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Gamma Ray Signatures of Neutrons From a Terrestrial Gamma Ray Flash
Author(s) -
Bowers G. S.,
Smith D. M.,
MartinezMcKinney G. F.,
Kamogawa M.,
Cummer S. A.,
Dwyer J. R.,
Wang D.,
Stock M.,
Kawasaki Z.
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2017gl075071
Subject(s) - gamma ray , physics , neutron , flash (photography) , nuclear physics , astrophysics , optics
Following a lightning strike to a wind turbine in Japan, we have observed a large burst of neutrons lasting 100 ms with a ground fluence of ~1,000 n cm −2 , thousands of times greater than the peak neutron flux associated with the largest ground level solar particle event ever observed. This is the first detection of an unequivocal signature of neutrons from a terrestrial gamma ray flash, consisting of a 2.223 MeV gamma‐ray spectral line from a neutron‐capture on hydrogen reaction occurring in our detector, and is shown to be consistent with the production of 10 12 –10 13 photoneutrons from a downward terrestrial gamma ray flash (TGF) at 1.0 km, with a gamma ray brightness typical of upward TGFs observed by satellites.