YEREVAN — The 14th annual meeting of “Thunderstorms and Elementary Particle Acceleration” (TEPA, Yerevan, Armenia, October 14-17), was organized by the Cosmic Ray Division (CRD) at the Yerevan Physics Institute. Attendees were from research institutes Armenia, the Czech Republic, Germany and Russia.
The traditional topics of observations of particle fluxes in the troposphere, in space, and on the earth’s surface was discussed. With the approach of the “solar maximum,” a period of maximum activity of the 25th 11-year solar activity cycle in 2024, the detection of solar events was included. Observations of solar activity have been conducted since the early 17th century, with the first telescopic observation of sunspots by Galileo Galilei and Christoph Scheiner around 1810.
The conference highlighted the synergy between cosmic ray physics and high-energy atmospheric physics, particularly through the interaction of processes in space and in the earth’s atmosphere. Acceleration processes in space supply the earth’s atmosphere with seed cosmic ray particles, resulting in Extensive Air Showers (EASs). These cascades of subatomic particles are produced when high energy primary cosmic ray particles interact with the earth’s atmosphere. Strong electric fields within thunderclouds can enhance this process, called Thunderstorm Ground Enhancements (TGEs). This significantly increases the number of electrons detected by instruments on the earth’s surface, thereby making it difficult to estimate the characteristics of the primary cosmic ray particles.
Since the inception of Thunderstorm Ground Enhancement (TGE) research in 2009, the CRD has consistently organized international conferences to explore problems in high-energy atmospheric physics and to advance collaborative studies.
In 2009, the CRD initiated TGE research on Mt. Aragats and established the SEVAN particle detector network to monitor TGEs across Eastern Europe, Germany, and Armenia. Atmospheric electron accelerators produce copious particles with energies of tens of million electron volts (MeV), covering vast atmospheric volumes and expansive areas on Earth’s surface. This substantial flux of electrons and gamma rays has coexisted with life on Earth for billions of years, undoubtedly influencing various aspects of the geospace and biosphere.
In 2023, at CRD ‘s Aragats research station, several episodes of minute-long stable electron fluxes spanning 50,000 square meters were observed. A massive electron beam emerged within a thundercloud, triggering gigantic avalanches of electrons, photons, and neutrons. This newly identified source of energetic radiation from thunderclouds represents a significant factor in geophysics and warrants inclusion in comprehensive Earth models.
