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connloyalist
Joined: 22 Jul 2020 Posts: 221 Location: the Netherlands
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Posted: Mon May 23, 2022 9:18 pm Post subject: Radon from thoriated glass |
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connloyalist wrote:
This is purely a scientific question, please correct my thinking here....
Today I was reminded that the radioactive decay chain of thorium 232 as used in some camera lenses runs through radon. However this is the radon 220 isotope with a half life of 55 seconds. When discussing radon gas problems in houses this is (usually?) radon 222 from the uranium 238 decay chain, with a longer half life of 3.8 days.
I presume that with the shorter half life of 55 seconds, radon 220 is less of a problem and consequently not a major concern when storing radioactive lenses? Or does the shorter half life indicate that the 220 isotope is more radioactive than the 222 isotope? I assume that quantity would also be a factor; I cannot imagine that thoriated camera lenses give off relevant amounts of radon? It might even in part remain trapped inside the glass?
Regards, C. |
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D1N0
Joined: 07 Aug 2012 Posts: 2483
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Posted: Mon May 23, 2022 10:37 pm Post subject: |
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D1N0 wrote:
It's still alpha radiation, stopped by a sheet of paper. It is only dangerous when breathing it in. The chances of that happening within 55 seconds are next to nothing. It will probably decay still inside the lens. _________________ pentaxian |
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RokkorDoctor
Joined: 27 Nov 2021 Posts: 1250 Location: Kent, UK
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Posted: Tue May 24, 2022 8:33 am Post subject: Re: Radon from thoriated glass |
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RokkorDoctor wrote:
connloyalist wrote: |
This is purely a scientific question, please correct my thinking here....
Today I was reminded that the radioactive decay chain of thorium 232 as used in some camera lenses runs through radon. However this is the radon 220 isotope with a half life of 55 seconds. When discussing radon gas problems in houses this is (usually?) radon 222 from the uranium 238 decay chain, with a longer half life of 3.8 days.
I presume that with the shorter half life of 55 seconds, radon 220 is less of a problem and consequently not a major concern when storing radioactive lenses? Or does the shorter half life indicate that the 220 isotope is more radioactive than the 222 isotope? I assume that quantity would also be a factor; I cannot imagine that thoriated camera lenses give off relevant amounts of radon? It might even in part remain trapped inside the glass?
Regards, C. |
I'm no expert in this area, but I would assume that the measurable amounts of radon gas in some houses built from granite etc. (a known issue in e.g. trad. Cornish houses in the UK https://www.cornwall.gov.uk/environment/environmental-protection/radon/), stems from the relatively large exposed surface area of the stone materials involved. I would hazard a guess that most of the Radon produced inside the lens' glass stays trapped inside the glass and only a truly minute amount of it may escape where it is produced in the first few atomic layers on the polished surface.
Perhaps an expert can confirm (or correct if my assumption is wrong) _________________ Mark
SONY A7S, A7RII + dust-sealed modded Novoflex/Fotodiox/Rayqual MD-NEX adapters
Minolta SR-1, SRT-101/303, XD7/XD11, XGM, X700
Bronica SQAi
Ricoh GX100
Minolta majority of all Rokkor SR/AR/MC/MD models made
Sigma 14mm/3.5 for SR mount
Tamron SP 60B 300mm/2.8 (Adaptall)
Samyang T-S 24mm/3.5 (Nikon mount, DIY converted to SR mount)
Schneider-Kreuznach PC-Super-Angulon 28mm/2.8 (SR mount)
Bronica PS 35/40/50/65/80/110/135/150/180/200/250mm |
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DConvert
Joined: 12 Jun 2010 Posts: 901 Location: Essex UK
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Posted: Tue May 24, 2022 8:58 am Post subject: Re: Radon from thoriated glass |
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DConvert wrote:
RokkorDoctor wrote: |
connloyalist wrote: |
This is purely a scientific question, please correct my thinking here....
Today I was reminded that the radioactive decay chain of thorium 232 as used in some camera lenses runs through radon. However this is the radon 220 isotope with a half life of 55 seconds. When discussing radon gas problems in houses this is (usually?) radon 222 from the uranium 238 decay chain, with a longer half life of 3.8 days.
I presume that with the shorter half life of 55 seconds, radon 220 is less of a problem and consequently not a major concern when storing radioactive lenses? Or does the shorter half life indicate that the 220 isotope is more radioactive than the 222 isotope? I assume that quantity would also be a factor; I cannot imagine that thoriated camera lenses give off relevant amounts of radon? It might even in part remain trapped inside the glass?
Regards, C. |
I'm no expert in this area, but I would assume that the measurable amounts of radon gas in some houses built from granite etc. (a known issue in e.g. trad. Cornish houses in the UK https://www.cornwall.gov.uk/environment/environmental-protection/radon/), stems from the relatively large exposed surface area of the stone materials involved. I would hazard a guess that most of the Radon produced inside the lens' glass stays trapped inside the glass and only a truly minute amount of it may escape where it is produced in the first few atomic layers on the polished surface.
Perhaps an expert can confirm (or correct if my assumption is wrong) |
I'm not an expert but I am a chemist and have some experience in radioactivity . I would also expect any radon produced to be trapped within the glass. Rocks are typically considerable more porous than glass, and the elements in glass are all bonded to each other. |
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Lightshow
Joined: 04 Nov 2011 Posts: 3669 Location: Calgary
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Posted: Sun May 29, 2022 1:17 am Post subject: |
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Lightshow wrote:
It's a non-issue, don't sleep with your lens, don't grind the lens to dust or smash it and you'll be fine, the background radiation will have more impact. _________________ A Manual Focus Junky...
One photographers junk lens is an artists favorite tool.
My lens list
http://www.flickr.com/photos/lightshow-photography/ |
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