arXiv subjects

Alexey Yushkov

Publications and source records attributed to Alexey Yushkov.

3 recordsLinked to original sources

arXiv2025

Constraints on the spread of nuclear masses in ultra-high-energy cosmic rays based on the Phase I hybrid data from the Pierre Auger Observatory

We present an analysis of the correlation between the depth of the maximum of air-shower profiles and the signal in water-Cherenkov stations in events registered simultaneously by the fluorescence and surface detectors of the Pierre Auger Observatory. The analysis enables us to place constraints on the spread of nuclear masses in ultra-high-energy cosmic rays with a minor impact from the experimental systematic uncertainties and uncertainties in air-shower simulations. Due to this unique feature, the correlation analysis has previously allowed us to exclude all pure and proton-helium compositions near the ankle in the cosmic-ray energy spectrum at 5$\sigma$ confidence level. The same property makes the correlation analysis an effective tool for testing the consistency of predictions of the post-LHC hadronic interaction models, including their latest versions such as EPOS LHC-R, QGSJet-III-01, Sibyll${}^\bigstar$ and Sibyll 2.3e. In this work, the correlation analysis using the Phase I hybrid data from the Pierre Auger Observatory is presented. The analysis uses the newest generation of hadronic interaction models and covers an extended energy range around the ankle in the cosmic-ray spectrum.

astro-ph.HE↗

arXiv2019

Depth of maximum of air-shower profiles: testing the compatibility of measurements performed at the Pierre Auger Observatory and the Telescope Array experiment

At the Pierre Auger Observatory and the Telescope Array, the measurements of depths of maximum of air-shower profiles, $X_\mathrm{max}$, are performed using direct observations of the longitudinal development of showers with the help of the fluorescence telescopes. Though the same detection technique is used at both installations, the straightforward comparison of the characteristics of the measured $X_\mathrm{max}$ distributions is not possible due to the different approaches to the analysis of the recorded events. In this work, the Auger-Telescope Array composition working group presents a technique to compare the $X_\mathrm{max}$ measurements from the Auger Observatory and the Telescope Array. Applying this technique the compatibility of the first two moments of the measured $X_\mathrm{max}$ distributions is qualitatively tested for energies $10^{18.2}~{\rm eV} < E < 10^{19.0}~{\rm eV}$ using the recently published Telescope Array data from the Black Rock Mesa and Long Ridge fluorescence detector stations. For a quantitative comparison, simulations of air showers with EPOS-LHC, folded with effects of the Telescope Array detector, are required along with the inclusion in the analysis of the systematic uncertainties in the measurements of $X_\mathrm{max}$ and the energies of the events.

astro-ph.HE↗

arXiv2016

Determination of the proton-to-helium ratio in cosmic rays at ultra-high energies from the tail of the $X_{\rm max}$ distribution

We present a method to determine the proton-to-helium ratio in cosmic rays at ultra-high energies. It makes use of the exponential slope, $Λ$, of the tail of the $X_{\rm max}$ distribution measured by an air shower experiment. The method is quite robust with respect to uncertainties from modeling hadronic interactions and to systematic errors on $X_{\rm max}$ and energy, and to the possible presence of primary nuclei heavier than helium. Obtaining the proton-to-helium ratio with air shower experiments would be a remarkable achievement. To quantify the applicability of a particular mass-sensitive variable for mass composition analysis despite hadronic uncertainties we introduce as a metric the `analysis indicator' and find an improved performance of the $Λ$ method compared to other variables currently used in the literature. The fraction of events in the tail of the $X_{\rm max}$ distribution can provide additional information on the presence of nuclei heavier than helium in the primary beam.

astro-ph.HE↗