The Pierre Auger Observatory, recently completed, has been operational since 2004. As a hybrid experiment, it allows for a wide range of measurements of UHECR-induced extensive air showers (EAS), including measurements of the EAS particle content on ground which is sensitive to high-energy hadronic interactions. We present the results of several independent measurements of the EAS muon content ...

The impact of properties of individual hadronic interactions like the inelastic cross section and the elasticity on the development of extensive air showers is investigated. Simulations of air showers are performed, their predictions are compared to measured values of integral muon multiplicities and the average depth of the shower maximum. Effects on the mean logarithmic mass derived from the ...

The Linsley standard atmospheric model is used to simulate the atmospheric EAS due to the passage of an Ultra High Energy Cosmic Ray (UHECR, Linsley, 1977). Adopting the AIR shower Extended Simulation (AIRES) program we derived the longitudinal and lateral distribution of the secondary particles produced in the atmosphere along the path of the primary. From these distributions one can distingui...

The KASCADE experiment detecting many observables of extensive air showers provides the possibility to handle data on event-by-event basis and to investigate details of the energy dependence of the primary cosmic ray flux in the energy range of 1014 1016 eV. We use Bayesian decision making and neural net approaches for data classification into multiple categories. A first attempt, approaching t...

AMIGA (Auger Muons and Infill for the Ground Array) is an upgrade of Pierre Auger Observatory to complement study ultra-high-energy cosmic rays (UHECR) by measuring muon content extensive air showers (EAS). It consists array 61 water Cherenkov detectors on a denser spacing in combination with underground scintillation used density measurement. Each detector composed three modules, 10 m$^2$ dete...

We analyse a sample of 33 extensive air showers (EAS) with estimated primary energies above 2·1019 eV and high-quality muon data recorded by the Yakutsk EAS array. We compare, event-by-event, the observed muon density to that expected from CORSIKA simulations for primary protons and iron, using SIBYLL and EPOS hadronic interaction models. The study suggests the presence of two distinct hadronic...

In any EAS array, the rejection of events with shower cores outside the detector boundaries is of great importance. A large difference between the true and the reconstructed shower core positions may lead to a systematic miscalculation of some shower characteristics. Moreover, an accurate determination of the shower core position for selected internal events is important to reconstruct the prim...

Measuring radio emission from air showers provides excellent opportunities to directly measure all air shower properties, including the shower development. To exploit this in large-scale experiments, a simple and analytic parameterization of the distribution of the radio signal at ground level is needed. Data taken with the LowFrequency Array (LOFAR) show a complex two-dimensional pattern of pu...

For most of the Ultra-High-Energy-Cosmic-Ray (UHECR) experiments and projects (HiRes, AUGER, TA, JEM-EUSO, TUS,...), the detection technique of Extensive Air Showers is based, at least, on the measurement of the air-fluorescence-induced signal. The knowledge of the Fluorescence-Light Yield (FLY) is of paramount importance for the UHECR energy reconstruction. The MACFLY experiment was designed t...

The following report describes the analysis for finding the speed of an extensive air shower produced by an ulta-high energy cosmic ray. Not only will this analysis be useful in measring the speed of cosmic ray showers but also it can help in correcting a bias in the detection instrumentation. As cosmic rays enter Earth’s upper atmosphere, they interact with nuclei, creating secondary particles...