xray sensitive materials

recoder wrote in news:73d22242-0998-4c7a-a78c- snipped-for-privacy@y7g2000yqa.googlegroups.com:

If you're ok with experimenting, try a white LED. LED's can be used as photodiodes, and the phosphors in a white LED will probably fluoresce with x- rays, so the emission might be detectable if you shroud the LED in darkness and it as a photodiode.

If you want something more ideal, specify whether you want the change to be temporary or permanent, as answers might vary hugely depending which you want.

Lostgallifreyan wrote in news:Xns9C44895AD5433zoodlewurdle@216.196.109.145:

and WIRE it as a photodiode...

The usual method is a scintillator plus a photodiode. You can probably find suitable materials inside an X-ray film cassette

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Just temporary,it has to return to its original state after exposure

Mike Harrison wrote in news: snipped-for-privacy@4ax.com:

White LED phospors no good? I looked up scintillator because that's what I had in mind too, and Googling returned a result that implied that scintillation is basically fluorescense.

If it works a white LED ought to be a neat idea because it's very self- contained, cheap, small...

More details on what you're trying to do would still be helpful - for instance, what's stopping you from using a good ol' Geiger tube, or a "scintillator" (generally a photomultiplier looking at a bit of sodium iodide or some such)?

Also, how specific does it have to be to X-rays (as in, the idea of watching for what happens with a white LED or some other phosphor- bearing device is a good one, but it's also going to fluoresce when exposed to UV, etc.).

Bob M.

"Bob Myers" wrote in news:h387c3$lk7$ snipped-for-privacy@usenet01.boi.hp.com:

"shroud the LED in darkness" :) Easy to do, many polymers are pretty much transparent to x-rays but will totally exclude light including both far ends of its spectrum, and it should help block electrons too, if you want to check for gamma rays while excluding beta particles. I'm more curious about whether the phosphors in the LED respond well to such shortwave emissions, and whether the LED degrades fatally after limited x-ray exposure. I'm in no position to test this so if anyone can supply answers, please do.

So I see that we have only xray to light conversion and then measure the light (like it is done in scintillators). Interesting..I thought that there were materials that change its resistance, capacitance etc. under exposure..

Note that I didn't say that X-ray -> light was the ONLY possible form of X-ray detection/measurement - it's just one of the more common. Off the top of my head, I am not aware of materials that change resistance, etc., upon exposure to X-rays, at least not in an especially useful fashion, but I suppose that such might exist. Again, what's really needed here is more info about what's really needed here, and why the more usual methods already mentioned can't be used.

Bob M.

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Though it may work, it would not be very sensitive as the fluorescent emissions may be mostly too long a wavelength for the LED to detect when used as a photo diode.

"JosephKK" wrote in news: snipped-for-privacy@4ax.com:

Thanks. Didn't think anyone was going to answer that. :)

I remember taking apart a small radiation dosimeter.. had a small crystal in it. I can't remember much about it but I think it was able to detect gamma (case would have blocked both alpha and beta I think.) I wonder if those might easily be made to detect X-rays.