development of plasma panel particle detectors yiftah silver tel-aviv university dec. 18 2013
DESCRIPTION
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 UniversityDecTRANSCRIPT
Development of Plasma Panel Particle Detectors
Yiftah SilverTel-Aviv University
Dec. 18 2013
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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 PhysicsRobert Ball, J. W. Chapman, Claudio Ferretti, Daniel Levin,Curtis Weaverdyck, Riley Wetzel, Bing Zhou
• Oak Ridge National Laboratory, Physics DivisionRobert Varner, James Beene
• Ion Beam Applications S.A. (IBA, Belgium)Hassan Bentefour
• General Electric Company, Reuter-Stokes Division (Twinsburg, OH)Kevin McKinny, Thomas Anderson
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Outline
• Motivation
• Plasma display panel (PDP) operational principles
• Plasma panel sensor (PPS) description
• Simulations
• Lab results
• Next generation design
• Summary
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Motivations • Hermetically sealed
– no gas flow– no expensive and cumbersome gas system
• Over 40 years of plasma panel manufacturing & cost reductions ($0.03/cm2 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
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TV Plasma Panel Structure
A Display panel is complicated structure with
– MgO layer– dielectrics/rib– phosphors– protective layer
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TV Plasma Panel Structure
• For detector, a simplified version with readout & quench resistor
– No MgO layer– No dielectric/rib– No phosphors– No protective layer
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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)
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Commercial Panel Designs
• Two operational modes:– AC televisions, monitors
employ dielectric layers on electrodes
– DC dot-matrix displays
use directly facing metalized anodes & cathodes
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Commercial Plasma Panel• Columnar Discharge (CD) – Pixels at intersections of orthogonal
electrode array• Electrodes sizes and pitch vary between different panels
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220 – 450 µm
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PPS with CD-Electrode Structure (≈ 20-25% active cell/pixel fill-factor)
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PDP PPS1. Remove or procure without gas 2. Alter manufacturer’s electrode material (replace SnO2 with Ni )3. Add a custom gas port and high quality VCR valve4. Subject panel to extended pump down, bake-out 5. Fill with commercial or in-house gas mixture6. 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
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Modified Commercial Panel (fill-factor 23.5%, cell pitch 2.5 mm)
“Refillable” gas shut-off valve
for R&D testing
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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 -1
mm
50 µm -1mm
• Gas gap becomes conductive• Voltage drops on quench
resistor • E-field inside the pixel drops• Discharge terminates
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A.K. Bhattacharya, GE CorPhys. Rev. A, 13,3 (1975)
14
Small variations in Penning mixtures dramatically affect breakdown voltage
Paschen discharge potential
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V610
510
410
310
[ ]pd Torr cm
010 210 310110
x = pressure * gap x0 = 1 Torr cm a, b = gas specific parameters
V
Lieberman and Lichtenberg, Principles of Plasma Discharges, Wiley 2005.
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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
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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 simulatedSingle cell SPICE model
Many cells SPICE modelY. Silver Tel-Aviv UniversityDec. 18 2013
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SPICE Simulated Signal
free parameterstotal charge, width of “” function
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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
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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
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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”
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Signals from Panel
1. Signals amplitudes: volts2. 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 & 3He fill
30 V
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1 mm electrode pitch
2.5 mm electrode pitch
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Response to Source
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vs applied High Voltage
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Quench Resistance Dependence ( Characteristic Response Curve )
Satu
ratio
n
Working Region
Secondary Pulses
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Position SensitivityProton Test beam & Lab
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PPS Proton Test Beam
March 2012
IBA ProCure Facility - Chicago
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• 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
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Position Scan• Two position scans (panel filled with 1% CO2 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
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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
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Collimated Source Position Scan
Motorized X-Y table Test Panel
• Light-tight , RF shielded box
• 1 mm pitch panel
• 20 readout lines • 1.25 mm wide
graphite collimator
106Ru collimated source
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Collimated β-Source Simulation
Primary electrons exiting the graphite collimator
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Dispersion of β-Particles in Panel(simulation)
Geant4 simulation:106Ru ’s 1.25 mm slit collimator2.25 mm glass
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Source Moved in 0.1 mm Increments(1 mm pitch panel)
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PPS Position ScanMean fit for β-source moved in 0.1 mm increments
*
*Electrode Pitch 1.0 mmCentroid measurement consistent with electrode pitch
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Position Resolution/Dispersion
Electrode Pitch = 1.0 mm
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source
2res = 2
meas - 2MC
Position resolution < 1 mm
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PPS Cosmic-Ray Muon Results
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Cosmic Muon Measurement Setup
30 HV lines24 RO channels
Trigger is 3” x 4’’ scintillation pads
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CR Muon Response
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2.5 days
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Response over active region
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All channels active
exhibit similar levels of activity
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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% CF4at 730 Torr
1100V
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= 40.1 0.9
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Time Spectrum
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Ar / 1% CF4 at 730 Torr
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Timing Resolution vs. Applied HV
930 980 1030 1080 1130 1180 1230 1280 1330 1380200
250
300
350
400
450
500
550
600
650
Volt
nsec Ar / 1% CF4, 600 Torr
Ar / 1% CF4, 730 TorrAr / 10% CF4, 730 Torr
930 980 1030 1080 1130 1180 1230 1280 1330 13800
20
40
60
80
100
120
140
160
180
200
Volt
nsec Ar / 1% CF4, 600 Torr
Ar / 1% CF4, 730 TorrAr / 10% CF4, 730 Torr
Mean arrival time Sigma of arrival time
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Timing Resolution using 65% He 35 % CF4 at 730 Torr
HV =1290 V
~ 10 ns
• trigger time subtracted;• arbitrary cable offset
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Timing Resolution using 80% 3He 20 % CF4 at 730 Torr
HV =1030 V
~ 3.5 ns
• trigger time subtracted;• arbitrary cable offset
trigger artifacts
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PPS Area Corrected Efficiency (10% CF4 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
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PPS Muon Test Beam
November 2012
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Setup
180 GeV BEAM
2 scintillation pads 4 cm2 each
Ni-SnO2 PPSAr / 7% CO2
600 TorrHV = 1090 V
16 channels
8 HV lines 100 MΩ quenched
Panel active area is 2 cm x 4 cm
AND
OR
AND
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Time Resolution
• Timing resolution with Ar-CO2 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%
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Neutron Detectionin collaboration with GE, Reuter-Stokes
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Objectives: high efficiency neutron detectors with high rejection develop alternate to 3He as neutron interaction medium
This test: explore PPS as a general detector structure for converting neutrons using thin gap 3He gas mixture
Gas fill: 80% 3He + 20% CF4 at 730 Torr
Panel: 2.5 mm pitch large panel used for CR muons Instrumented pixels = 600 Area: 6 in2
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.
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neutron sources
252 Cf , 241Am-Be, 239Pu-Be
nested in stainless capsule, Pb cylinder, high density polyethylene (HDPE)
Gamma transparent, neutron blocking plates
(~ 0.1% transmission ) PPS panel
Setup
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Results PPS panel
Neutron blocking plate
neutron source ( 252 Cf )
Background subtracted datais neutrons only
efficiency plateau
Background: from source
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PPS panel
3x105 /sec at instrumented region
g source ( 137 Cs )
Reasonably good rejection before any optimizations offered by:
thin substrateslower gas pressurethinner metallizationImproving internal dielectrics around pixels
VPE HV (V)
detection rate Hz
efficiency
970 0.09 3.0e-07
1000 1.2 3.7e-06
1030 7.9 2.5e-05
Rejection
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Spatial Position
PPS panel
blocking plate with 5 mm slit
neutron source (239Pu-Be)
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Microcavity-PPS
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Microcavity Concept
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E-field
glass
Equipotential lines
COMSOL simulation:
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radial discharge gaps cavity depth longer path lengthsindividually quenched cells isolation from neighbors
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Microcavity Prototype (Back Plate)
Via Plug
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Sealed Microcavity-PPS
Bottom Half of “Open” Bakeout Oven
Microcavity-PPS attached to vacuum-line / gas-fill system
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SummaryWe 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 (3He ) ] & 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
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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
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Cathodes: metalized inner cavity surfaces connected to HV bus with resistive via Anodes: pads on top plate
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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.
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