Estimation of the radiation risk to aircrew and aircraft passengers associated with atmospheric electricity events such as terrestrial gamma ray flashes and gamma ray glows

Thunderstorms produce high-energy events discovered in the 1990's, named terrestrial gamma ray flashes (TGFs) and gamma ray glows. TGFs are bursts of gamma rays, detectable by satellite, which last less than 100 μs. The energy of produced photons can reach ∼40 MeV. Concerning gamma ray glows, they are increases of the background radiation level in thunderstorms, with longer durations (from seconds to tens of minutes) but generating photon fluxes less important. Both events are produced by the same physical processes implying high-energy electrons, named relativistic runaway electron avalanches (RREAs). Those events are produced between 10 and 15 km of altitude, being coincident with commercial flight altitudes. In this thesis, we address the possible additional exposure due to these events for passengers and commercial aircrews. We performed several set of tools to answer this problematic. First, the theoretical estimation of radiation doses delivered by TGFs using numerical simulations shows that high doses are generated by source electrons, however in compact regions. Then, a statistical study estimates the probability for an aircraft to be hit by a TGF, using satellite data and flight routes, is weak. Finally, we present the development of a gamma ray spectrometer to detect these events in close proximity and predictions on the future measurements that will be performed for TGFs and gamma ray glows. (author)