84 research outputs found
Azimuthal modulation of the event rate of cosmic ray extensive air showers by the geomagnetic field
The Earth's magnetic field effect on the azimuthal distribution of extensive
air showers (EAS) of cosmic rays has been evaluated using a bulk of the Yakutsk
array data. The uniform azimuthal distribution of the EAS event rate is
rejected at the significance level 10^(-14). Amplitude of the first harmonics
of observed distribution depends on zenith angle as A1=0.2*sin^2(theta) and is
almost independent of the primary energy; the phase coincides with the magnetic
meridian. Basing upon the value of measured effect, the correction factor has
been derived for the particle density depending on a geomagnetic parameter of a
shower.Comment: 4 pages, 3 figures in ps file
Influence of Primary Cosmic Radiation Mass Composition on the Estimation of Eas Energy
At the Yakutsk EAS array E_em is determined by using measurements of EAS
Cherenkov light flux and charged particle flux. It is known from calculations
that these characteristics depend on a sort of primary particle and, therefore,
the estimation of E_em depends on a primary particle mass. In the work the
dependence of the E_em/E_0 ratio on the energy is given and experimental data
are compared with calculations by the QGSJET model. The calculations have been
carried out for the primary proton and iron nucleus. The average calculated
meaning of the value of E_em/E_0 ratio (between the proton and iron nucleus)
within experimental errors is in agreement with experimental data that doesnt
contradict to the mixed mass composition of primary cosmic radiation.Comment: 19th European Cosmic Ray Symposium. Aug 30 - Sep 3 2004, Florence,
Italy. 3 pages, 1 figure. Subbmitted for publication in International Journal
of Modern Physics
Fluctuations of Xmax and Primary Particle Mass Composition in the Range of Energy 5 10^{17} - 3 10^{19} ev by Yakutsk Data
The experimental distributions of \Xmax obtained with the Yakutsk EAS array
at fixed energies of , and
eV are analysed. A recent version of the QGSJET model is used as a tool of our
analysis. In the framework of this model, the most adequate mass composition of
primary particles satisfying the experimental data on \Xmax is selected.Comment: 19th European Cosmic Ray Symposium, Aug 30 - Sep 3 2004, Florence,
Italy. 3 pages, 1 figure. Submitted for publication in International Journal
of Modern Physics
Upper limit on the ultra-high-energy photon flux from AGASA and Yakutsk data
We present the interpretation of the muon and scintillation signals of
ultra-high-energy air showers observed by AGASA and Yakutsk extensive air
shower array experiments. We consider case-by-case ten highest energy events
with known muon content and conclude that at the 95% confidence level (C.L.)
none of them was induced by a primary photon. Taking into account statistical
fluctuations and differences in the energy estimation of proton and photon
primaries, we derive an upper limit of 36% at 95% C.L. on the fraction of
primary photons in the cosmic-ray flux above 10^20 eV. This result disfavors
the Z-burst and superheavy dark-matter solutions to the GZK-cutoff problem.Comment: revtex, 8 pages, 4 figure
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