators Amos Breskin Best operation, confirmed at RT: Ne/CH 4 or Ne/CF 4 b) radiation LXe e- THGEM GPM EGEG Secondary scintillation Xe UV-window 10 6 GPM in noble-gas: gain affected by lack of impurities arXiv:1001.4741 arXiv:1001.4741 GPM w window: better control of counting gas / stability RICH2010 Cassis Higher gain & lower HV

28. Cryo-GPM for LXe Medical Compton Camera THGEM : thickness = 400  m hole Ø = 300  m hole spacing = 700  m rim size = 50  m  V THGEM 4 mm  V THGEM Double-THGEM layout MgF 2 UV window Reflective CsI photocathode Ne/CH 4 GPM location LXe TPC gamma-converter with field shaping Subatech-Nantes/Weizmann 44 Sc  +  emitter LXe Gamma Camera PET 2009 JINST 4 P12008 RICH2010 Cassis Amos Breskin

29. Samuel Duval, Ran Budnik & Marco Cortesi (WIS) 10 5 182K Double-THGEM RT & CRYO-T 150-158K Double-THGEM/CsI at RT & CRYO-T Preliminary results @ CRYO-T in “improvised“ setup at Weizmann Cryo-medium: LN 2 /ethanol Soon: studies at Nantes with LXe TPC 10 2 RT Ne/5%CH 4 Single-UV Preliminary results in Ne/CF4 @ Coimbra: at RT, similar gain @ 1-3 bar HV limit (connector) RICH2010 Cassis

30. XEMIS LXe Compton Camera Amos Breskin LXe-TPC GPM  Tests in LXe: May 2010 @ Nantes cryostat RICH2010 Cassis

31. 2-phase DM detectors XENON100Kg: running with PMTs! PROBLEM: cost & natural radioactivity of multi-ton detectors! Proposed design of XENON 1ton Possible design of the XENON 1 ton two-phase LXe DM TPC detector with ~ 121 QUPID vacuum photon detectors. Background: 1mBq/tube Expectation: < 1 WIMP interaction/Kg/Day Aprile/XENON WIMP interaction LXe e- THGEM GPM Detector Primary scintillation EGEG ELEL Secondary scintillation Xe THGEM GPM Detector UV-window Ne/CF4 ? RD51: Weizmann/Nantes/Coimbra THGEM-GPM (gas photomultiplier): Simple, flat (save LXe), robust Low-cost Radio-clean ? Lower thresholds ? RICH2010 Cassis Amos Breskin

32. Large THGEM electrodes Industry: square-meters possible 300x300mm 2 THGEM 90,000 0.5mm diameter holes (Print Electronics, IL) 600x600mm 2 THGEM 600,000 0.4mm diameter holes (Eltos, IT) Status: so far only “mechanical” electrodes WEIZMANN TRIESTE RICH2010 Cassis

33. SUMMARY a versatile robust electron multiplier Good suitability for photon detection with Ne-mixtures RICH: expected photon detection efficiency ~20% @ 170nm Good stability in background environment Comparative results with MWPC/CsI: talk by PESKOV Various ongoing and potential applications @ RT & low-T UV-photon detectors for RICH Sampling elements for Digital Hadron Calorimeters Neutron-imaging detectors Cryogenic UV-photon detectors for medical imaging and dark matter Large-area moderate-resolution tracking detectors Amos Breskin RICH2010 Cassis

34. Amos Breskin SPARE SLIDES RICH2010 Cassis

35. Amos Breskin Double-THGEMTHGEM+Micromegas GPM: Double-THGEM vs THGEM+Micromegas 2-THGEM THGEM+MM 10 7 Ne/CF 4 (5-10%) THGEM: Thickness t=400  m, hole dia d=300  m, pitch a=700  m, rim R=50  m. MICROMEGAS: t 5  m, d 30  m, a 60  m. ~25 photons pulse Weizmann/Nantes Nov. 2009 Samuel Duval, Ran Budnik & Marco Cortesi RICH2010 Cassis

36. Amos Breskin 2-THGEM THGEM+MM 10 7 Samuel Duval, Ran Budnik & Marco Cortesi 10 2 Room temperature Ne/CF 4 2-THGEM vs THGEM-MicromegasMicromegas in Ne-mixtures GPM: Double-THGEM vs THGEM+Micromegas RICH2010 Cassis

37. MICROMEGAS (InGrid) covered with CsI photon CsI PC Chip area: 14x14mm 2. (256×256 pixels of 55×55 μm 2 ) TIMEPIX Ingrid without CsI Ingrid with CsI PC: 2D UV Image of a 10mm diameter mask Few-micron resolutions UV absorbed by the fingerprint on the window Melai, 2009 http://arxiv.org/abs/1003.2083http://arxiv.org/abs/1003.2083 Fransen 2009 INGRID/CMOS PHOTON IMAGING DETECTOR 50  m mesh RICH2010 Cassis Amos Breskin