A. G. Tyumentsev

On inconsistency of experimental data on primary nuclei spectra with sea level muon intensity measurements

For the first time a complete set of the most recent direct data on primary cosmic ray spectra is used as input into calculations of muon flux at sea level in a wide energy range E μ = 1 - (3 × 10 5 ) GeV. Computations have been performed with the CORSIKA/QGSJET and CORSIKA/VENUS codes. Comparison of the obtained muon intensity with the data of muon experiments shows that measurements of primary nuclei spectra conform to sea level muon data only up to several tens of GeV and result in essential deficit of muons at higher energies. As it follows from our examination, uncertainties in muon flux measurements and in the description of nuclear cascades development are not suitable to explain this contradiction, and the only remaining factor, leading to this situation, is underestimation of primary light nuclei fluxes. We have considered systematic effects, that may distort the results of the primary cosmic-ray measurements with the application of the emulsion chambers. We suggest, that re-examination of these measurements is required with the employment of different hadronic interaction models. Also, in our point of view, it is necessary to perform estimates of the possible influence of the fact that a sizable fraction of events, identified as protons, actually are antiprotons. Study of this cosmic-ray component begins to draw much attention, but today nothing definite is known for the energies >40 GeV. In any case, to realize whether the mentioned, or some other reasons are the sources of disagreement of the data on primaries with the data on muons, the indicated effects should be thoroughly analysed.

Energy spectrum and mass composition of primary cosmic rays in the vicinity of the “knee” in a model with two types of sources

An analysis of the data on the spectra of cosmic rays in the context of the proposed model with two types of sources suggests that the main contribution to the spectrum of all particles in the range of 105−107 GeV is made by the sources in which the exponent in the spectrum of particles’ generation p ≈ 2.85. The complex structure of the spectrum in the vicinity of the “knee” may arise owing to the presence of an additional supernova-type source that accelerates the particles to the energies of ∼3 × 104Z GeV if the energy output of this source is ∼2 × 1048 erg/source.

Spectra of cosmic-ray protons and nuclei from 10 10 to 10 20 eV within the galactic origin scenario of cosmic rays

Results from calculating the cosmic ray energy spectrum within the Galactic origin scenario are presented. Key elements of the approach are the assumed existence of Galactic sources that accelerate particles up to ∼1011 GeV and a highly inhomogeneous (fractal type) distribution of matter and magnetic fields in the Galaxy that leads to large free paths for particles (Levy flights), along with an overwhelming contribution to the cosmic ray fluxes observed in the energy range of 109–1011 GeV from particles reaching the Solar System without scattering. It is shown that the proposed scenario allows us to describe the main features of the observed cosmic ray spectrum from 1010 to 1020 eV. The behavior of the cosmic ray mass composition in the ultra-high energy region is discussed.

Cosmic ray spectrum in a fractal-like galactic medium for different particle acceleration mechanisms in a source

The cosmic ray spectra in a fractal-like galactic medium have been calculated for two mechanisms of particle acceleration in a source: standard acceleration by shock waves in the supernova remnants and acceleration by shock waves with nonlinear amplification of the initial magnetic field by accelerated particles. It is shown that a unified self-consistent description of the experimental data on the spectra of several nuclear groups and the spectrum of all particles cannot be obtained within these two scenarios.

Electrons generation spectrum in galactic sources of cosmic rays

A electrons generation spectrum in galactic sources of cosmic rays is reconstructed within the fractal diffusion model according to the energy spectrum of particles and synchrotron radiation observed in the Solar system. It is shown that a self-consistent description of the experimental data can be obtained if the exponent of the electrons generation spectrum in the sources within the range of 0.1–103 GeV varies from p = 2.6 in the low energy range to p = 2.85 at E ≥ 103 GeV.

Deficit of the calculated muon flux at sea level for Eµ ≳ 100 GeV: Analysis of possible reasons

The reasons why a deficit of the calculated muon flux for Eµ ≳ 100 GeV arises if use is made of data from direct measurements of the spectra of primary cosmic rays and present-day nuclear-interaction models are considered. It is shown that this problem may stem from significantly underestimating the primary-nucleon flux in balloon-borne experiments employing the technique of emulsion chambers. This procedure relies on an extrapolation of accelerator data; therefore, it is necessary to estimate, on the basis of various Reggeon models of hadron interactions, the systematic error introduced by this circumstance in the results of the measurements. Such an analysis would make it possible to refine the behavior of the spectra of primary cosmic rays, to reduce the methodological part of the error in the calculation of the fluxes of secondary cosmic rays in the atmosphere, and to draw more precise conclusions on the flaws in present-day interaction models without invoking new accelerator data.

Influence of the finiteness of particle velocity on the energy spectrum of cosmic rays in an anomalous diffusion model with Lévy flights

An estimate of the influence the finiteness of particle velocity has on the results of a fractional differential (anomalous) model of cosmic ray propagation in the Galaxy with Lévy flights developed by the authors is considered. The results from Monte Carlo simulations of particle diffusion in random walk models with finite and infinite velocities are presented. It is shown that considering particle velocity finiteness has almost no effect on the cosmic ray energy spectrum obtained for E > 1 GeV in the anomalous diffusion model with Lévy flights for nearby young sources.

Fraction of cosmic-ray positrons in the galaxy: Results from using the fractional diffusion approach

The fraction of positrons in the electron-positron component of cosmic rays is calculated in a scenario where electrons and positrons are generated by Galactic sources with the same spectral index. It is shown that the proposed scenario allows us to reproduce the existing experimental data on the fraction of positrons if the relative yield of positrons in a source is e+/e− ≈ 0.3.

ON THE DEFICIT OF CALCULATED MUON FLUX AT SEA LEVEL FOR ENERGIES > 100 GEV

In this paper we discuss the problem why the use of the direct data on primary nuclei spectra together with the modern hadronic interaction models leads to a significant deficit of computed vertical muon flux at sea level for energies above 100 GeV. We suggest that to find out the source of this inconsistency it is necessary to perform an analysis of sensitivity of emulsion chamber data to variations of hadron-nucleus interaction characteristics. Such analysis will give more ground for discussion of adequacy of the up-to-date interaction models and of mutual compatibility of primary nuclei spectra, obtained in direct and EAS experiments.