New Method Offers Remote Detection of Radioactive Materials

New Method Offers Remote Detection of Radioactive Materials

Picture of one of 663 containers of the radioactive substance Cobalt-60 kept in water at an institute in Elektrogorsk, 75 km (48 miles) outside Moscow, February 12. Scientists at the institute, which is short of funds, say the level of radiation is extremely high and that there is a risk of an explosion if electricity or water supplies are cut off. They say this could cause radioactivity to spread over a wide distance. - RTXHOI6

This post is also available in: heעברית (Hebrew)

Radioactive materials are routinely used at hospitals for diagnosing and treating diseases, at construction sites for inspecting welding seams, and in research facilities. Cobalt-60, for example, is used to sterilize medical equipment, produce radiation for cancer treatment, and preserve food, among many other applications. 

Cobalt-60 and many other radioactive elements emit highly energetic gamma rays when they decay. The gamma rays strip electrons from the molecules in the surrounding air, and the resulting free electrons lose energy and readily attach to oxygen molecules to create elevated levels of negatively charged oxygen ions around the radioactive materials.

It is the increased ion density that the University of Maryland researchers aim to detect with their new method. According to Homeland Security News Wire, they calculate that a low-power laser aimed near the radioactive material could free electrons from the oxygen ions. A second, high-power laser could energize the electrons and start a cascading breakdown of the air. When the breakdown process reaches a certain critical point, the high-power laser light is reflected back. The more radioactive material in the vicinity, the more quickly the critical point is reached.

The proposed remote radiation detection method is not the first, but it has advantages over other approaches. For example, terahertz radiation has also been proposed as a way to breakdown air in the vicinity of radioactive materials, but producing terahertz radiation requires complicated and costly equipment. Another proposed method would use a high-power infrared laser to both strip electrons and break down the air, but the method requires the detector be located in the opposite direction of the laser, which would make it impractical to create a single, mobile device.

So far the researchers at the University of Maryland have analyzed the feasibility of the new approach and experiments are underway to test it in the lab.