Signature of antimatter detected in lightning

[saul]

The best way to see that antimatter really exists is to look at it's first discovery, namely positrons in cosmic rays. At first people thought they were electrons going up into the cloud chamber.. when they could determine the direction they found they were going down, and from the track in the magnetic field must be positively charged with the mass of an electron.

The peak at 511keV in the terrestrial gamma ray flashes is almost certainly from e- e+ annihilation. The question is how enough particles in the lightning could get enough energy to produce positrons in collisions, which then annihilate with electrons. I found this in the newsgroups from Tom Roberts:

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I agree that e+ e- pair production is almost surely the mechanism for
generating antimatter in lightning. At the tops of clouds, around 25,000
feet, air density is about 0.3 - 0.6 mg/cm^3. The range of a 1 MeV
electron in air at such densities is about 6 - 15 meters. So it must be
extremely rare for an electron to be accelerated to such an energy by
the few kV/meter fields of clouds. But out of something like 10^25
electrons in a lightning bolt, rare processes can occur. Especially if
some mechanism greatly reduces the air density within the bolt (which
transiently occurs while generating thunder) -- of course this is a
rather different time scale than the electric currents.

Note that the bolt is a plasma, and I don't know how possible it might
be for there to be local fields sufficient to accelerate a few electrons
to a few MeV; plasma wakefield acceleration might be possible, but I
don't know enough about it to evaluate whether a lightning bolt could
use it to reach such an energy. I do know that GV/meter fields have been
achieved, but in conditions far removed from a lightning bolt (20 GeV
electrons in a plasma at SLAC).

There are enough unknowns here that I don't think that antimatter
observation in lightning seriously challenges our current theories of
physics -- there are obviously megavolt potentials present. But it
likely does challenge our knowledge of the details inside a lightning bolt.

Tom Roberts
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[Anaconda]

@ saul:

I appreciate your commenting, here, in this forum.

Have you eliminated the possibility that these gamma rays are the product of classical electromagnetic reactions?

If not, then to speculate about matter -- anti-matter reactions is premature.

Dr. Anthony Peratt of Los Alamos National Laboratory has writtten of gamma ray production in the plasma physics laboratory, Physics of the Plasma Universe pp 34,35:

Gamma Ray and X ray. Most emissions at these wavelengths [infrared to gamma] is likely to be produced by electrons with energies in excess of 100 eV. We know that processes in magnetized plasmas, especially concerning electric fields aligned by magnetic fields, accelerate auroral electrons to keV energies. Similar plasma processes in solar flares produce energies of 1-10 GeV. Under cosmic conditions, relativistic double layers (Chapter 5) may generate even higher energies in magnetized cosmic plasmas.
Therefore we can assume with some confidence that the X rays and gamma rays we observe derive mainly from magnetized plasmas with energies in excess of 100 eV. Therefore, we call the picture we get from these wavelengths the high-energy plasma universe, or simply the plasma universe.
The energy densities of radiation in the gamma ray and X ray bands are approximately 10^(-18) J per cubic meter and 10^(-16) J per cubic meter respectively, and may arise from the total contribution of discrete sources (Section 6.7.5).

It might not be as exotic or "sexy" as speculation of matter -- anti-matter reactions, but there is confirmation of gamma ray production in the laboratory from high energy plasma physics.

Excluding possible alternatives is part of the Scientific Method.

Occam's Razor is a good general rule of thumb and it suggests that the simplest explanation is usually the best explanation, high energy electromagentic plasma physics is the simpler explanation.

And the high energy plasma physics of lightning is because lighting is part of an Earth -- ionosphere transference of electromagnetic energy (see link below):

http://www.thunderbolts.info/tpod/2004/ ... acitor.htm

Many natural systems form capacitors as well. For example, the Earth's surface and its ionosphere are two conducting layers separated by air. The surface-ionosphere capacitor is of particular interest in the study of sprites. Small "leaks" in the form of lightning can trigger much larger "leaks" (sprites, etc.) at high altitudes above them.

In both everyday electronics and advanced plasma research the capacitor is important for its ability to rapidly store and release electrical energy. Some of the highest energy experiments in the world are performed using large rooms full of charged capacitors to produce intense discharges.

If the, above, link provides an accurate physical explanation of lightning, then there would be plenty of plasma energy to produce gamma rays.

Sorry to be a "stick in the mud"