{"127931":{"#nid":"127931","#data":{"type":"news","title":"Novel Radiation Surveillance Technology Could Help Thwart Nuclear Terrorism","body":[{"value":"\u003Cp\u003EAmong 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.\u003C\/p\u003E\u003Cp\u003ETo support the nation\u2019s 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.\u003C\/p\u003E\u003Cp\u003E\u201cU.S. security personnel have to be on guard against two types of nuclear attack \u2013 true nuclear bombs, and devices that seek to harm people by dispersing radioactive material,\u201d said Bernd Kahn, a researcher who is principal investigator on the project. \u201cBoth of these threats can be successfully detected by the right technology.\u201d\u003C\/p\u003E\u003Cp\u003EThe 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.\u003C\/p\u003E\u003Cp\u003EDetails of the research were presented April 23, 2012 at the SPIE Defense, Security, and Sensing Conference held in Baltimore, MD.\u003C\/p\u003E\u003Cp\u003EScintillation 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.\u003C\/p\u003E\u003Cp\u003EBoth 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.\u003C\/p\u003E\u003Cp\u003E\u201cEach reaction to a gamma ray takes a very short time \u2013 a fraction of a microsecond,\u201d Wagner said. \u201cBy 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\u0027re dealing with.\u201d\u003C\/p\u003E\u003Cp\u003EBut 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.\u003C\/p\u003E\u003Cp\u003EA 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 \u2013 200 degrees below zero Celsius -- to function properly, which poses problems for use in the field.\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EThe Nanoscale Advantage\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003ETo 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.\u003C\/p\u003E\u003Cp\u003E\u201cA nanopowder can be much easier to make, because you don\u2019t have to worry about producing a single large crystal that has zero imperfections,\u201d Wagner said.\u003C\/p\u003E\u003Cp\u003EA scintillator crystal must be transparent to light, he explained, a quality that\u2019s 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.\u003C\/p\u003E\u003Cp\u003EHowever, when a transparent material \u2013 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\u2019t reach the photo-multiplier in a uniform manner, and the resulting readings are badly skewed.\u003C\/p\u003E\u003Cp\u003ETo 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.\u003C\/p\u003E\u003Cp\u003E\u201cThink of it as a big ocean wave coming in,\u201d Wagner said. \u201cThat wave would definitely interact with a large boat, but something the size of a beach ball doesn\u2019t affect it.\u201d\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003ERare Earths and Silica\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003EAt 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. \u003Cbr \/\u003EMore 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.\u003C\/p\u003E\u003Cp\u003EKahn 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.\u003C\/p\u003E\u003Cp\u003EInstead, the light emission role here falls to a second component \u2013 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.\u003C\/p\u003E\u003Cp\u003EThe 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.\u003C\/p\u003E\u003Cp\u003E\u201cWe\u0027re optimistic that we\u0027ve identified a productive methodology for creating a material that could be effective in the field,\u201d Wagner said. \u201cWe\u2019re continuing to work on issues involving purity, uniformity and scaling, with the aim of producing a material that can be successfully tested and deployed.\u201d\u003C\/p\u003E\u003Cp\u003E\u003Cem\u003EThis 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.\u003C\/em\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EResearch News \u0026amp; Publications Office\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EGeorgia Institute of Technology\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003E75 Fifth Street, N.W., Suite 314\u003C\/strong\u003E\u003Cbr \/\u003E\u003Cstrong\u003EAtlanta, Georgia 30308 USA\u003C\/strong\u003E\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EMedia Relations Contacts\u003C\/strong\u003E: John Toon (404-894-6986)(\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E) or Kirk Englehardt (404-894-6015)(\u003Ca href=\u0022mailto:kirk.englehardt@comm.gatech.edu\u0022\u003Ekirk.englehardt@comm.gatech.edu\u003C\/a\u003E).\u003C\/p\u003E\u003Cp\u003E\u003Cstrong\u003EWriter\u003C\/strong\u003E: Rick Robinson\u003C\/p\u003E\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":[{"value":"Prototype uses uses rare-earth elements and other materials at the nanoscale"}],"field_summary":[{"value":"\u003Cp\u003EGeorgia Tech researchers have developed a prototype radiation-detection system that uses rare-earth elements and other materials at the nanoscale. The system could be used to enhance radiation-detection devices used at ports, border crossings, airports and elsewhere.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"Researchers have developed a prototype radiation-detection system that uses rare-earth elements and other materials at the nanoscale."}],"uid":"27303","created_gmt":"2012-05-02 15:01:22","changed_gmt":"2016-10-08 03:12:09","author":"John Toon","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2012-05-02T00:00:00-04:00","iso_date":"2012-05-02T00:00:00-04:00","tz":"America\/New_York"},"extras":[],"hg_media":{"127891":{"id":"127891","type":"image","title":"Radiation Detection Research","body":null,"created":"1449178622","gmt_created":"2015-12-03 21:37:02","changed":"1475894751","gmt_changed":"2016-10-08 02:45:51","alt":"Radiation Detection Research","file":{"fid":"194554","name":"radiation-detector10.jpg","image_path":"\/sites\/default\/files\/images\/radiation-detector10_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/radiation-detector10_0.jpg","mime":"image\/jpeg","size":1335425,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/radiation-detector10_0.jpg?itok=74XBAq_E"}},"127901":{"id":"127901","type":"image","title":"Radiation Detection Research2","body":null,"created":"1449178622","gmt_created":"2015-12-03 21:37:02","changed":"1475894751","gmt_changed":"2016-10-08 02:45:51","alt":"Radiation Detection Research2","file":{"fid":"194555","name":"radiation-detector91.jpg","image_path":"\/sites\/default\/files\/images\/radiation-detector91_0.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/radiation-detector91_0.jpg","mime":"image\/jpeg","size":1315080,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/radiation-detector91_0.jpg?itok=BlQnPT3y"}},"127911":{"id":"127911","type":"image","title":"Radiation Detection Research3","body":null,"created":"1449178622","gmt_created":"2015-12-03 21:37:02","changed":"1475894751","gmt_changed":"2016-10-08 02:45:51","alt":"Radiation Detection Research3","file":{"fid":"194556","name":"radiation-detector114.jpg","image_path":"\/sites\/default\/files\/images\/radiation-detector114_1.jpg","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/radiation-detector114_1.jpg","mime":"image\/jpeg","size":1519288,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/radiation-detector114_1.jpg?itok=YXyHOaOL"}}},"media_ids":["127891","127901","127911"],"groups":[{"id":"1188","name":"Research Horizons"}],"categories":[{"id":"145","name":"Engineering"},{"id":"154","name":"Environment"},{"id":"147","name":"Military Technology"},{"id":"149","name":"Nanotechnology and Nanoscience"}],"keywords":[{"id":"415","name":"Georgia Tech Research Institute"},{"id":"945","name":"homeland security"},{"id":"544","name":"Nuclear"},{"id":"32481","name":"nuclear device"},{"id":"7617","name":"radiation"},{"id":"32451","name":"radiation detection"}],"core_research_areas":[{"id":"39451","name":"Electronics and Nanotechnology"},{"id":"39471","name":"Materials"},{"id":"39481","name":"National Security"}],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003EJohn Toon\u003C\/p\u003E\u003Cp\u003EResearch News \u0026amp; Publications Office\u003C\/p\u003E\u003Cp\u003E(404) 894-6986\u003C\/p\u003E\u003Cp\u003E\u003Ca href=\u0022mailto:jtoon@gatech.edu\u0022\u003Ejtoon@gatech.edu\u003C\/a\u003E\u003C\/p\u003E","format":"limited_html"}],"email":["jtoon@gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}