M. B. Amelchakov

NEVOD-DECOR experiment: results and future

Russian-Italian NEVOD-DECOR experiment on the measurements of the local muon density spectra (LMDS) at various zenith angles gave possibility to obtain information on primary cosmic ray flux and interaction characteristics in a record wide energy range from 1015 to more than 1018 eV. Comparison of the measurement results with CORSIKA-based simulations showed the increase of LMDS slope at PeV energies of primaries (corresponding to the first knee); a trend to a heavier primary mass composition above the knee; indication for a second knee (a further increase of the spectrum slope near 1017 eV). At large zenith angles and high muon densities (corresponding to primary energies around 1018 eV) a considerable excess of muon bundle events in comparison with the expectation based on independent estimates of the primary spectrum and widely used hadron interaction models has been found. In 2011, a new phase of measurements of the energy spectrum of cascade showers initiated by high-energy muons in water and of the energy deposit of muon bundles at various zenith angles and muon multiplicities started. Further plans include the deployment of a traditional EAS array around the NEVOD-DECOR complex.

Measuring the spectrum of the local density of charged particles on the SCT setup

The first results from measuring spectra of the local density of charged particles in extensive air showers in the energy range of ∼1014–1015 eV on the SCT setup (part of the NEVOD experimental complex), obtained using two independent methods, are presented. Experimental data are compared to calculations performed using the CORSIKA program.

A proposed NEVOD-EAS installation for the detection of extensive air showers

A new installation is dedicated to the independent evaluation of extensive air shower (EAS) energies detected in the NEVOD-DECOR experiment in the knee region of the energy spectrum. The design for the measuring system of the shower installation is based on clusters of scintillation detectors that are located on the roofs of laboratory buildings at MEPhI (Moscow) and will detect the electromagnetic (for near-vertical showers) and muon (for large zenith angles) EAS components. Features of the measuring system, the system for data acquisition and processing, and the results from investigating the characteristics of a single detector are discussed, along with the algorithm for event formation by the data of separate clusters.

Status of the NEVOD-EAS experiment

The NEVOD-EAS setup is designed for independent estimation of the EAS parameters recorded in the NEVOD-DECOR experiment in the region of the energy spectrum knee. The setup’s recording system is based on the clusters of scintillation detectors for the EAS electron-photon component, located on the territory of MEPhI. Characteristics of the shower array recording system that ensure detection, data acquisition and primary processing, and the time synchronization of clusters are discussed, along with results of studying the nonuniformity of NEVOD-EAS scintillation detector responses.

Proposal of NEVOD-EAS shower array

New setup for detection of EAS electromagnetic component at the knee region of primary energies is under construction on the basis of the experimental complex NEVOD (Moscow, Russia). The measuring system of the EAS array has a cluster organization. Clusters are located on the roofs of laboratory buildings of MEPhI (Moscow). Features of measuring and DAQ systems, results of investigations of characteristics of a single counter and the event formation algorithm from the data of separate clusters are discussed.

Muon Calibration of the Cherenkov Water Detector NEVOD

The problem of calibrating a Cherenkov water detector (CWD) and the possibilities for its use based on the example of the CWD NEVOD are discussed. Results of the calibration of quasi-spherical modules in water volume by means of vertical muons selected by scintillation telescopes and compared to the results from measurements performed at test facilities are presented.

Observation of UHECRs in horizontal flux

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.

Muon bundles produced by UHE cosmic rays at large zenith angles

The first experimental results on a new EAS observable, the local muon density spectra measured with a large area coordinate detector DECOR in a wide range of zenith angles, are presented. These data correspond to the interval of primary particle energies from 1015 to 1018 eV. Some features of local muon density phenomenology are considered on the basis of an analytical model. Expected distributions of the events in the muon density have been calculated by means of the CORSIKA code and compared with experimental data.

Experimental complex for multi-component registration of the EAS in a wide energy range

The Experimental complex (EC) NEVOD includes a number of unique experimental facilities for studies of main components of cosmic rays on the Earths surface. The complex is used for basic research of CR flux characteristics and their interactions in the energy range 1015 – 1019 eV. To extend the experimental capabilities nowadays new large-scale detectors are being deployed around the EC NEVOD: an array for the EAS registration (NEVOD-EAS), a detector of atmospheric neutrons (URAN) and a large-area coordinate-tracking detector (TREK). The description of experimental capabilities of the complex is given, and first results of simultaneous detection of various EAS components are discussed.

(10^{15} - 10^{19} eV)

A description of the detection and data-acquisition systems of the Cherenkov water calorimeter of the NEVOD Experimental Complex, which is a unique scientific facility located on the Earth’s surface, is presented. In the development of these systems, a solution is sought to the problem of measuring the energy of cascade showers initiated by single muons and the energy deposited by high-multiplicity muon bundles in a wide energy range.