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Physicists Produce Antineutrino Map of the World
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."
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."
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."
Lost at C:>. Found at C.
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...
Slashdot, fix the reply notifications... You won't get away with it...
Saying that, I imagine various navies and intelligence agencies will be paying a great deal of attention to this research, if they're not already doing so.
We don't have any direct evidence of nuclear fusion in the sun's core either (maybe the neutrino detectors count for that lately), but we pretty much 'know' it is happening. Lack of 'direct evidence' != 'lack of evidence good enough to say with almost certainty'. 'Scientists know' can be shorthand for 'the established scientific consensus allows us have a very high degree of confidence'.
Sure we do. We haven't yet seen neutrinos from each step of the process (still need to confirm the small fraction of CNO process), but all the other ones have been found. The sun works as advertised (to something a bit less than the 10% error level).
Researchers don't "know" squat. They have lots of theories, none of which have supporting data. That's what makes the heat of the Earth's core a mystery. By all rights it should not be this hot. It should be dead cold like the moon.
How about "scientists have a pretty good idea". Here's a recent review article on geoneutrinos, which does compare direct neutrino observations and the overall heat budget.
Don't know everything, but the more tools you can turn on the problem, the more clear things become. Adds up to something a bit more than "squat".
No. The map was made using existing data on known nuclear reactors and their power output and extrapolating what their antineutrino signature should look like. However, if geophysicists install detectors that show strong signatures that do not match up with the map given here, then that might be evidence for clandestine nuclear activity.
Yes. I see from the map that it's missing a number of known nuclear stations, for which the IAEA is unable to obtain data, and it's missing a number of "natural reactors" such as Oklu in Gabon, as well as a significant number of former Soviet reactors that are known to still be in use. It's also missing data for several Middle East reactors, known sites in South America, and a number of U.S. Military sites.
Assuming they get their experiment detectors running at all, they should be able to detect unreported nuclear reactor activity, but they'll have a hard time distinguishing it from the non-reactor related events they are seeking with the detectors.
Before the neutrino results came in, the correct phrase would be "scientists believe...".
Now, it's "scientists know..."
"I do not agree with what you say, but I will defend to the death your right to say it"
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."
I'm not sure where you are getting your numbers from, but they don't seem to make any sense. Considering the heat released by the Earth is on the order of 40 TW, and frictional energy loss by the moon on the order of 3 TW (tidal heating from the sun much less) most of which is near the surface, this becomes a rather insignificant contribution to the heating of Earth.
You also keep claiming that the math just doesn't work for radioactive decay. If you assumed it was all from U-238, you would need about 4e18 kg of it to produce the required heating. If it was only located in the inner core, that amounts to only 40 ppm, which is a factor of 20 larger than the crustal abundance. If this was evenly spread out among the inner and outer core, you're talking about 2 ppm, which is not much higher than the crustal abundance.
There are a lot of questions about the specific details of the heat from which decay and exactly where in the Earth's structure. But that is wholly different than saying we have no idea and acting like the math is no where near the realm of possibility.