653 research outputs found
Proton Modulation in the Heliosphere for Different Solar Conditions and Prediction for AMS-02
Spectra of Galactic Cosmic Rays (GCRs) measured at the Earth are the
combination of several processes: sources production and acceleration,
propagation in the interstellar medium and propagation in the heliosphere.
Inside the solar cavity the flux of GCRs is reduced due to the solar
modulation, the interaction which they have with the interplanetary medium. We
realized a 2D stochastic simulation of solar modulation to reproduce CR spectra
at the Earth, and evaluated the importance in our results of the Local
Interstellar Spectrum (LIS) model and its agreement with data at high energy.
We show a good agreement between our model and the data taken by AMS-01 and
BESS experiments during periods with different solar activity conditions.
Furthermore we made a prediction for the flux which will be measured by AMS-02
experiment.Comment: Accepted for publication in the Proceedings of the ICATPP Conference
on Cosmic Rays for Particle and Astroparticle Physics, Villa Olmo (Como,
Italy), 7-8 October, 2010, to be published by World Scientific (Singapore
Universal properties of primary and secondary cosmic ray energy spectra
Atomic nuclei appearing in cosmic rays are typically classified as primary or
secondary. However, a better understanding of their origin and propagation
properties is still necessary. We analyse the flux of primary (He, C, O) and
secondary nuclei (Li, Be, B) detected with rigidity (momentum/charge) between 2
GV and 3 TV by the Alpha Magnetic Spectrometer (AMS) on the International Space
Station. We show that -exponential distribution functions, as motivated by
generalized versions of statistical mechanics with temperature fluctuations,
provide excellent fits for the measured flux of all nuclei considered. Primary
and secondary fluxes reveal a universal dependence on kinetic energy per
nucleon for which the underlying energy distribution functions are solely
distinguished by their effective degrees of freedom. All given spectra are
characterized by a universal mean temperature parameter 200 MeV which
agrees with the Hagedorn temperature. Our analysis suggests that QCD scattering
processes together with nonequilibrium temperature fluctuations provide a
plausible explanation for the observed universality in cosmic ray energy
spectra. Our analysis suggests that QCD scattering processes together with
nonequilibrium temperature fluctuations imprint universally onto the measured
cosmic ray spectra, and produce a similar shape of energy spectra as high
energy collider experiments on the Earth.Comment: 16 pages, 3 figure
A silicon imaging calorimeter prototype for antimatter search in space: experimental results
Abstract This report presents the results obtained with a prototype silicon-tungsten (Si-W) electromagnetic calorimeter, conceived as a fine-grained imaging device to carry out studies of the antimatter component in primary cosmic radiation. The calorimeter prototype contains 20 x , y sampling layers interleaved with 19 showering material planes. One sensitive layer is obtained with two silicon strip detectors (Si-D) (60 × 60) mm 2 , each divided into 16 strips, 3.6 mm wide; the two detectors are assembled back to back with perpendicular strips. This allows the transverse distributions of the shower in both coordinates at each sampling (0.5 X 0 ) to be pictured. The basic characteristics of the design and the experimental results obtained on a test beam at the CERN proton synchrotron (PS) for electrons and pions are reported. The main results presented are the response of the calorimeter to the electron at various energies (1–7 GeV), and the transverse shower profiles at different calorimeter depths as well as the patterns of the electromagnetic shower and those of the interacting and non-interacting pions. The capability of the calorimeter in measuring the direction of the incoming electromagnetic particle from the pattern of the shower has been evaluated at different energies. These results are encouraging in view of the possible use of this detector to search for high-energy γ sources in space
Current status and desired accuracy of the isotopic production cross-sections relevant to astrophysics of cosmic rays II. Fluorine to Silicon (and updated LiBeB)
High-precision cosmic-ray data from ongoing and recent past experiments
(Voyager, ACE-CRIS, PAMELA, ATIC, CREAM, NUCLEON, AMS-02, CALET, DAMPE) are
being released in the tens of MeV/n to multi-TeV/n energy range. Astrophysical
and dark matter interpretations of these data are limited by the precision of
nuclear production cross-sections. In Paper I, PRC 98, 034611 (2018), we set up
a procedure to rank nuclear reactions whose desired measurements will enable us
to fully exploit currently available data on CR Li to N () species. Here
we extend these rankings to O up to Si nuclei (), also updating our
results on the LiBeB species. We also highlight how comprehensive new high
precision nuclear data, that could e.g. be obtained at the SPS at CERN, would
be a game-changer for the determination of key astrophysical quantities
(diffusion coefficient, halo size of the Galaxy) and indirect searches for dark
matter signatures.Comment: 38 pages (18p main text + 20p App.), 17 figures, 16 tables (all f_abc
coeffs available at https://doi.org/10.5281/zenodo.8143305
Unveiling the nature of galactic TeV sources with IceCube results
IceCube collaboration reported the first high-significance observation of the
neutrino emission from the Galactic disk. The observed signal can be due to
diffuse emission produced by cosmic rays interacting with interstellar gas but
can also arise from a population of sources. In this paper, we evaluate both
the diffuse and source contribution by taking advantage of gamma-ray
observations and/or theoretical considerations. By comparing our expectations
with IceCube measurement, we constrain the fraction of Galactic TeV gamma-ray
sources (resolved and unresolved) with hadronic nature. In order to be
compatible with the IceCube results, this fraction should be less than corresponding to a cumulative source flux integrated in the 1-100 TeV energy range
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