Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Homeland Defense: Novel Radiation Surveillance Technology Could Help Thwart Nuclear Terrorism

Examples of scintillators that were produced from molten glass by the researchers. The wormlike blue structure is an artifact from the glass-molding process. (Credit: Gary Meek)
Examples of scintillators that were produced from molten glass by the researchers. The wormlike blue structure is an artifact from the glass-molding process.

(Credit: Gary Meek)

Abstract:
Among terrorism scenarios that raise the most concern are attacks involving nuclear devices or materials. For that reason, technology that can effectively detect smuggled radioactive materials is considered vital to U.S. security.

Homeland Defense: Novel Radiation Surveillance Technology Could Help Thwart Nuclear Terrorism

Atlanta, GA | Posted on May 1st, 2012

To support the nation's nuclear-surveillance capabilities, researchers at the Georgia Tech Research Institute (GTRI) are developing ways to enhance the radiation-detection devices used at ports, border crossings, airports and elsewhere. The aim is to create technologies that will increase the effectiveness and reliability of detectors in the field, while also reducing cost. The work is co-sponsored by the Domestic Nuclear Defense Office of the Department of Homeland Security and by the National Science Foundation.

"U.S. security personnel have to be on guard against two types of nuclear attack - true nuclear bombs, and devices that seek to harm people by dispersing radioactive material," said Bernd Kahn, a researcher who is principal investigator on the project. "Both of these threats can be successfully detected by the right technology."

The GTRI team, led by co-principal investigator Brent Wagner, is utilizing novel materials and nanotechnology techniques to produce improved radiation detection. The researchers have developed the Nano-photonic Composite Scintillation Detector, a prototype that combines rare-earth elements and other materials at the nanoscale for improved sensitivity, accuracy and robustness.

Details of the research were presented April 23, 2012 at the SPIE Defense, Security, and Sensing Conference held in Baltimore, MD.

Scintillation detectors and solid-state detectors are two common types of radiation detectors, Wagner explained. A scintillation detector commonly employs a single crystal of sodium iodide or a similar material, while a solid-state detector is based on semiconducting materials such as germanium.

Both technologies are able to detect gamma rays and subatomic particles emitted by nuclear material. When gamma rays or particles strike a scintillation detector, they create light flashes that are converted to electrical pulses to help identify the radiation at hand. In a solid-state detector, incoming gamma rays or particles register directly as electrical pulses.

"Each reaction to a gamma ray takes a very short time - a fraction of a microsecond," Wagner said. "By looking at the number and the intensity of the pulses, along with other factors, we can make informed judgments about the type of radioactive material we're dealing with."

But both approaches have drawbacks. A scintillation detector requires a large crystal grown from sodium iodide or other materials. Such crystals are typically fragile, cumbersome, difficult to produce and extremely vulnerable to humidity.

A germanium-based solid-state detector offers better identification of different kinds of nuclear materials. But high-purity single-crystal germanium is difficult to make in a large volume; the result is less-sensitive devices with reduced ability to detect radiation at a distance. Moreover, germanium must be kept extremely cold - 200 degrees below zero Celsius -- to function properly, which poses problems for use in the field.

The Nanoscale Advantage

To address these problems, the GTRI team has been investigating a wide variety of alternative materials and methodologies. After selecting the scintillation approach over solid-state, the researchers developed a composite material -- composed of nanoparticles of rare-earth elements, halides and oxides -- capable of creating light.

"A nanopowder can be much easier to make, because you don't have to worry about producing a single large crystal that has zero imperfections," Wagner said.

A scintillator crystal must be transparent to light, he explained, a quality that's key to its ability to detect radiation. A perfect crystal uniformly converts incoming energy from gamma rays to flashes of light. A photo-multiplier then amplifies these flashes of light so they can be accurately measured to provide information about radioactivity.

However, when a transparent material - such as crystal or glass -- is ground into smaller pieces, its transparency disappears. As a result, a mixture of particles in a transparent glass would scatter the luminescence created by incoming gamma rays. That scattered light can't reach the photo-multiplier in a uniform manner, and the resulting readings are badly skewed.

To overcome this issue, the GTRI team reduced the particles to the nanoscale. When a nanopowder reaches particle sizes of 20 nanometers or less, scattering effects fade because the particles are now significantly smaller than the wavelength of incoming gamma rays.

"Think of it as a big ocean wave coming in," Wagner said. "That wave would definitely interact with a large boat, but something the size of a beach ball doesn't affect it."

Rare Earths and Silica

At first the team worked on dispersing radiation-sensitive crystalline nanoparticles in a plastic matrix. But they encountered problems with distributing the nanopowder uniformly enough in the matrix to achieve sufficiently accurate radiation readings.

More recently, the researchers have investigated a parallel path using glass rather than plastic as a matrix material, combining gadolinium and cerium bromide with silica and alumina.

Kahn explained that gadolinium or a similar material is essential to scintillation-type particle detection because of its role as an absorber. But in this case, when an incoming gamma ray is absorbed in gadolinium, the energy is not efficiently emitted in the form of luminescence.

Instead, the light emission role here falls to a second component - cerium. The gadolinium absorbs energy from an incoming gamma ray and transfers that energy to the cerium atom, which then acts as an efficient light emitter.

The researchers found that by heating gadolinium, cerium, silica and alumina and then cooling them from a molten mix to a solid monolith, they could successfully distribute the gadolinium and cerium in silica-based glasses. As the material cools, gadolinium and cerium precipitate out of the aluminosilicate solution and are distributed throughout the glass in a uniform manner. The resulting composite gives dependable readings when exposed to incoming gamma rays.

"We're optimistic that we've identified a productive methodology for creating a material that could be effective in the field," Wagner said. "We're continuing to work on issues involving purity, uniformity and scaling, with the aim of producing a material that can be successfully tested and deployed."

This material is based upon work supported by the U.S. Department of Homeland Security under Grant Award Number 2008-DN-077-ARI001-02. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Department of Homeland Security.

Writer: Rick Robinson

####

For more information, please click here

Contacts:
Research News & Publications Office
Georgia Institute of Technology
75 Fifth Street, N.W., Suite 314
Atlanta, Georgia 30308 USA

Media Relations Contacts:
John Toon
404-894-6986


Kirk Englehardt
404-894-6015

Copyright © Georgia Institute of Technology

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Designing ultrasound tools with Lego-like proteins August 29th, 2016

A nanoscale wireless communication system via plasmonic antennas: Greater control affords 'in-plane' transmission of waves at or near visible light August 27th, 2016

Forces of nature: Interview with microscopy innovators Gerd Binnig and Christoph Gerber August 26th, 2016

A promising route to the scalable production of highly crystalline graphene films August 26th, 2016

Law enforcement/Anti-Counterfeiting/Security/Loss prevention

Nanotech Security Featured by Simon Fraser University: Company's Anti-Counterfeiting Technology Developed With the Help of University's 4D LABS Materials Research Institute August 21st, 2016

Down to the wire: ONR researchers and new bacteria August 18th, 2016

Hexagonal boron nitride semiconductors enable cost-effective detection of neutron signals: Texas Tech University researchers demonstrate hexagonal boron nitride semiconductors as a cost-effective alternative for inspecting overseas cargo containers entering US ports August 17th, 2016

'Sniffer plasmons' could detect explosives: Scientists have proposed a graphene-based spaser that can detect even small amounts of various substances, including explosives August 16th, 2016

Powders

NRL reveals novel uniform coating process of p-ALD April 21st, 2016

Ceramics and Nanoceramic Powders Market To 2015: Acute Market Reports July 20th, 2015

Global Nanoclays Market Analysis, Size, Growth, Trends And Segment Forecasts, 2015 To 2022: Grand View Research, Inc June 15th, 2015

Reducing energy usage with nano-coatings April 9th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Analog DNA circuit does math in a test tube: DNA computers could one day be programmed to diagnose and treat disease August 25th, 2016

New approach to determining how atoms are arranged in materials August 25th, 2016

Johns Hopkins scientists track metabolic pathways to find drug combination for pancreatic cancer August 25th, 2016

New electrical energy storage material shows its power: Nanomaterial combines attributes of both batteries and supercapacitors August 25th, 2016

Sensors

A promising route to the scalable production of highly crystalline graphene films August 26th, 2016

Down to the wire: ONR researchers and new bacteria August 18th, 2016

'Sniffer plasmons' could detect explosives: Scientists have proposed a graphene-based spaser that can detect even small amounts of various substances, including explosives August 16th, 2016

Perpetual 'ice water': Stable solid-liquid state revealed in nanoparticles: Gallium nanoparticles that are both solid and liquid are stable over a range of 1000 degrees Fahrenheit August 5th, 2016

Discoveries

Designing ultrasound tools with Lego-like proteins August 29th, 2016

A promising route to the scalable production of highly crystalline graphene films August 26th, 2016

Graphene under pressure August 26th, 2016

New electrical energy storage material shows its power: Nanomaterial combines attributes of both batteries and supercapacitors August 25th, 2016

Announcements

Designing ultrasound tools with Lego-like proteins August 29th, 2016

A nanoscale wireless communication system via plasmonic antennas: Greater control affords 'in-plane' transmission of waves at or near visible light August 27th, 2016

Forces of nature: Interview with microscopy innovators Gerd Binnig and Christoph Gerber August 26th, 2016

A promising route to the scalable production of highly crystalline graphene films August 26th, 2016

Tools

Designing ultrasound tools with Lego-like proteins August 29th, 2016

Nanofiber scaffolds demonstrate new features in the behavior of stem and cancer cells August 25th, 2016

50 years after the release of the film 'Fantastic Voyage,' science upstages fiction: Science upstages fiction with nanorobotic agents designed to travel in the human body to treat cancer August 25th, 2016

University of Puerto Rico and NASA back in the news XEI reports August 23rd, 2016

Homeland Security

Down to the wire: ONR researchers and new bacteria August 18th, 2016

Hexagonal boron nitride semiconductors enable cost-effective detection of neutron signals: Texas Tech University researchers demonstrate hexagonal boron nitride semiconductors as a cost-effective alternative for inspecting overseas cargo containers entering US ports August 17th, 2016

'Sniffer plasmons' could detect explosives: Scientists have proposed a graphene-based spaser that can detect even small amounts of various substances, including explosives August 16th, 2016

'Second skin' protects soldiers from biological and chemical agents August 5th, 2016

Events/Classes

Stretchy supercapacitors power wearable electronics August 25th, 2016

Semblant to Present at China Mobile Manufacturing Forum 2016 August 25th, 2016

Nanoparticles that speed blood clotting may someday save lives August 23rd, 2016

Impressive List of Doctors, Scientists Coming to Vail for Scientific Summit: The Second Vail Scientific Summit Convenes the Greatest Minds in Regenerative Medicine and Science August 17th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic