Unusual and multicore extensive air showers

Unusual and multicore extensive air showers are detected in some experiments. Study of these kinds of showers is an important issue in nuclear collisions at high energies and need to be interpreted by hadronic interaction models. In the work, taking into account results Sleptsova et al. of which emphasized shower size variations at energies above [Formula: see text][Formula: see text]eV, and also by using of the auger experimental data, some characteristics of multicore events are investigated. Intense nuclear variations are seen in energy range of [Formula: see text]–[Formula: see text][Formula: see text]eV, and nuclear distinctive properties of multicore showers relative to normal showers are shown.

Towards a better estimation of energy and species of primary cosmic rays in the knee region with the Tibet hybrid experiment: Utilization of refined EAS lateral distributions

A new hybrid experiment (YAC-II+Tibet-III+MD) located at Yangbajing has started to improve the capability of explicit measurements of the cosmic-ray components (P, He, CNO, Fe, etc) at the knee energy region since 2014. Considering the different features of air shower development for different primary cosmic-ray nuclei, using a full Monte Carlo simulation, we modified the lateral distribution functions for proton-induced, helium-induced and iron-induced air showers, respectively. The results show that the air shower size of different nuclei obtained by the modified Nishimura-Kamata-Greisen function is consistent with the true shower size within 5% systematic errors. Furthermore, we studied the Extensive Air Shower age parameter determination from the lateral distribution functions of charged particles near the air shower core with the Tibet hybrid experiment. The derived age parameter can be well used to estimate the particle type of the incident primary cosmic rays.

DETECTION OF A CHANGE OF SLOPE IN THE SPECTRUM OF HEAVY MASS COSMIC RAYS PRIMARIES BY THE KASCADE-GRANDE EXPERIMENT

KASCADE-Grande is an extensive air shower experiment devoted to the study of cosmic rays in the 1016 ÷ 1018 eV energy range. The array is composed by different detectors allowing independent measurements of the number of muons (Nμ) and charged particles (Nch) of extensive air showers (EAS). These two observables are then used to study the primary energy spectrum, separating the events in two samples, on the basis of the shower size ratio, corrected for attenuation in the atmosphere, lnNμ/ lnNch. The two samples represent the light and heavy mass groups of the primaries. In the studied energy range only the spectrum of heavy primaries shows a significant change of slope, the energy (estimated using the QGSJET II hadronic interaction model) of this feature is in agreeement with the expectations of a rigidity dependent knee feature.

An investigation of mass composition of ultra-high energy cosmic rays with energies above 1019 eV via the study of extensive air showers

The electron and muon components of extensive air shower (EAS) with energies above 1019 eV are analyzed via various giant EAS arrays. A varying property of showers is observed for two energy ranges; higher and lower than (3 ? 4) x 1019 eV. The age parameter, zenith angle, shower size dependence on muon size and shower size dependence on primary energy show an increment of mass composition (MC) above (3?4)x 1019eV. Comparison of the observed EAS results with the simulations of Capdevielle et al. (2000) and Shinozaki et al. (2005) gives at most 20% photon fraction for primary energies above 1019 eV. The arrival directions of showers above 4x1019 eV indicate an increasing concentration towards the super galactic plane.