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Science

Physicists Produce Antineutrino Map of the World 75

Posted by Unknown Lamer
from the neon-green-antineutrinos dept.
KentuckyFC (1144503) writes "The origin of the heat generated inside the Earth is one of the great mysteries of geophysics. Researchers know that almost all this heat is generated by the decay of radioactive elements such as potassium-40, thorium-232 and uranium-238. But what they don't know is how these elements are distributed inside the planet and how much heat each contributes. In the next few years, they hope to get some answers thanks to the emerging science of antineutrino geophysics. Since radioactive decay produces antineutrinos, an experiment that measures these particles coming out of the Earth should provide a detailed picture of the distribution of the elements within it.

But there's a problem. Nuclear reactors also produce copious numbers of antineutrinos and these can swamp the signal from inside the Earth. What's needed is a map showing the distribution of reactor antineutrinos so that geophysicists can choose the best places to put their experiments. Just such a map is exactly what a team of nuclear physicists has now produced. The map shows that planned experiments in Hawaii and Curacao, off the coast of Venezuela, are in excellent locations and that Japan has recently become a much better site thanks to the shut down of the country's nuclear industry following the 2011 Tohoku earthquake. But a European experiment currently being planned in south-east France doesn't come off so well."
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Physicists Produce Antineutrino Map of the World

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  • Hmmmm ... (Score:5, Insightful)

    by gstoddart (321705) on Wednesday March 26, 2014 @09:49AM (#46584033) Homepage

    So, would this map let them locate any 'sneaky'/unreported reactors?

    I should think that some people would like to be able to say "gee, I see something in country x which shouldn't be there, we should have a closer look."

  • Half-life (Score:5, Insightful)

    by hcs_$reboot (1536101) on Wednesday March 26, 2014 @10:32AM (#46584363)

    Researchers know that almost all this heat is generated by the decay of radioactive elements such as potassium-40, thorium-232 and uranium-238

    Half-life of (K40, U238, Th232) is (1.2, 4.5, 14.0) x 10^9 years. Age of Earth is 4.5 x 10^9 years. That explains why we still have such elements...

  • Re:Hmmmm ... (Score:5, Insightful)

    by quenda (644621) on Wednesday March 26, 2014 @10:46AM (#46584469)

    Is it safe to assume that even nuclear weapons will emit a considerable amount of anti-neutrinos?

    Yes, but only very briefly, and only once.

  • by mbeckman (645148) on Wednesday March 26, 2014 @01:23PM (#46586205)
    When you survey the literature on geothermal heating, you find that friction is indeed _the_ major component of core heat. Especially tidal friction due to lunar gravity, which is far more significant that even meteor strikes, because it's a continuously varying force. But the physics of friction are well understood, and basic calculations show that friction is still not nearly a large enough source for measured temperatures and theoretical time spans.

    In fact, radioactive heating was originally postulated as a source to make up for the inadequacies of frictional heating. But the magnitude of radioactive heating is orders of magnitude less than even frictional. As mathematicians would say, it may be "necessary, but not sufficient."

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