Doctor of Philosophy (PhD)


Physics and Astronomy

Document Type



Terrestrial gamma-ray flashes (TGFs) are sub-millisecond duration intense bursts of gamma-rays discovered to be correlated with thunderstorms. These events, radiation associated with lightning leaders, and longer duration increases in rate have been observed both by satellites and detectors on the ground. The TGF and Energetic Thunderstorm Rooftop Array II (TETRA-II) experiment is a ground-based array of bismuth-germanate (BGO) scintillators deployed in Baton Rouge, Louisiana; Utuado, Puerto Rico; and Panama City, Panama to detect these thunderstorm-related events. After 3 years of operation, 23 gamma-ray bursts have been detected with an average duration of 970 s with on average 70 photons detected in the 200 keV - 8 MeV energy range. Of the 23 events, 20 have a radio signal observed within 1.3 ms of the beginning of the event, indicating that these events are produced by the final stages of the lightning step leader process that occurs before the radio emission. The TETRA-II equipment and design, details on the short duration bursts, and a search for longer duration events are presented.



Committee Chair

Cherry, Michael