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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.

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In a neat marriage of science and art, researchers used x-rays from a particle accelerator to reveal an early portrait of a woman by Vincent Van Gogh, which the impoverished artist later painted over with a meadow scene. The hidden image bears a striking resemblance to a series of somber portraits the artist produced in the Dutch town of Nuenen, where he composed “The Potato Eaters,” completed in 1885 and regarded as his first major work [Los Angeles Times].

An earlier analysis using conventional x-rays had shown the rough shape of a head hidden beneath the surface of a painting called “Patch of Grass,” but provided no details. To get a clearer image, the researchers used high-intensity x-rays from a particle accelerator in Hamburg, Germany to compile a two-dimensional map of the metallic atoms on the painting beneath “Patch of Grass.”… Knowing that mercury atoms were part of a red pigment and the antimony atoms were part of a yellow pigment, they were able to chart those colors in the underlying image. “We visualized — in great detail — the nose, the eyes, according to the chemical composition.” [researcher Joris] Dik said. Scanning a roughly 7-inch square of the larger portrait took two full days [AP].

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