1,281 research outputs found
Large scale cosmic-ray anisotropy with KASCADE
The results of an analysis of the large scale anisotropy of cosmic rays in
the PeV range are presented. The Rayleigh formalism is applied to the right
ascension distribution of extensive air showers measured by the KASCADE
experiment.The data set contains about 10^8 extensive air showers in the energy
range from 0.7 to 6 PeV. No hints for anisotropy are visible in the right
ascension distributions in this energy range. This accounts for all showers as
well as for subsets containing showers induced by predominantly light
respectively heavy primary particles. Upper flux limits for Rayleigh amplitudes
are determined to be between 10^-3 at 0.7 PeV and 10^-2 at 6 PeV primary
energy.Comment: accepted by The Astrophysical Journa
KASCADE-Grande Limits on the Isotropic Diffuse Gamma-Ray Flux between 100 TeV and 1 EeV
KASCADE and KASCADE-Grande were multi-detector installations to measure
individual air showers of cosmic rays at ultra-high energy. Based on data sets
measured by KASCADE and KASCADE-Grande, 90% C.L. upper limits to the flux of
gamma-rays in the primary cosmic ray flux are determined in an energy range of
eV. The analysis is performed by selecting air showers
with a low muon content as expected for gamma-ray-induced showers compared to
air showers induced by energetic nuclei. The best upper limit of the fraction
of gamma-rays to the total cosmic ray flux is obtained at eV with . Translated to an absolute gamma-ray
flux this sets constraints on some fundamental astrophysical models, such as
the distance of sources for at least one of the IceCube neutrino excess models.Comment: Published in The Astrophysical Journal, Volume 848, Number 1. Posted
on: October 5, 201
First Experimental Characterization of Microwave Emission from Cosmic Ray Air Showers
We report the first direct measurement of the overall characteristics of
microwave radio emission from extensive air showers. Using a trigger provided
by the KASCADE-Grande air shower array, the signals of the microwave antennas
of the CROME (Cosmic-Ray Observation via Microwave Emission) experiment have
been read out and searched for signatures of radio emission by high-energy air
showers in the GHz frequency range. Microwave signals have been detected for
more than 30 showers with energies above 3*10^16 eV. The observations presented
in this Letter are consistent with a mainly forward-directed and polarised
emission process in the GHz frequency range. The measurements show that
microwave radiation offers a new means of studying air showers at energies
above 10^17 eV.Comment: Accepted for publication in PR
Energy Spectra of Elemental Groups of Cosmic Rays: Update on the KASCADE Unfolding Analysis
The KASCADE experiment measures extensive air showers induced by cosmic rays
in the energy range around the so-called knee. The data of KASCADE have been
used in a composition analysis showing the knee at 3-5 PeV to be caused by a
steepening in the light-element spectra. Since the applied unfolding analysis
depends crucially on simulations of air showers, different high energy hadronic
interaction models (QGSJet and SIBYLL) were used. The results have shown a
strong dependence of the relative abundance of the individual mass groups on
the underlying model. In this update of the analysis we apply the unfolding
method with a different low energy interaction model (FLUKA instead of GHEISHA)
in the simulations. While the resulting individual mass group spectra do not
change significantly, the overall description of the measured data improves by
using the FLUKA model. In addition data in a larger range of zenith angle are
analysed. The new results are completely consistent, i.e. there is no hint to
any severe problem in applying the unfolding analysis method to KASCADE data.Comment: accepted for publication in Astroparticle Physic
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