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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)
(Score: 2) by FatPhil on Thursday November 23 2017, @03:10PM (6 children)
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)
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)
>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, @08:47PM
See khallows post here where he seems to claim this cannot get rid of the problem (you still have multiple rings with the same c14 ratio):
https://soylentnews.org/comments.pl?noupdate=1&sid=22701&page=1&cid=600798#commentwrap [soylentnews.org]
That is the problem I am talking about.
(Score: 0) by Anonymous Coward on Thursday November 23 2017, @05:11PM (2 children)
Its really hard to find anything that looks reliable on this question... but here is another one:
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)
The interpretation is the calibration.
(Score: 0) by Anonymous Coward on Thursday November 23 2017, @06:53PM
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.