Physicists Produce Antineutrino Map of the World 75
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."
Hmmmm ... (Score:5, Insightful)
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."
Re: (Score:2)
Re: (Score:2)
Re:Hmmmm ... (Score:4, Interesting)
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 ?
Submarines Move (Score:3)
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)
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.
Re: (Score:2)
Another question can you use this technology to effectively defeat the stealth of the nuclear subs?
Re: (Score:2)
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)
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.
Re: (Score:2)
I think he meant the antineutrino signatures of the nuclear reactors that power nuclear submarines.
Re:Hmmmm ... (Score:5, Insightful)
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.
Re: (Score:1)
Heh, same as I said, but in a snappier and funnier way.
+1
Re: (Score:3)
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)
the secret is to bang the rocks together (Score:2)
yeah, you can take that as a slam against Alaska, Arizona, see if I care.
Re:Hmmmm ... (Score:5, Informative)
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.
Re: (Score:3)
Correct. (Score:4, Interesting)
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.
Re: (Score:1)
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.
Re: (Score:2)
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)
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: (Score:2)
In other news, water is wet. If their half-lives didn't exceed the age of the planet, we wouldn't be having the discussion.
How did that post get marked up?
Re:Half-life (Score:4, Funny)
Half-life (Score:3)
Half-Life 3, Confirmed.
[Of course this only works if folks mod so that score remains at three...]
Re: (Score:2)
Faced with a choice between clean, safe power for people (France's nuclear power plants) and physicists having it a bit easier to discover the answer to a question that 99.9999999999999% of the world's population could care less about, I'd opt for the former. I'm pro-science, but I'm for a science that respects people first and foremost. Not one with an exaggerated sense of its own importance (i.e. Carl Sagan) or one that's in league with those intent in carrying out H. G. Wells' nasty agenda of having a select few run the lives of the rest of humanity. And I'm for a science with enough backbone to take up moral causes, such as opposition to legalized abortion.
I don't think anyone is saying, in this case, that it's an either/or situation. They are just looking to make sure that their experiments are not affected by man-made nuclear reactors. So they made a map to show the likely spots that would and would not be problematic for them.
Re: (Score:2)
Faced with a choice between clean, safe power for people (France's nuclear power plants)
That is true, but there is one problem: France has no Uranium Uranium supply in its own territory. What I do not know is how much reserve is available, in case of a supply problem (because of a war in supplier country, for instance)
The Core (Score:2)
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...
Re: (Score:2)
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"
Re: (Score:2)
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.
Re: (Score:3)
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'.
Re: (Score:3)
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).
Re: (Score:2)
You are right and I mentioned the neutrinos, but up until a few years ago when the neutrino physicists accepted neutrino oscillations, the neutrinos detected from the sun did not at all agree with theory, that situation lasted for at least a couple of decades. And nuclear fusion in the sun was well accepted before any of the neutrino results came in. Maybe not the greatest example on my part.
Re: (Score:3)
Before the neutrino results came in, the correct phrase would be "scientists believe...".
Now, it's "scientists know..."
Re: (Score:1)
What tripe. "We don't know" is what drives science.
You're spouting the same shit over semantics that creationists do over the "theory" of evolution. The only things we can know for certain are mathematical proofs.
Outside pure mathematics, all we can do is form models that make predictions which most accurately match our observations.
There are holes in most of our scientifically accepted theories. That doesn't mean you need to throw the baby out with the bathwater, just that modifications need to be made to
Re: (Score:1)
...they always say AGW can result in any conceivable data, including an ice age.
Citation:
http://curiosity.discovery.com... [discovery.com]
Re: (Score:1)
That's not AGW, that's just "GW".
Anthropomorphic Global Warming suggests *we* are a major cause of rapid global warming. With enough data, that can be disproved - you can compare current records with past & future records to see if man made CO2 (& other gases) has made any difference to global trends.
I personally prefer the term "Climate Change", as "Global Warming" only describes one part of the trend. That the global climate goes through cycles & changes is not under debate in the scientific c
Re: (Score:1)
For what it's worth, current models do predict brief periods of cooling between increasing warmer periods.
My biochemist son has a phrase that I think fits here: "The absence of data is not data." Models are not data, and none of the models have done an even remotely viable job of predicting climate. But even if they had, simulation is not empirical science. Just because a model occasionally agrees with experiment in no way means the model is correct. There is plenty of mathematical research indicating that climate simulation is an intractable problem, due primarily to chaos.
You might want to shift gears and
Re: (Score:2)
To falsify it? How about thirty years of falling temperatures while CO2 levels stay the same or rise?
Re: (Score:1)
Re: (Score:3)
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 [arxiv.org] 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".
Re: (Score:2)
But you can't say "scientists have a pretty good idea" about planetary formation.
I wasn't saying that: just that we've got a reasonable window into the thermal budget of the Earth at the present time. Looking back in the thread, that's what you opened up being worried about.
Re: (Score:2, Insightful)
In fact, radioactive heating was originally postulate
Re: (Score:2, Interesting)
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 4e
Re: (Score:2)
no, very well known it should NOT be "dead cold like the moon", the latent heat of formation is expected to be roughly half the heat. But the surprising thing is how hot the core is, much more than expected, so we'll give you partial credit.
Re: (Score:2)
mainstream science:
http://en.wikipedia.org/wiki/E... [wikipedia.org]
and even moon had recent cooling:
http://www.nasa.gov/mission_pa... [nasa.gov]
its smaller diameter means it loses heat faster anyway, even if it were stone cold in interior would not be valid point to make
Re: (Score:2)
... In the 1800s, famed physicist Lord Kelvin (for whom the absolute Kelvin temperature scale is named) was the first to calculate that even if the earth was born in an incandescent molten state (and there is no evidence for this), it would have cooled to its current temperature billions of years sooner than the 4.6 billion years accepted today. Even using generous assumptions about the thermal energy produced by radioactive decay (which also have no direct evidence), the earth would still cool to its current temperature much sooner than 4.6 billion years...
No, this is not what Lord Kelvin calculated. What he calculated was that if the Earth cooled by conduction alone it would only take 20 to 400 million years (he later settled on 20 to 40 million) for the surface to cool to the present temperature, but that the core would still be quite molten. In other words he calculated how long it would take an (effectively solid) body to achieve a surface temperature profile (how quickly it gets hot as you descend into the Earth) such that the surface temperature profi
Re: (Score:1)
Re: (Score:2)
...And no planetary scientist I talk to believes there is any way to account for the current heat of the core
The only way I can credit this assertion is in the sense of it being vacuously true [wikipedia.org], that you have never spoken to a planetary scientist.
To the extent that a problem ever existed, it was the reverse of what you say - finding ways to cool the Earth down to the level that we see today. Kelvin's model predicted an extremely hot Earth's core. Look at "A Decade of Progress in Earth's Internal Properties and Processes", Science, Vol. 213, 3 July 1981, pp. 76-77. The problem they were grappling with then was gett
Hawaii Has Nuclear Subs (Score:2)
Hawaii? (Score:2)
Venezuela (Score:1)
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