If neutrinos are everywhere, why isn't Cherenkov's Radiation?


by Ralphonsicus
Tags: cherenkov, neutrino, particle physics, science, superluminal
Ralphonsicus
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#1
Jan19-12, 02:59 PM
P: 47
Why isn't all water being infiltrated by neutrinos and giving off a blue glow?

P.S: I know they're not literally everywhere.
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mathman
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#2
Jan19-12, 03:23 PM
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Quote Quote by Ralphonsicus View Post
Why isn't all water being infiltrated by neutrinos and giving off a blue glow?

P.S: I know they're not literally everywhere.
There is no interaction (almost) between the neutrinos and water. More important, they are uncharged.
Naty1
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#3
Jan19-12, 03:24 PM
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Neutrinos react very weakly with ordinary matter and usually pass through virtually unaffected.


Detection

Main article: Neutrino detector

Neutrinos cannot be detected directly, because they don't ionize the materials they are passing through (they don't carry electric charge and other proposed effects, like the MSW effect, do not produce traceable radiation).
http://en.wikipedia.org/wiki/Neutrino#Detection

Naty1
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#4
Jan19-12, 03:28 PM
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If neutrinos are everywhere, why isn't Cherenkov's Radiation?


Did not realize this volume:

Most neutrinos passing through the Earth emanate from the Sun. About 65 billion (6.51010) solar neutrinos per second pass through every square centimeter perpendicular to the direction of the Sun in the region of the Earth.
http://en.wikipedia.org/wiki/Neutrino
phinds
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#5
Jan19-12, 03:50 PM
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Quote Quote by Ralphonsicus View Post
Why isn't all water being infiltrated by neutrinos and giving off a blue glow?

P.S: I know they're not literally everywhere.
Actually, they ARE, pretty much. See the post directly above.
Ralphonsicus
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#6
Jan19-12, 03:50 PM
P: 47
http://www.youtube.com/watch?v=zaOSLTfG_H8

So is this video completely wrong then?!
AdrianTheRock
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#7
Jan19-12, 03:56 PM
P: 136
No. The Cerenkov radiation only happens when a neutrino actually interacts with another particle, and comes from an electron given off by the interaction that moves faster than light in the water. These interactions are very rare. All water would give off occasional blue glows, but so few they're not noticeable without special detectors.
mike372
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#8
Jan23-12, 05:13 PM
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The standard understanding of Cherenkov radiation is that it is produced when a (electrically) CHARGED particle passes through a medium at a speed faster the the speed of light in that medium. So neutrinos do not produce this type of radiation simply because they are not charged.

Interestingly however one of the more favoured arguments for why the supposed observation of superluminal neutrinos by the OPERA experiment is wrong is the argument by Cohen and Glashow that if neutrinos did move superluminally they would then emit a kind of cherenkov radiation and thus lose energy and would therefore not arrive at the OPERA experiment with the observed energy. However note that this is not really the same as cherenkov radiation as the dominant radiation is to electron-positron pairs. The details of all this are in the original short paper http://arxiv.org/abs/1109.6562 and also there is a really nice review of all this by Matt Strassler here.
mal4mac
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#9
Jan26-12, 07:58 AM
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Quote Quote by AdrianTheRock View Post
No. The Cerenkov radiation only happens when a neutrino actually interacts with another particle, and comes from an electron given off by the interaction that moves faster than light in the water. These interactions are very rare. All water would give off occasional blue glows, but so few they're not noticeable without special detectors.
Could you put a really good telescope in the deep ocean and detect it? If it's deep enough wouldn't photons/cosmic rays/etc be blocked leaving only neutrinos? Volcanoes and strange glowing creatures might be a problem. Could they be avoided?

Google search shows I'm not quite as dumb as I think I am:

http://www.newscientist.com/article/...cean-life.html

And this:

http://www.phys.hawaii.edu/~sdye/CEROS_final_report.pdf

Interesting stuff!
ZapperZ
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#10
Jan26-12, 08:11 AM
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Quote Quote by mal4mac View Post
Could you put a really good telescope in the deep ocean and detect it? If it's deep enough wouldn't photons/cosmic rays/etc be blocked leaving only neutrinos? Volcanoes and strange glowing creatures might be a problem. Could they be avoided?

Google search shows I'm not quite as dumb as I think I am:

http://www.newscientist.com/article/...cean-life.html

And this:

http://www.phys.hawaii.edu/~sdye/CEROS_final_report.pdf

Interesting stuff!
But one also needs to consider the logistic when designing an experiment, and also one other important factor: how much it will cost! If we live in an ideal world, I can easily tell you a bunch of amazing experiments that we can do. But we are not living in that world.

For example, the DUESL lab at the Homestake mine is already having issues with getting funding for LBNL experiment. And this is in a place that's already built (pre-existing mine deep underground) with some existing infrastructure. Think of the hurdle to do such a thing in some place new.

Zz.
AdrianTheRock
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#11
Jan26-12, 02:22 PM
P: 136
Actually, they're doing a not-all-that-dissimilar experiment at the south pole, but using a stretch of ice-cap rather than liquid water. See http://icecube.wisc.edu/.


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