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

TL;DR

This paper compares calibration methods for ultra-high energy extensive air showers at Yakutsk and Telescope Array, analyzing their consistency and the impact of different measurement techniques on energy estimates.

Contribution

It provides a detailed comparison of calibration procedures and results between Yakutsk and Telescope Array, highlighting the agreement and discrepancies in energy measurements.

Findings

Energy estimates for vertical showers are consistent between arrays.

Fluorescent detector calibration yields lower energy estimates than surface detectors.

Simulations with CORSIKA and QGSJet-II.04 support the calibration results.

Abstract

An analysis of calibrations of extensive air showers with zenith angles $\theta \le 50^{\circ}$ 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 $\theta = 0^{\circ}$ 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 $E_{\text{FD}} = 0.787 \times E_{\text{SD}}$.