Radiation sensing

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Radiation sensing

Postby BotherSaidPooh » June 12th, 2013, 2:09 am

Hi all.
You might remember me from the H-a-D comments as "BothersaidPooh"

I am still working on my discovery dating from early 2008, that pyrolytic graphite can be used to pass alpha particles while blocking nearly everything else apart from X-rays and gammas.
It might also pass betas, this is possibly what I am seeing on the 'scope traces.

The isotope I'm using is 241Am aka the one used in smoke alarms.
This is perfectly safe as long as it is kept in a fairly robust box, the alpha particles have a very short range in air (less than 20cm) and as long as you don't actually eat the source it can be used safely.

I did notice something interesting though, back when my CMOS camera worked properly it was showing traces of several heights on the sensor which could indicate some details about alpha energy.
This is directly linked to the isotope as when I later tried it with a thorium 232 source the pulses looked completely different and were all the same height.

Sorry to be so vague, my test equipment is very primitive and it is hard to get the components to build this again as most new cameras use leaded glass to stop radiation.
More recent CMOS and CCD units use colour filters and microlenses which stop a lot of the particles from hitting the bare silicon, although you can often still see a few scattered flashes where there are exposed edges etc.

I did explore the effect of magnetic fields on the alphas, also another interesting modification would be to evacuate all the air from the sensor casing and seal it off.
This would allow biasing of the sensor negative wrt the alphas and should increase sensitivity by allowing even low energy alphas to trigger an event.

Another interesting effect, if pyrolytic graphite entangles any of the alphas then this could increase their range in air and change their properties wrt detection.
I've yet to test this hypothesis but if this is possible then these quasi-particles could travel far from a source; both bismuth and pyrolytic graphite should show the effect even if shielded.
This has all sorts of implications for long distance radiation detection, so could be used to detect 40K in say land mines or IEDs without setting them off.
It would rely on diamagnetic contamination of the material but this is likely to be possible, a single entangled alpha would reliably indicate detection.

Can anyone who has a decent laboratory help me please? this is just too interesting to set aside.

Kind regards, -A
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Joined: June 12th, 2013, 1:37 am

Re: Radiation sensing

Postby Moldings » June 20th, 2013, 6:53 am

Thanks for sharing..
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Joined: June 20th, 2013, 6:50 am

Re: Radiation sensing

Postby BotherSaidPooh » June 25th, 2013, 11:40 pm


I follow the Linus approach to technology ie it is better to share what you know so that others can improve upon it, than hoard it behind paywalls and spend one's entire life fighting off hordes of patent lawyers.

This approach is becoming more common as seen on sites like superconductors.org and 4HV, as such you could argue that publishing on a forum
counts as "peer review" as incorrect information quickly gets discovered and removed.

OK it is not an official science journal but it does get a lot of traffic and many people have commented on my work :-)

Does anyone have any moderately large pieces ( ie 20mm2 * 1mm ) of pyrographite that they'd be interested to sell or trade please?
Also in the meerkat for some decently pure ie 99.99% BaCO3 or BaO if someone has any.

Re. alternate cameras, the ISight ones used on old 22" Macs with the x3 and x2 sensors work well.
The filters seem to muck up the effect though but with no pyrographite it still detects alphas.

I've wondered about an alternate hypothesis that it may be a manifestation of Hawking radiation, but there's no way to prove this for sure without some very VERY expen$ive equipment and a gaggle of PhD's working on it for months.

Kind regards, -A
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Joined: June 12th, 2013, 1:37 am

Re: Radiation sensing

Postby leadacid » June 28th, 2013, 7:08 am

I have nothing to contribute, but it sounds interesting!
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Joined: January 27th, 2011, 4:47 pm
Location: Wisconsin

Re: Radiation sensing

Postby BotherSaidPooh » November 9th, 2013, 2:35 am

Hi, I've just received some samples of pyrographite from the USA.
Some of them do seem to work but watch out for pinholes.
I've since determined that even a single pinhole ruins the effect which might explain some of the problems people have been having wrt replication of what has been dubbed the "Conundrum Effect" by the folks on 4HV.

If you are unlucky enough to run into this problem I've explored the possibility of blocking off the holes with silver paint then sanding off the top layer to remove any excess.
Also worth trying is painting the porous graphite with Luxprint EL phosphor as this should make it fluoresce nicely when hit with radiation.
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Joined: June 12th, 2013, 1:37 am

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