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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 @10:49AM (#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."

    • by bberens (965711)
      Is it safe to assume that even nuclear weapons will emit a considerable amount of anti-neutrinos? Because that'd be.. Oh wait, there's a knock at the door.
      • Re:Hmmmm ... (Score:4, Interesting)

        by Anonymous Coward on Wednesday March 26, 2014 @11:21AM (#46584263)

        What about nuclear submarines ? Will navy provide their locations at any given time? Can a foreign military pinpoint submarines location by their anti-neutrino emissions ?

        • Nuclear submarines move. So if the experiment is run for long enough, then the skew caused by having one pass by in the nearest stretch of ocean won't be a worry.

          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.

          • Re:Submarines Move (Score:5, Interesting)

            by habig (12787) on Wednesday March 26, 2014 @12:46PM (#46585137) Homepage

            When the Borexino experiment was being built (under the Appenines in Italy), they calculated that if a nuclear sub parked for more than a couple weeks in the same spot in the Adriatic, they'd be able to see it using neutrinos.

            Not sure if anyone's redone that calculation now that the experiment works, but the preliminary one attracted some interest from the defense side of things.

            There is a reasonably well thought out set of specs for "if DoD wants to use neutrino detectors to monitor nuke activity in, say North Korea, what would they have to build". Done from the perspective of the particle physics guys saying "if we can get DoD to spend some of its semi-infinite pile of cash on some neutrino detectors we're interested in, how would we do it?". The answer turns out to be almost feasible, actually. Here's only the most recent paper [arxiv.org] I bumped across, there are many others.

          • by DarkOx (621550)

            Another question can you use this technology to effectively defeat the stealth of the nuclear subs?

          • by chihowa (366380) *

            If they move, but travel along consistent paths, those will become apparent after enough data is collected. Similarly, given enough time you could tell where the never travel or where they tend to dwell longer.

      • Re: (Score:3, Informative)

        by Eunuchswear (210685)

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

        Doubt it.

        Nukes are not doing very much when they're not going bang.

        See, for example, Japan going dark as the reactors are taken off line.

        • by r1348 (2567295)

          I think he meant the antineutrino signatures of the nuclear reactors that power nuclear submarines.

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

        by quenda (644621) on Wednesday March 26, 2014 @11:46AM (#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.

        • Heh, same as I said, but in a snappier and funnier way.

          +1

        • Probably not, actually. Neutrinos come from beta decay, which isn't what produces the energy in a fission chain reaction. Even the fusion reaction in a hydrogen bomb isn't itself neutrino producing. The fission products left over would produce neutrinos as they decay, but that would occur steadily over time and over a wide area, as they'd have been dispersed by the explosion.

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

      by SeeSchloss (886510) on Wednesday March 26, 2014 @11:00AM (#46584113) Homepage
      The map is actually produced from IAEA data, not from measurements, so no it won't help. On the contrary, the idea is that these measurements are so difficult/expensive to make that it's better to choose a place far from nuclear plants which would skew them. We can't just measure antineutrinos worldwide (at least for now).
    • Re:Hmmmm ... (Score:5, Informative)

      by Anonymous Coward on Wednesday March 26, 2014 @11:02AM (#46584129)

      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. It should be possible to determine the origin of the antineutrinos from their energy signature--i.e., whether they come from natural or artificial sources. Which actually sounds like a pretty straightforward way to get a project like this funded.

      • by delt0r (999393)
        The current nuclear detection network is struggling to keep its funding. So no this angle will probably not help with funding.
      • Correct. (Score:4, Interesting)

        by tlambert (566799) on Wednesday March 26, 2014 @02:24PM (#46586231)

        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.

    • by Anonymous Coward

      unfortunately this map is calculated and not measured. You can see that even with the assumptions of 100% efficiency you still get very few counts. Since the scale on the map is linear it is hard to tell what background count rates are, but even near reactors it is only in the lower hundred TNUs (1 TNU= 1 event/yr/10^32 detectors) which means you would have to count for a long time or have massive amounts of detectors.

    • I'd kind of like to have them point this "UP"

      Just how many reactors do you think we have in orbit now? I bet you it's more than a few.

  • Half-life (Score:5, Insightful)

    by hcs_$reboot (1536101) on Wednesday March 26, 2014 @11:32AM (#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...

  • I just watched the movie "The Core", and if it reflects the current state of science, it seems our understanding of what is inside the Earth is flawed on a more basic level...

    • by Immerman (2627577)

      Well, it came out of Hollywood, so it's probably safe to assume that its relationship to actual scientific understanding is somewhere between "slim" and "none"

    • by daem0n1x (748565)

      I just watched the movie "The Core", and if it reflects the current state of science, it seems our understanding of what is inside the Earth is flawed on a more basic level...

      No, it reflects the current state of movie making, which is pretty dire.

  • Pearl Harbor is a base for a classified number of nuclear submarines. I don't think this map reflects that.
  • Ummm... hasn't anyone told these scientists that Hawaii is the Pacific headquarters of the US Navy, including such things as nuclear powered aircraft carriers and nuclear powered submarines? I would think this is a horrible place to run an experiment given the fact that you would never know if the results were due to a submarine entering, leaving, or patrolling....
  • Keep out of Venezuela if you want to keep your precious neutrino sensors. They basically confiscated the brazilian gas plant there and the government is turning into a de-facto dictatorship much like the Cuba of old or worse

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