Nuclear photonics: Gamma rays search for concealed nuclear threats

May 02, 2011

Gamma rays are the most energetic type of light wave and can penetrate through lead and other thick containers. A powerful new source of gamma rays will allow officials to search for hidden reactor fuel/nuclear bomb material.

These gamma rays, called MEGa-rays (for mono-energetic gamma rays), are made by using a beam of fast-moving to convert laser photons (light at a lesser energy) into the gamma ray part of the . The incoherent gamma rays can be tuned to a specific energy so that they predominantly interact with only one kind of material.

A beam of MEGa-rays, for example, might be absorbed by the uranium-235 while passing through other substances including the more common (but less dangerous) isotope uranium-238. That sort of precision opens the door to “nuclear photonics,” the study of nuclei with light. “It is kind of like tunable laser absorption spectroscopy but with ,” says Chris Barty of Lawrence Livermore National Laboratory, who will present on MEGa-rays at this year's Conference on Lasers and Electro Optics (CLEO: 2011, May 1- 6 in Baltimore).

In the last couple of years, MEGa-ray prototypes have identified elements like lithium and lead hidden behind metal barriers. The next-generation of MEGa-ray machines, which should come on-line in a couple of years, will be a million times brighter, allowing them to see through thick materials to locate specific targets in less than a second.

Barty will present several MEGa-ray applications in use today and will describe the attributes of next-generation devices. Work is under way on a MEGa-ray technology that could be placed on a truck trailer and carried out into the field to check containers suspected of having bomb material in them. At nuclear reactors, MEGa-rays could be used to quickly identify how enriched a spent fuel rod is in . They could also examine nuclear waste containers to assess their contents without ever opening them up. MEGa-ray technology might also be employed in medicine to track drugs that carry specific isotope markers.

Explore further: Physicists develop miniature Raman laser sensors for single nanoparticle detection

More information: Presentation ATuF2, “Mono-Energetic Gamma-rays (MEGa-rays) and the Dawn of Nuclear Photonics,” by Chris Barty is at 4:30 p.m. Tuesday, May 3.

Provided by American Institute of Physics

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