Friday, October 29, 2010

Got a particle accelerator in your desk drawer?

Not a facetious question: yes, you do, if you have a roll of Scotch tape (the old kind, not the newer 'Magic Transparent' stuff).

It's been known since the precursor to the current tape was invented in the 1930's that if you quickly peeled off the tape from its roll, it emits a very faint blue light. You can actually see this if you want to take the time a trouble: take a roll of this tape (the package-sealing size works well) into a completely dark room, like a closed closet with no lights. Wait about 30 minutes, so that your eyes become adjusted to the lack of light (see 'rhodopsin' or 'visual purple' on the web for the reasons). Then, very quickly peel back a length of tape from the roll -- you should clearly see a faint blue light coming from the region where the tape is being pulled from the roll. The reason: the all-important conservation of mass/energy: the breaking of molecular bonds at this boundary causes electrons to change their energy state, and the excess energy is emitted as photons: particles of light in a particular blue part of the spectrum.

(PS: a similar phenomenon can be observed -- in the same 'dark closet scenario' -- with two people: one observer and one person crunching/chewing peppermint hard candies. The same blue light phenomenon can be observed, although in this case, there are concommittent dangers - deflection of proper attention if the members are sexually attracted, and the danger of tooth or filling damage from crunching hard candies.

So, back to the 'particle accelerator' thing:
it has recently been discovered and reported that this same 'peeling Scotch tape off the roll' function -- if done at high and continuous speed in a vacuum -- actually generates a relatively coherent beam of X-rays, strong enough for example to image human finger bones on photographic plates.
Reference: http://www.sciencenews.org/view/generic/id/64111/title/Tale_of_the_tape_
So, your roll of Scotch packing tape is really, a particle accelerator (X-ray machine) in disguise (well, given a good vacuum and the right equipment to peel it off.)
The physical explanation for this phenomenon is still unknown.


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