X-rays from scotch tape {was: Re: [Rockhounds] flashing cleavages}

[Axel Emmermann]

Kreigh,
 
> Sticky Tape X-Rays (The Movie)
>   http://www.nature.com/nature/videoarchive/x-rays/

> Correlation between nanosecond X-ray flashes and stick-slip friction in
> peeling tape p1089
>   http://www.nature.com/nature/journal/v455/n7216/abs/nature07378.html

[Axel] The light from the tape, the visible portion I mean, interests me
too. If crashing electrons are causing X-rays then the spectrum of the
visible light must hold some VERY energetic UV too.
I don't believe that breaking the bonds of glue is what causes this. Glue is
designed to have large organic molecules become physically entangled, a bit
like why rubber is elastic. 
These bonds are specifically designed NOT to be rigid. Now, very rigid bonds
would logically produce higher energies through triboluminescence than
flexible bonds. You don't get much more rigid than in silicates, do you?
According to http://adsabs.harvard.edu/abs/1997APS..MAR.C1807K this produces
three spectral bands peaking at 250, 430 and 620 nm. These are SW UV, blue
and orange-red. VERY far from even the softest X-ray.
 
> But I did find that the x-rays produced from the scotch tape have a
> power of 15K electronvolts...

 [Axel] I First thought that was a mistake and they meant 15 eV, which
corresponds with  82.66 nm and could be considered (very broadly
interpreting the definition of x-rays ;-) as "in the transition zone"
between UV and X-rays.
Then I saw and heard the number 15 KeV spoken on the video. OK, no more
argument: 15 KeV it is. But then you're looking at 0.083 nm which is quite
short wave. It would explain why the x-rays are only generated in vacuum.
The "hospital" variety X-ray that is used in radiology has a rather long
wavelength and travels through your body and air and walls.... This 0.083 nm
radiation is so energetic that it immediately ionizes anything that it
passes. It will travel a few dozen micrometers through air but then its gets
stopped. I work with a rhodium-target X-ray tube of 60 KeV daily and I don't
even have to wear a radiation dosimeter.

The real question is: where does this energy come from! 
To illustrate this: an eV is the energy that an electron gets by being
accelerated by a potential difference of 1 volt. 
15.000 volts.... aaargh
Getting 300.000 photons/sec and counting 1 photon per electron could allow
you to calculated how many coulombs are involved. If you have the dielectric
capacity (farad) of a vacuum you could deduct the electric field involved.
Somehow....


> ...so it really is feasible to make an XRD unit, 

[Axel] if you know how to build the necessary detectors (you only need 5 of
those) and build a goniometer that is precise to 1000th of a degree....

or drive nuclear
> fusion reactions (even if it takes more energy than you would produce).
> Faster unrolling speeds should produce even more energy, at least to a
> point.
> 
> This is science you could do at home. A Mason jar will hold a vacuum.
> Something to unroll tape could fit inside a Mason jar. Add the vacuum
> pump, power supplies, etc., and it should still fit on your dining room
> table (any bets the wife would not complain?). I wonder what new
> windows to learning x-ray fluorescence would open to amateurs.
[Axel] 
Alas, 0.08 nm is not enough for XRF... you'd have to get below 0.07 nm or
17.7 Kev. Otherwise you'd miss out on the rare earth elements.

Cheers
Axel