Apple Disk ][ X-Ray

[Grant Stockly]

At 02:20 PM 1/3/2007, you wrote:
>Joachim Thiemann wrote:
>>On 1/3/07, Grant Stockly <grant at stockly.com> wrote:
>>Actually, I've been wondering: What is the effect of x-rays on EPROMS?
>Umm they glow in the dark afterwords.  :)

Actually, you aren't too far off if you consider out of this world tests...

A linear accelerator emitting electrons, not x-rays, can put a charge in 
plastic and cause it to glow.

Here is some text from a neat test at a lab...  (they have a lot of fun)  I 
have all the pictures from these tests if you guys are interested.  These 
guys also make diamonds turn blue.  : )

The answer(s): Using electrons with much higher ionizing/charging ability 
than x-rays, (the "ozone" (O3) was very apparent in the shelter by the 
way!) the damage ("tree/branch" appearance) is done by the electrons 
leaping out/suddenly discharging through the Plexiglas. As a lightning 
strike parts the air, it will also part Plexiglas in an obviously similar 
fashion.

What we are doing is pushing a bunch of electrons (electron 'charge', as if 
it were a capacitor) into the Plexiglas from one side. Unlike X-Rays which 
easily pass through >3" of carbon steel at this energy level, these 
electrons only penetrate 4mm for every 1 MeV (Million Electron Volts) of 
energy. The penetration in this 'experiment' was about 1/2" or 12 mm.

We were running 60 mA (Milliamperes) each pulse at 50 PPS (Pulses per 
second) with a 4.5 microsecond pulse width. That's about 12 Microamperes 
average. We ran for 1.5 minutes max for a charge of 1 Millicoulomb.(A unit 
of electrical charge equal to the amount of charge transferred by a current 
of 1 ampere in 1 second) At 3 MeV (Million Electron Volts) (the system I 
was using here)  that's 3.24kj or  Kilojoules. (Joules:  A unit of 
electrical energy equal to the work done when a current of one ampere 
passes through a resistance of one ohm for one second

With the Plexiglas thus full of electrons, ("charged" as would be a 
capacitor just before it conducts) we pick it up and put it on a board, and 
whack the edge with a pointed object. After first making sure that the 
point is grounded. It can also be done using a drill press, with a 
sharpened nail in the chuck.

This causes a stress crack in the Plexiglas, which encourages some of the 
electrons to exit. This tears a track in the Plexiglas, which permits more 
of the electrons to come out. The electrons coming out tear/rip a path in 
the Plexiglas just as lightning tears a path in the air leaving behind a 
witness path, such as you see in the pictures. And like lightning the 
process is accompanied by a loud bang and a flash. The Plexiglas continues 
to 'sparkle' with bright blue 'sprits' running along the small branches for 
several minutes.  It is truly a beautiful appearance.....at least in MY 
opinion!

This plus the final pattern (which is obviously different every time) is 
great at entertaining the multitude.