BY JOSEPH DAGDIGIAN
The 14th annual meeting on “Thunderstorms and Elementary Particle Acceleration” was held from October 14 to 17, organized by the Cosmic Ray Division at the Yerevan Physics Institute. Attendees included individuals from research institutes in Armenia, the Czech Republic, Germany and Russia.
Conference participants discussed standard topics, including the observations of particle fluxes in the troposphere, in space and on the earth’s surface. Using the “solar maximum” approach—a period of maximum activity of the 25th 11-year solar activity cycle in 2024—the detection of solar events was also included. Observations of solar activity have been conducted since the early 17th century, with Galileo Galilei and Christoph Scheiner first observing sunspots by telescope 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. 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. 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 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, 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.
Studies of particle fluxes from thunderclouds measured by orbiting satellites, high flying aircraft, and by instrumentation on the ground often use different terminology. Conference participants strongly advocated for a community-wide discussion on standardizing the terminology to describe these phenomena. This revision aims to eliminate confusion in future research and agree on a proper citation practice in publications.
During an excursion to the Aragats Research Station atop Armenia’s Mt. Aragats at 9,800ft altitude, conference participants visited new facilities and particle detectors from various countries hosted at this prime location. A Czech Group from the Nuclear Physics Institute in Prague installed a new detector at Aragats. A group from the French National Centre for Space Studies (CNES) installed their detector in November, and in 2025 additional groups from Norway and France plan to deploy a particle spectrometer. The joint operation of these detectors on Mt. Aragats ensures that detectors for future balloon, aircraft, and space missions will be calibrated using the detectors and facilities on Aragats. The station is expected to register tens of TGEs annually, with the strongest events exhibiting significant electron content.
The 14th Annual TEPA Meeting underscored the critical interplay between cosmic rays and atmospheric physics. The conference facilitated international collaborations, showcased advancements at the Aragats Research Station, and emphasized the need for standardized terminology to streamline future research endeavors. The continued efforts of the CRD and its partners promise significant advancements in our comprehension of high-energy atmospheric phenomena and their broader impacts on Earth’s geospace and biosphere.
For more information on TEPA, visit the link.
