Doctor of Philosophy (PhD)


Physics and Astronomy

Document Type



Terrestrial Gamma ray Flashes (TGFs) -- very short, intense bursts of electrons, positrons, and energetic photons originating from terrestrial thunderstorms -- have been detected with satellite instruments. The TGF and Energetic Thunderstorm Rooftop Array (TETRA), an array of NaI(Tl) scintillators at Louisiana State University, has now been used to detect similar bursts of 50 keV to over 2 MeV gamma rays at ground level. After 3.3 years of observation, twenty-eight events with durations 0.02 - 4.2 msec have been detected associated with nearby lightning, three of them coincident events observed by detectors separated by ~1000 m. Nine of the events occurred within 6 msec and 3 miles of negative polarity cloud-to-ground lightning strokes with measured currents in excess of 20 kA. The events reported here constitute the first catalog of TGFs observed at ground level in close proximity to the acceleration site. The ability to observe ground-level Terrestrial Gamma Flashes from close to the source also allows a unique analysis of the storm cells producing these events. The results of this analysis are presented here. In addition to the ground-based TETRA array, a balloon-borne detector (the Lightning-Associated Gamma-ray Observer, LAGO) has been constructed and flown. Results from an engineering flight of this balloon payload are presented. Plans for an upgraded version of the ground-based array are also included.



Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Cherry, Michael