It is proposed a new approach for estimating the composition of cosmic rays. It is found that the zenith angle distributions and muon components of EAS for energies E>10^19 eV and E>4.10^19 eV differ from each other. It is shown that the cosmic rays above E>4.10^19 eV is heavier than the cosmic rays at energy E~ 10^19 eV. According to our estimation the SUGAR array detected 8 showers above 10^20 eV. It is concluded that no sign of Greisen-Zatsepin-Kuzmin (GZK) cut off in the spectrum of cosmic rays and all cosmic rays are galactic.
This is a review of the most resent results from the investigation of the Ultrahigh Energy Cosmic Rays, particles of energy exceeding 10$^{18}$ eV. After a general introduction to the topic and a brief review of the lower energy cosmic rays and the d
etection methods, the two most recent experiments, the High Resolution Flys Eye (HiRes) and the Southern Auger Observatory are described. We then concentrate on the results from these two experiments on the cosmic ray energy spectrum, the chemical composition of these cosmic rays and on the searches for their sources. We conclude with a brief analysis of the controversies in these results and the projects in development and construction that can help solve the remaining problems with these particles.
The apparent lack of suitable astrophysical sources for cosmic rays with E > 10^{19.7} eV (UHECRs) is the GZK Paradox. We argue that whatever mechanism produces them must also account for events down to ~10^{18.7} eV, including their isotropy and spe
ctral smoothness. This rules out galactic sources, distributed sources such as topological defects, and Gamma Ray Bursts (GRBs). We are lead to identify the powerful radio galaxy Cen A, at 3.4 Mpc, as the probable source of most UHECRs observed at Earth today, and to estimate the extragalactic magnetic field to be ~0.3 microG.
In this paper we review the extragalactic propagation of ultrahigh energy cosmic-rays (UHECR). We present the different energy loss processes of protons and nuclei, and their expected influence on energy evolution of the UHECR spectrum and compositio
n. We discuss the possible implications of the recent composition analyses provided by the Pierre Auger Observatory. The influence of extragalactic magnetic fields and possible departures from the rectilinear case are also mentioned as well as the production of secondary cosmogenic neutrinos and photons and the constraints their observation would imply for the UHECRs origin. Finally, we conclude by briefly discussing the relevance of a multi messenger approach for solving the mystery of UHECRs.
We describe the current situation of the data on the highest energy particles in the Universe - the ultrahigh energy cosmic rays. The new results in the field come from the Telescope Array experiment in Utah, U.S.A. For this reason we concentrate on
the results from this experiments and compare them to the measurements of the other two recent experiments, the High Resolution Flys Eye and the Southern Auger Observatory
The muon charge ratio of ultrahigh energy cosmic rays may provide information to detect the composition of the primary cosmic rays. We propose to extract the charge information of high energy muons in very inclined extensive air showers by analyzing
their relative lateral positions in the shower transverse plane.
A.A. Mikhailov
,N.N. Efremov
,N.S. Gerasimova
.
(2005)
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"Estimate of the Mass Composition of Ultrahigh Energy Cosmic Rays"
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Aleksei Mikhailov Alekseevich
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