Peeling a roll of ordinary sticky tape can generate 100 milliwatt pulses of X-rays, enough to capture a human finger on X-ray film, according to a new study by UCLA scientists. They claim to have found the cheapest way to produce X-rays of that scale. “At some point we were a little bit scared,” says Juan Escobar, a member of the research team. But he and his co-workers soon realized that the X-rays were only emitted when the kit was used in a vacuum [Nature News].
Their kit consisted of a vacuum-enclosed machine, reminiscent of a video casette player, that peeled a roll of Photo Safe 3M Scotch tape at a rate of 3 cm per second. Rapid pulses of X-rays, each about a billionth of a second long, emerged from very close to where the tape was coming off the roll. That’s where electrons jumped from the roll to the sticky underside of the tape that was being pulled away, a journey of about two-thousandths of an inch, Escobar said. When those electrons struck the sticky side they slowed down, and that slowing made them emit X-rays [AP]. This type of energy release is known as triboluminescence — the same principle behind the fun trick of crunching on Wint-O-Green Live Savers to produce blue sparks.

In a neat marriage of science and 