arXiv subjects

K. G. Lebedev

Publications and source records attributed to K. G. Lebedev.

11 recordsLinked to original sources

arXiv2026

The puzzle of composition of cosmic rays with energies (2-12.5) EeV according to muon detectors data of the Yakutsk EAS array

The results of a study of the cosmic ray composition in individual events in the energy range (2-12.5) EeV using the muon correlation method is presented. The considered sample included showers with zenith angles less than 60 degrees recorded in the period 1974-2018. The existence of four separate groups of primary particles with different origins is confirmed. The obtained results have potential importance for understanding the composition of cosmic rays in the specified primary energy range.

astro-ph.HE↗

arXiv2025

Giant Atmospheric Showers Detected by the Yakutsk Extensive Air Shower Array

The two most powerful extensive air showers (EAS) with energies of about $10^{20}$ eV, registered at the Yakutsk EAS array during the entire observation period of 1974-2024, are considered. Both showers hit the array near the center and triggered all surface detectors and underground muon detectors with a threshold energy of $E_μ = 1.0 \times \cos θ$ GeV. These events have an abnormally high fraction of muons, which is beyond current model predictions. This may change our understanding of hadron interactions at ultra-high energy, but there is also a possibility that these showers were initiated by some exotic primary particles.

astro-ph.HE↗

arXiv2024

Explanation to the article "On the calibration of ultra-high energy EASs at the Yakutsk array and Telescope Array"

We provide a detailed commentary on the energy calibration of the TA experiment described in our paper (arXiv:2404.16948 [astro-ph.HE]). That paper concludes that the TA energy estimation, which is tied to optical measurements, might be incorrect. A response from members of the TA Collaboration (arXiv:2407.12892 [astro-ph.HE]) states that this conclusion is wrong and "stems from a misinterpretation and an incorrect application of the TA energy deposit formula". Here we demonstrate that our formula for energy deposit is not in fact a rescaled modification of the TA equation, but follows from description of the processes occurring during the passage of charged particles through 1.2 cm thick scintillator. Our estimation of the TA detector response implies the correctness of the cosmic ray spectrum derived from readings of surface detectors of the array.

astro-ph.HE↗

arXiv2024

Estimation of the composition of ultra-high energy cosmic rays using the muon correlation method based on Yakutsk EAS array data

In this article a new method is proposed for estimating the mass composition of cosmic rays in individual events with energies above $1.25 \times 10^{19}$ eV. It is based on a joint analysis of experimental data and simulation results obtained using the QGSJet-II.04 model for muons with threshold energy $E_μ = 1.0 \times \cosθ$ GeV in air showers with zenith angles up to 60 degrees. The data from ground-based and underground scintillation detectors of the Yakutsk EAS array were used. Separate groups of nuclei and other primary particles were found.

astro-ph.HE↗

arXiv2024

On the calibration of ultra-high energy EASs at the Yakutsk array and Telescope Array

An analysis of calibrations of extensive air showers with zenith angles $θ\le 50^{\circ}$ and energies $E_{\text{SD}} \ge 10^{18.5}$ eV was carried out in experiments at the Yakutsk array and Telescope Array. The values of $E_{\text{SD}}$ were determined from particle densities measured with ground-based scintillation detectors at a distance $r = 800$ m from shower axis. Measured densities were compared with the values obtained in simulations preformed with the use of CORSIKA code within the framework of QGSJet-II.04 hadron interaction model for primary protons. For showers with $θ= 0^{\circ}$ the $E_{\text{SD}}$ estimates of both arrays are very close, and their energy spectra are similar in shape and absolute value. Another Telescope Array calibration, based on measuring the EAS fluorescent radiation with optical detectors, gives underestimated energy $E_{\text{FD}} = 0.787 \times E_{\text{SD}}$.

astro-ph.HE↗

arXiv2024

A Direct Comparison of Muon Measurements at the Yakutsk Array and the Pierre Auger Observatory

Here we consider the results of direct measurements of muons in extensive air showers with zenith angles $θ\le 45^{\circ}$ and energy above $10^{17}$ eV, obtained at the Pierre Auger Observatory and Yakutsk array. In both experiments muons were registered with underground scintillation detectors with $\approx 1.0 \times \secθ$ GeV energy threshold. Measured density values were compared to theoretical predictions calculated within the framework of the QGSJet-II.04 hadron interaction model. They differ by factor $1.53 \pm 0.13$(stat). We demonstrate that this difference is due to overestimation of muon densities by 1.22 times and underestimation of primary energy by 1.25 times in the Auger experiment.

astro-ph.HE↗

arXiv2023

Muon puzzle in ultra-high energy EASs according to Yakutsk array and Auger experiment data

The lateral distribution of particles in extensive air showers from cosmic rays with energy above $10^{17}$ eV registered at the Yakutsk complex array was analyzed. Experimentally measured particle densities were compared to the predictions obtained within frameworks of three ultra-high energy hadron interaction models. The cosmic ray mass composition estimated by the readings of surface-based and underground detectors of the array is consistent with results based on the Cherenkov light lateral distribution data. A comparison was made with the results of direct measurement of the muon component performed at the Pierre Auger Observatory. It is demonstrated that the densities of muon flux measured at Yakutsk array are consistent with results of fluorescent light measurements and disagree with results on muons obtained at the Auger array.

astro-ph.HE↗

arXiv2023

Muons in EASs with $E_0 = 10^{19}$ eV according to data of the Yakutsk Array

Lateral distribution functions of particles in extensive air showers with the energy $E_0 \simeq 10^{19}$ eV recorded by ground-based and underground scintillation detectors with a threshold of $E_μ \simeq 1.0 \times \secθ$ GeV at the Yakutsk array during the continuous observations from 1986 to 2016 have been analyzed using events with zenith angles $θ\le 60^{\circ}$ functions have been compared to the predictions obtained with the QGSJet01 hadron interaction model by applying the CORSIKA code. The entire dataset indicates that cosmic rays consist predominantly of protons.

astro-ph.HE↗

arXiv2023

Zenith-Angular Characteristics of Particles in EASs with $E_0 \simeq 10^{18}$ eV According to the Yakutsk Array Data

Particle lateral distributions were investigated in cosmic ray air showers with energy $E_0 \simeq 10^{18}$ eV registered at the Yakutsk array with surface and underground scintillation detectors with $\simeq 1 \times \secθ$~GeV threshold during the period of continuous observations from 1986 to 2016. The analysis covers events with arrival direction zenith angles $θ\le 60^{\circ}$ within five intervals with step $Δ\cosθ= 0.1$. Experimental values were compared to simulation results obtained with the use of CORSIKA code within the framework of QGSJet01 hadron interaction model. The whole dataset points at probable cosmic ray composition which is close to protons.

astro-ph.HE↗

arXiv2023

Content of muons in extensive air showers measured by Yakutsk array

Lateral distribution of muons in extensive air showers registered at the Yakutsk array was investigated. The analysis covers two periods of observation: before 2018 and after 2020, when the revision of muon detectors with 1-GeV threshold was complete. Measured values of muon density are compared to computational results obtained within the framework of two hadron interaction models. Within the energy domain above $10^{18}$ eV the best agreement is observed for proton composition primary cosmic rays.

astro-ph.HE↗

arXiv2021

Status of the Yakutsk air shower array and future plans

The Yakutsk Extensive Air Shower Array has been continuously operating for more than 50 years (since 1970) and up until recently it has been one of world's largest ground-based instruments aimed at studying the properties of cosmic rays in the ultra-high energy domain. In this report we discuss results recently obtained at the array - on cosmic rays energy spectrum, mass composition and directional anisotropy - and how they fit into the world data. Special attention is paid to the measurements of muonic component of extensive air showers. Theoretical results of particle acceleration at shocks are also briefly reviewed. Future scientific and engineering plans on the array modernization are discussed.

astro-ph.IM↗