Comment on "'Seed' electrons from muon decay for runaway mechanism in the terrestrial gamma ray flash production," by Gerson S. Paiva, Antonio C. Pavão, and Cristiano C. Bastos
Dwyer, Joseph R.
Smith, David M.
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In summary, the paper by Paiva et al.  assumes unrealistically large electric fields and cosmic ray fluxes to produce an electron source that, even at this exaggerated level, would be insignificant compared with the electrons produced more directly by the same cosmic rays. Even with this artificially high level of seed particles, an unreasonably large avalanche multiplication factor must still be assumed in order to explain TGFs. We note that the 1010 avalanche multiplication factor that the authors claim to be a prediction of their model (in their section 4) is actually a parameter that was adjusted to fit the TGF observations (calculated in their section 3). It is incorrect and a circular argument to claim that this parameter is in good agreement with observations and other work, as they do in their conclusion. Furthermore, the 35 MeV electron energy predicted by the authors (see their section 4) is not a characteristic energy of runaway electron seeds in any model; rather it is close to the highest energy reached in a fully evolved avalanche (well above the average energy of 7 MeV), and therefore irrelevant to a discussion of seeding. Copyright 2010 by the American Geophysical Union.