1,069 research outputs found
Flux of atmospheric muons: Comparison between AIRES simulations and CAPRICE98 data
We report on a comparison between the flux of muons in the atmosphere
measured by the CAPRICE98 experiment and simulations performed with the air
shower simulation program AIRES. To reduce systematic uncertainties we have
used as input the primary fluxes of protons and helium nuclei also measured by
the CAPRICE98 experiment. Heavy nuclei are also taken into account in the
primary flux, and their contribution to the muon flux is discussed. The results
of the simulations show a very good agreement with the experimental data, at
all altitudes and for all muon momenta. With the exception of a few isolated
points, the relative differences between measured data and simulations are
smaller than 20 %; and in all cases compatible with zero within two standard
deviations. The influence of the input cosmic ray flux on the results of the
simulations is also discussed. This report includes also an extensive analysis
of the characteristics of the simulated fluxes.Comment: Accepted for publication in Physical Review
Progresses in the validation of the FLUKA atmospheric neutrino flux calculations
The FLUKA calculation of the atmospheric neutrino fluxes have been
cross-checked by comparing predictions on lepton fluxes in atmosphere to
experimental data. The dependence of predicted neutrino fluxes on the shape and
normalization of primary spectrum is also investigatedComment: Presented at TAUP2001 (Sep. 8-12, Assergi, Italy). 5 pages, 1 figur
Spatial Resolution of Double-Sided Silicon Microstrip Detectors for the PAMELA Apparatus
The PAMELA apparatus has been assembled and it is ready to be launched in a
satellite mission to study mainly the antiparticle component of cosmic rays. In
this paper the performances obtained for the silicon microstrip detectors used
in the magnetic spectrometer are presented. This subdetector reconstructs the
curvature of a charged particle in the magnetic field produced by a permanent
magnet and consequently determines momentum and charge sign, thanks to a very
good accuracy in the position measurements (better than 3 um in the bending
coordinate). A complete simulation of the silicon microstrip detectors has been
developed in order to investigate in great detail the sensor's characteristics.
Simulated events have been then compared with data gathered from minimum
ionizing particle (MIP) beams during the last years in order to tune free
parameters of the simulation. Finally some either widely used or original
position finding algorithms, designed for such kind of detectors, have been
applied to events with different incidence angles. As a result of the analysis,
a method of impact point reconstruction can be chosen, depending on both the
particle's incidence angle and the cluster multiplicity, so as to maximize the
capability of the spectrometer in antiparticle tagging.Comment: 28 pages, 18 figures, submitted to Nuclear Instruments and Methods in
Physics Research
Impact of the spectral hardening of TeV cosmic rays on the prediction of the secondary positron flux
The rise in the cosmic-ray positron fraction measured by the PAMELA satellite
is likely due to the presence of astrophysical sources of positrons, e.g.
pulsars, on the kpc scale around the Earth. Nevertheless, assessing the
properties of these sources from the positron data requires a good knowledge of
the secondary positron component generated by the interaction of cosmic rays
with the interstellar gas. In this paper, we investigate the impact of the
spectral hardening in the cosmic-ray proton and helium fluxes recently reported
by the ATIC2 and CREAM balloon experiments, on the predictions of the secondary
positron flux. We show that the effect is not negligible, leading to an
increase of the secondary positron flux by up to 60% above 100 GeV.
We provide fitting formulae that allow a straightforward utilization of our
results, which can help in deriving constraints on one's favorite primary
positron source, e.g. pulsars or dark matter.Comment: 8 pages, 4 figures (accepted in MNRAS 04-01-2011
Average Inhomogeneities in Milky Way SNII and The PAMELA Anomaly
A model is presented to estimate the fraction of Supernova Type-II events
(SNII) occurring inside vs. outside a spiral arm for a given star formation
episode. The probability distribution function (PDF) for this fraction is given
for use in models similar to those of Shaviv et al. [13][11]. The calculated
PDF for the SNII fraction, SNII_{in/total}, defined as the number of SNII
inside a spiral arm divided by the total number of SNII from a star formation
event, provides a constraint on the magnitude of supernova remnant (SNR)
concentrations used in cosmic ray propagation models attempting to explain the
PAMELA anomaly. Despite the concentration of star formation within spiral arms,
this model predicts the majority of SNII events actually occur in inter-arm
regions and calls into question the SNR concentration assumption of Shaviv et
al.Comment: 8 pages, 2 figures, 2 table; accepted by Astroparticle Physic
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