1. Development of Plasma Panel Particle Detectors Yiftah Silver Tel-Aviv University Dec. 18 2013

2. 2222 Collaborators Tel Aviv University, School of Physics & Astronomy Yan Benhammou, Meny Ben Moshe, Erez Etzion, Yiftah Silver Integrated Sensors, LLC Peter Friedman University of Michigan, Department of Physics Robert Ball, J. W. Chapman, Claudio Ferretti, Daniel Levin, Curtis Weaverdyck, Riley Wetzel, Bing Zhou Oak Ridge National Laboratory, Physics Division Robert Varner, James Beene Ion Beam Applications S.A. (IBA, Belgium) Hassan Bentefour General Electric Company, Reuter-Stokes Division (Twinsburg, OH) Kevin McKinny, Thomas Anderson Y. Silver Tel-Aviv UniversityDec. 18 2013

3. 3333 Outline Motivation Plasma display panel (PDP) operational principles Plasma panel sensor (PPS) description Simulations Lab results Next generation design Summary Y. Silver Tel-Aviv UniversityDec. 18 2013

4. 444 Motivations Hermetically sealed – no gas flow – no expensive and cumbersome gas system Over 40 years of plasma panel manufacturing & cost reductions ( $ 0.03/cm 2 for plasma panel TVs) Potential for scalable dimensions, low mass profile, long life – meter size with thin substrate capability Potential to achieve contemporary performance benchmarks – Timing resolution  approx 1 ns – Granularity (cell pitch)  50-200 µm – Spatial resolution  tens of µm Potential applications in – Nuclear and high energy physics, medical imaging, homeland security, etc Y. Silver Tel-Aviv UniversityDec. 18 2013

5. 5555 TV Plasma Panel Structure A Display panel is complicated structure with – MgO layer – dielectrics/rib – phosphors – protective layer Y. Silver Tel-Aviv UniversityDec. 18 2013

6. 6666 TV Plasma Panel Structure For detector, a simplified version with readout & quench resistor – No MgO layer – No dielectric/rib – No phosphors – No protective layer Y. Silver Tel-Aviv UniversityDec. 18 2013

7. 777 Commercial Panel Designs Two basic configurations for the electrodes: CD and SD Discharge dimensions ≈ 100 µm Gas pressure ≈ 400-600 Torr (usually Ne, Xe, Ar, Kr, He) Applied voltage typically hundreds of volts Surface Discharge (SD) Columnar Discharge (CD) Y. Silver Tel-Aviv UniversityDec. 18 2013

8. 888 Commercial Panel Designs Two operational modes: – AC  televisions, monitors employ dielectric layers on electrodes – DC  dot-matrix displays use directly facing metalized anodes & cathodes Y. Silver Tel-Aviv UniversityDec. 18 2013

9. 999 Commercial Plasma Panel Columnar Discharge (CD) – Pixels at intersections of orthogonal electrode array Electrodes sizes and pitch vary between different panels Y. Silver Tel-Aviv University 220 – 450 µm Dec. 18 2013

10. 10 PPS with CD-Electrode Structure (≈ 20-25% active cell/pixel fill-factor) Y. Silver Tel-Aviv UniversityDec. 18 2013

11. 11 PDP  PPS 1.Remove or procure without gas 2.Alter manufacturer’s electrode material (replace SnO 2 with Ni ) 3.Add a custom gas port and high quality VCR valve 4.Subject panel to extended pump down, bake-out 5.Fill with commercial or in-house gas mixture 6.Close valve, mount panel for exposure to source or CR trigger 7.Configure with HV feed, quench resistors, signal readout & DAQ  Panels operable for several months (even 1 year) after gas-filling without hermetic seal (i.e. only with “closed” shut-off valve)  Investigate the behavior for different conditions – Gas composition, pressure, HV, termination, Electrode materials – Sources and Configurations , CR & test beam muons, beam protons, neutrons, gammas Triggered, untriggered, collimated, uncollimated Y. Silver Tel-Aviv UniversityDec. 18 2013

12. 12 Modified Commercial Panel (fill-factor 23.5%, cell pitch 2.5 mm) “Refillable” gas shut-off valve for R&D testing Y. Silver Tel-Aviv UniversityDec. 18 2013

13. 13 Principles of Operation Accelerated electrons begin avalanche Large electric field leads to streamers Streamers lead to breakdown - roughly follows Paschen’s law. “A Theory of Spark Discharge”, J. M. Meek, Phys. Rev. 57, 1940 anode cathode Charged particle track HV(-) 50-100  10-1000 M  Gas volume in pixel 250 µm -1mm 50 µ m -1mm Gas gap becomes conductive Voltage drops on quench resistor E-field inside the pixel drops Discharge terminates Y. Silver Tel-Aviv UniversityDec. 18 2013

14. A.K. Bhattacharya, GE Cor Phys. Rev. A, 13,3 (1975) 14 Small variations in Penning mixtures dramatically affect breakdown voltage Paschen discharge potential Y. Silver Tel-Aviv University x = pressure * gap x 0 = 1 Torr cm a, b = gas specific parameters V Lieberman and Lichtenberg, Principles of Plasma Discharges, Wiley 2005. Dec. 18 2013

15. 15 Electromagnetic Field Model Each cell is modeled as a capacitor COMSOL model for the electric field inside the cell Capacitances and inductances are also calculated E-field in the PDP pixels 5 mm 0 -5 mm E-field is localized No E-field Y. Silver Tel-Aviv UniversityDec. 18 2013

16. 16 Equivalent Circuit Simulations SPICE simulation incorporates the inductances and capacitances calculated with COMSOL Electrical pulse is injected into the cell and the output signal is simulated Single cell SPICE model Many cells SPICE model Y. Silver Tel-Aviv UniversityDec. 18 2013

17. 17 SPICE Simulated Signal free parameters total charge, width of “  ” function Y. Silver Tel-Aviv UniversityDec. 18 2013

18. 18 Design & Operating Parameters Cell Design: fill-factor - open vs. closed architecture - columnar vs. surface discharge Electrodes: pitch, width, material Cell capacitance Operating voltage Quench resistance Gas mixture & pressure Substrate material (e.g. thickness, density) Dielectric surfaces Y. Silver Tel-Aviv UniversityDec. 18 2013

19. 19 Performance Issues ( some of which we have begun to address ) After pulsing & discharge spreading Gas hermeticity & decomposition Response in magnetic field Electrode degradation Radiation hardness High rate response Spatial uniformity Spatial response Time response Efficiency Readout Cost Y. Silver Tel-Aviv UniversityDec. 18 2013

20. 20 Experimental Results All results reported here obtained with prototype detectors adapted from: glass sealed, open architecture, columnar discharge, monochromatic, DC display panels shut-off valve “seal” Y. Silver Tel-Aviv UniversityDec. 18 2013

21. 21 Signals from Panel 1.Signals amplitudes: volts 2.Good signal to noise ratios. 3.Fast rise times O(ns) 4.Pulse shape uniform for a given panel design  pulse from Xe fill 2003, tested 2010  panel sealed & tested in 2013, pulse from neutron source & 3 He fill 30 V Y. Silver Tel-Aviv University 1 mm electrode pitch 2.5 mm electrode pitch Dec. 18 2013

22. 22 Response to  Source Y. Silver Tel-Aviv University vs applied High Voltage Dec. 18 2013

23. 23 Quench Resistance Dependence ( Characteristic Response Curve ) Saturation Working Region Secondary Pulses Y. Silver Tel-Aviv UniversityDec. 18 2013

24. 24 Position Sensitivity Proton Test beam & Lab Y. Silver Tel-Aviv University24Dec. 18 2013

25. 25 PPS Proton Test Beam March 2012 IBA ProCure Facility - Chicago Y. Silver Tel-Aviv UniversityDec. 18 2013

26. 26 Beam energy 226 MeV, Gaussian distributed with 0.5 cm width Proton rate was larger than 1 GHz on the entire spread of the beam IBA Proton Beam Test Y. Silver Tel-Aviv UniversityDec. 18 2013

27. 27 Position Scan Two position scans (panel filled with 1% CO 2 in Ar at 600 Torr) – 1 cm steps - using brass collimator with 1 cm hole, 2.5 cm from beam center – 1 mm steps with 1 mm hole directly in beam center Rate of protons through 1 mm hole in center of beam was measured at 2 MHz The Panel Y. Silver Tel-Aviv UniversityDec. 18 2013

28. 28 1 mm Scan Number of hits per channel Reconstructed centroid of hit map vs. PDP relative displacement with respect to the panel’s initial position Y. Silver Tel-Aviv UniversityDec. 18 2013

29. 29 Collimated Source Position Scan Motorized X-Y tableTest Panel Light-tight, RF shielded box 1 mm pitch panel 20 readout lines 1.25 mm wide graphite collimator 106 Ru collimated source Y. Silver Tel-Aviv UniversityDec. 18 2013

30. 30 Collimated β -Source Simulation Primary electrons exiting the graphite collimator Y. Silver Tel-Aviv UniversityDec. 18 2013

31. 31 Dispersion of β -Particles in Panel (simulation) Geant4 simulation: 106 Ru  ’s 1.25 mm slit collimator 2.25 mm glass Y. Silver Tel-Aviv UniversityDec. 18 2013

32. 32 Source Moved in 0.1 mm Increments (1 mm pitch panel) Y. Silver Tel-Aviv UniversityDec. 18 2013

33. 33 PPS Position Scan Mean fit for β-source moved in 0.1 mm increments * *Electrode Pitch 1.0 mm Centroid measurement consistent with electrode pitch Y. Silver Tel-Aviv UniversityDec. 18 2013

34. 34 Position Resolution/Dispersion Electrode Pitch = 1.0 mm Y. Silver Tel-Aviv University  source  2 res =  2 meas -  2 MC Position resolution < 1 mm Dec. 18 2013

35. 35 PPS Cosmic-Ray Muon Results Y. Silver Tel-Aviv UniversityDec. 18 2013

36. 36 Cosmic Muon Measurement Setup 30 HV lines 24 RO channels Trigger is 3” x 4’’ scintillation pads Y. Silver Tel-Aviv UniversityDec. 18 2013

37. 37 CR Muon Response Y. Silver Tel-Aviv University 2.5 days Dec. 18 2013

38. 38 Response over active region Y. Silver Tel-Aviv University All channels active exhibit similar levels of activity Dec. 18 2013

39. 39 Time Spectrum Pulse “arrival” time (includes arbitrary trigger offset)  = timing resolution (jitter) of the detector We repeat this measurement with various gases and voltages Ar / 1% CF4 at 730 Torr 1100V Y. Silver Tel-Aviv University  = 40.1  0.9 Dec. 18 2013

40. Time Spectrum 40 Ar / 1% CF 4 at 730 Torr Y. Silver Tel-Aviv UniversityDec. 18 2013

41. 41 Timing Resolution vs. Applied HV Ar / 1% CF4, 600 Torr Ar / 1% CF4, 730 Torr Ar / 10% CF4, 730 Torr Ar / 1% CF4, 600 Torr Ar / 1% CF4, 730 Torr Ar / 10% CF4, 730 Torr Mean arrival time Sigma of arrival time Y. Silver Tel-Aviv UniversityDec. 18 2013

42. Y. Silver Tel-Aviv University42 Timing Resolution using 65% He 35 % CF4 at 730 Torr HV =1290 V  ~ 10 ns trigger time subtracted; arbitrary cable offset Dec. 18 2013

43. Y. Silver Tel-Aviv University43 Timing Resolution using 80% 3 He 20 % CF4 at 730 Torr HV =1030 V  ~ 3.5 ns trigger time subtracted; arbitrary cable offset trigger artifacts Dec. 18 2013

44. 44 PPS Area Corrected Efficiency (10% CF 4 in Ar, at 740 Torr, 0.38 mm gas gap) Maximum Pixel Efficiency: 60% pixel efficiency = 53% ( 88% of maximum possible) Assumptions: Uniform trigger response Constant effective pixel size Y. Silver Tel-Aviv UniversityDec. 18 2013

45. PPS Muon Test Beam November 2012 H8 at CERN

46. 46 Setup 180 GeV BEAM 2 scintillation pads 4 cm 2 each Ni-SnO 2 PPS Ar / 7% CO 2 600 Torr HV = 1090 V 16 channels 8 HV lines 100 MΩ quenched Panel active area is 2 cm x 4 cm ANDOR AND Y. Silver Tel-Aviv UniversityDec. 18 2013

47. 47 Time Resolution Timing resolution with Ar-CO 2 better than 10 nsec Geometrical acceptance times efficiency ≈ 2% (pixel efficiency is much higher). Did not have beam time to optimize or even raise the voltage! Active area fill-factor for PPS detector is 23.5% Y. Silver Tel-Aviv UniversityDec. 18 2013

48. Neutron Detection in collaboration with GE, Reuter-Stokes Y. Silver Tel-Aviv University48 Objectives: high efficiency neutron detectors with high  rejection develop alternate to 3 He as neutron interaction medium This test: explore PPS as a general detector structure for converting neutrons using thin gap 3 He gas mixture Gas fill: 80% 3 He + 20% CF 4 at 730 Torr Panel: 2.5 mm pitch large panel used for CR muons Instrumented pixels = 600 Area: 6 in 2 Method: irradiate panel with thermal neutrons from various sources high activity (10 mrem/hr) gammas conduct count rates experiment with & w/o neutron mask plates. Dec. 18 2013

49. Y. Silver Tel-Aviv University49 neutron sources 252 Cf, 241 Am-Be, 239 Pu-Be nested in stainless capsule, Pb cylinder, high density polyethylene (HDPE) Gamma transparent, neutron blocking plates (~ 0.1% transmission )  PPS panel Setup Dec. 18 2013

50. Y. Silver Tel-Aviv University50 Results PPS panel Neutron blocking plate neutron source ( 252 Cf ) Background subtracted data is neutrons only efficiency plateau Background:  from source Dec. 18 2013

51. Y. Silver Tel-Aviv University51 PPS panel 3x10 5  /sec at instrumented region  source ( 137 Cs ) Reasonably good  rejection before any optimizations offered by: thin substrates lower gas pressure thinner metallization Improving internal dielectrics around pixels VPE HV (V)  detection rate Hz  efficiency 9700.093.0e-07 10001.23.7e-06 10307.92.5e-05  Rejection Dec. 18 2013

52. Y. Silver Tel-Aviv University52 Spatial Position PPS panel blocking plate with 5 mm slit neutron source ( 239 Pu-Be) Dec. 18 2013

53. 53 Microcavity-PPS Y. Silver Tel-Aviv UniversityDec. 18 2013

54. 54 Microcavity Concept 54 E-field glass Equipotential lines COMSOL simulation: Y. Silver Tel-Aviv University radial discharge gaps cavity depth  longer path lengths individually quenched cells isolation from neighbors Dec. 18 2013

55. 55 Microcavity Prototype (Back Plate) Via Plug Y. Silver Tel-Aviv UniversityDec. 18 2013

56. 56 Sealed Microcavity-PPS Bottom Half of “Open” Bakeout Oven Microcavity-PPS attached to vacuum-line / gas-fill system Y. Silver Tel-Aviv UniversityDec. 18 2013

57. 57 Summary We have demonstrated functioning of modified plasma displays as highly pixelated arrays of micro-discharge counters – sensitive to highly ionizing & minimum ionizing charged particles:  ’s,  ’s CR and test beam, intense proton beams, neutrons [with appropriate conversion ( 3 He ) ] & high  rejection – Panels have operated for up to 1 year (sealed only by valve) – Timing resolution < 10 ns, approaching 3 ns for some gasses – Spatial response at level of pixel granularity Y. Silver Tel-Aviv UniversityDec. 18 2013

58. 58 Near Term Efforts Near term effort – microcavity PPS program Final fabrication & initial testing – 2D readout – Pursue higher resolution panels, faster timing – stacked panels for tracking Y. Silver Tel-Aviv UniversityDec. 18 2013

59. Y. Silver Tel-Aviv University59 Cathodes: metalized inner cavity surfaces connected to HV bus with resistive via Anodes: pads on top plate Dec. 18 2013

60. Y. Silver Tel-Aviv University60 Example of microcavity arrays produced by chemical etching processes commonly used in PDP fabrication. Cavity scale is 100 microns. Yong-Seog Kim, Woong Sik Kim, Yoo-Seong Kim, “Cost Effective Technologies for Barrier Rib Processing of HD PDPs” (Invited Paper), SID 2006 Digest of Technical Papers, Vol. XXXVII (June 2006), 1480-1483. Dec. 18 2013