Could aid in the protection of ports, stadiums and other large facilities
A team of LLNL researchers has developed the first plastic material capable of efficiently distinguishing neutrons from gamma rays, something not thought possible for the past five decades or so.
As a result, the new technology could assist in detecting nuclear substances such as plutonium and uranium that might be used in improvised nuclear devices by terrorists and could help in detecting neutrons in major scientific projects.
With the material’s low cost, huge plastic sheets could be formed easily into dramatically larger surface areas than other neutron detectors currently used and could aid in the protection of ports, stadiums and other large facilities.
For years, plastic materials have been used in large, low-cost detectors for portals and high-energy physics facilities, and while they could detect neutrons and gamma rays, they have been incapable of distinguishing one from the other, which is key to identifying nuclear substances such as uranium and plutonium from benign radioactive sources.
“However, by studying mixed crystals and mixed liquids, we found that to achieve neutron discrimination from gamma rays, we had to increase the dye concentration in the plastics by at least ten-fold greater than would typically be used,” Zaitseva said.
In their paper, the team wrote: “Efficient pulse shape discrimination (PSD) (between neutrons and gamma rays) combined with easy fabrication and advantages in deployment of plastics over liquids may lead to widespread use of new PSD materials as large-volume and low-cost neutron detectors.” Zaitseva’s colleague, fellow LLNL materials scientist Steve Payne, noted that in some ways it is a particularly good time to develop a new method for detecting neutrons, given the advantages and drawbacks of current methods.
Organic crystals serve as one of the best neutron detectors, but the crystals can be difficult to grow and obtain in large volumes. Liquid scintillators present some hazards that hinder their use. Gas detectors that rely on helium-3, a byproduct of tritium’s radioactive decay, have run into problems because the United States now produces markedly less tritium.
Plastics have more flexibility in their composition and structure than crystals, as well as having none of the hazards associated with liquid scintillators.
Bookmark this page for “detecting nuclear materials” and check back regularly as these articles update on a frequent basis. The view is set to “news”. Try clicking on “video” and “2” for more articles.