2,389 research outputs found
Absolute calibration of the LOPES antenna system
Radio emission in extensive air showers arises from an interaction with the
geomagnetic field and is subject of theoretical studies. This radio emission
has advantages for the detection of high energy cosmic rays compared to
secondary particle or fluorescence measurement methods. Radio antennas like the
LOPES30 antenna system are suited to investigate this emission process by
detecting the radio pulses. The characteristic observable parameters like
electric field strength and pulse length require a calibration which was done
with a reference radio source resulting in an amplification factor representing
the system behavior in the environment of the KASCADE-Grande experiment.
Knowing the amplification factor and the gain of the LOPES antennas LOPES30 is
calibrated absolutely for systematic analyses of the radio emission.Comment: 5 pages, Proceedings of International Workshop on Acoustic and Radio
EeV Neutrino detection Activities: ARENA, May 17-19, 2005, DESY Zeuthe
Detection and imaging of atmospheric radio flashes from cosmic ray air showers
The nature of ultrahigh-energy cosmic rays (UHECRs) at energies >10^20 eV
remains a mystery. They are likely to be of extragalactic origin, but should be
absorbed within ~50 Mpc through interactions with the cosmic microwave
background. As there are no sufficient powerful accelerators within this
distance from the Galaxy, explanations for UHECRs range from unusual
astrophysical sources to exotic string physics. Also unclear is whether UHECRs
consist of protons, heavy nuclei, neutrinos or gamma-rays. To resolve these
questions, larger detectors with higher duty cycles and which combine multiple
detection techniques are needed. Radio emission from UHECRs, on the other hand,
is unaffected by attenuation, has a high duty cycle, gives calorimetric
measurements and provides high directional accuracy. Here we report the
detection of radio flashes from cosmic-ray air showers using low-cost digital
radio receivers. We show that the radiation can be understood in terms of the
geosynchrotron effect. Our results show that it should be possible to determine
the nature and composition of UHECRs with combined radio and particle
detectors, and to detect the ultrahigh-energy neutrinos expected from flavour
mixing.Comment: Nature, May 19, 2005 issue (PDF, 14 pages),
http://www.astro.ru.nl/lopes/?loc=publication
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
Progress in Air Shower Radio Measurements: Detection of Distant Events
Data taken during half a year of operation of 10 LOPES antennas (LOPES-10),
triggered by EAS observed with KASCADE-Grande have been analysed. We report
about the analysis of correlations of radio signals measured by LOPES-10 with
extensive air shower events reconstructed by KASCADE-Grande, including shower
cores at large distances. The efficiency of detecting radio signals induced by
air showers up to distances of 700 m from the shower axis has been
investigated. The results are discussed with special emphasis on the effects of
the reconstruction accuracy for shower core and arrival direction on the
coherence of the measured radio signal. In addition, the correlations of the
radio pulse amplitude with the primary cosmic ray energy and with the lateral
distance from the shower core are studied.Comment: Accepted for publication in Astroparticle Physic
Dissecting the knee - Air shower measurements with KASCADE
Recent results of the KASCADE air shower experiment are presented in order to
shed some light on the astrophysics of cosmic rays in the region of the knee in
the energy spectrum. The results include investigations of high-energy
interactions in the atmosphere, the analysis of the arrival directions of
cosmic rays, the determination of the mean logarithmic mass, and the unfolding
of energy spectra for elemental groups
KASCADE: Astrophysical results and tests of hadronic interaction models
KASCADE is a multi-detector setup to get redundant information on single air
shower basis. The information is used to perform multiparameter analyses to
solve the threefold problem of the reconstruction of (i)the unknown primary
energy, (ii) the primary mass, and (iii) to quantify the characteristics of the
hadronic interactions in the air-shower development. In this talk recent
results of the KASCADE data analyses are summarized concerning cosmic ray
anisotropy studies, determination of flux spectra for different primary mass
groups, and approaches to test hadronic interaction models. Neither large scale
anisotropies nor point sources were found in the KASCADE data set. The energy
spectra of the light element groups result in a knee-like bending and a
steepening above the knee. The topology of the individual knee positions shows
a dependency on the primary particle. Though no hadronic interaction model is
fully able to describe the multi-parameter data of KASCADE consistently, the
more recent models or improved versions of older models reproduce the data
better than few years ago.Comment: to appear in Nucl. Phys. B (Proc. Suppl.), Proc. of the XIII
ISVHECRI, Pylos 2004 - with a better quality of the figure
Primary Proton Spectrum of Cosmic Rays measured with Single Hadrons
The flux of cosmic-ray induced single hadrons near sea level has been
measured with the large hadron calorimeter of the KASCADE experiment. The
measurement corroborates former results obtained with detectors of smaller size
if the enlarged veto of the 304 m^2 calorimeter surface is encounted for. The
program CORSIKA/QGSJET is used to compute the cosmic-ray flux above the
atmosphere. Between E_0=300 GeV and 1 PeV the primary proton spectrum can be
described with a power law parametrized as
dJ/dE_0=(0.15+-0.03)*E_0^{-2.78+-0.03} m^-2 s^-1 sr^-1 TeV^-1. In the TeV
region the proton flux compares well with the results from recent measurements
of direct experiments.Comment: 13 pages, accepted by Astrophysical Journa
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