A new way to make sticky tape see-through

WASHINGTON (Reuters) - Researchers have found a new "see-through" use for commonplace clear adhesive 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."