2024-04-29 08:46:09

Research papers published by CRD scientists in the first quarter of 2024 and citations summary

In a remarkable first quarter of 2024, scientists from the Cosmic Ray Division at the Alikhanyan National Laboratory have unveiled significant findings in high-energy atmospheric physics and solar physics, contributing important insights into thunderstorm-induced particle dynamics, magnetospheric disturbances, and atmospheric electric fields. These discoveries advance our understanding of atmospheric electric fields, the operation of the electron accelerators in thunderclouds, and Space Weather issues.

  1. Physical Review D 109, 062003 (2024)

    Atmospheric Positron Flux Modulation During Thunderstorms
    Authors: A. Chilingarian, B. Sargsyan

We report the discovery of a novel phenomenon in high-energy atmospheric physics: a significant increase in ground-level positrons during thunderstorm events. This phenomenon is associated with the development of a Lower Positively Charged Region (LPCR) at the base of thunderclouds. As electric field strength in the lower atmosphere surpasses a critical threshold, seed electrons from cosmic rays undergo acceleration, leading to the formation of relativistic runaway electron avalanches. These avalanches, consisting of millions of electrons and gamma rays with energies reaching up to 50 MeV, modify the electric field's polarity near the Earth's surface. This alteration in field polarity causes a deceleration in electron movement and an acceleration in positron movement, thereby augmenting the flux of 511 keV "annihilation" gamma rays. By detecting these gamma rays, we can trace the formation of the LPCR and monitor the dynamics of the charge structure within the lower thundercloud regions. Our findings underscore the modulation of atmospheric electric fields during thunderstorms and their influence on fluxes of cosmic ray electrons, gamma rays, muons, and neutrons. This research highlights the importance of charged structures within thunderclouds in modulating positron fluxes.

2. Advances in Space Research, in press, doi.org/10.1016/j.asr.2024.02.041
           Remarkable Impulsive Enhancement of Particle Fluxes Observed at Aragats on May 23, 2023
Authors: A. Chilingarian, G. Hovsepyan, B. Sargsyan, T. Karapetyan, D. Aslanyan, L. Kozliner

A groundbreaking Thunderstorm Ground Enhancement (TGE) event was recorded on May 23, 2023, at Mount Aragats, Armenia's highest peak. This event demonstrated a peak flux intensity exceeding 3 million particles per minute per square meter for energies above 0.4 MeV, with a measured fluence of approximately 700 particles/cm². The sophisticated instrumentation at the Aragats research station, comprising various spectrometers and detectors, facilitated a precise cross-correlation of measurements. Observations confirmed a flux of high-energy electrons at levels around 55,000 particles per minute per square meter for energies exceeding 10 MeV. Additional data, including cloud base heights and corona discharge detections, supported the recorded electric field intensity of approximately 2.1 kV/cm at elevations 50–100 m above ground level. These observations affirm the universality and significance of TGE as a major atmospheric event, impacting the global electrical circuit and necessitating integration into Earth’s atmospheric models for enhanced safety in aviation and aerospace operations.

3. Advances in Space Research, in press, doi.org/10.1016/j.asr.2024.03.013
Synergy of Space and Atmospheric Particle Accelerators in Influencing Extensive Air Showers and Atmospheric Electric Fields
Author: A. Chilingarian

Spaceborne particle accelerators disseminate high-energy particles (primary cosmic rays) throughout the galaxy. Upon entering Earth's atmosphere, these particles initiate extensive air showers (EASs), which consist of millions of secondary cosmic rays and cover large ground areas. During thunderstorms, strong atmospheric electric fields significantly modulate the energy spectra of EAS secondary particles, affecting the size and composition of these showers and influencing the frequency and energy estimations of ground-based detector triggers. This modulation is evidenced by substantial increases in particle fluxes during thunderstorm conditions, termed Thunderstorm Ground Enhancements (TGEs). Over the years, a comprehensive network of particle detectors, electric field sensors, and lightning locators has been developed, providing critical data for the establishment of a robust field of high-energy physics within the atmosphere. This paper discusses the ongoing advancements in our understanding of these complex interactions and their implications for atmospheric and space physics.
4. Journal of Environmental Radioactivity 274 (2024) 107409
Investigating the Sudden Increase in Natural Gamma Radiation During Thunderstorms on Mountain Tops
Authors: A. Chilingarian, B. Sargsyan

Our study elucidates the correlation between sudden increases in Natural Gamma Radiation (NGR) and enhanced atmospheric electric fields during thunderstorms, specifically attributing these spikes to Thunderstorm Ground Enhancements (TGEs). TGEs, characterized by transient, several-minute-long increases in particle fluxes, originate from natural electron accelerators within thunderclouds. Additionally, more prolonged yet less pronounced increases in NGR, which can last several hours, are attributed to gamma radiation from radon progeny and enhanced positron fluxes. This radon, released from terrestrial materials, is transported upward by the Near-Surface Electric Field (NSEF). We employ an ORTEC detector and custom-built large NaI (Tl) spectrometers with lead filters to distinguish between cosmic ray fluxes and radon progeny radiation accurately. Our detailed analysis differentiates the radiation enhancements during positive and negative NSEF episodes. The resultant comprehensive dataset provides critical measurements of principal isotopes and positron flux during thunderstorms compared to fair weather conditions, underscoring the global significance of these phenomena in atmospheric processes. The inclusion of these effects in numerical models of Earth’s atmosphere is essential due to their substantial planetary impact.


5. EPL - A Letter Journal Exploring Frontiers of Physics 146 (2024) 24001
Helio-Magnetic Disturbance Impact on Ground-Based Cosmic-Ray Detectors, 5 November 2023
Authors: A. Chilingarian1, T. Karapetyan1, B. Sargsyan1, M. Zazyan1, J. Knapp2, M. Walter2, T. Rehm3

The recent upsurge in solar activity in fall 2023, following a period of relative calm during the 24th solar activity cycle, signals the approach of the solar maximum of the 25th cycle expected in 2024. The complex interplay between disturbed interplanetary magnetic fields and Earth’s geomagnetic fields results in a variety of effects, ranging from potential damage to satellite electronics to the production of spectacular auroras. Understanding these interactions is increasingly vital as large magnetized clouds ejected from the Sun influence near-Earth environments. Networks of ground-based particle detectors provide essential insights into these processes by continuously monitoring cosmic ray flux. This letter discusses a rare Magnetospheric Effect observed by these networks at middle latitudes on mountaintops and presents, for the first time, the energy spectrum of the particles responsible for the observed enhancement in count rates, highlighting the intricate solar-magnetospheric interactions.

6. Physics Open 18 (2024) 100202
Spatial and Temporal Structure of Thunderstorm Ground Enhancements (TGEs) Observed on Aragats, May 23, 2023
Authors: A. Chilingarian, D. Pokhsraryan, F. Zagumennov, M. Zazyan

This study analyzes the structure of the largest Thunderstorm Ground Enhancement (TGE) event recorded on May 23, 2023, on Aragats Mountain. Through a detailed statistical analysis of particle arrival times on a nanosecond scale, we confirm that the TGE is composed of multiple independent runaway electron avalanches. The electron accelerator, triggered by the dipole emerging in the lower part of the thundercloud, directs a continuous flow of electrons and gamma rays towards Earth's surface, sustaining the particle flux for minutes. Experimental findings are bolstered by simulations of electron multiplication and acceleration in strong atmospheric electric fields. We compare these TGEs to Terrestrial Gamma Flashes (TGFs), brief bursts detected by orbiting gamma-ray detectors and associated with atmospheric discharges. Our results provide a deeper understanding of the mechanics behind these atmospheric phenomena and their implications for high-energy atmospheric physics.
7. Astroparticle Physics 156 (2024) 102924


Comparative Analysis of Energy Spectra from Thunderstorm Ground Enhancements (TGEs) at Zugspitze and Aragats

*Authors: A. Chilingarian a, T. Karapetyan a, B. Sargsyan a, J. Knapp b, M. Walter b, T. Rehm c

This research presents the first comparative analysis of the energy spectra from Thunderstorm Ground Enhancements (TGEs) recorded at the SEVAN detector sites on Zugspitze and Aragats. Significant advancements were made by updating the electronics board of the SEVAN detector at the Umwelt-Forschungs-Station (UFS, Schneefernerhaus, 2650 m asl), enabling the precise measurement of energy releases up to 50 MeV. This enhancement allows for a clear distinction between Radon progeny gamma radiation and the energetic products of relativistic runaway electron avalanches. On May 23, 2023, the first TGE registered on Zugspitze revealed a gamma-ray flux enhancement of 44%, correlating to a count rate peak enhancement of 44σ. Simultaneously, a large TGE observed on Aragats demonstrated a flux increase exceeding 200% over fair-weather levels, with a peak significance of 400σ. This paper explores the newly expanded capabilities of the SEVAN detectors and their pivotal role in advancing high-energy atmospheric physics research by offering insights into the mechanisms behind thunderstorm-induced particle accelerations and their potential implications.

8. Mendeley Data, V1, (2024) doi: 10.17632/z4ry54hccb.1
Comprehensive Catalog of Extreme Thunderstorm Ground Enhancements Registered on Aragats in 2023
Authors: Ashot Chilingarian, Tigran Karapetyan, Davit Aslanyan, Balabek Sargsyan

We present a detailed catalog of Thunderstorm Ground Enhancements (TGEs) monitored around the clock on the slopes of Mt. Aragats throughout 2023. This catalog, an update to our series previously published in Mendeley from 2013-2022, includes data on 12 parameters for 55 TGEs observed during the year. Each TGE event is linked to a comprehensive dataset comprising hundreds of measurement channels, providing an invaluable resource for further research. This catalog serves as a cornerstone for ongoing scientific inquiry, allowing researchers worldwide to perform detailed correlation analyses and to derive new physical insights into the dynamics of high-energy atmospheric phenomena.

9. Atmospheric Research, in press, 107403, https://doi.org/10.1016/j.atmosres.2024.107403
Corrigendum to "Termination of Thunderstorm-Related Bursts of Energetic Radiation and Particles by Inverted Intracloud and Hybrid Lightning Discharges"
Authors: A. Chilingarian, Y. Khanikyants, V. Rakov

In this corrigendum, we address findings from our expanded analysis covering 163 Thunderstorm Ground Enhancement (TGE) events from 2012 to 2021, a significantly larger dataset than the 49 events analyzed in our original 2020 study. The revised analysis provides new insights that challenge some of our earlier conclusions regarding the frequency and impact of lightning discharges on TGEs. Specifically, we found that the association between inverted intracloud (IC) flashes and hybrid flashes and the resultant particle flux reductions was not as pronounced as previously reported. This corrigendum is part of our commitment to updating the scientific community on our findings as new data becomes available, ensuring that our research reflects the most accurate and current understanding of these complex atmospheric interactions.

10. Pure and Applied Geophysics, Springer Nature Switzerland AG
Integrated Measurements of Particle Fluxes, Electric Fields, and Lightning Occurrences at the Aragats Space-Environmental Center (ASEC)
Authors: A. Chilingarian, T. Karapetyan, B. Sargsyan, Y. Khanikyanc, S. Chilingaryan

This paper presents an integrated overview of the measurement capabilities at the Aragats Space-Environmental Center (ASEC), focusing on the simultaneous tracking of cosmic ray species, near-surface electric fields, and lightning events. Our advanced Data Extraction Infrastructure (ADEI) facilitates rapid access to and analysis of this vast data set, which spans the highest mountains of Armenia and Eastern Europe. By elucidating the mechanisms of particle acceleration and the distribution of charge within the lower atmosphere, our work aims to catalyze transformative advancements in High-energy Physics in the Atmosphere (HEPA). The exploration of high-energy atmospheric phenomena, intracloud electric fields, and lightning initiation offers new insights into the complex interplay between these elements. Furthermore, the integration of wideband radio emissions and particle flux measurements provides a comprehensive view of the dynamic atmospheric processes occurring during thunderstorm events. This paper underscores the importance of multidisciplinary approaches in advancing our understanding of atmospheric sciences and highlights the potential for future discoveries in particle acceleration mechanisms, both terrestrial and cosmic. By examining temporal datasets and correlating surges in particle flux intensity with variations in electric field strength and precipitation patterns, we not only deepen our understanding of atmospheric processes but also enhance our ability to predict and mitigate the impacts of these high-energy events on terrestrial and aerospace systems. Our findings contribute to the broader field of geophysics by offering detailed methodologies for extracting meaningful physical insights from complex environmental data, thus paving the way for innovative research in atmospheric physics and its applications.

Most Cited CRD Papers (17 April 2024)

KASCADE Experiment

  1. "KASCADE measurements of energy spectra for elemental groups of cosmic rays: Results and open problems"

    Authors: T. Antoni, W.D. Apel, A.F. Badea, K. Bekk, A. Bercuci, J. Blümer, H. Bozdog, et al.
    Journal: Astroparticle Physics, Vol. 24, Issues 1-2, Pages 1-25
    Citations: 865

  2. "A non-parametric approach to infer the energy spectrum and the mass composition of cosmic rays"

    Authors: T. Antoni, W.D. Apel, F. Badea, K. Bekk, K. Bernlöhr, H. Blümer, E. Bollmann, et al.
    Journal: Astroparticle Physics, Vol. 16, Issue 3, Pages 245-263
    Citations: 110

MAGIC Experiment

  1. "Variable very high energy γ-ray emission from Markarian 501"

    Authors: J. Albert, E. Aliu, H. Anderhub, P. Antoranz, A. Armada, C. Baixeras, J.A. Barrio, et al.
    Journal: The Astrophysical Journal, Vol. 669, Issue 2, Page 862
    Citations: 760

Aragats Experiments and Data Analysis Papers

  1. "Methods for multidimensional event classification: a case study using images from a Cherenkov gamma-ray telescope"

    Authors: R.K. Bock, A. Chilingarian, M. Gaug, F. Hakl, T. Hengstebeck, M. Jiřina, et al.
    Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
    Citations: 327

  2. "Ground-based observations of thunderstorm-correlated fluxes of high-energy electrons, gamma rays, and neutrons"

    Authors: A. Chilingarian, A. Daryan, K. Arakelyan, A. Hovhannisyan, B. Mailyan, et al.
    Journal: Physical Review D, Vol. 82, Issue 4, Article 043009
    Citations: 279

  3. "Particle bursts from thunderclouds: Natural particle accelerators above our heads"

    Authors: A. Chilingarian, G. Hovsepyan, A. Hovhannisyan
    Journal: Physical Review D, Vol. 83, Issue 6, Article 062001
    Citations: 155

  4. "Correlated measurements of secondary cosmic ray fluxes by the Aragats Space-Environmental Center monitors"
    Authors: A. Chilingarian, K. Arakelyan, K. Avakyan, V. Babayan, N. Bostanjyan, et al.
    Journal: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
    Citations: 99