Detecting nuclear materials when
they're shielded by steel shipping containers is a difficult task,
but a novel low-energy imaging technique might just take away the
headache. The method works by firing a combination of neutrons and
high-energy photons, and looking for a unique emission signature
released in response.
Millions of cargo containers are moved across the globe every year, and making sure that dangerous nuclear materials don't slip through the cracks is an extremely difficult task. There's been some progress when it comes to detection methods, but a new system could make finding nuclear materials much easier.
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The new technology makes use of an ion accelerator, which produces heavy isotopes of hydrogen. These are targeted at boron, resulting in the emission of neutrons and high-energy photons, focused in a fan-shaped beam that can be used to scan containers.
Imaging detectors are placed around the container, ready pick up on the emissions caused by the beam. A combination of the photons and neutrons excite any nuclear material present, causing it to emit gamma rays and neutrons. The characteristics of the different particles provide information about the materials inside the container.
When the particles come into contact with fissile material, both prompt and delayed neutrons are generated. The delayed particles can be detected through the thick metal of shipping containers, and they aren't generated by non-fissionable materials such as lead. As such, it's possible to use them an indicator as to whether materials intended for nuclear weapon development are present.
While the technique is yet to be put to the test out in the real world, it has been put through its paces under laboratory conditions. A collaborative team from the Georgia Institute of Technology and MIT found that the particles were able to pass through the shielding, with the detectors positioned opposite successfully picking up the tell-tale particles.
If real-world testing of the technique backs up the promising lab results, then the new technology could have a big security impact, improving abilities to detect the shipping of the dangerous materials. Its low-energy nature should also avoid the scanning process from causing damage to electronics or anything inside the container that's sensitive to radiation.
Full details of the study are published online in the journal Scientific Reports.
Source: Georgia Tech