Giving DHS a Crystal Ball

• By Laura Williams
• Jul 25, 2011

Powerful crystals seem more the province of video games or fantasy novels, but researchers at Wake Forest and Fisk universities are aiming to bring the objects’ mystique to bolster the country’s national security.

Researchers at Fisk and other laboratories have recently discovered that when crystals of the compound strontium iodide are “doped” with traces of the rare Earth element europium, they detect and analyze radiation better than most other “scintillators” –materials that emit light as a result of being hit by radiation – according to Richard Williams, a physics professor at Wake Forest University. He and other researchers at the university just received a grant to pursue further study on the radiation-detecting capabilities of these scintillators, as they’re called.

The researchers will use a high-speed laser to model the crystal’s radiation-detecting capabilities to determine the configuration at which the material can best detect radiation – that is, the point at which it has the greatest resolution.

By doing so, they are hoping to improve the quality of radiation detection available at a lower price point. Sodium iodide with thallium, for example, is relatively cheap and widely used, but it does a poor job of identifying substances. Germanium, on the other end of the scale, is highly accurate but outrageously expensive.

“We are optimistic that strontium iodide with europium can be developed to provide resolution close to high-purity germanium at a cost close to sodium iodide with thallium – the best of both worlds,” Williams said.

Williams is aiming for a lower cost because he envisions that the device that results from his research could be put to use for national security purposes, screening incoming cargo and people at ports, borders and airports for the radiation that could give away a potentially deadly plot.

Currently, detectors’ have a limited ability to pick up weak signals that result from trace amounts of radioactive material or from larger quantities located far away from detectors. A higher-resolution scintillator such as the once the Wake Forest team aims to enable would make this possible.

But transportation isn’t the only industry that the improved detection technology could secure. “The idea that someday our research might lead to wheeling up a large crystal outside a nuclear reactor and evaluating detailed conditions inside from afar – with potentially minimal human intervention – could have huge implications on how we deal with radiation threats in the future,” Williams said.

In the wake of the meltdown of Japan’s Fukushima reactor, this would be welcome news to those who work around nuclear plants.

The greater detection ability could also have some applications in the medical field, improving procedures that involve keeping track of where drugs and compounds are concentrated and used in the body.

“Future experiments can benefit from better scintillators,” Williams said. “The possibilities are numerous.”