Cosmic Rays Detect Hidden Nuclear Cargo

October 22, 2008

by Gene Charleton

Here’s a question for you. How would you find a nuclear bomb in the millions of trucks and cargo containers that come into the United States every year? The answer worries anti-terrorism experts a lot. Nobody knows.

Cosmic rays may help. Engineers and scientists at the Los Alamos National Laboratory are building a new sensor that uses cosmic rays to detect uranium or lead used to shield it. In case you’ve forgotten, cosmic rays are streams of particles that bombard the earth all the time from space.

These particles – physicists call them muons – zip right through most things, including you and me. Steel plates hardly slow them down. Ditto for aluminum. They cruise right along until they hit something really dense. Like lead or uranium. Then they bounce, or scatter.

The useful thing about all this is that the particles scatter differently depending on what they hit. Steel scatters differently from lead. Lead scatters differently from uranium. And you can program a computer to tell the difference. You don’t even need a person to interpret an x-ray image. The new sensor should be safer and more sensitive than x-rays, big enough to handle big trucks and cargo containers and fast enough that it won’t cause traffic jams at ports and border crossings. Find out more by listening to the podcast on Engineering Works!

Images: top: Eightfish; bottom: NASA

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Gene Charleton is a science writer at the Texas Engineering Experiment Station and Texas A&M University in College Station, Texas. He’s been watching and writing about science and technology for more than 30 years. Engineering Works! was born five years ago, in 2003, as a two-minute radio show on Texas A&M University’s NPR outlet, KAMU-FM.