RE: [TCML] Need ALPHA WINDOW to detect x-rays in phantom streams

[Nick Andrews <nicothefabulous@xxxxxxxxxxx>]

> Date: Thu, 22 Nov 2012 21:04:07 -0800
> From: billb@xxxxxxxxxx
> To: tesla@xxxxxxxxxx
> CC: jeff_behary@xxxxxxxxxxx
> Subject: [TCML] Need ALPHA WINDOW to detect x-rays in phantom streams
> 
> On detecting TC x-rays, here's a possible source of confusion of which to 
> be aware.  Geiger counters are extremely sensitive to x-rays; much more 
> sensitive than any phosphor screen ...but this only is true of fairly hard 
> x-rays.  Down below 20KV, soft x-rays have a hard time getting through a 
> glass x-ray tube, much less a metal GM counter wall.  They also don't 
> penetrate far into water, so they're responsible for the early cases 
> of melanoma (back before the medical designers learned to include a 
> low-cut filter.)
> 
> So, in order to solidly reject the possibility of soft x-rays, you really 
> need an alpha-window GM counter.  If you only have an inexpensive 
> beta/gamma detector, then you cannot use it to reject the existence of 
> all x-rays.
> 
> But also, I've seen one GM counter which, when a "vacuum tester" coil was 
> waved about 9" away from the probe cable, responded with great quantities 
> of random-seeming clicks.  I wouldn't have expected such RF interference 
> to sound like a particle flux, yet it did.   No buzz, no 120Hz.  Best to 
> use a tiny kit-style GM counter inside a metal box with a screen-window.
> 
> Here's a brief holiday sale on a tiny GM counter kit, $9.00 without GM 
> tube...
> 
>    http://www.goldmine-elec-products.com/prodinfo.asp?number=G18410
> 
> Then just buy a 712 alpha-window tube for about $100 from sparkfun etc., 
> https://www.sparkfun.com/products/8875?
> http://www.lndinc.com/products/711/
> http://www.imagesco.com/geiger/geiger-counter-tubes.html
> 
> Also:
>    https://www.sparkfun.com/products/10742?
>    http://www.electronickitsbychaneyelectronics.com/prodinfo.asp?number=c6998
> 
> 
> (((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))
> William J. Beaty                            SCIENCE HOBBYIST website
> billb at amasci com                         http://amasci.com
> EE/programmer/sci-exhibits   amateur science, hobby projects, sci fair
> Seattle, WA  206-762-3818    unusual phenomena, tesla coils, weird sci

Hi Bill,

Interesting about the noise.  At 9" I wouldn't expect a spark tester to do that either.  Was the GC you detected the random noise/RF on using a shielded cable between the probe and counter?  What cable type?  Was the counter well-shielded in its enclosure?  Kit type or pro (Ludlum, Eberline, etc?)?  Most of my alpha-window probes are pancake tubes that are hard to get after the Fukushima incident, so I don't want to risk zapping them with HV, even with a screen over it...  Maybe you could have the GC/probe assembly ungrounded and near the path of spark from the Tesla coil with a breakout point to a ground point.  Or how about an alpha scintillator type with radfilm over the crystal?

Did you see the supposedly non-working GM tubes at $7 at Electronic Goldmine?  Report on the GC list was that they all worked in 3 sets a member ordered at reasonable voltages.  They just probably don't work with their kit GCs.  I think the guy tested them on a Ludlum 177.  I ordered 3 sets, and will test them on a 177-45 or my Ludlum Model 16 when they arrive.

Nick A
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