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Carbon nanotubes drive X-ray scanner

A tiny technology for producing X rays in a novel way could increase the sensitivity of luggage screening at airports, medical imaging, and other techniques for looking through things and make their use more widespread.

In conventional X-ray machines, a metallic filament heated to 1,000° C emits electrons that barrel down a vacuum tube and collide with a piece of metal to produce the rays. The new X-ray device, designed by Otto Zhou of the University of North Carolina at Chapel Hill and his colleagues, relies instead on a film of carbon nanotubes that emits electrons at room temperature when exposed to an electric field. It's a much less energy-consuming process, Zhou says.

Inside the new device, each of five carbon-nanotube films yields an image of an object from a separate angle. Computer software compiles the images to produce a three-dimensional picture.

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