294 research outputs found
Systematic uncertainties in MonteCarlo simulations of the atmospheric muon flux in the 5-line ANTARES detector
The ANTARES detector was operated in a configuration with 5 lines for a
period of 10 months from February until November 2007. The duty cycle was
better than 80% during this period and almost 2*10**7 atmospheric muon triggers
were collected. This large sample was used to test Monte Carlo simulation
programs and to evaluate possible systematic effects due to uncertainties on
environmental parameters and detector description. First results are presented
and discussed.Comment: 4 pages, 7 figures, presented at the International Workshop on a Very
Large Volume Telescope for the Mediterranean Sea, 22-24 Oct. 2007,
Toulon, Franc
Muon Production in Relativistic Cosmic-Ray Interactions
Cosmic-rays with energies up to eV have been observed. The
nuclear composition of these cosmic rays is unknown but if the incident nuclei
are protons then the corresponding center of mass energy is TeV. High energy muons can be used to probe the composition of these
incident nuclei. The energy spectra of high-energy ( 1 TeV) cosmic ray
induced muons have been measured with deep underground or under-ice detectors.
These muons come from pion and kaon decays and from charm production in the
atmosphere.
Terrestrial experiments are most sensitive to far-forward muons so the
production rates are sensitive to high- partons in the incident nucleus and
low- partons in the nitrogen/oxygen targets. Muon measurements can
complement the central-particle data collected at colliders. This paper will
review muon production data and discuss some non-perturbative (soft) models
that have been used to interpret the data. I will show measurements of TeV muon
transverse momentum () spectra in cosmic-ray air showers from MACRO, and
describe how the IceCube neutrino observatory and the proposed Km3Net detector
will extend these measurements to a higher region where perturbative QCD
should apply. With a 1 km surface area, the full IceCube detector should
observe hundreds of muons/year with in the pQCD regime.Comment: 4 pages, 2 figures - To appear in the conference proceedings for
Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee. Tweaked
formatting at organizers reques
FLUKA as a new high energy cosmic ray generator
FLUKA is a multipurpose Monte Carlo code, which can transport particles over
a wide range of energies in user-defined geometries. Here we present a new
FLUKA library, which allows the interaction and propagation of high energy
cosmic rays in the Earth atmosphere and the transport of high energy muons in
underground/underwater environmentsComment: Presented by A.Margiotta at the Very Large Volume neutrino Telescope
Workshop 2009 - VLVnT09, Athens, October 2009. 3 pages, 1 figure. To be
published in NIM
QGSJET-II: results for extensive air showers
The new hadronic Monte Carlo model QGSJET-II is applied for extensive air
shower (EAS) calculations. The obtained results are compared to the predictions
of the original QGSJET and of the SIBYLL 2.1 interaction models. It is shown
that non-linear effects change substantially model predictions for
hadron-nucleus interactions and produce observable effects for calculated EAS
characteristics. Finally the impact of the new model on the interpretation of
air shower array data is discussed.Comment: To appear in the proceedings of 13th International Symposium on Very
High-Energy Cosmic Ray Interactions at the NESTOR Institute, Pylos, Greece,
6-12 Sep 200
Composition of Primary Cosmic-Ray Nuclei at High Energies
The TRACER instrument (``Transition Radiation Array for Cosmic Energetic
Radiation'') has been developed for direct measurements of the heavier primary
cosmic-ray nuclei at high energies. The instrument had a successful
long-duration balloon flight in Antarctica in 2003. The detector system and
measurement process are described, details of the data analysis are discussed,
and the individual energy spectra of the elements O, Ne, Mg, Si, S, Ar, Ca, and
Fe (nuclear charge Z=8 to 26) are presented. The large geometric factor of
TRACER and the use of a transition radiation detector make it possible to
determine the spectra up to energies in excess of 10 eV per particle. A
power-law fit to the individual energy spectra above 20 GeV per amu exhibits
nearly the same spectral index ( 2.65 0.05) for all elements,
without noticeable dependence on the elemental charge Z.Comment: Accepted for publication in the Astrophysical Journal (3-Jan-08), 37
pages, 15 figure
Nonextensive thermal sources of cosmic rays?
The energy spectrum of cosmic rays (CR) exhibits power-like behavior with a
very characteristic "knee" structure. We consider a possibility that such a
spectrum could be generated by some specific nonstatistical temperature
fluctuations in the source of CR with the "knee" structure reflecting an abrupt
change of the pattern of such fluctuations. This would result in a generalized
nonextensive statistical model for the production of CR. The possible physical
mechanisms leading to these effects are discussed together with the resulting
chemical composition of the CR, which follows the experimentally observed
abundance of nuclei.Comment: 16 pages, 3 figures, rewritten and updated version, to be published
in Centr. Eur. J. Phy
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
A new method for detection of induced mutations in wheat
Contains fulltext :
141188.pdf (preprint version ) (Open Access
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
A study on the sharp knee and fine structures of cosmic ray spectra
The paper investigates the overall and detailed features of cosmic ray (CR)
spectra in the knee region using the scenario of nuclei-photon interactions
around the acceleration sources. Young supernova remnants can be the physical
realities of such kind of CR acceleration sites. The results show that the
model can well explain the following problems simultaneously with one set of
source parameters: the knee of CR spectra and the sharpness of the knee, the
detailed irregular structures of CR spectra, the so-called "component B" of
Galactic CRs, and the electron/positron excesses reported by recent
observations. The coherent explanation serves as evidence that at least a
portion of CRs might be accelerated at the sources similar to young supernova
remnants, and one set of source parameters indicates that this portion mainly
comes from standard sources or from a single source.Comment: 13 pages, 4 figures, accepted for publication in SCIENCE CHINA
Physics, Mechanics & Astronomy
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