The Scotch-Tape X-Ray Machine

General Questions
#1

I hope I didn’t miss a thread about this already, but this seems to be something we should properly evaluate. A couple of guys at UCLA have set up a mechanism that uniformly peels scotch tape at ordinary speeds (3-5 cm/s) in a vacuum and discovers copious quantities of x-rays are emitted (enough to actually expose dental x-ray film).

Short article in Wired

Video with explanation

My BS meter is pegged on this, but the video looks convincing, and if light can be visibly emitted by peeling tape in the dark, perhaps x-rays could be similarly emitted in a vacuum where static voltage would undoubtedly be much higher. Is there really a plausible mechanism for this?

#2

The proposed mechanism is something like this:

Although the details are unclear:

From here: www.news.com.au

#3

Seems plausible to me, though wonderously unexpected and fascinating.

One way to think about it, is that as the tape pulls away from the roll, it creates a tiny bit of static electricity. Possibly because of the geometry, the static charge builds up until it ‘sparks’ across a tiny gap between the roll and the peeled tape. In a vacuum, the spark is a little different than in the atmosphere, and so it sets off some X-rays.

#4

If, in fact, this is a hoax, using Nature as a medium or a facsimile of Nature, it is worthy of high praise for its quality. That is, after all, a highly regarded journal. Seems legit to me, and I have absolutely no credentials.

#5

There was a thread on this in the past week. Search on scotch tape, not sure if it was in GQ.

#6

Thanks, I just found it in MPSIMS. Not much to that thread - I was hoping someone might be able to provide an explanation that was a bit more technical. Is this K-shell emission, or something else? It does not seem to be the Bremsstrahlung process and is almost certainly not synchrotron radiation.

#7

I’m sure it is not the Bremsstrahlung process! Are you crazy??? That would require positron emission x-rays in the frammis zone, which is not consistent with the gezornenblatt hypothesis. Definitely not Bremsstrahlung.

Bremsstrahlung. Puleeeze!

#8

This was recently discussed on CBC’s Quirks & Quarks. If anyone is interested, the interview with Dr. Carlos Camara of UCLA is available for download.

#9

>It does not seem to be the Bremsstrahlung process

Gee, I figured it probably was. “Static” electricity - I mean, triboelectrically generated electricity - can and did run the older X-ray machines. Having a spark in open air would be less efficient and harder to control, but it should certainly work. By “copious amounts” I think we mean pretty tiny power, much much less than a watt. I don’t know if there is a mechanism other than sparks, but if there are sparks, well, why not? The electrons still have to slow down at the end.

I don’t see how there would be any shells involved; I picture radiation like the continuum part of the X-Ray spectrum emitted by a tube.

Hell, some dumb old rocks emit what would be called X-Rays if they came from an X-Ray machine (the definitions of gamma and X radiation include the origins of the photons, but a photon of a particular energy could be either unless you know its history). It is hard to make nice powerful sharp well controlled X-Rays for medical purposes, but it’s not that hard to make just ANY old X-Ray.

#10

You’re a few days late:

#11

I glanced at the paper, and it took me a second to understand that the unfamiliar abbrevation they used to describe average power meant nanoWatts. [That’s the average power including both the ‘sparks’ and the time between ‘sparks’; the average power during a ‘spark’ is about 0.1 Watt]

#12

I haven’t read any technical info on this finding (anyone got a link to the actual paper?) but I would have guessed that it’s mostly K or L shell emission. Those are usually dominant in low-energy (soft X-ray) electron impact X-ray sources.

I think photons indirectly created by nuclear decay (e.g. alpha particles hitting nearby atoms) are legitimate X-rays.

#13

The wired article has a link to the Nature website, which has the paper (I think the Wired link says something like ‘more video from Nature’).
I think the paper says that a negative charge builds up on the adhesive as it separates (or vice versa) and electrons are accelerated across the gap between the unwound adhesive and the tape still on the roll. The electron’s KE is then converted to X-rays when it hits the roll. I assume in the presence of air, the electrons are slowed enough by collisions with air molecules that there’s not enough KE for X-rays to be produced (only visible light).

#14

[quote=“Jas09, post:2, topic:469796”]

The proposed mechanism is something like this:

My old friend triboluminescence! Easily demonstrated by cracking wintergreen Lifesaver’s with pliers in the dark. I also read somewhere (in CRC?) that you can get it from uranium nitride (or nitrate, I forget).

I’ve also seen visible light emitted when pulling open the adhesive-lined packaging of certain bandages; again, in the dark. I didn’t expect X-Rays, though.

I don’t remember what I was trying to bandage in the dark.

#15

I used to work in a darkroom. The tape at the end of a roll of film would give off a greenish light when I peeled it off the spool.