GENERAL INFORMATION:

TIME: September 22-25, 2025

LOCATION: Yerevan, Armenia

VENUE: Conference Hall of the Cosmic Ray Division of Yerevan Physics Institute,

2 Alikhanyan Brothers Street, Yerevan, Armenia

ORGANIZER: Cosmic Ray Division (CRD) of Yerevan Physics Institute, Armenia

Figure 1. Relativistic Runaway Electron Avalanches (RREA) produce extended particle fluxes in the upper and lower atmosphere. Surface detectors and detectors on board aircraft register numerous particle bursts over huge areas with durations from seconds to tens of minutes.

BACKGROUND:

Thunderstorms generate intense electric fields that extend across large areas within and around the storm system. Charge separation in thunderclouds, driven by updrafts of warm air and interactions among hydrometeors, generates oppositely directed dipoles within the cloud. The upper dipole consists of the main negative and positive charge layers in the middle and top of a thundercloud (first dipole). The gamma-ray glows, generated in the upper atmosphere, are detected by airborne experiments flying above thunderstorms. The most energetic gamma rays occasionally reach orbiting gamma observatories 400-700 km from the source, registering microsecond bursts of particles known as terrestrial gamma flashes (TGFs). Closer to the ground, the lower dipoles, comprising charge layers in the cloud and their induced counterparts on Earth’s surface, accelerate electrons and produce runaway avalanches. The main negative layer and an induced mirror charge in the Earth’s surface formed a second dipole. A third dipole forms between the main negative layer and a transient “pocket” of positively charged particles in the lower part of the cloud (LPCR), which is often associated with falling graupel. Electrons accelerated in 2 lower dipoles create electron-gamma ray avalanches detected on the ground as thunderstorm ground enhancements (TGEs), comprising millions of gamma rays, electrons, and neutrons. A fourth dipole between the LPCR and its mirror in the Earth accelerates positrons and positive muons while decelerating electrons and negative muons. Understanding charge structures and their particle acceleration mechanisms provides critical insights into high-energy atmospheric physics (HEPA). These processes affect atmospheric science, space weather forecasting, and even potential global climate change.

Establishing synchronized sensor networks for continuous particle flux monitoring has revolutionized HEPA research. These advancements enable the integration of cosmic ray studies with atmospheric physics, offering practical applications such as predicting geomagnetic storms that threaten satellites and power grids. Moreover, understanding the effects of extreme electric fields during solar flares contributes to mitigating risks associated with natural disasters. The new understanding of thunderclouds as media full of radiation opens up new avenues for research, including developing theories on cloud electrification and its potential impact on climate change.

As the field evolves, the Astroparticle and Atmospheric physics intersection offers unprecedented opportunities. Enhanced understanding of thundercloud electrification, gamma-ray generation, and their potential links to climate systems opens new research frontiers. Collaboration between researchers in solar, astrophysical, and atmospheric physics, combined with technological innovation, will pave the way for groundbreaking discoveries. This conference is a platform for fostering such collaborations, advancing geospace physics, and addressing global challenges like natural disasters and climate change.

STRUCTURE OF THE SYMPOSIUM:

We anticipate the following sessions:

Multivariate observations of particles from the Earth’s surface, in the atmosphere, and from space (TGEs, gamma glows, and TGFs)
Correlated measurements of the atmospheric discharges, lightning flashes, and particle fluxes;
Space Weather and Solar physics with SEVAN network;
Influence of the atmospheric electric field on experiments using the atmosphere as a target (Surface Arrays and Cherenkov Imaging Telescopes);
Remote sensing and modeling of the atmospheric electric fields;
Instrumentation;
Data organization and correlation analysis of multivariate remote measurements assisted by AI.

We plan to discuss the most intriguing problems related to high-energy physics in the atmosphere and explore possible directions for advancing collaborative studies. Additionally, we will report on the results of the international competition for annual projects in high-energy physics in the atmosphere that will be performed on Aragats.

Topics to be covered during oral and poster sessions:

Energy spectra of electrons and gamma rays measured on the earth’s surface, in the atmosphere,

and space; their relation to the strength and location of the electric field;

Abrupt termination of the particle flux by the lightning flash;
Registration of neutron and positron fluxes during thunderstorms;
SEVAN particle detector network as a tool of HEPA research;
Methods of remote sensing of thundercloud charge structure and atmospheric electric fields;
Relations to the climate and space weather issues;
Monitoring of lightning flashes by fast cameras;
Influence of the atmospheric electric fields on Extensive Air Showers (EASs);
The possibility of joint observations by aircraft and ground-based facilities.

ABSTRACT SUBMISSION:

Abstracts should be submitted electronically on the Symposium website. The deadline for abstract submission is August 1, 2025

REGISTRATION:

Registration for TEPA 2025 should be done online via the Symposium website. We will provide participants with their accounts on the Symposium website. These accounts will be used to submit abstracts and papers for Symposium proceedings and provide information about accompanying persons.

Registration fees will be paid at the conference desc:

▪ Regular Attendees 200 EUR

▪ Undergraduate and Graduate Students 50 EUR

The fee covers coffee breaks, reception, logistics, and excursion to Aragats. The conference site will list hotels and restaurants near the Yerevan Physics Institute. We plan an excursion to Aragats research station.

CONFERENCE DEADLINES:

- 1 August 2025 Abstract submission deadline.

- 1 September 2025 Contributions selected and participants notified.

- 15 September 2025 Symposium program at the Conference site.

CORRESPONDENCE:

Zara

Asaturyan

TEPA 2025 Secretary

zaraasaturyan.87@gmail.com

Phone: +374 93721159