Development of Plasma Panel Based Neutron Micropattern Detectors

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Development of Plasma Panel Based Neutron Micropattern

DetectorsYan Benhammou

Tel Aviv Universityfor the PPS Collaboration

Oct 15, 2013

14/10/13 Y. Benhammou Tel Aviv University

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Collaborators• University of Michigan, Department of Physics

Robert Ball, J. W. Chapman, Claudio Ferretti, Daniel Levin (PI), Curtis Weaverdyck, Riley Wetzel, Bing Zhou

• Integrated Sensors, LLC Peter Friedman (PI)

• Oak Ridge National Laboratory, Physics Division Robert Varner (PI) , James Beene

• Tel Aviv University (Israel), School of Physics & AstronomyYan Benhammou, Meny Ben Moshe, Erez Etzion (PI), Yiftah Silver

• General Electric Company, Reuter-Stokes Division (Twinsburg, OH)Kevin McKinny (PI), Thomas Anderson

• Ion Beam Applications S.A. (IBA, Belgium)Hassan Bentefour (PI)


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Outline

• Motivation

• Plasma panel operational principles and description

• Neutrons detection

• 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 Plasma Panel• Columnar Discharge (CD) – Pixels at intersections of orthogonal

electrode array• Electrodes sizes and pitch vary between different panels


220 – 450 µm

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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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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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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


1 mm electrode pitch

2.5 mm electrode pitch

Neutron Detectionin collaboration with GE, Reuter-Stokes

14/10/13 Y. Benhammou Tel Aviv University 11

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.


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

Signal from neutrons


• Pulse “arrival” time (includes arbitrary trigger offset)

• = timing resolution (jitter) of the detector

~ 3ns

5 ns


Results PPS panel

Neutron blocking plate

neutron source ( 252 Cf )

Background subtracted datais neutrons only

efficiency plateau

Background: from source

results

• GE Geant4 simulation of the neutron capture rate based on source activity: 0.70 ± 0.14 Hz

• PPS measured rate: 0.67 ± 0.02 Hz


Approximately 100% of the captured neutrons were detected


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


Spatial Position

PPS panel

blocking plate with 5 mm slit

neutron source (239Pu-Be)

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SummaryWe have demonstrated functioning of modified plasma displays as

highly pixelated arrays of micro-discharge counters

– Sensitive neutrons [with appropriate conversion (3He ) ] & high rejection

– Timing resolution less than 3 ns

– Spatial response at level of pixel granularity

– New PPS devices start to be designed to replace the He-3 panel tested using B-10 and Gd-157 conversion layers. They should use much thinner substrates to improve gamma/neutron discrimination ratio. Should be ready next year.


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Microcavity-PPS


202020202020

Microcavity Concept

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E-field

glass

Equipotential lines

COMSOL simulation:


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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Position Sensitivity


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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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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

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*Electrode Pitch 1.0 mmCentroid measurement consistent with electrode pitch


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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 thru 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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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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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


= 40.1 0.9

Time Spectrum

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Ar / 1% CF4 at 730 Torr



Timing Resolution using 65% He 35 % CF4 at 730 Torr

HV =1290 V

~ 10 ns

• trigger time subtracted;• arbitrary cable offset

PPS Muon Test Beam

November 2012

H8 at CERN

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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%


Documents

Development of Plasma Panel Based Neutron Micropattern Detectors