Sticky Tape Gives Off X-Rays "There are a lot of S-rays," says Juan Escobar, PhD candidate in physics at UCLA. "There are enough that you can actually take a picture of your finger — an X-ray picture of your finger. It's very exciting. It's actually a little bit scary."

Sticky Tape Gives Off X-Rays

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That roll of tape in your desk, it looks innocuous enough. I mean, it's just sitting there, right? Acting all noncholant, like it's waiting for you to tear something. But the secret truth is, when you put it in the right conditions, that everyday roll of tape can produce x-rays and lots of them. It's this week's Science Out of the Box.

(Soundbite of music)

SEABROOK: In the current issue of the journal, Nature, researchers at UCLA published their findings that scotch tape, when pulled off the roll, shoots off surprisingly strong subatomic fireworks. Juan Escobar is a Ph.D. candidate in Physics at UCLA, and he joins us from NPR West. Hello.

Mr. JUAN ESCOBAR (Ph.D. candidate in Physics, UCLA): Hi, Andrea. How are you?

SEABROOK: How does this work?

Mr. ESCOBAR: Well, what's happening is that, whenever you put two surfaces in contact with each other, they are bound to get charged. In most of the cases, what you have are electrons are flowing from one material to the other. And then when you separate the surfaces, and if you do it fast enough, then the charges are still there, and that generates an electric field between them. So, these charges really, really want to jump to the other side of the tape. And when they do that, they emit x-rays.

SEABROOK: So does that mean the roll of scotch tape over in the corner of my desk is actually shooting off x-rays at me?

Mr. ESCOBAR: No. Actually, so far, for the brands we've tried, the tape has to be in vacuum. If you just do it in normal pressure, there are no x-rays.

SEABROOK: If you have to do this in a vacuum to shoot off x-rays, what were you doing using tape in a vacuum?

Mr. ESCOBAR: Yeah, that's very...

SEABROOK: How did you figure this out in the first place?

Mr. ESCOBAR: Yeah, that's a good question. This all comes from other studies that have been done in the lab where this was developed at UCLA. We've been looking at how surfaces get charged and what happens after they get charged. And we found some old papers from Russia from the 1930s going all the way to '89 where they suggested first that the electrons that they would find in (unintelligible) tape would generate x-rays, and they actually found the x-rays. And our contribution was that these x-rays, there's a lot of them. The flux is very, very high. It's high enough that you can actually take an x-ray picture of your finger.


Mr. ESCOBAR: Yes, yes, it's very exciting. It's actually a little bit scary.

SEABROOK: Yeah, yeah. But it does sound like you could actually use the effect for some kind of x-ray machine in the future.

Mr. ESCOBAR: Absolutely. There are, of course, some technical obstacles that would have to be overcome. But, in principle, this could provide an extremely inexpensive way of producing x-rays. We are excited about the possibility of bringing this to rural areas of third-world countries where electricity is expensive.

SEABROOK: Neat. OK, so you did scotch tape. Have you tried anything else? What about the best kind of tape - duct tape?

Mr. ESCOBAR: We have tried other kinds of tape, and some of them have given x-rays, some of them haven't. And we think that, by tweaking the chemistry and by engineering them in the proper way, the fluxes that we can get can be improved at least by a factor of 10.

SEABROOK: But really? Duct tape? Does it give an effect to x-rays?

Mr. ESCOBAR: We haven't tried duct tape.

SEABROOK: You haven't tried duct tape?

Mr. ESCOBAR: We haven't tried duct tape.

SEABROOK: Well, next on the list please. America says so.

Mr. ESCOBAR: It is absolutely - oh, you have no idea. We have a whole stock of tapes that we're just about to try.

(Soundbite of laughter)

SEABROOK: Juan Escobar is a Ph.D. candidate in physics at UCLA. Thanks very much for coming in.

Mr. ESCOBAR: Thank you, Andrea.

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