Ultra-high Energy Extensive Air Showers Research Articles

An approach for identification of ultrahigh energy extensive air showers with scintillation detectors at TAIGA experiment

The TAIGA astroparticle observatory is under development at Tunka valley close to the Baikal Lake. This simulation study is concentrated on the ultrahigh energy extensive air showers (EAS) induced by gamma-quanta or proton in the range from 1 PeV to 10 PeV and zenith angle ranging 0°–45°. For this work, a set of air showers was created by CORSIKA software package. The list of useful secondary particles at the ground level is produced using the COAST library package. The interaction of secondary particles with the soil and detectors was simulated with GEANT4 package. The method based on neural network has been developed for the separation of EAS induced by gamma-quanta or proton. The air showers having energy ranging 1–10 PeV show more than 90% of identification efficiency of protons while keeping identification efficiency of gamma around 50% or more.

On the parametrization of the distributions of depth of shower maximum of ultra-high energy extensive air showers

The distribution of depth in which a cosmic ray air shower reaches its maximum number of particles (Xmax) is studied and parametrized. Three functions are studied for proton, carbon, silicon, and iron primary particles with energies ranging from 1017 eV to 1020 eV for three hadronic interaction models: EPOS-LHC, QGSJetII.04, and Sibyll2.3c. The function which best describes the Xmax distribution of a mixed composition is also studied. A very large number of simulated showers and a detailed analysis procedure are used to guarantee negligible effects of undersampling and of fitting in the final results. For the first time, a comparison of several functions is presented under the same assumption with the intention of selecting within them the best functional form to describe the Xmax distribution. The Generalized Gumbel distribution is shown to be the best option among the options for a general description of all cases. The Log-normal distribution is also a good choice for some cases while the Exponentially Modified Gaussian distribution has shown to be the worst choice in almost all cases studied. All three functions are parametrized as a function of energy and primary mass.

Investigating the influence of diffractive interactions on ultrahigh-energy extensive air showers

The understanding of the basic properties of the ultrahigh-energy extensive air showers is dependent on the description of hadronic interactions in an energy range beyond that probed by the LHC. One of the uncertainties present in the modeling of air showers is the treatment of diffractive interactions, which are dominated by nonperturbative physics and usually described by phenomenological models. These interactions are expected to affect the development of the air showers, since they provide a way of transporting substantial amounts of energy deep in the atmosphere, modifying the global characteristics of the shower profile. In this paper, we investigate the impact of diffractive interactions in the observables that can be measured in hadronic collisions at high energies and ultrahigh-energy cosmic ray interactions. We consider three distinct phenomenological models for the treatment of diffractive physics and estimate the influence of these interactions on the elasticity, number of secondaries, longitudinal air shower profiles and muon densities for proton-air and iron-air collisions at different primary energies. Our results demonstrate that even for the most recent models, diffractive events have a non-negligible effect on the observables and that the distinct approaches for these interactions, present in the phenomenological models, still are an important source of theoretical uncertainty for the description of the extensive air showers.

Optic detectors calibration for measuring ultra-high energy extensive air showers Cherenkov radiation by 532 nm laser

Calibration of a PMT matrix is crucial for the treatment of the data obtained with Cherenkov tracking detector. Furthermore, due to high variability of the aerosol abundance in the atmosphere depending on season, weather etc. A constant monitoring of the atmospheric transparency is required during the measurements. For this purpose, besides traditional methods, a station for laser atmospheric probing is used.

Measurements of the muon content of air showers at the Pierre Auger Observatory

The Pierre Auger Observatory offers a unique window to study cosmic rays and particle physics at energies above 3 EeV (corresponding to a centre-of-mass energy of 75 TeV in proton-proton collisions) inaccessible to accelerator experiments. We discuss the different methods of estimating the number of muons in showers recorded at the Pierre Auger Observatory, which is an observable sensitive to primary mass composition and to properties of the hadronic interactions in the shower. The muon content, derived from data with these methods, is presented and compared to predictions from the post-LHC hadronic interaction models for different primary composition. We find that models do not reproduce well the Auger observations, displaying a deficit of muons at the ground. In the light of these results, a better understanding of ultra-high energy extensive air showers and hadronic interactions is crucial to determine the composition of ultra-high energy cosmic rays. We report on the upgrade plans of the Pierre Auger Observatory to achieve this science goal.

Relation between hadronic interactions and ultra-high energy extensive air showers

The simulation of hadronic interactions is of fundamental importance for the analysis of extensive air showers. The details of the relation between the measurement of hadronic interactions at accelerators and the impact on the air shower development is very difficult to evaluate. Several possibilities to study this relation are presented here.

Исследование радиоизлучения на частоте 32 МГц на Якутской установке широких атмосферных ливней

There is described new method of measurements of ultra-high energy extensive air showers (EAS) of radio emission obtained for period 2009-2011. There is given short overview of detection method, detection equipment and program package. First results of experimental data analysis are presented.

Galactic origin of ultrahigh energy cosmic rays

The arrival directions of ultrahigh energy extensive air showers (EAS) by Yakutsk, AGASA, P. Auger array data are analyzed. For the first time, the maps of equal exposition of celestial sphere for the distribution of particles by AGASA and P. Auger arrays data have been constructed. The large-scale anisotropy of cosmic particles at E>4.1019 eV by Yakutsk, AGASA and P. Auger array data has been detected. The problem of cosmic particle origin is discussed.

Extensive air showers with the small muon content in the region of ultrahigh energies

Ultrahigh-energy extensive air showers registered at the Yakutsk EAS array have been considered. The showers without the muon component are detected. Almost one half of them forms the clusters, the arrival directions of which correlate with the nearest pulsars. The classification of showers by muon composition has been carried out and the existence of four classes of showers has been shown. The problem of mass composition and origin of ultrahigh-energy cosmic rays are discussed.

Simulations of radio emission from ultrahigh-energy extensive air showers

The radio emission from extensive air showers with energies up to 1017 eV has been calculated. The calculated lateral distribution of the radio emission is in good agreement with the LOPES-10 experimental data.

Pulsars as the most probable sources of ultrahigh-energy cosmic rays

The arrival directions of ultrahigh-energy extensive air showers detected at the Yakutsk extensive air shower array are considered. The maxima revealed in the distribution of the arrival directions of showers and doublets are found to correlate with the coordinates of pulsars located in the Galactic plane. It is shown that the three showers detected at the Yakutsk extensive air shower with the highest energies E > 1020 eV correlate with the nearest pulsars.

Estimation of the energy of the electron-photon component of cosmic rays on the basis of data for Cherenkov light from ultrahigh-energy extensive air showers

The energy fraction E em/E 0 dissipated to the electron-photon component of extensive air showers (EASs) for E 0=1015−1019 eV is estimated using data on Cherenkov radiation and charged particles from the Yakutsk EAS array. The results are compared with models with different dissipations to the electron-photon component and with calculations for various primary nuclei. In the energy range 1015−1016 eV and 1018−1019 eV, the ratio E em/E 0 is equal to 77 ± 2 and 88 ± 2, respectively, in agreement with the mixed and proton contents of primary cosmic rays in the former and latter energy ranges, respectively.

Classification of ultrahigh-energy extensive air showers in terms of the muon content

Ultrahigh-energy extensive air showers detected at the Yakutsk array are analyzed. Showers different in the muon content are revealed. Four classes of showers are separated.

Test of Lorentz invariance through observation of the longitudinal development of ultrahigh-energy extensive air showers

An idea that Lorentz invariance can be violated was proposed by Coleman and Glashow to overcome the astrophysical problems of air showers of ultrahigh energies E>1020 eV. This statement can be tested by analyzing experimental data on these showers. The longitudinal development of showers and the distribution of the depths of shower maxima were calculated in the model of quark-gluon strings with allowance made for the Landau-Pomeranchuk-Migdal effect and the interactions of ultrahigh-energy neutral pions. Comparison of the calculations with available experimental data provides a new bound |cγ−cπ°| <0−20 for the possible difference between the speeds of photons and neutral pions. This bound becomes |cγ−cπ°|<10−22 when one takes the upper limiting value for the observed depth of maximum.