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I recently read about Cherenkov Radiation and the neat blue glow it creates in underwater nuclear reactors, and my understanding of it is that it occurs due to particles ($\beta$ particles in the case I am about to describe) travelling faster than the speed of light in that medium.

Coming to Uranium glass, I know it is usually made from depleted Uranium, which I interpret as U-238. U-238 decays to Th-234, which finally gives off a $\beta$ particle to decay further.

So, assuming glass having a refractive index of about 1.5, would it be possible to observe Cherenkov Radiation from Uranium glass?

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    $\begingroup$ Certainly pre-1941 uranium glasses were made from naturally occurring isotope distributions. $\endgroup$
    – Jon Custer
    Commented Aug 7, 2020 at 14:22

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I would say yes, but... It will be to faint to see with the naked eye.

Uranium glass will produce internal beta decays, which will give off Cherenkov radiation. However the quantity of decays is very very small. You could eat out of a uranium glass bowl your whole life and only have a slightly increased risk of cancer. A lower risk of dying than a 1 hr commute to work. But the cool glow you get around spent fuel rods will kill you within minutes if you were to swim into it.

Since the refractive index of uranium glass is higher than water, and it is a blue color in water, I suspect the bulk of the Cherenkov radiation would be in the ultra violet spectrum. This would cause the Uranium glass to fluoresce though.

If you had a sensitive enough spectrometer, you could differentiate most of the fluorescent photons from the Cherenkov radiation photons. Cherenkov radiation would have a smooth distribution from the peak wavelength down to IR, produced as the charged particle decelerates. But the fluorescent photons will have sharp peaks characteristic of the electron shell energy levels of the fluorescent material (The uranium compounds in the glass).

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That would be difficult, I think.

Glass should show Cerenkov radiation, but in uranium glass I expect that visible emissions would be dominated by fluorescence.

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  • $\begingroup$ I see. But, the radiation would have a definite spectrum, right? So if I did have a spectrometer I would be able to differentiate the peaks formed by the Cherenkov radiation from the ones formed by fluorescence, correct? $\endgroup$
    – Extr3mis
    Commented Aug 7, 2020 at 9:25
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    $\begingroup$ @Extr3mis I suppose it might be possible to see scintillations in uranium glass plate of suitable thickness as with a spinthariscope (but I have never tried). Cerenkov would be weaker I think. And I doubt there would be enough intensity left after filtering out the broad green emission. $\endgroup$
    – user137289
    Commented Aug 7, 2020 at 23:31
  • $\begingroup$ I see, thanks for the insight. $\endgroup$
    – Extr3mis
    Commented Aug 8, 2020 at 5:41
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    $\begingroup$ With good equipment, you could also separate Čerenkov and fluorescence by temporal gating. Their decay time scale will be many orders of magnitude different. $\endgroup$
    – dominecf
    Commented Sep 25, 2020 at 13:05

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