Date of Award


Document Type


Degree Name

Master of Science (MS)


Physics and Astronomy

Committee Chair

James A. Miller

Committee Member

Don A. Gregory

Committee Member

Massimiliano Bonamente


Gamma ray detectors., Scintillation counters., Pilot balloons.


Terrestrial Gamma-ray Flashes (TGFs) are intense bursts of gamma-rays which are produced in the atmosphere and thought to be correlated with intra-cloud and positive cloud-to-ground lightning. The leading theories suggest strong electric fields inside of thunderstorms can become momentarily destabilized by a stroke of lightning, which causes the acceleration of electrons in the opposite direction of the electric field. However, the specifics of these theories, including the electric field direction and intensity, TGF beam profile, and TGF source location, are still unknown. The High Energy Lightning Emission Network (HELEN) project, designed and built at the University of Alabama in Huntsville (UAH), uses four balloon-borne detector systems flown together to form a network of detectors. Each balloon line consists of a gamma/neutron spectrometer and an electric field meter. The spectrometers, a photomultiplier tube mounted with scintillator crystals, will record a gamma-ray and neutron spectrum while the electric field meter will record the local electric field strength and direction. The four detectors flown simultaneously around the thunderstorm on four different balloons are able to make detailed multi-point measurements of a single TGF event, something that has not been done before with a balloon-borne instrument. Such measurements can provide answers to the key questions of TGF formation.



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