A Statistic Model for Galactic Cosmic Rays

Supposed that all of cosmic ray particles of energy below 3×10¹⁸eV are mainly originated and accelerated in an individual explosion of the galactic supernovae(SNs).By using an isotropic diffusion propagation model,non-steady state density of the iron nucleus is investigated.Considering the effect of extra-galactic cosmic rays and the variety of the galactic cosmic ray nuclei,the statistic model of galactic cosmic rays with a reasonable distribution of the SNs in space and time can account for the spectrum of cosmic ray in the energy range of 10¹²—10²⁰eV quitewell.     

What should be the spectrum of galactic cosmic rays?

Numerous experimental data on cosmic rays sensitive to the spectrum of primary cosmic rays were analyzed in the energy range E>1 TeV. They proved to be incompatible with the pure power-law spectrum of primary particles. The spectral index of the proton spectrum is derived from the data considered. It was found to be 0.4±0.1 greater than for the nuclei with Z≥2. Therefore, the flux of galactic cosmic rays consisting of protons and nuclei with Z≥2 cannot be described by a unified power law in the energy range 0.1–10³ TeV.     

The Study of Primary Cosmic Ray Mass Composition Around the

The lg N_e-N_μ relationship has been studied from 4.4×10⁴ events (total observation time is 2.9×10⁶s)collected from Mt. Liang Wang Array (24.5°N, 102.9°E, 2720m above sea level). In order to study the mass composition at the knee, Monte-Carlo simulations for the EAS development and detection under same event selection criteria as used in the experimental data have been performed. The result shows that the mass composition of primary cosmic rays has no obvious change and the dominant component is light nuclei around the knee.     

A DEDUCTION ON PRIMARY COSMIC PAY COMPOSITION AND SPECTRA ABOVE 1014eV

The spectra of primary cosmic ray nuclei are fitted from experimental data under 10¹⁴eV and extrapolated to their bending energies. The primary cosmic ray composition above 10¹⁴eV is deduced according to the rigidity cut off model by selecting an appropriate bending energy for proton so that the sum of various nucleus components is consistent with the experimental total particle spectrum. The method used is independent on the behaviour of hadronic interaction.     

The extensive air shower muon number spectrum beyond the knee in the cosmic-ray energy spectrum

The extensive air shower (EAS) muon number spectrum is obtained with increased statistics using the central muon detector of the EAS MSU array, which records muons with energies above 10 GeV. The dependence of the mass composition of primary cosmic rays on the energy is considered. The conclusion is confirmed that for energies from 3 × 10¹⁵ eV (the primary energy spectrum knee) up to 10¹⁷ eV a change in the composition associated with an increase in the proportion of heavy nuclei occurs; however, after the energy of 10¹⁷ eV, the proportion of heavy nuclei begins to decrease and the composition becomes lighter. A comparison with similar data from other experiments is conducted. The existence of an additional component of cosmic rays is confirmed; earlier an indication of its presence was derived from data on the EAS electron number spectrum.     

Meson cascade in the atmosphere,uncertainties in calculating the fluxes of high-energy muons,and data of direct measurements

A new calculation of the atmospheric fluxes of cosmic-ray hadrons and muons in the energy range 10–10⁴ GeV is performed on the basis of the method for solving nuclear-cascade equations with allowance for a nonscaling behavior of inclusive hadron-production cross sections, the growth of cross sections for inelastic hadron-nucleus collisions with increasing energy, and a non-power-law character of the primary spectrum. The fluxes of secondary cosmic rays at various levels in the atmosphere are calculated for three models of the spectrum and composition of primary cosmic rays. The effect of uncertainties in the spectrumand composition of primary cosmic rays on the flux of atmosphericmuons and their charge ratio at sea level is investigated. The calculated energy spectra of muons at sea level are compared with the results of previous experiments and the results of recent measurements performed by means of the L3 + Cosmic and CosmoALEPH spectrometers, as well as with the results of other calculations.     

Cosmic ray spectrum obtained from the energy scattered by the particles of extensive air showers in the atmosphere and the galactic model

The differential energy spectrum of cosmic rays that is obtained on the basis of the measurements of Cherenkov radiation from extensive air showers in an energy range of 10¹⁵–10²⁰ eV is compared with the model of the propagation of primary particles in the interstellar medium with fractal properties. It is found that the shape of the experimental spectrum is in good agreement with the shape of the calculated spectrum of “all particles” at 10¹⁵–10¹⁸ eV. The average mass composition of cosmic rays that is calculated on the basis of five components does not contradict the average mass composition obtained from the experimental data for several parameters in this energy range.     

On the composition of cosmic rays with E 0 ≥ 1017 eV according to the Yakutsk EAS array data

The energy spectrum and anisotropy of primary cosmic rays, as well as the lateral distribution functions of electrons and muons in extensive air showers (EASs) with E ₀ ≥ 10¹⁷ eV, are presented according to the Yakutsk EAS array data. It has been shown that the spectrum and lateral distribution functions in some energy ranges have different shapes for the particles that arrive from the disc of the Supergalaxy (Local Supercluster of galaxies) and from the other part of the celestial sphere. This is interpreted as the manifestation of the interaction of extragalactic primary cosmic rays with the gas of the Supergalaxy that possibly leads to the production of new ultra-high-energy particles.     

Cosmic rays of energies in the range 103–105 TeV and higher

Over a period of more than 30 years, the knee in the spectrum of extensive air showers (EAS) generated by cosmic radiation has been explained in two ways: as a consequence of a cusp in the energy spectrum of primary cosmic rays or as a consequence of a change undergone by the process of multiparticle hadron production in the interactions of primary protons with nuclei of air atoms. Investigations at the Tien Shan EAS array confirm a change in the properties of showers generated by protons near the upper boundary of the atmosphere and evince the invariability of the energy spectrum of protons in the energy range 10³–10⁵ TeV.     

Modernization of the Carpet-2 array of the Baksan Neutrino Observatory

The state of the art and the project of modernization of the extensive-air-shower array Carpet-2 of the Baksan Neutrino Observatory of the Institute for Nuclear Research, Russian Academy of Sciences are described. The modernized array will allow the performance of detailed study of variations in the cosmic ray intensity, the energy spectra and composition of primary cosmic rays in the energy range 10¹³–10¹⁶ eV, and the anisotropy of primary cosmic rays with energies above 10¹³ eV.     

Modeling Source Spectra and Composition of Ultrahigh Energy Cosmic Rays

The inverse problem of cosmic ray transport of ultra-high energy cosmic rays is considered. The source spectrum and composition are derived based on the recent Auger data on energy spectrum, energy dependence of mean logarithm of atomic mass number and its variance. The dependence of results on the extrapolation of observable spectrum beyond energies 10²⁰ eV is investigated.

     

Cosmic ray energy spectrum from measurements of air showers

This review focuses on high-energy cosmic rays in the PeV energy range and above. Of particular interest is the knee of the spectrum around 3 PeV and the transition from cosmic rays of Galactic origin to particles from extra-galactic sources. Our goal is to establish a baseline spectrum from 1014 to 10^20 eV by combining the results of many measurements at different energies. In combination with measurements of the nuclear composition of the primaries, the shape of the energy spectrum places constraints on the number and spectra of sources that may contribute to the observed spectrum.     

Energy spectrum and mass composition of primary cosmic rays at energies 10<Superscript>15</Superscript>–10<Superscript>18</Superscript> eV

Data on muon and electron components of extensive air showers (EAS) (obtained with the EAS MSU array) were used to derive the primary cosmic ray (PCR) mass composition. It is shown that for energies beyond the knee at energy 3 × 10¹⁵ eV the abundance of heavy nuclei increases with energy. But at energies above 10¹⁷ eV the abundance of light nuclei starts to grow. The primary cosmic ray spectrum in the range 10¹⁵–10¹⁸ eV is analyzed. It is shown that at energies above 10¹⁷ eV the additional component appears and it differs from the bulk of Galactic cosmic rays generated by shocks in SN remnants.     

On the Mass and the States of the Dark Mater Partcles

We discuss a category of stable dark matter particles which are weakly interacting and related to the superstructure of the universe.These particles may be degenerate fermions and the bosons near a high temperature state.In both cases,we deduce that the particle mass is ～10^－1eV and the absolute value of its chemical potential is <<10^－1eV.This result is not in contradiction with the dip phenomena of the ultra high energy primary cosmic ray spectrum at ～10¹⁵eV and ～10¹⁸eV.     

THE PRECISION MEASUREMENT OF THE ENERGY OF THE SURVIVAL PHOTON PASSED THROUGH A MEDIUM

The initial photon energy 14.4 keV and the energy of the survival photons passed through a medium were measured with a γ ray spectrometer composed of a recoilless nuclear γ ray source and a nuclear resonant absorber. The peak positions of the γ ray spectrum lines of these two measurements were compared and the energy change of the photon was determined. The experimental results show that for a 0.4g/cm². Al absorber two peak positions coincide with each other within the accuracy of 3×10^-10 eV.     

Cosmic ray spectrum obtained from the energy scattered by the particles of extensive air showers in the atmosphere and the galactic model

The differential energy spectrum of cosmic rays that is obtained on the basis of the measurements of Cherenkov radiation from extensive air showers in an energy range of 10¹⁵–10²⁰ eV is compared with the model of the propagation of primary particles in the interstellar medium with fractal properties. It is found that the shape of the experimental spectrum is in good agreement with the shape of the calculated spectrum of “all particles” at 10¹⁵–10¹⁸ eV. The average mass composition of cosmic rays that is calculated on the basis of five components does not contradict the average mass composition obtained from the experimental data for several parameters in this energy range. Original Russian Text ? S.P. Knurenko, A.A. Ivanov, A.V. Saburov, 2007, published in Pis’ma v Zhurnal éksperimental’noĭ i Teoreticheskoĭ Fiziki, 2007, Vol. 86, No. 10, pp. 709–712.     

Determining the primary cosmic ray energy from the total flux of Cherenkov light measured at the Yakutsk EAS array

We present a method for determining the energy of the primary particle that generates an extensive air shower (EAS) of comic rays based on measuring the total flux of Cherenkov light from the shower. Applying this method to Cherenkov light measurements at the Yakutsk EAS array has allowed us to construct the cosmic ray energy spectrum in the range 10¹⁵ ? 3 × 10¹⁹ eV.     

Effect of the near-Earth electric field on the intensity of the soft component of cosmic rays

The transformation of the energy spectrum of the electron-positron component of cosmic rays in the energy range 10–100 MeV in the near-Earth electric field of thunderstorm atmosphere has been estimated analytically by solving the kinetic equation for secondary cosmic rays in the one-dimensional case. The solution obtained adequately describes the observed variations in the soft component in moderate electric fields (±7 kV m^?1).     

STUDY ON RADIATION DAMAGE OF CHINESE-MADE HIGH-Z SCINTILLATION CRYSTALS

Radiation damage effects of several Chinese-made high-Z scintillation crystals have been studied on a ⁶⁰Co irradiation unit of 100KCi Results on small size BGO crystals irradiated by 60Co γ rays with various doses from 5×10³ to 7.5×10⁵rad are presented.The decrease in scintillation light output depends non-linearly on the dose applied and saturation effects above 5×10⁴rad have been observed.The spontaneous recovery of the light output can be described by the sum of at least three exponential functions.The radiation damage effects of small size BaF₂,CsI(Tl) and ZnWO₄ crystals at 5×10⁵rad were also investigated.Serious damage to BaF₂ has been found.Preliminary analyses indicate that this may be attributed to the inclusion of certain critical elements in the crystal.CsI(T1) after irradiation does not exhibit strong afterglow of noticeable coloration as were reported in the literature.