8. TEPA conference is succesfully over

The recent achievements in the research of the powerful electron accelerators operating in the earth’s atmosphere were reported during the 8th iteration of the Thunderstorms and elementary particle accelerators (TEPA) conference in Prague, October 17-20, 2022. The conference in the premises of Department of Radiation Dosimetry (DRD) of the Nuclear Physics Institute of the CAS was organized by the Cosmic Ray Division of Yerevan Physics Institute, Armenia, and by the Research Centre of Cosmic Rays and Radiation Events in Atmosphere (CRREAT), leaded by NPI of the CAS.

After two-years delay due to covid19 pandemia, physicists from Armenia, France, Czech Republic, Slovakia, Germany, Japan, and Sweden again gathered together for discussing new exciting results in this fast-developing scientific field.

The new emerging field of high-energy physics in the atmosphere (HEPA) has been enriched recently by important observations of particle fluxes on Earth’s surface, in the troposphere, and in space. HEPA presently includes three main types of measurements: Terrestrial Gamma Ray Flashes (TGFs) – brief bursts of gamma radiation (sometimes also electrons and positrons) registered by orbiting gamma ray space observatories, Thunderstorm ground enhancements (TGEs) – short and prolonged electron and gamma ray fluxes registered on the Earth’s surface, and Gamma glows – gamma ray bursts observed in the thunderclouds by instrumentation on balloons and aircraft. 

The main scientific results of the conference can be summarized as follows:

The origin of the enhanced particle fluxes from the thunderous atmosphere is relativistic runaway electron avalanches (RREAs), emerging in the lower atmosphere each time when the strength of the atmospheric electric field exceeds the critical value specific for the air density (height above the sea level). The enhanced fluxes of the electrons and gamma rays detected on the earth’s surface as thunderstorm ground enhancements (TGEs) can be enormously high, reaching hundreds of percent above the fair-weather level. The intensity of the atmospheric neutron flux can be doubled during TGEs. On average, each second the earth’s surface is bombarded by 10^18 high-energy leptons (with energy above 100 KeV). These foundings are presented in the recent catalogs published by Armenian and Japanese groups, and by detecting numerous TGEs by the same type SEVAN detectors, in the Czech Republic at Mileshovka site, at Lomnicky Mt. in Slovakia, and Mt. Musala in Bulgaria, and by other groups worldwide.

During the excursion to Mileshovka hill where the majority of CRREAT project facilities are located, the conference participants see big progress of CRREAT group in preparing new experimental facilities, including optical lightning monitoring capabilities and in detecting TGEs with SEVAN detector.

During TEPA conference, the Aragats Space Environmental Center (ASEC) consultative board meeting chaired by J. Knapp took place. The board listed A.Chilingarian’s report on the 2022 research activities and gave recommendations concern 2023 scientific program.