A COMPLETE MICRO/NANOSYSTEM SOLUTION FOR ALPHA, BETA, GAMMA, AND NEUTRON DETECTION

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A COMPLETE MICRO/NANOSYSTEM SOLUTION FOR ALPHA,
BETA, GAMMA, AND NEUTRON DETECTION

• Dr. Chester Wilson
• Louisiana Tech University
• President, Cybercorps Interactive

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Why Is Nuclear Energy a Big Part of The Answer?

• Decades of operational safety exceeding other
  energy producers.
• Zero greenhouse gas emissions.
• Fantastic power densities.
• Domestic energy production.

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Why Is Nuclear Energy a Big Part of The Answer?

• Decades of operational safety exceeding other
  energy producers.
• Zero greenhouse gas emissions.
• Fantastic power densities.
• Domestic energy production.
• Around 40 of plant fuel comes from reprocessed
  ex-soviet nuclear weapons.

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Weapons Grade Plutonium Becoming Energy
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Other Guys Want it Too
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Traditional Radiation Detectors
Traditional Method of Detection is Geiger
Counter. Problem Most detect Alphas, Betas,
Gammas, but not Neutrons. He3 and BF3 tubes
detect neutrons, but are toxic and expensive.
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Traditional Radiation Detectors
Traditional Method of Detection is Geiger
Counter. Problem Most detect Alphas, Betas,
Gammas, but not Neutrons. He3 and BF3 tubes
detect neutrons, but are toxic and expensive.
Important because weapons grade plutonium emits
neutrons, not much else does
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How do you shield neutrons?
Terrorist
Lead ?
Bomb Maker
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Neutrons vs. Lead

• Neutron interacting with Pb

• Since the mass of the neutron is much smaller
  than the larger Pb atoms, the neutron recoils
  without losing much energy. The neutrons
  continuously bounce around able to exit the lead
  shielding.

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NEED FOR DETECTORS
Terrorist
Plastic ?
Bomb Maker
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NEED FOR DETECTORS
Neutron interacting with H

• Since the mass of the neutron is approximately
  equal to the H atoms, the neutron can transfer up
  to its full energy. The recoil H nuclei has a
  small range losing energy quickly.

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Nanoparticle Neutron Detection
Gadolinium oxide is opaque, but
Transparency! This scintillator is loaded with
30 gadolinium oxide, but because the
nanoparticles are too small to scatter light, it
is transparent.
And this allows a patternable film to make
imaging Arrays with better spatial resolution
and gamma selectivity.
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Nanoparticle Neutron Detection
Neutron detection is enabled through gadolinium
nanoparticles, 255,000 barn absorption 1000X
smaller than anything else. Measurements taken at
Entergy Nuclears Grand Gulf Facility
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Four Channel Device

• Problem limited to the types of radiation
  detected
• Solution dope with charge conversion
  nanoparticles

Radiation impinging on tailored nanoparticles
create electrons, which
scintillates a background matrix. WO3 Beta
Detection Pb3O4 Gamma/X-ray Detection Glass
Alpha Detection Gd2O3 Neutron Detection
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DEVICE DESIGN

• Four channels embedded into a sandblasted glass
  substrate
• Optical cross talk barrier to reduce cross talk
  between detector channels

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RESULTS

• Gamma detection
• 60Co emits both gammas and betas so lead sheets
  are used to block betas in order to detect only
  gammas and demonstrate the difficulty in
  shielding gammas.

Pulse height spectroscopy Tailored resins use
different conversion mechanisms producing varying
PM tube outputs
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MULTIPLE LAYERSMORE INFORMATION

• Varying thicknesses for top layer scintillator
  allows for different count rates
• Energy spectroscopy capability by determining
  where the energy deposition took place as a
  function of top layer thickness

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RESULTS

• Bottom layer
• With a decay constant of 285 ns, the
  created photons do not produce a ringing pulse.

• Top layer
• With a decay constant of 2.3 ns, the created
  photons produce a ringing pulse.

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PRINTED CIRCUIT BOARD

• Power
• Converter

High Voltage
Pulse Shaping
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PRINTED CIRCUIT BOARD

• Design the printed circuit board using Eagle
  software.

• Autoroute function to layout the copper traces
  after the components are placed.

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Microscale Photomultiplier Tube

• Photomultiplier tube components

• Photocathode
• Series of Dynodes
• Anode

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Beating the State of the Art

• The count rates increase from non-doped
  scintillator to heavier doped scintillator.
• Neutron sensitivity around 11 vs. around 0.2 on
  tube

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Working Towards Cheap Pen Size Detector

• Fully integrated radiation detector
• Build smaller and cheaper components
• Integrated Circuits
• Miniaturized PM tube
• Goal
• Hockey puck style detector
• Pager sized
• Eventually pen sized

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Thanks

• Funding Sources
• Entergy Nuclear
• Department of Energy
• National Science Foundation
• Office of the Director of National Intelligence