Radio emission of air showers with extremely high energy measured by the Yakutsk Radio Array

Abstract

The Yakutsk Array is designed to study cosmic rays at energy 10 15 -10 20 eV. It consists several independent arrays that register charged particles, muons with energy E≥1 GeV, Cherenkov light and radio emission. The paper presents a technical description of the Yakutsk Radio Array and some preliminary results obtained from measurements of radio emission at 30-35 MHz frequency induced by air shower particles with energy ε ≥ 1·10 17 eV. The data obtained at the Yakutsk array in 1986-1989 (first set of measurements) and 2009-2014 (new set of measurements). Based on the obtained results we determined:Lateral distribution function (LDF) of air showers radio emission with energy ≥ 10 17 eV. Radio emission amplitude empirical connection with air shower energy. Determination of depth of maximum by the ratio of amplitude at different distances from the shower axis. For the first time, at the Yakutsk array, radio emission from the air shower with energy > 10 19 eV was registered including the shower with the highest energy ever registered at the Yakutsk array with energy ∼2 · 10 20 eV.

Characteristics of air showers with energy more than 1017 eV reconstructed by the Yakutsk array radio emission measurements

“…For 24h observation times at frequencies up to 20 MHz, it is not possible to distinguish radio pulses with sufficient efficiency because of the presence of a large natural radio noise of predominantly thunderous origin [13]. Therefore, it is reasonable to select frequencies above 20 MHz, since ionosphere noise decreases dramatically in the transition to higher frequencies and is about (0.5-1) µV•m −1 •MHz −1 at frequency ∼20 MHz.…”

“…The use of additional data from other detectors of the Yakutsk array allowed us to find correlations between radio emission and air shower parameters [13].…”

Longitudinal development of EAS in the energy range $10^{15} - 10^{20}$ eV by observation in the period of 1994-2014 at the Yakutsk

“…Similarly works Small Cherenkov array but in this case triggering is performed by the Cherenkov detectors. The main array includes experiments on the study of radio emission of EAS at frequencies of 30-35 MHz [3], points for studying the space-time structure of the EAS disk and delayed particles [4], laser sounding of the atmosphere at a wavelength of 532 nm and spectrometric measurements of the aerosol of air [5], etc.…”

Yakutsk array cherenkov telescope prototype

“…allow us to discriminate some scenarios.The latest updates with the method of registration of radio emission of ultrahigh energy particles at Yakutsk array described in [8].…”