'No hiding place' for illicit nuclear materials

"Basically, we can see nuclear material that is no longer there," said Robert Hayes, lead author of paper describing the work and an associate professor of nuclear engineering at North Carolina State University. "For example, we could identify and characterise a dirty bomb based on samples taken from a room the bomb was in a year ago.

"This is a valuable tool for emergency responders, nuclear non-proliferation authorities and forensics, because it allows us to get a rough snapshot of the size of a radiation source, where it was located, how radioactive it is, and what type of radioactive material it is," Hayes says.

The technique is said to take advantage of the fact that radioactive material changes the arrangement of valence electrons - or outer electrons - in insulator materials, such as brick, porcelain, and glass. Radiation does this by displacing electrons at defect sites in the crystalline structure of these materials.