Nuclear detectionGamma rays search for concealed nuclear threats
Gamma rays are the most energetic type of light wave and can penetrate through lead and other thick containers; 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
The world’s leading researchers in laser science, optoelectronics, and quantum optics will present their findings at the Conference on Lasers and Electro-Optics (CLEO: 2011), to be held 1-6 May at the Baltimore Convention Center. The more than 1,700 presentations at the conference will cover areas from energy and biophotonics to ultrafast lasers and quantum communication.
One of the presentations that caught our eye deals with nuclear detection.
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 and nuclear bomb material.
An OSA release notes that these gamma rays, called MEGa-rays (for mono-energetic gamma rays), are made by using a beam of fast-moving electrons to convert laser photons (light at a lesser energy) into the gamma ray part of the spectrum. 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 nuclear fuel 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 gamma-rays,” says Chris Barty of Lawrence Livermore National Laboratory, who will present on MEGa-rays at CLEO: 2011.
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 uranium-235. 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.
Chris Barty’s presentation, “Mono-Energetic Gamma-rays (MEGa-rays) and the Dawn of Nuclear Photonics,” will be held at 4:30 p.m. Tuesday, 3 May.
