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 Lightning Fusing Hydrogen?

[DumbSwede]

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 [slashdot.org]

Not so simple

[DumbSwede]

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

This is new ?????

[Anonymous Coward]

I have chaired sessions at meetings of the American Geophysical Union where this topic was discussed - over ten years ago!

THe Stanford radio science group is very active in modelling runaway electron acceleration such as this. In addition to gamma rays, free neutrons can also be produced.

Re:I thought the atmosphere was opaque to gamma ra

[Ambitwistor]

There are ground based gamma ray detectors (Google [google.com]). They don't detect the gamma rays directly, but rather the showers as the gamma rays interact with molecules in the atmosphere.

Some numbers

[Wilson_6500]

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.

Depends on who you're talking to.

[Wilson_6500]

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.

Re:They are X-rays, not gamma rays

[ceoyoyo]

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.

Re:Radiation Overdose?

[StrongAxe]

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.

Suspected relation

[RogerWilco]

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.
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 [physorg.com]
http://www.lofar.org/workshop/23Apr07_Monday02/LOF ARWorkshop_Apr07_HeinoFalcke.pdf [lofar.org]

Re:This is self evidently garbage.

[iamlucky13]

I'm not sure if you're joking or not, so I'll reply anyways. From the paper:

A.) This is regularly detected at multiple nuclear plants, but is not caused by them. It is serendipitous because the plants already the gamma-ray detectors for operational monitoring.

B.) Superlatives like "lowest levels of radiation" are seldom meaningful in science. The detectors would have a minimum level they can reliably sense. Also, they can't determine the direction or frequency of the photons. The team that authored this paper set up a detector that can. Presumably they chose to set it up at that particular plant so they could correlate their detailed observations with those from the plant's detectors.

C.) The research was conducted by the University of Tokyo and the Japanese Space Agency (and others). The effect is not unique to Japan, rather the work was done in Japan. And yes, Japan does have magic special super clouds, but they are licensed to the makers of the Final Fantasy series.

Lastly, the effect was first suggested in 1925, but hasn't been investigated much since. Again, it's not caused by the nuclear plant (the submitter wasn't very clear about that). The plant just happened to be a convenient laboratory.