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posted by Fnord666 on Thursday November 23 2017, @09:48AM   Printer-friendly
from the so-that's-what's-in-the-warp-nacelles dept.

Lightning can transmute nitrogen into carbon-14 and cause the emission of a positron, the antimatter counterpart of the electron:

Lightning can accelerate some electrons to almost the speed of light, and the electrons can then produce γ-rays. [Leonid] Babich proposed that when one of these γ-rays hits the nucleus of a nitrogen atom in the atmosphere, the collision can dislodge a neutron. After briefly bouncing around, most of the neutrons get absorbed by another nitrogen nucleus. This adds energy to the receiving nucleus and puts it in an excited state. As the receiving nucleus relaxes to its original state, it emits another γ-ray — contributing to the giveaway γ-ray glow.

Meanwhile, the nitrogen nucleus that has lost one neutron is extremely unstable. It decays radioactively over the next minute or so; in so doing, it emits a positron, which almost immediately annihilates with an electron, producing two 511-keV photons. This was the third signal, Enoto says. He suspects that his detectors were able to see it only because the briefly radioactive cloud was low, and moving towards the detectors. This combination of circumstances might help to explain why the photonuclear signature has been seen so rarely. Enoto says that his team has observed a few similar events, but that the one described in the paper is the only clear-cut event so far.

Babich also predicted that not all of the neutrons dislodged from nitrogen by a γ-ray are absorbed. Some of them instead will trigger the transmutation of another nitrogen nucleus into carbon-14, a radioactive isotope that has two more neutrons than ordinary carbon. This isotope can be absorbed by organisms; it then decays at a predictable rate long after the organism's death, which makes it a useful clock for archaeologists.

The main source of the carbon-14 in the atmosphere has generally been considered to be cosmic rays. In principle, lightning could also contribute to the supply. But it is not clear yet how much of the isotope is produced in this way, says Enoto, in part because it's possible that not all bolts initiate photonuclear reactions.

Photonuclear reactions triggered by lightning discharge (DOI: 10.1038/nature24630) (DX)


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  • (Score: 2, Interesting) by anubi on Thursday November 23 2017, @10:31AM (5 children)

    by anubi (2828) on Thursday November 23 2017, @10:31AM (#600599) Journal

    If lightning can do it, will an arc-welder do it too?

    --
    "Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
    • (Score: 4, Informative) by khallow on Thursday November 23 2017, @10:52AM

      by khallow (3766) Subscriber Badge on Thursday November 23 2017, @10:52AM (#600603) Journal

      If lightning can do it, will an arc-welder do it too?

      No, lightning arcs over miles. That's due to the much higher voltage differences (can be a million volts [wikipedia.org] per foot) that lead to lightning strikes and current tends to be much higher as well (thousands to tens of thousands of amps for extreme short periods of time). The voltage indicates high energies are possible for charged particles due to acceleration along the electric fields and the huge surge of current means that the charged particles achieve a relatively high intensity, both conducive to particle collisions.

      However, we do have table top fusion (such as the fusor [wikipedia.org]) that operate on similar principles.

    • (Score: 0) by Anonymous Coward on Thursday November 23 2017, @11:14AM (3 children)

      by Anonymous Coward on Thursday November 23 2017, @11:14AM (#600611)

      If lightning can do it, will an arc-welder do it too?

      arc welder is only a few volts. You are much more likely to cause this by rubbing your feet on the carpet and discharging static electricity since then we are talking 10,000 - 100,000V. But lightning is another step up like that, so yeah. So maybe static discharge on your feet doesn't cause nuclear reaction, but probably some x-rays at least ;)

      • (Score: 0) by Anonymous Coward on Thursday November 23 2017, @02:00PM

        by Anonymous Coward on Thursday November 23 2017, @02:00PM (#600660)

        So maybe static discharge on your feet doesn't cause nuclear reaction, but probably some x-rays at least ;)

        That stinky fungus on my feet? Deadly, but surely not by x-ray emission.

      • (Score: 2) by Yog-Yogguth on Thursday November 23 2017, @02:47PM (1 child)

        by Yog-Yogguth (1862) Subscriber Badge on Thursday November 23 2017, @02:47PM (#600671) Journal

        And if that should fail there's always the option of peeling some tape which gives micro-bursts of x-rays:
        Correlation between nanosecond X-ray flashes and stick–slip friction in peeling tape [nature.com] (only abstract, ridiculous price for subscription that no ordinary person would pay if it was their own money).

        Needs "moderate vacuum" so maybe some creative use of a vacuum cleaner? :P

        [If anyone writes that one up please publish it as Open Access so the science can actually be shared like it is supposed to to make it actual science...]

        Anyway am I the only one who is a bit surprised at how fresh this story is? I just read about it in the news before seeing it on Soylent —which is cool :)

        --
        Bite harder Ouroboros, bite! tails.boum.org/ linux USB CD secure desktop IRC *crypt tor (not endorsements (XKeyScore))
  • (Score: 1, Interesting) by Anonymous Coward on Thursday November 23 2017, @11:17AM (20 children)

    by Anonymous Coward on Thursday November 23 2017, @11:17AM (#600613)

    Is it substantial enough to meaningfully affect carbon-14 dating or no? Lets say for some reason about 1k years ago there was a year of constant thunderstorms, how off would the dating be?

    • (Score: 3, Informative) by kanweg on Thursday November 23 2017, @11:31AM (12 children)

      by kanweg (4737) on Thursday November 23 2017, @11:31AM (#600615)

      It wouldn't matter because the amount of 14C generated each year is know to vary. While this variation is only very minor, it is still corrected for to get an as accurate date as possible.

      The calibration curve is obtained from trees (year rings). As there are very many of them, there is an overlapping series of tree rings (which also happens to prove that the earth is not 6000 years old, but that was not the goal).

      https://en.wikipedia.org/wiki/Calibration_of_radiocarbon_dates [wikipedia.org]

      Bert

      • (Score: 0) by Anonymous Coward on Thursday November 23 2017, @12:07PM (11 children)

        by Anonymous Coward on Thursday November 23 2017, @12:07PM (#600620)

        This sounds wrong, its known that if people in the future date objects from the 1950s to today they will think the artifacts are much more recent: https://en.m.wikipedia.org/wiki/File:Radiocarbon_bomb_spike.svg [wikipedia.org]

        So this does happen, it is only a matter of magnitude. How much lightening would it take to have an effect similar to the nuclear tests?

        • (Score: 1, Insightful) by Anonymous Coward on Thursday November 23 2017, @01:58PM (10 children)

          by Anonymous Coward on Thursday November 23 2017, @01:58PM (#600657)

          This sounds wrong,

          And that is what is wrong. If it "sounds" wrong then it must be wrong? The only thing wrong here is you since you don't seem to understand what calibration is suppose to be doing anyway.

          • (Score: 0) by Anonymous Coward on Thursday November 23 2017, @04:16PM (9 children)

            by Anonymous Coward on Thursday November 23 2017, @04:16PM (#600700)

            So if I search I find stuff like this:

            Krane points out that future carbon dating will not be so reliable because of changes in the carbon isotopic mix. Fossil fuels have no carbon-14 content, and the burning of those fuels over the past 100 years has diluted the carbon-14 content. On the other hand, atmospheric testing of nuclear weapons in the 1950s and 1960s increased the carbon-14 content of the atmosphere. Krane suggests that this might have doubled the concentration compared to the carbon-14 from cosmic ray production.

            http://hyperphysics.phy-astr.gsu.edu/hbase/Nuclear/cardat.html [gsu.edu]

            I wouldnt call that a truly reliable source but could not find anyone claiming this problem will be calibrated away.

            • (Score: 1) by khallow on Thursday November 23 2017, @05:16PM (8 children)

              by khallow (3766) Subscriber Badge on Thursday November 23 2017, @05:16PM (#600718) Journal

              I wouldnt call that a truly reliable source but could not find anyone claiming this problem will be calibrated away.

              It's just a natural conclusion from knowing what the C14 concentration is over the period in time. It does mean that C14 dating is weakened as a measure somewhat, because now, there is the potential for carbon dating to result in several possible dates rather than just one.

              • (Score: 0) by Anonymous Coward on Thursday November 23 2017, @07:43PM (7 children)

                by Anonymous Coward on Thursday November 23 2017, @07:43PM (#600782)

                Thanks, but I'm not seeing why you would be more uncertain of the date once the calibration was performed.

                • (Score: 2, Informative) by khallow on Thursday November 23 2017, @08:26PM (6 children)

                  by khallow (3766) Subscriber Badge on Thursday November 23 2017, @08:26PM (#600798) Journal
                  Because variation in C14 concentrations can result in organic material from different times having the same C14 ratios. For example, nuclear weapons tested ended decades ago, but production of low C14 CO2 from fossil fuel burning has gone up. This has resulted [wikipedia.org] in a short term peak in C14 concentration in 1963, followed by a long decay to present. Consider an organic item with the 1963 concentration of C14 buried at the time. It will take ~5700 years for the C14 in that item to decay to pre-nuclear weapon testing levels of C14 (which are almost exactly half the peak) and around 4000-4500 years to decay to present levels. So year 1963 organic objects will appear newer than year 2017 objects, if one naively uses the constant C14 approximation.
                  • (Score: 0) by Anonymous Coward on Thursday November 23 2017, @08:43PM (5 children)

                    by Anonymous Coward on Thursday November 23 2017, @08:43PM (#600808)

                    Yes, this is the problem I was originally mentioning. And I asked how much lightning would be required to cause a similar issue.

                    I thought you were saying the tree ring/whatever calibration was supposed to get rid of this problem. Now I do not know what your point is, you seem to be agreeing with me.

                    • (Score: 1) by khallow on Thursday November 23 2017, @09:11PM (4 children)

                      by khallow (3766) Subscriber Badge on Thursday November 23 2017, @09:11PM (#600827) Journal

                      I thought you were saying the tree ring/whatever calibration was supposed to get rid of this problem.

                      Hmm, trees will absorb fairly predictable amounts of C14 and thus would be decent indicators of what past C14 concentrations were. So you can calibrate with good tree ring data. But you can't fix variation in C14 levels. No matter how perfect the knowledge of C14, there will still be some uncertainties with dating modern era organics with it.

                      • (Score: 0) by Anonymous Coward on Friday November 24 2017, @05:38AM (3 children)

                        by Anonymous Coward on Friday November 24 2017, @05:38AM (#600946)

                        C-14 has a half-life of 5730 years. Then the doubling (eg due to nuclear testing) would introduce an uncertainty of that 5730 years. That is near the duration of all recorded human history... This is not insubstantial. All I was asking is whether the lightning effect could cause something similar.

                        • (Score: 1) by khallow on Friday November 24 2017, @07:00AM (2 children)

                          by khallow (3766) Subscriber Badge on Friday November 24 2017, @07:00AM (#600976) Journal

                          Then the doubling (eg due to nuclear testing) would introduce an uncertainty of that 5730 years.

                          It's not uncertainty. Things like trees and flesh absorb carbon in predictable ways.

                          All I was asking is whether the lightning effect could cause something similar.

                          Don't know. If climate change models are correct, more extreme storms should have higher levels of lightning and more lightning-based C14 generation. All I can say is that any enhanced production is being swamped by fossil fuel emissions which are very low in C14.

                          • (Score: 0) by Anonymous Coward on Friday November 24 2017, @06:34PM (1 child)

                            by Anonymous Coward on Friday November 24 2017, @06:34PM (#601098)

                            All I can say is that any enhanced production is being swamped by fossil fuel emissions which are very low in C14.

                            This was going on 1000 years ago? Honestly just the weird responses in this thread and what I've seen looking it up makes me think this whole carbon dating (maybe radioisotope dating in general?) strategy has some deep flaws. Its like people cant even understand simple questions about it.

                            • (Score: 1) by khallow on Friday November 24 2017, @11:20PM

                              by khallow (3766) Subscriber Badge on Friday November 24 2017, @11:20PM (#601177) Journal

                              This was going on 1000 years ago?

                              A previous poster, kanweg noted [soylentnews.org] that there has been variation in the past, but it wasn't enough to cause problems via tree ring data spanning the past 50,000 years.

                              Honestly just the weird responses in this thread and what I've seen looking it up makes me think this whole carbon dating (maybe radioisotope dating in general?) strategy has some deep flaws. Its like people cant even understand simple questions about it.

                              Don't see that myself. You (or other ACs) asked questions, you got pretty non-weird answers. Doesn't get more straightforward than that. Keep in mind you have a bunch of different people talking and not everyone reads the whole thread (I didn't) or remembers it even when they have read the whole thread. I came in after an AC comment about nuclear testing causing large variations in C14. So I was expecting a discussion about the very recent and large perturbations of C14, not the variations a thousand years ago which are much smaller.

    • (Score: 2) by FatPhil on Thursday November 23 2017, @03:10PM (6 children)

      by FatPhil (863) <pc-soylentNO@SPAMasdf.fi> on Thursday November 23 2017, @03:10PM (#600681) Homepage
      Right now, there are constant thunderstorms too, if you look at the atmosphere as a whole. Fortunately, there's lots and lots of mixing of air around the whole world, so localised storms can feed C14 into the pores of plants the whole world round. However, yes, it is possible for there to be variations, as with other climate-related inputs, but spikes will be averaged, and the kind of periods carbon-dating is used for will likely cover many peaks and troughs, so will average out.
      --
      Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
      • (Score: 0) by Anonymous Coward on Thursday November 23 2017, @04:41PM (2 children)

        by Anonymous Coward on Thursday November 23 2017, @04:41PM (#600706)

        Obviously I meant a period with so much more lightning than usual that it effects C-14 levels.

        I cannot find a source saying future researchers would be able to calibrate for the "bomb effect". Either the issue is not brought up or they say there will be problems. Of course, if you know about the bomb effect then you can adjust for it... but I am talking about if you are unaware that happened.

        • (Score: 2) by Immerman on Thursday November 23 2017, @06:09PM (1 child)

          by Immerman (3985) on Thursday November 23 2017, @06:09PM (#600739)

          >but I am talking about if you are unaware that happened.

          That's why you calibrate - the "bomb effect" will be clearly visible in the growth rings of trees that lived through those years. You may not know what caused it, but those rings will have a greater concentration of C-14 than the rings on either side.

      • (Score: 0) by Anonymous Coward on Thursday November 23 2017, @05:11PM (2 children)

        by Anonymous Coward on Thursday November 23 2017, @05:11PM (#600713)

        Its really hard to find anything that looks reliable on this question... but here is another one:

        Sources of Error
        -f. Changes of C14 concentration in the atmosphere.

        Effect upon Age Determination
        -Industrial effect ca -2.5% and atom bomb effect +160% in atmosphere

        Measures to minimise the error incurred
        -Interpretation of results

        http://www.c14dating.com/corr.html [c14dating.com]

        That site does not claim calibration will deal with it, just that the results have to be interpreted in the light of the industrial and bomb effects. Why not?

        • (Score: 1) by khallow on Thursday November 23 2017, @05:17PM (1 child)

          by khallow (3766) Subscriber Badge on Thursday November 23 2017, @05:17PM (#600719) Journal

          That site does not claim calibration will deal with it, just that the results have to be interpreted in the light of the industrial and bomb effects. Why not?

          The interpretation is the calibration.

          • (Score: 0) by Anonymous Coward on Thursday November 23 2017, @06:53PM

            by Anonymous Coward on Thursday November 23 2017, @06:53PM (#600763)

            I agree that "interpretation of results" is pretty vague. However, in the table it explicitly says "tree ring calibration" for other entries, but not here. So that makes me think something else is meant.

  • (Score: 3, Interesting) by TheRaven on Thursday November 23 2017, @12:44PM (2 children)

    by TheRaven (270) on Thursday November 23 2017, @12:44PM (#600632) Journal
    I remember reading that lightning can generate antimatter in New Scientist back in the '90s. What is the new contribution for this?
    --
    sudo mod me up
    • (Score: -1, Redundant) by Anonymous Coward on Thursday November 23 2017, @02:03PM

      by Anonymous Coward on Thursday November 23 2017, @02:03PM (#600662)

      Somebody tell me WTF is a "lightning can"?

    • (Score: 5, Informative) by Yog-Yogguth on Thursday November 23 2017, @03:01PM

      by Yog-Yogguth (1862) Subscriber Badge on Thursday November 23 2017, @03:01PM (#600674) Journal

      The difference seems to be "definitive proof" (rather than "not observed conclusively" but everybody accepting it as the only explanation), at least according to the abstract of the paper. I'll paste it here and add some splashes of bold, the stuff before the first bold sentences sort of sums up the past and the stuff after that is what they did and the last bold sentence is the claim being made:

      Lightning and thunderclouds are natural particle accelerators1. Avalanches of relativistic runaway electrons, which develop in electric fields within thunderclouds2,3, emit bremsstrahlung γ-rays. These γ-rays have been detected by ground-based observatories4,5,6,7,8,9, by airborne detectors10 and as terrestrial γ-ray flashes from space10,11,12,13,14. The energy of the γ-rays is sufficiently high that they can trigger atmospheric photonuclear reactions10,15,16,17,18,19 that produce neutrons and eventually positrons via β+ decay of the unstable radioactive isotopes, most notably 13N, which is generated via 14N + γ → 13N + n, where γ denotes a photon and n a neutron. However, this reaction has hitherto not been observed conclusively, despite increasing observational evidence of neutrons7,20,21 and positrons10,22 that are presumably derived from such reactions. Here we report ground-based observations of neutron and positron signals after lightning. During a thunderstorm on 6 February 2017 in Japan, a γ-ray flash with a duration of less than one millisecond was detected at our monitoring sites 0.5–1.7 kilometres away from the lightning. The subsequent γ-ray afterglow subsided quickly, with an exponential decay constant of 40–60 milliseconds, and was followed by prolonged line emission at about 0.511 megaelectronvolts, which lasted for a minute. The observed decay timescale and spectral cutoff at about 10 megaelectronvolts of the γ-ray afterglow are well explained by de-excitation γ-rays from nuclei excited by neutron capture. The centre energy of the prolonged line emission corresponds to electron–positron annihilation, providing conclusive evidence of positrons being produced after the lightning.

      I could be wrong, I'm not a physicist.

      --
      Bite harder Ouroboros, bite! tails.boum.org/ linux USB CD secure desktop IRC *crypt tor (not endorsements (XKeyScore))
  • (Score: 0) by Anonymous Coward on Thursday November 23 2017, @03:11PM (1 child)

    by Anonymous Coward on Thursday November 23 2017, @03:11PM (#600682)

    Great. Every summer I'm terrified by thunderstorms and lightings, and now there is a chance that the universe will be destroyed by a freak matter-antimatter chain reaction.

    • (Score: 1) by khallow on Thursday November 23 2017, @05:19PM

      by khallow (3766) Subscriber Badge on Thursday November 23 2017, @05:19PM (#600720) Journal

      Every summer I'm terrified by thunderstorms and lightings, and now there is a chance that the universe will be destroyed by a freak matter-antimatter chain reaction.

      Move to a universe without lightning. Duh! Another weighty problem solved by the internets.

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