Researchers, from left, Jana Petrovic, Bo Cederwall and Alf Göök test the new imaging technology on a mock-up of radioactive waste drum scanner.

Neutron-gamma detector could intercept nuclear threats

Image credit: Biswarup Das

Scientists in Sweden have developed a scanning device capable of detecting small amounts of nuclear materials. They hope the imaging technology could help prevent acts of nuclear terrorism.

The system is a form of tomography which enables quick 3D imaging of the source of neutron and gamma ray emissions from weapons-grade plutonium and other special nuclear materials.

Bo Cederwall, a professor of physics at KTH Royal Institute of Technology who helped develop the device, said industry can use the technology in airports and seaports for routine inspection of passengers and goods.

According to the researchers, the Neutron-Gamma Emission Tomography (NGET) system goes beyond the capabilities of existing radiation portal monitors, by measuring the time and energy correlations between particles emitted in nuclear fission, and using machine learning algorithms to visualise where they’re coming from.

A 3D representation of how two sources of radiation of different strengths would appear when imaged at the same time.

A 3D representation of how two sources of radiation of different strengths would appear when imaged at the same time.

Image credit: Bo Cederwall

The system looks for coincidences of neutron and gamma ray emissions – which when mapped together in real-time allow pinpointing their origin, the research group explained.

“The technology has an acute sensitivity and can within a few seconds detect gram-amounts of plutonium depending on the application and the plutonium isotope composition,” Cederwall explained. “It takes a little longer to get a really good picture so you can see exactly where the plutonium is. However, this can be done completely automatically.”

The team said NGET detects not only nuclear weapons and radiation-dispersing “dirty bombs” – but it can also detect environmental radiation, such as leaks from nuclear facilities or natural resources.

Cederwall said the research group is looking to equip drones with the NGET system for this purpose. “In case of a radiological emergency, it is extremely important to map the radioactive contamination in the environment in order to protect the population in the best possible way,” he explained.

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