Lateral distribution of radio signal measured in showers with energy 5*10^16-10^18 eV at the Yakutsk EAS array

We present of measurements of radio emission from EAS at the frequency 32 MHz performed in 2008-2012. Showers were selected by zenith and azimuth directions, sampled by energy. A mean lateral distribution function was fitted to the data each interval. The paper presents unied approximation formula for all three energy intervals of lateral distribution, using connection between equation (1) and (2) coefficients with energy and geomagnetic angle. Here we analyze the connection between the shape of lateral distribution and the depth of the maximum shower development Xmax too.Comment: 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 201

Correlation of AOT with Relative Frequency of Air Showers with energy 10^{15} - 10^{16} eV by Yakutsk Data

Long-term series of measurement of spectral transparency of the atmosphere (\lambda = 430 nm) and atmospheric optical thickness (AOT) measured by multimode photometer CE 318 in the region of Yakutsk array are analyzed. Correlation of AOT with intensity of air showers with small energies 10^{15} - 10^{16} eV is found. The variability of aerosol composition of the atmosphere during the registration period of the Cherenkov light should be taken into account since it may affect the quality of determining characteristics of air showers.Comment: XXV ECRS 2016 Proceedings - eConf C16-09-04.

The depth of maximum shower development and its fluctuations: cosmic ray mass composition at E_0 >= 10^17 eV

We present new data on Cherenkov light observations obtained during the period 1994-2009, after a modernization of the Yakutsk EAS array. A complex analysis of \xmax and its fluctuations \sigma(\xmax) was performed over a wide energy range. With the new data, according to QGSJet II model, an estimation was made of the cosmic ray mass composition for \E \sim 10^{17} - 3 \times 10^{19} eV. The result points towards a mixed composition with a large portion of heavy nuclei at \E \sim 10^{17} eV and the dominance of light nuclei at \E \sim 10^{19} eV. The analysis of \sigma(\xmax) energy dependence for the same energies qualitatively confirms this result. The shape of the \xmax distribution at fixed energy $10^{18}$ eV is analysed to make more precise conclusions on cosmic ray mass composition.Comment: Contributed paper to the XVI International Symposium on Very High Energy Cosmic Ray Interactions ISVHECRI 2010, Batavia, IL, USA (28 June - 2 July 2010). 4 pages, 5 figure

Spectrum and mass composition of cosmic rays in the energy range 10^15-10^18 eV derived from the Yakutsk array data

A spectrum of cosmic rays within energy range 10^15 - 3x10^17 eV was derived from the data of the small Cherenkov setup, which is a part of the Yakutsk complex EAS array. In this, work a new series of observation is covered. These observations lasted from 2000 till 2010 and resulted in increased number of registered events within interval 10^16 - 10^18 eV, which in turn made it possible to reproduce cosmic ray spectrum in this energy domain with better precision. A sign of a thin structure is observed in the shape of the spectrum. It could be related to the escape of heavy nuclei from our Galaxy. Cosmic ray mass composition was obtained for the energy region 10^16 - 10^18 eV. A joint analysis of spectrum and mass composition of cosmic rays was performed. Obtained results are considered in the context of theoretical computations that were performed with the use of hypothesis of galactic and meta-galactic origin of cosmic rays.Comment: Proc. 32nd ICRC, Aug.11-18, Beijing, Chin

The nature of pulses delayed by 5 mcs in scintillation detectors from showers with the energy above 1E17 eV

Here we consider EAS events with energy above 1E17 eV with recorded pulses delayed by t>=5 mcs in scintillation detectors with different thresholds: 10, 5 and 1.8 MeV. In order to identify pulses from electrons, muons and neutrons, experimental data were compared to computational results performed within the framework of QGSJET01d model. Preliminary, one may speculate of registration of low-energy electrons arisen from moderation of neutrons in a detector or a medium surrounding a detector or in the snow cover and frozen crust (albedo particles). The fact that such pulses were registered mostly in low-threshold detectors confirms this hypothesis.Comment: Proc. of the 33rd ICRC (2013), Rio de Janeiro, Brazi

Air shower registration algorithm and mathematical processing of showers with radio signal at the Yakutsk array

The paper describes the techniques and method of registration of air shower radio emission at the Yakutsk array of extensive air showers at a frequency of 32 MHz. At this stage, emission registration involves two set of antennas, the distance between them is 500m. One set involves 8 antennas, second - 4 antennas. The antennas are perpendicularly crossed dipoles with radiation pattern North South,West East and raised 1.5 m above the ground. Each set of antennas connected to an industrial PC. The registration requires one of two triggers. First trigger are generated by scintillation detectors of Yakutsk array. Scintillation detectors cover area of 12 km^2 and registers air showers with energy more than 10^17 eV. The second trigger is generated by Small Cherenkov Array that covers area of 1 km^2 and registers air showers with energy 10^15 - 5*10^17 eV. Small Cherenkov Array is part of Yakutsk array and involve Cherenkov detectors located at a distance of 50, 100, 250 m. For further selection we are using an additional criterion the radio pulse must be localized in the area corresponding to the delay time on first and second triggers. In addition, descriptions of the algorithm and the flowcharts of the program for the air shower selection and further analysis are given. This method registers EAS radio emission with energy 10^16 - 10^19 eV. With the absolute calibration, the amplitudes of all antennas converted to a single value. Air shower radio emission dependences from zenith angle and shower energy are plotted.Comment: Contributions to the 33rd International Cosmic Ray Conference, Rio de Janeiro, Brazil, July 201

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

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$\geq$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 $\varepsilon$ $\geq$ 1$\cdot$10$^{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 $\geq$ 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 $\sim$2 $\cdot$ 10$^{20}$ eV.Comment: 11 pages, 20 figures, 2 tables, accepted for publication in NIM A. arXiv admin note: text overlap with arXiv:1609.0327

The energy spectrum of cosmic rays above 10^15 eV as derived from air Cherenkov light measurements in Yakutsk

The Yakutsk array observes the Cherenkov light emitted by UHECR in atmosphere. Recently, an autonomous subarray is added consisting of photomultipliers to measure the showers in the knee region. Our aim is to analyze the combined data set in order to derive the cosmic ray spectrum in the energy range as wide as possible using the same technique. The advantage of the air Cherenkov light measurement is the model independent estimation of the EAS primary energy using the total light flux emitted in the atmosphere. A set of the light lateral distributions observed in the extended energy range is presented also.Comment: 11 pages, 5 figures, submitted to Nuclear Physics B (Proceedings Supplements

Behavior of some characteristics of EAS in the region of knee and ankle of spectrum

The energy dependence of such characteristics as a ratio of the total number of charged particles to the total flux of EAS Cherenkov radiation, a ratio of E(thr)>=1GeV muon flux density at the distance of 600m from a shower core to charged particle flux density, a ratio of the energy transferred to the electromagnetic component of EAS to the primary particle energy is presented. Their comparison with two-component mass composition of cosmic rays (p-Fe) in the framework of calculations by a QGSJET model is given.Comment: 6 pages, 9 figure

Fluctuations of the depth of maximum in extensive air showers and cross-section of p-air inelastic interaction for energy range 10^15-10^17 eV

We present estimation of proton-air inelastic interaction cross-section obtained for different energy values are. Results are compared with different hadron interaction models.Comment: Proc. 32nd ICRC, Aug. 11-18, Beijing, Chin