AE21A-04
An Intense Terrestrial Gamma-ray Flash Observed at Ground Level

Tuesday, 15 December 2015: 08:45
3001 (Moscone West)
J Eric Grove1, Bernard F. Phlips1, Eric A. Wulf1, Anthony L. Hutcheson1, Lee J. Mitchell1, Richard S. Woolf1, W. Neil Johnson1, Meagan Schaal1, Martin A Uman2, Douglas Jordan2, Brian Hare2, Hamid Rassoul3 and Alan Bozarth3, (1)Naval Research Lab DC, Washington, DC, United States, (2)Univ Florida, Gainesville, FL, United States, (3)Florida Institute of Technology, Melbourne, FL, United States
Abstract:
We report on an intense gamma-ray flash observed at ground level in August 2014 at the International Center for Lightning Research and Testing, Camp Blanding, Florida, that occurred 13 ms after the initiation of the first stroke of an altitude-triggered lightning discharge. The measurements were made with an array of 78 plastic, liquid, and fast inorganic scintillators for robust spectroscopy of high-rate transients. The gamma-ray spectrum, time-intensity profile, and luminosity at the putative source altitude are consistent with those of a Terrestrial Gamma-ray Flash (TGF). The fluence of >100 keV gamma rays at ground level in the ~200 μs flash was in excess of 10 photons / cm2, an order of magnitude brighter than typical TGFs observed from low-Earth orbit. The proximity of the TGF to our large scintillator array allows these to be the most detailed gamma-ray measurements ever made of a TGF.

Work at NRL was sponsored by the Chief of Naval Research.

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