A new way to make sticky tape see-through

WASHINGTON (Reuters) - Researchers have found a new "see-through" use for clear sticky tape -- it produces X-rays when it is peeled off the roll.

The report in the journal Nature confirms a theory dating back to 1930 -- that the process of peeling the tape releases energy not only in the form of a flash of visible light, but also an X-ray.

Many children hiding in closets have demonstrated that unwinding sticky tape produces sparks of light. The phenomenon is called triboluminescence and is caused by the movement of one surface against another.

Carlos Camara of University of California, Los Angeles and colleagues used a motorized peeling machine to unwind a roll of tape in a vacuum.

They generated enough X-rays to show the bones inside their fingers.

"The tape has to be in the vacuum. Your hand can be outside," Camara said in a telephone interview on Thursday.

"If you unroll the tape on your office desk in ambient conditions you only get visible light. You don't get X-rays," he added. This is because gases in the air slow down the electrons that produce the X-rays.

"What always makes X-rays in general is electrons that are moving very fast and suddenly get stopped," Camara, a physicist, said.

"They are flying from one side of the tape to the other as you separate them. You get something like a miniature lightning strike."

This property might be used to make nuclear fusion, Camara and his team said. All it would take is about 10 times as much energy as was produced during the experiment, he said.

It might be possible to unroll the tape even faster to get the effect, Camara said.

"It's just an energy issue. We have managed to get X-rays with this. If you could go another factor of 10 you could get that much more energy and fusion would be proof of that much energy," he said.

This would not be the kind of nuclear fusion that produces energy, or an explosion. Unrolling the tape will require putting in more energy than would be produced, Camara said.

"Obtaining nuclear fusion in the lab is not that hard. What is really hard is obtaining excess energy from nuclear fusion," he said.

So-called tabletop nuclear fusion was achieved in 2005 -- but using conventional electricity that required more energy going in that was produced by the reaction.

(Reporting by Maggie Fox)