1. Cryogenic Thick-GEM (THGEM) detectors and their applications Cryogenic Thick-GEM (THGEM) detectors and their applications Affordable instrumentation for Dark-Matter Searches & other fields A. Breskin Astrophysics & Particle Physics Weizmann Institute of Science A. Breskin IWAD Kolkata; October 28 2014 1

2. Weizmann Detector Physics Group Research topics:  Basic detection-related phenomena:  New detector concepts  Detector applications: HEP (LHC, ILC, RHIC); “Astro” (DM, SN); Medical; Homeland security… Prostate Tumor Zn X-ray beam X-ray detector Zn characteristic X- ray Rectal wall WIMP Gas Liquid e E photomultiplier Xe Prostate cancer DNA damage MAIN INTERESTS: - GAS-AVALANCHE DETECTORS - DIGITAL HADRON CALORIMETRY - NOBLE-LIQUID DETECTORS DM & n/  radiography e - multipliers Gas photomultipliers Optical-TPC Noble-liquid detectors n-imaging Ionization patterns A. Breskin IWAD Kolkata; October 28 2014

3. Chechik 2004 Thickness 0.5-1mm drilled etched SIMPLE, ROBUST, LARGE-AREA Printed-circuit technology (Also of radio-clean materials) Double-THGEM: 10-100 higher gains The Thick Gas Electron Multiplier (THGEM) Robust, if discharge no damage Effective single-electron detection Few-ns RMS time resolution Sub-mm position resolution >MHz/mm 2 rate capability Cryogenic operation: OK Broad pressure range: 1mbar - few bar Room Temperature - UV detectors for RICH Gas Photomultipliers GPM - Sampling elements for calorimetry - Tracking with moderate resolution - Fast-neutron detectors (with converters) 0.4 - 1 mm E 1 e - in ~10 4 e - out  V THGEM A. Breskin IWAD Kolkata; October 28 2014 3

4. Room-temperature applications Very thin 5-6mm multipliers: sampling elements for DHCAL (ILC) 300x300 mm 2 THGEM/APV/SRS pad-readout UV-photon detectors for RICH Converter-foils/THGEM for neutron imaging Tessarotto, Trieste Cortesi, PSI Weizmann Inst. A. Breskin IWAD Kolkata; October 28 2014 4 6% efficiency w Fast neutrons

5. Single-stage THGEM-like configurations ALL: sufficient gain for MIPs with VLSI electronics, e.g. APV/SRS, MICROROC THGEM + induction gap WELL detector Resistive-WELL RWELL Segmented Resistive-WELL SRWELL Resistive-Plate RPWELL A. Breskin IWAD Kolkata; October 28 2014 Arazi 2014 JINST 9 P04011 Bressler 2013 JINST 8 C12012 5

6. 300x300mm 2 single-THGEM/induction gap Image of Cosmic trigger APV/SRS readout COSMICs response Discharge rate vs injected primary electrons 10 4 primary electrons Gain2 10 100 E ind = 3 5 kV/cm --------------------------- R&D within RD51 project A. Breskin IWAD Kolkata; October 28 2014 Gain1 250 25 6

7. High efficiency @ low multiplicity 7 COMPETITIVE WITH OTHER PROPOSED SAMPLING CONCEPTS A. Breskin IWAD Kolkata; October 28 2014 Bressler 2013 JINST 8 C12012 Signals proportional to dE/dx

8. LEM (THGEM) for ArDM & GLACIER 100kton LAr neutrino observatory Cryogenic THGEM (LEM) for charge detection in noble-liquid TPCs for charge detection in noble-liquid TPCs A. Rubbia 2013 JINST 8 P04012 Detection: e.g. of WIMP-induced ionization electrons in LAr for dark-matter search Problem: Low gain <100 in pure Ar, due to photon feedback! Remark: easier situation in Xe, because of lower photon energy (smaller feedback). A. Breskin IWAD Kolkata; October 28 2014 Other cryo-THGEM R&D: Buzulutskov, Peskov, Lightfoot

9. Possible solutions: Use cascaded THGEMs (to mask final-avalanche photons) Operate THGEM at low gain; use optical readout with additional gain: gAPD* (SiPM), LAAPDs. * e.g. new UV-sensitive by Hamamatsu Gain limits in noble gases Two-phase Ar detector with THGEM/gAPD optical readout in the NIR Bondar, Buzulutskov JINST 2010 THGEMs in gas A. Breskin IWAD Kolkata; October 28 2014 Buzulutskov 2012 JINST 7 C02025

10. Cryogenic Photon detectors for LXe-TPC Nantes/Weizmann 171K RT 10 7 10 4 1-THGEM 171K Duval 2011 JINST 6 P04007 173K, 1100mbar CsI photocathode A. Breskin IWAD Kolkata; October 28 2014 10

11.  l = f  E,  x,  y,  z )  511keV E 0 = 1,157 MeV (E 1, x 1, y 1, z 1 ) (E 2, x 2, y 2, z 2 )  Δ Compton telescope LXe TPC & GPM: 3  imaging Large Gaseous Photomultiplier-GPM S. Duval et al., 2009 JINST 4 P12008 Scandium 44 Radioisotope : (  +,  ) emitter GPM SUBATECH, Nantes C. Grignon et al., NIM A571(2007)142 Single-phase LXe TPC LXe PET A. Breskin IWAD Kolkata; October 28 2014

12. Detection of explosives and nuclear materials Main interest: Nuclear materials (enriched U, Pu) in air and marine cargo and in vehicles ( 150 g) ALL present techniques (Bremsstrahlung, dual energy, neutrons...):  poor discrimination in Low-Z (low-density explosives vs benign organic goods)  No discrimination in high-Z between special nucl materials & other materials of similar density (Pu, U, W, Ta) New combined system: Fast-Neutron Resonance Radiography (FNRR) for low-Z range (elemental specificity) Dual Discrete Energy Gamma Radiography (DDEGR) for high-Z range (higher Z-contrast) 11 B(d,n) 12 C : source of fast neutrons (continuous; 1-20 MeV) source of 2 discrete Gammas (4.4 & 15.1 MeV ) A. Breskin IWAD Kolkata; October 28 2014 A. B. 2012 JINST 7 C06008

13. R&D on a novel combined neutron and gamma detector concept for fast pulsed sources: LXe SCINTILLATOR with GAS PHOTON IMAGING DETECTOR Neutrons: E-selection by TOF Gammas: easy pulse-height discrimination of 4.4 & 15.1 MeV Large-area, efficient, economic Neutrons and gamma-rays detected by same detection medium (LXe) LXe technologies: mastered, rather simple  suits large systems! Proposed novel detector concept A. Breskin IWAD Kolkata; October 28 2014 A. B. 2012 JINST 7 C06008 13

14. 2D Imaging concept of Fast-Neutrons & Gammas Fast-neutron /Gamma imaging detector. Neutrons/gamma interact with liquid-xenon; the resulting scintillation (UV) photons are detected with a double-THGEM, CsI-coated gaseous photomultiplier. Plain LXe volume or thin capillaries filled with liquid xenon (LXe) LXe hν hν UV- WINDOW CsI- Photocathode THGEM Multipliers Pulsed-beam fast-n &  Scintillation light is confined within capillaries by total internal reflection  better localization capability Readout electrode 10m TOF: Gammas: ~30ns Fast-n: ~200-500ns  Camera “opens” twice: 1 st for gammas 2 ed for n’s 11 B(d,n+  ) 12 C Gas converter GPM* *gas-avalanche photomultiplier A. Breskin IWAD Kolkata; October 28 2014 A. B. 2012 JINST 7 C06008 14

15. LXe converter-scintillator LXe SCINTILLATOR: High density (2.85 g/cm 3 ) Fast (2ns) Cryogenic (-100 o C) Good spectral match with CsI-photocathodes: QE~30% @ 178nm 5cm LXe in capillaries: high detection efficiencies: n: ~20% (2-14MeV)  : ~30% (2-14MeV) Scintillation yield*: Gammas: 46 photons per deposited KeV Neutrons: 7 photons per deposited KeV (E recoil 10 keV) [*] Aprile et al. 2009 Phys. Rev. C79, 045807 SIMULATED POSITION RESOLUTIONS: Gamma (2-14MeV): 2.5-4mm FWHM Neutrons (14-2 MeV): 2-6mm FWHM A. Breskin IWAD Kolkata; October 28 2014 A. B. 2012 JINST 7 C06008 15

16. 9-10MeV Neutrons, Objects widths=6cm 4.4MeV γ, Objects widths=2cm Radiography Simulations (20X20mm objects) Material separation by Gamma - Gamma Material separation by Neutron resonances Carbon - (6.85-7.2 MeV)/(7.7-8.83 MeV)Oxygen - (2.31-2.37 MeV)/(3.26-3.785 MeV) Typical error 2% CARBON OXYGEN “heavies” GAMMA NEUTRONS A. Breskin IWAD Kolkata; October 28 2014 Israelashvili 2014 16

17. Search for Dark Matter Direct Dark matter searches: Weakly Interacting Massive Particles  Physics beyond the Standard Model Expected flux: ~10 4 -10 6 WIMPs/cm 2 ∙s Expected process: WIMP scattering off nuclei Expected nucleus recoil energy: keV-scale few events/ton/year Expected rate: few events/ton/year Challenge: Detection of extremely rare, feeble signals Within “enormous” radiation background Challenge: Detection of extremely rare, feeble signals Within “enormous” radiation background Latest observation of Planck Mission: 4.9% of Universe is baryonic, 26.8% Dark Matter, 68.3% Dark Energy A. Breskin IWAD Kolkata; October 28 2014 17

18. A two-phase TPC. WIMPs interact with noble liquid (low cross-section elastic scattering off nuclei); primary scintillation (S1) is detected by bottom PMTs immersed in liquid. Ionization-electrons from the liquid are extracted into the saturated-vapor above liquid; they induce electroluminescence in the gas phase – detected with the top PMTs (S2). The ratio S2/S1 provides means for discriminating gamma background from WIMPs recoils, due to the different scintillation-to-ionization ratio of nuclear and electronic recoils. DUAL-PHASE NOBLE-LIQUID TPC for DM SEARCHES Present: XENON100, LUX…. Under assembly: XENON1ton Future: MULTI-TON (e.g. DARWIN): COST STABILITY THRESHOLD few-tens keV recoil Few photoelectrons/event! XENON experiment: CERN COURIER 10/2013 A. Breskin IWAD Kolkata; October 28 2014 18

19. 118 kg x 85 days 34 kg x 225 days ~ 1 ton x 3 years Dark Matter: Low cross sections  Size matters! L. Baudis Lower Detector Threshold  lower-mass WIMPs! 30 cm 2m 20 t LXe (LAr also under study) 1.05m 0.95m 3.5 t LXe XENON100 @ LNGS: taking data (~34 kg fiducial) dual-phase, 242 PMTs 161 kg LXe DARWIN : @ LNGS or Modane; concept R&D (~12 t fiducial); ~ 1050 PMTs (???) physics in 2018? XENON1T : at LNGS under construction (~1000 kg fiducial), dual-phase, 248 PMTs, physics: in 2015 20 t LXe WIS is member of XENON & DARWIN Detector Size 19 Sensitivity limit: Neutrino coherent scattering A. Breskin IWAD Kolkata; October 28 2014

20. PMTs for Dark Matter searches Well suited for present experiments: High quantum efficiency (QE) Low radioactivity Cryogenic operation But: Only ~50-60% filling factor Pixel size = PMT size (present: 3” dia.) Single PMT ~8k$  ~ 10 7 $ in multi-ton experiments Is there a different solution? A. Breskin IWAD Kolkata; October 28 2014 20

21. Cost effective coverage of large areas QE eff ~20% @ 175 nm with high filling factor (~90%) Can be of low radioactivity Flat, thin geometry Pixelated readout May allow 4π coverage Basic technology well understood and mastered Gaseous Photomultipliers? QE >30% @ 175 nm (QE eff < 20% ; low fill factor) Low radioactivity Off-the-shelf Years of proven operation … But: ~M$/m 2 Limited filling factor (~50%) Pixel size = PMT diameter Present day PMTs for DM searches Cryogenic GPMs for future large-scale DM searches A. Breskin IWAD Kolkata; October 28 2014 21

22. WIS – million-liter Mu-Veto Cherenkov Water-Tank XENON1t Now: XENON1t XENONntDARWIN Next users: XENONnt and/or DARWIN LNGS A. Breskin IWAD Kolkata; October 28 2014 22

23. WIS: TWO NEW 4  DM DETECTOR CONCEPTS Dual-phase TPC Relatively low-cost (in-house module assembly) 4 π coverage  lower threshold  lower-mass WIMPs 10-fold better localization (vs PMTs)  better background discrimination Relatively low-cost (in-house module assembly) 4 π coverage  lower threshold  lower-mass WIMPs 10-fold better localization (vs PMTs)  better background discrimination Gaseous Photomultiplier R&D in course @ WIS within DARWIN GPMs wire-GPMs WIMP Problematic (?) liq.-gas region In large detectors XENON100 compared to XMASS 4  light sensitivity: ~ 50-100-fold improvement in sensitivity below 6 GeV/c 2 A. Breskin IWAD Kolkata; October 28 2014 23

24. WIS Liquid Xenon (WILiX) R&D facility 1) Vacuum Chamber, 2) Xenon-TPC Chamber wrapped with super-insulator 3) Heat Exchanger, 4) Xe liquefier, 5-9) Gas-system manifold, control & purification system. WILiX schematic view LXe TPC A. Breskin IWAD Kolkata; October 28 2014 24

25. 4” Gaseous Photomultiplier: GPM CsI photocathode THGEM 4” dia. CsI coated THGEM 4” GPM + LXe TPC A. Breskin IWAD Kolkata; October 28 2014 25

26. 4” GPM with Dual-Phase Xe TPC The night of October 24 The dream came true…! Alpha-induced S1 and S2 signals In dual-phase Xe TPC with 4” GPM A. Breskin IWAD Kolkata; October 28 2014 Lior Arazi AN APPETIZER FOR REAL EXCITING R&D ~20% FWHM S1 in Xe dual-phase / GPM 26 GPM gain ~10 5

27. Towards single-phase TPCs? Simpler techniques? Sufficient signals? Lower thresholds? Cheaper? How to record best scintillation & ionization S1, S2? A. Breskin IWAD Kolkata; October 28 2014 27

28. Single-phase option for PANDA Karl Giboni 2011 GPM 4  geometry with immersed GPMs LXe level S1: Primary scintillation & S2: Ionization-induced Electroluminescence on wires A. Breskin IWAD Kolkata; October 28 2014 28

29. Electroluminescence on thin wires Recent alpha-induced scintillation S1 and S2 electroluminescence signals recorded from a 10 micron diameter wire in LXe. Setup shown on left. Limited charge & light gain. E. Aprile; arXiv 1408.6206 R&D in course for S2 in single-phase A. Breskin IWAD Kolkata; October 28 2014 29

30. NEW SINGLE-PHASE 4  DM DETECTOR CONCEPT Single-phase TPC Relatively low-cost (in-house module assembly) 4 π coverage  lower threshold  lower-mass WIMPs 10-fold better localization (vs PMTs)  better background discrimination Relatively low-cost (in-house module assembly) 4 π coverage  lower threshold  lower-mass WIMPs 10-fold better localization (vs PMTs)  better background discrimination Gaseous Photomultiplier LHM Noble Liquid WIMP R&D in course @ WIS within DARWIN A. Breskin IWAD Kolkata; October 28 2014 30

31. Similar to electron multiplication on PMT dynodes… S2 electrons: Collected into holes S1 photons: Photoelectrons from CsI collected into holes (QE~23% in LXe @ 178nm; Aprile IEEE ICDL 2005, p345 ) Amplification: Electroluminescence (optical gain) S1 & S2 with Liquid Hole-Multiplier LHM A.B. JPCS 460 (2013) 012020; arXiv:1303.4365 Light amplification in cascaded hole-multipliers immersed in the LIQUID Electroluminescence A. Breskin IWAD Kolkata; October 28 2014 31

32. Prior Art High QE (25% at 178nm) from CsI photocathodes in LXe E. Aprile, K.L. Giboni, S. Kamat, P. Majewski, K. Ni, B.K. Singh and M. Yamashita. IEEE ICDL 2005, p345 Electroluminescence observed in LXe on few-micron diameter WIRES Threshold field for proportional scintillation: ~400 kV/cm Threshold field for avalanche multiplication: ~1 MV/cm Doke NIM 1982 Maximum charge gain measured 200-400 on: wires, strips, spikes… Electroluminescence from THGEM holes in LAr ~ 500 UV photons/e - over 4  ~ 60kV/cm electroluminescence threshold Lightfoot, JINST 2009; similar: Buzulutskov JINST 2012 Photon-assisted multiplicationPhoton-assisted multiplication Veloso, A.B. et al. 2006 JINST 1 P08003 radiation Scintillation light converted to photoelectrons on a CsI photocathode V hole Photon gain in 1 bar Xe ~ 1000 Charge gain In MHSP 1 Photon-induced Charge gain In MHSP 2 RESOLUTION MAINTAINED A. Breskin IWAD Kolkata; October 28 2014 32

33. Setup for testing the LHM A. Breskin IWAD Kolkata; October 28 2014 33

34. THGEM Cathode Mesh Interpretation: S2 generated inside the liquid (but at surprisingly low electric fields ~ 30kV/cm) Thickness 0.4mm Estimated Photon yield: ~800 photons/e @ 2.5kV (based on electroluminescence along the hole) A. Breskin IWAD Kolkata; October 28 2014 Arazi 2013 JINST 8 C12004 Single-THGEM in LXe: Alphas 34

35. Photon yield in THGEM in LXe Photon yield: ~800 photons/e/4  @ 2.5kV TOO MANY PHOTONS AT SUCH LOW FIELD IN THE HOLES: ~30kV/cm A. Breskin IWAD Kolkata; October 28 2014 Arazi 2013 JINST 8 C12004 35

36. Our present understanding: a “Bubble Chamber” Hypothesis: S2 is produced in a gas layer trapped under the THGEM (likely as bubbles) Steady S2 signals already at few kV/cm (as in Xe gas) S2 responds to pressure: – Disappears after step increase in P (bubbles collapse) – Reappears when decreasing P (bubbles form again) A. Breskin IWAD Kolkata; October 28 2014 36

37. Step increase in cold finger temperature  step increase in pressure  bubbling stops Chamber bottom temperature rising slowly, reaching a point of bubbles re-generation Bubbling is initially super-steady (nucleate boiling regime?)  high resolution Future : controlled bubbling by carefully-adjusted heating  super-high resolution Bubbles formation A. Breskin IWAD Kolkata; October 28 2014 37

38. S2 generation in bubbles is surprisingly steady Energy resolution with non- spectroscopic Alpha particles 14 Stability + controlled effect + resolution + low-field operation  should be exploited towards single-phase noble-liquid DM detectors! Repeatable S2 yields over many weeks 19/6 – 26/8 2014 Resolution ~ 14% ~same as in XENON100with PMTs! Several tens of photons/e- @ 3kV Oct. 2014 A. Breskin IWAD Kolkata; October 28 2014 38

39. Proposed Implementation in single-phase TPC THGEM top coated with CsI photocathode Resistive wires underneath, to form bubbles in controlled way In cascaded-LHM, bubbles formed in each element. S1 photoelectrons & S2 electrons trapped by the holes. They induce electroluminescence in the gas- bubbles. A. Breskin IWAD Kolkata; October 28 2014 39

40. Summary THGEM detectors THGEM detectors: Robust multipliers; numerous applications at Room Temperature; single- and cascaded elements Cryogenic THGEM detectors: Cryogenic THGEM detectors: - In noble-gas: gain limited due to UV-photon feedback - In “counting gases”: high gain GPM Applications: UV Gas Photomultipliers (GPM) in LXe Compton camera; LXe n/  radiography; Noble-liquid dark-matter detectors - Dual-phase LXe TPC: 4  readout  possible lower threshold  lower mass WIMPS LHM - Single-phase LXe TPC: Liquid Hole Multipliers (LHM)  4  GPM readout  potentially simpler approach for large-volume DM-TPCs LHM: LHM: electron & photon amplification through photon-assisted electroluminescence - Status: First signals recorded with  and  in  THGEM-holes in LXe - Photon multiplication factor in a single LHM: ~800photons/electron @ ~30kV/cm - NEW: experiment-supported hypothesis: electroluminescence in gas bubbles - Extensive studies in course towards a single-phase LHM-based LXe TPC New detector physics Applications beyond DM searches: Solar neutrino, Double Beta Decay… A. Breskin IWAD Kolkata; October 28 2014 We offer good postdoc positions in this field! 40