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mcjosh

Cherenkov Radiation: Why Not?

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H2O, even "pure" such, will form ions, and therefore conduct some electricity.

I am saying in a purely theoretical stance of pure H2O therefore no ions. Anyways, back to the original subject!

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Aren't beta particles electrons, and as such will shy away from molecules that aren't "missing" one? Or are they just too high-powered in this case to give a crap about their charge?

Puny particle radiation aside, what about gamma radiation then? It is a reactor after all.

Correction. Beta particles can be electrons or positrons and either get repelled, or ionise the molecules they hit.

You should know that gamma radiation is not strictly matter, and thus the probability of interaction is nothing to do with the 'amount' of radiation.

It is in fact proportional to thickness, density and absorbent cross sectional area. (the surface area of the object facing the source)

Although there are more ways for gamma radiation to ionise(Photoelecrtic effect, compton scattering, and the other one I always forget), it is less ionising than beta.

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I am saying in a purely theoretical stance of pure H2O therefore no ions. Anyways, back to the original subject!

If you were talking about a theoretical substance, then why the phone metaphor?

Correction. Beta particles can be electrons or positrons and either get repelled, or ionise the molecules they hit.

You should know that gamma radiation is not strictly matter, and thus the probability of interaction is nothing to do with the 'amount' of radiation.

Hm, seems I remembered wrongly about the betas then, again.

But gamma radiation is the one that causes mutation and cancer, and if the reactor makes the water glow it means there are charged particles going about in there, which means gamma radiation would have no problem getting through, right? Or maybe it waas a bit too long since I went through my notes about this.

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Iand if the reactor makes the water glow it means there are charged particles going about in there

Charge isn't blue. The reason the water in the reactor glows is because the Beta radiation emitted is moving through the water at about 75% of the speed of light in a vacuum, which is actually faster than the speed of light in water (This is what Cherenkov was observing afaik). Rayleigh scattering makes the light emitted at the lower end of the EM spectrum, hence the blue glow.

EDIT: But for fucks sake, do not ask me why it isn't purple. I haven't taken a physics degree. I doubt even people with degrees would be able to tell you.

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Charge isn't blue. The reason the water in the reactor glows is because the Beta radiation emitted is moving through the water at about 75% of the speed of light in a vacuum, which is actually faster than the speed of light in water (This is what Cherenkov was observing afaik). Rayleigh scattering makes the light emitted at the lower end of the EM spectrum, hence the blue glow.

EDIT: But for fucks sake, do not ask me why it isn't purple. I haven't taken a physics degree. I doubt even people with degrees would be able to tell you.

Yes, that was my point. If there are Betas in the water there are probably gamma escaping the water. Also, the speed of light is constant, it just takes a circuitous road which creates the illusion of it moving slower, or how I should explain it.

Also also; XKCD fan I take it?

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or how I should explain it.

Another way to say it would be like a party. You (Photons) want to get from one end of the room to another. When there is no one in the room (vacuum) you get there very fast because there is no one in your way. When there are people in the room (matter i.e. water) you bump into people and its more like a zigzag to get from one side of the room to the other. Your speed does not decrees but you travel for a longer period of time. Got to love discovery channel for these fun facts and examples.

This is a crude example I know but the concept it there.

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snip

That's a bit long though.

Sigh...

okay, the PHASE VELOCITY of light in water is less than that of a vacuum. Christ...

Only nitpicking because some people in my school , even though they have gone on some physics classes, still believed that lights speed wasn't constant, and it took quite some convincing before he accepted it. He claimed wikipedia was wrong! Unheard of! :P

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EDIT: But for fucks sake, do not ask me why it isn't purple. I haven't taken a physics degree. I doubt even people with degrees would be able to tell you.

Presume I don't know anything about anything, but wouldn't it be for the same reason that the ocean is blue rather than purple?

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Presume I don't know anything about anything, but wouldn't it be for the same reason that the ocean is blue rather than purple?

Tsk tsk tsk xylord. You just can't expect everything to be that simple.

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The awkward moment when I actually get a Nobel prize for this sentence.

That would be amazing! ROFL!

That's a bit long though.

It might be long but it explains it well. Also, it's simpler for those that are not nuclear engineers.

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