Narrow Results

The origin of the neutron bursts in Extensive Air Showers (EAS) is explained using results of the experiments and CORSIKA based Mont–Carlo simulations. It is shown that events with very high neutron multiplicity observed last years in neutron monitors as well as in surrounding detectors, are caused by the usual EAS core with primary energies >1 PeV. No exotic processes were needed for the explanation.

The problem of the knee in primary cosmic ray at energy about 3–5 PeV is the most exciting problem in cosmic ray physics. Since 1958, physicists have been trying to solve this problem. In our opinion, the problem could be solved from the experimental point of view, whereas the primary spectrum would follow a pure power law. A key to the "knee" problem lies in the hadronic structure of EAS and its propagation in the Earth's atmosphere. Neither exotic processes nor new physics are used. An explanation of the approach and some results of Monte Carlo simulations are given below.

Using the AIRES code, we have generated a large number of Extensive Air Showers corresponding to Ultra high energy cosmic ray gammas, protons and iron nuclei with energy range 10¹⁵ – 10²² eV. These simulations clearly show the different atmospheric depths of the Extensive Air Shower maxima in this energy range.

We summarize the main results reported by EAS-TOP in the study of cosmic rays in the energy range 10¹² – 10¹⁶ eV (from the direct measurements up to above the "knee"), i.e. the region which is generally considered to represent the high energy galactic radiation.

LOFAR is a new digital radio interferometer that is being build in The Netherlands. By sampling the radio waves with fast ADCs it can digitally store the whole waveform information and analyze transient events like air showers after they have been recorded. To demonstrate its ability to measure air showers we are building LOPES (a LOFAR PrototypeStation) at the site of an existing air shower array (KASCADE-Grande). The first phase consisting of 10 antennas is already running. It has demonstrated how digital interference suppression and beamforming can overcome the problem of radio interference and pick out air shower events.

Radio emission from cosmic ray air showers has the potential to become an additional, cost-effective observing technique for cosmic ray research, being largely complementary to the well-established particle detector and air fluorescence techniques. We present Monte Carlo simulations of radio emission from extensive air showers in the scheme of coherent geosynchrotron radiation from electron-positron pairs gyrating in the earth's magnetic field. Preliminary results of our simulations are the predicted frequency, primary particle energy, shower zenith angle, shower azimuth angle and polarization dependence of the radio emission. These properties can be directly related to data measured by LOPES and other experiments.

Preliminary results of muon bundle studies in of zenith angle range θ ≥ 60° and multiplicities by means of coordinate detector DECOR are discussed. Estimates of muon bundle characteristics at large zenith angles obtained with CORSIKA code demonstrate the ability of such not large detector as NEVOD-DECOR complex to perform cosmic ray studies in a very wide energy range from 10¹¹ eV to more than 10¹⁷ eV.

The paper considers the possibility of EAS production by charmed particles and direct muons (muons produced in decays of particles with a very short life-time comparing to that of charmed particles, as, for example, in decays of resonances). At large angles (≳ 70°) charmed particles and direct muons could be completely responsible for EAS measured at the sea level. The estimations are made for the primary nucleon energy 10¹⁹ eV and the angles 45–72°.

Energy is among the characteristics of Ultra High Energy Cosmic Rays (E > 5 ×10¹⁹eV) which could be estimated experimentally based on simulations. This paper attempts to estimate the energy of an UHECR proton by applying a Monte Carlo simulation code. A number of extensive air showers, vertical and inclined, are simulated to derive the lateral distribution functions of the shower particles. The scenario of simulations is adapted to the P. Auger Observatory site.

The KASCADE–Grande experiment measures extensive air showers induced by primary cosmic rays in the energy range of 10¹⁴ — 10¹⁸ eV. As extension of the original KASCADE experiment it allows the investigation of the knee and the possible second knee in the cosmic ray energy spectrum. An overview of the experimental setup and preliminary results are given.