Mapping the radioactive heat beneath our feet


Geochemical bods tell us that the Earth is heated from within by the decay of various isotopes, mainly uranium, thorium and potassium. Knowing the distribution of these elements is crucial for understanding the Earth’s inner dynamics.

Geochemists have penty of ideas about how the Earth’s interior may work but no way of taking measurements to prove their ideas. For example, they think there are far more of these hot elements in the Earth’s crust than its mantle but without data, they can’t prove it.

But the geobods ain’t givin’ up and are a-hopin’ and a-prayin’ that the humble neutrino is gonna come to their rescue. The process of radioactive decay gives off neutrinos that would alert geobods to exactly what’s going on and where, if only they could measure ’em.

Truble is that neutrinos are hard to catch at the best of times. Physicists have recently spotted terrestrial neutrinos for the first time, although only by their energy spectrum, not by their direction which is what will be needed if geochems are to work out the distribution of radioactive stuff down there.

Now Stephen “Live and Let” Dye at the University of Hawaii and a pal have worked out exactly what will be needed to map the radioactive brew within the planet. They reckon a large ocean-based detector plus a smaller land based one should do the trick (both will have to be well away from nuclear power stations which produce unwanted neutrinos that would swamp the signal).

The technology to do this is available now but whether they can drum up the support (and the money) needed to make it happen is another question.

Ref: Estimating Terrestrial Uranium and Thorium by Antineutrino Flux Measurements

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