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Gamma Rays From Thunderclouds
KentuckyFC sends us a report of gamma rays detected at a Japanese nuclear plant, whose origin was thunderclouds high overhead (abstract, article PDF). The theory is that showers of electrons caused by cosmic rays, when they encounter the high electric fields present in thunderstorm clouds, can be accelerated to energies above 10 MeV and result in bremsstrahlung photons detectable on the ground.
Or possibly the fusion of deuterium/hydrogen in rain water by lightning?
I actually posted an article about this back in 2005. Lightning Fusion And Other Hot News
Letter To Iran
And neutrons will crash into other nuclei and there will be secondary fissions and fusions. Neither fission nor fusion is an entirely straight forward reaction with only one set of byproducts. Muon catalyzed fusion produces gamma rays directly.
Our own star the Sun produces gamma rays from the PP-I fusion chain 4 1H 1 4He + 2 positrons + 2 neutrinos + 2 gamma rays The by-products provide the source of luminosity: * Positrons: anti-electrons (e+) - collide with electrons (e-) * Neutrinos: rapidly escape from the star * Gamma rays (photons): travel outwards through star interacting many times with atomic gas. Energy is also provided by the PP-II and PP-III chains
Letter To Iran
A basic calculation indicates that as many as 0.7-3% of 10 MeV gammas could make it down from 2000 m. Put another way, any gamma headed for their detector will make it there about that percentage of the time. Starting with a high flux could mean that a significant number of gammas make it to the scintillators, which can trigger off of relatively small numbers of photons.
That having been said, 2000m is the lower end of the altitude range (as I understand it) for storm clouds, and my calculation assumed dry air at sea level. The attenuation of photons does go up pretty sharply as you get to energies less than 10 MeV, as well.
It's really one of those jargon-related things that happen so often in physics. Your average physicist uses "intensity" in ways that make optical scientists rip their hair out, since in optics intensity has a very specific definition. In the same vein, radiation scientists reserve "gamma" to describe photons originating from nuclear processes. Physicists in other specializations generally just go by energy because gammas tend to be higher in energy than X-rays. It's not necessarily the case though.
Yup. The cosmic ray usually isn't a photon, it's a particle of some type that slams into the atmosphere and turns into a bunch of other particles, which slam into the atmosphere some more and eventually turn into some sort of photon. That is opposed to the gamma ray which IS a photon.
If thunderclouds can accelerate radiation energy, how come I never heard of people died in places where there are lots of thuderstorm activities due to radiation overdose?
The gamma rays were only detected because they were near a nuclear power plant. Presumably such plants have very sensitive radiation detection equipment, and the number of ACTUAL gamma ray photos is sufficiently low that only very sensitive equipment could actually notice them.
There is a suspected but yet unproven relation between cosmic rays and lightning. The theory is that when a cosmic particle strikes the atmophere, it ionises a path though the atmophere. This then provides a conduit for lightning.
F ARWorkshop_Apr07_HeinoFalcke.pdf
This is currently a hot research topic in particle physics and meteorology.
A professor in Nijmegen and a collegue of mine are studying this phenomena (Heino Falcke and Lars Bähren)
http://www.physorg.com/news4162.html
http://www.lofar.org/workshop/23Apr07_Monday02/LO
RogerWilco the Adventurous Janitor