Expected Spectra of Muon-Induced Cascades in IceCube

The neutrino telescope IceCube is capable to reconstruct the energy spectrum of muons in very high energy region by means of measurements of muon-induced cascades. To compare with experimental data, the expected spectra of cascades were theoretically estimated. Calculations were performed for two variants of muon spectrum on the ice surface: a simple power-law energy spectrum with a differential slope index −3.7, and a composite spectrum combined of two power spectra with differential indexes −3.7 and −2.7. The differential spectra of cascades for different zenith angles and integral cascade spectra calculated for two variants of muon spectra are discussed.     

Investigation of the Energy Loss of Muon Bundles in the Cherenkov Water Calorimeter

Investigations of the energy loss of muon bundles are being conducted at the Experimental complex NEVOD. Such investigations are directed to detailed study of “muon puzzle” (the excess of multi-muon events observed in several cosmic ray experiments at ultra-high energies). Results of measurements of the muon bundle energy deposit during a long period of observations in primary cosmic ray energy range 10–1000 PeV have been obtained and have been compared with simulations performed on the basis of the CORSIKA code.     

Effect of the muon component of cosmic rays on the results of hadron experiments with the big ionization calorimeter (BIC) of the Tien Shan station

A full-scale simulation of the response of the big ionization calorimeter (BIC) at the Tien Shan station to the passage of single protons and muons was performed on the basis of the GEANT4 package in order to estimate the contribution of the muon cosmic-ray component to the generation of unusual events (such as Anti-Centauros), which were recorded by this facility, and to the imitation of the long-flying component, which changes the shape of the average cascade curve. A comparison of the results of this simulation with experimental data reveals that the appearance of Anti-Centauros may be reasonably explained by the contribution of multiple interactions of single muons, but that muon events are insufficient for explaining the change in the shape of the cascade curve (in particular, the emergence of a second maximum).     

Spatial distribution of Cherenkov light from cascade showers in water

The spatial distribution of the Cherenkov light generated by cascade showers is analyzed using the NEVOD Cherenkov water detector. The dependence of the Cherenkov light intensity on the depth of shower development at various distances from the shower axis is investigated for the first time. The experimental data are compared with the Cherenkov light distributions predicted by various models for the scattering of cascade particles.     

Role of very-high-energy muons in generation of penetrating cascades in the Pamir experiment

The question of processes responsible for some unusual events with the energy deposition over 100 TeV recorded in X-ray emulsion chambers (XECs) of the Pamir experiment is still open. Among the events of this type are penetrating cascades in deep lead XECs. The evaluations show that these events can be qualitatively explained by multiple interactions of muons with energies in the PeV range. In this work, the expected number of penetrating cascades induced in the Pamir XECs by very-high-energy muons is calculated for different muon generation processes in the atmosphere.     

Comparison of Models of Nucleus–Nucleus Interactions Implemented in CORSIKA

Physics of Atomic Nuclei - Four most widely used models of hadronic interactions at high energies implemented in CORSIKA program were compared basing on the simulation of the first...     

Coupling functions for muon hodoscopes

The specific features of calculating the coupling functions for muon hodoscopes are considered. The results of calculating the main coupling functions for three versions of the primary spectra of cosmic rays (CR)—galactic CR, solar CR during proton events, and galactic CR variations during Forbush decreases-are presented. The calculations have been performed based on modeling CR propagation through the Earth’s atmosphere using the CORSIKA code. The mean and median CR energies, contributing to the muon detector counting rate, have been calculated for different zenith angles. It has been shown that muon detectors are sensitive to different energies of primary CRs for different directions.     

Reconstruction of Characteristics of Extensive Air Showers Detected with the NEVOD-EAS Array

Physics of Atomic Nuclei - In 2018, the creation of the central part of the NEVOD-EAS cluster-type array aimed at detection of the electron-photon component of extensive air showers in the energy...     

Investigation of the spectrum of high-energy muons by the method of multiple interactions on the basis of data from the Baksan underground scintillation telescope

Experimental data obtained with the aid of the Baksan underground scintillation telescope over a long period of its operation are analyzed with the aim of searches for an excess flux of ultrahigh-energy (≥100 TeV)muons. The multiple-interaction method, which is based on the ideas of the pair-meter technique, is used to analyze the energy spectrum of the muons. The phenomenological parameters of this method and its sensitivity to the shape of the spectrum are discussed. The experimental distributions are compared with the results of calculations for various versions of the muon spectrum. The possibility of separating ultrahigh-energy muons that fly in the vicinity of the axis of extensive air showers is assessed on the basis of the integrated number of recorded and simulated events featuring large energy depositions.     

Local Muon Density Spectra at Various Zenith Angles Measured with NEVOD-DECOR

Data on cosmic ray muon bundles accumulated at the NEVOD-DECOR complex over the period from May 2012 to December 2018 have been analyzed. Local muon density spectra at various zenith angles have been reconstructed and compared with CORSIKA-based simulations. At large zenith angles and high muon multiplicities corresponding to primary particle energies more than about 3 × 1017 eV an excess of multi-muon events compared to simulations is clearly seen. Present data are compatible with the expectation for recent LHC-adjusted hadron interaction models only under assumption of extremely heavy (iron group nuclei) primary composition. The assumption of a heavy composition is however in contradiction with other EAS observables, such as maximum depth and its fluctuations.