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Antimatter from Thunderstorms

January 14, 2011 at 6:17 am

Now this is cool: an orbiting gamma-ray telescope has detected the creation of antimatter by earthly thunderstorms

This is strange and delightful.  I'm a little taken aback that people apparently predicted this quite a long time ago.  (And it's in the literature, so they really did.)

Since I spent my graduate student days thinking about high energy radiation processes, I can't help but speculate about this.

Postulating the creation and annihilation of antimatter as a method for generating all gamma rays within a thunderstorm strikes me as putting the cart before the horse.  It makes much more sense to me that a preexisting gamma above the electron pair-creation threshold would be the source of the positrons, which then create a secondary population of gammas via pair annihilation.  One can imagine Compton scattering scenarios that would boost a lower-energy X-ray photon up to the pair-creation threshold, thus starting the process.  (We already know thunderstorms can produce X-rays.)  But if the antimatter is the original source of the gammas, you have to speculate about a pair-creation process that doesn't already invoke such high energy photons—which is much more difficult at these energies.

But  what do I know.  I write books about Nazis.

I'm tickled that this discovery was made by the Fermi telescope.  When I was in grad school, it was called GLAST (for Gamma-Ray Large Area Space Telescope), and it hadn't been launched yet.  I wrote about the potential impact of GLAST observations in my thesis.  If I had stayed in the field, I would have loved to incorporate GLAST/Fermi data into further iterations of that research. 

Oh, well.

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