Recovering of the TGE electron and gamma ray energy spectra

Abstract

Strong electric fields inside thunderclouds give rise to enhanced fluxes of high-energy electrons and, consequently, gamma rays and neutrons. During thunderstorms at Mount Aragats, hundreds of Thunderstorm Ground Enhancements (TGEs) comprising millions of energetic electrons and gamma rays, as well as neutrons, were detected at Aragats Space Environmental Center (ASEC) on 3200 m altitude. Observed large TGE events allow for the first time to measure the energy spectra of electrons and gamma rays well above the cosmic ray background. We describe the methodology of solving cosmic ray physics inverse problem to recover the energy spectra of electrons and gamma rays incident on particle detectors located at mountain altitudes. The energy spectra of the electrons have an exponential shape and extend up to 30-40 MeV. Recovered energy spectra of the gamma rays is also exponential in energy range 5-10 MeV, then turns to power law and is extending up to 100 MeV.