New Type of Imager Could Help Spot Smuggled Nuclear Materials

sciencehabit shares a report from Science Magazine: Much as a smoke detector gives only a vague idea of where a fire is, current methods to detect smuggled nuclear materials are slow and imprecise. But a new technique that images nuclear materials based on the neutrons and gamma rays they shed can locate these dangers in record time, scientists report. The new technique -- neutron-gamma emission tomography (NGET) detection -- relies on detectors that emit light when struck by either a neutron or a gamma ray and measure the time of arrival with nanosecond precision. Suppose two detectors sit face to face, separated by 1 meter or so, and that a nucleus decays and emits a neutron that hits one detector and a gamma ray that hits the other. The difference in the arrival times, when accounting for the detailed physics of the nuclear decay process, defines a fuzzy, somewhat spherical shell in space in which the nucleus could have been. Timing many neutron-gamma ray pairs with several detectors produces a set of probability shells that should intersect at a point -- the location of the source. The ability to pinpoint a source may offer a "paradigm shift" in nuclear safeguards, the researchers say. NGET detectors might also be shrunk to fit on a drone. That offers "a really fascinating possibility" of quickly mapping radiological contamination at disaster sites like Fukushima or Chernobyl, they say. The findings appear in the journal Science Advances.

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