1,017 research outputs found
Neutrino and astroparticle physics
We report on the neutrinos and astroparticle session of this workshop and discuss the present status and future perspectives of this research field
Critical sets of nonlinear Sturm-Liouville operators of Ambrosetti-Prodi type
The critical set C of the operator F:H^2_D([0,pi]) -> L^2([0,pi]) defined by
F(u)=-u''+f(u) is studied. Here X:=H^2_D([0,pi]) stands for the set of
functions that satisfy the Dirichlet boundary conditions and whose derivatives
are in L^2([0,pi]). For generic nonlinearities f, C=\cup C_k decomposes into
manifolds of codimension 1 in X. If f''0, the set C_j is shown to be
non-empty if, and only if, -j^2 (the j-th eigenvalue of u -> u'') is in the
range of f'. The critical components C_k are (topological) hyperplanes.Comment: 6 pages, no figure
The Cosmic-Ray Proton and Helium Spectra measured with the CAPRICE98 balloon experiment
A new measurement of the primary cosmic-ray proton and helium fluxes from 3
to 350 GeV was carried out by the balloon-borne CAPRICE experiment in 1998.
This experimental setup combines different detector techniques and has
excellent particle discrimination capabilities allowing clear particle
identification. Our experiment has the capability to determine accurately
detector selection efficiencies and systematic errors associated with them.
Furthermore, it can check for the first time the energy determined by the
magnet spectrometer by using the Cherenkov angle measured by the RICH detector
well above 20 GeV/n. The analysis of the primary proton and helium components
is described here and the results are compared with other recent measurements
using other magnet spectrometers. The observed energy spectra at the top of the
atmosphere can be represented by (1.27+-0.09)x10^4 E^(-2.75+-0.02) particles
(m^2 GeV sr s)^-1, where E is the kinetic energy, for protons between 20 and
350 GeV and (4.8+-0.8)x10^2 E^(-2.67+-0.06) particles (m^2 GeV nucleon^-1 sr
s)^-1, where E is the kinetic energy per nucleon, for helium nuclei between 15
and 150 GeV nucleon^-1.Comment: To be published on Astroparticle Physics (44 pages, 13 figures, 5
tables
Two years of flight of the Pamela experiment: results and perspectives
PAMELA is a satellite borne experiment designed to study with great accuracy
cosmic rays of galactic, solar, and trapped nature in a wide energy range
(protons: 80 MeV-700 GeV, electrons 50 MeV-400 GeV). Main objective is the
study of the antimatter component: antiprotons (80 MeV-190 GeV), positrons (50
MeV-270 GeV) and search for antinuclei with a precision of the order of
). The experiment, housed on board the Russian Resurs-DK1 satellite,
was launched on June, 2006 in a orbit with an
inclination of 70 degrees. In this work we describe the scientific objectives
and the performance of PAMELA in its first two years of operation. Data on
protons of trapped, secondary and galactic nature - as well as measurements of
the December 2006 Solar Particle Event - are also provided.Comment: To appear on J. Phys. Soc. Jpn. as part of the proceedings of the
International Workshop on Advances in Cosmic Ray Science March, 17-19, 2008
Waseda University, Shinjuku, Tokyo, Japa
Time dependence of the electron and positron components of the cosmic radiation measured by the PAMELA experiment between July 2006 and December 2015
Cosmic-ray electrons and positrons are a unique probe of the propagation of
cosmic rays as well as of the nature and distribution of particle sources in
our Galaxy. Recent measurements of these particles are challenging our basic
understanding of the mechanisms of production, acceleration and propagation of
cosmic rays. Particularly striking are the differences between the low energy
results collected by the space-borne PAMELA and AMS-02 experiments and older
measurements pointing to sign-charge dependence of the solar modulation of
cosmic-ray spectra. The PAMELA experiment has been measuring the time variation
of the positron and electron intensity at Earth from July 2006 to December 2015
covering the period for the minimum of solar cycle 23 (2006-2009) till the
middle of the maximum of solar cycle 24, through the polarity reversal of the
heliospheric magnetic field which took place between 2013 and 2014. The
positron to electron ratio measured in this time period clearly shows a
sign-charge dependence of the solar modulation introduced by particle drifts.
These results provide the first clear and continuous observation of how drift
effects on solar modulation have unfolded with time from solar minimum to solar
maximum and their dependence on the particle rigidity and the cyclic polarity
of the solar magnetic field.Comment: 11 pages, 2 figure
A new measurement of the antiproton-to-proton flux ratio up to 100 GeV in the cosmic radiation
A new measurement of the cosmic ray antiproton-to-proton flux ratio between 1
and 100 GeV is presented. The results were obtained with the PAMELA experiment,
which was launched into low-earth orbit on-board the Resurs-DK1 satellite on
June 15th 2006. During 500 days of data collection a total of about 1000
antiprotons have been identified, including 100 above an energy of 20 GeV. The
high-energy results are a ten-fold improvement in statistics with respect to
all previously published data. The data follow the trend expected from
secondary production calculations and significantly constrain contributions
from exotic sources, e.g. dark matter particle annihilations.Comment: 10 pages, 4 figures, 1 tabl
Time dependence of the e^- flux measured by PAMELA during the July 2006 - December 2009 solar minimum
Precision measurements of the electron component in the cosmic radiation
provide important information about the origin and propagation of cosmic rays
in the Galaxy not accessible from the study of the cosmic-ray nuclear
components due to their differing diffusion and energy-loss processes. However,
when measured near Earth, the effects of propagation and modulation of galactic
cosmic rays in the heliosphere, particularly significant for energies up to at
least 30 GeV, must be properly taken into account. In this paper the electron
(e^-) spectra measured by PAMELA down to 70 MeV from July 2006 to December 2009
over six-months time intervals are presented. Fluxes are compared with a
state-of-the-art three-dimensional model of solar modulation that reproduces
the observations remarkably well.Comment: 40 pages, 18 figures, 1 tabl
Time dependence of the proton flux measured by PAMELA during the July 2006 - December 2009 solar minimum
The energy spectra of galactic cosmic rays carry fundamental information
regarding their origin and propagation. These spectra, when measured near
Earth, are significantly affected by the solar magnetic field. A comprehensive
description of the cosmic radiation must therefore include the transport and
modulation of cosmic rays inside the heliosphere. During the end of the last
decade the Sun underwent a peculiarly long quiet phase well suited to study
modulation processes. In this paper we present proton spectra measured from
July 2006 to December 2009 by PAMELA. The large collected statistics of protons
allowed the time variation to be followed on a nearly monthly basis down to 400
MV. Data are compared with a state-of-the-art three-dimensional model of solar
modulation.Comment: 17 pages, 5 figures, 1 table, to appear in Astrophysical Journal.
Corrected two elements of Table
Geomagnetically trapped, albedo and solar energetic particles: trajectory analysis and flux reconstruction with PAMELA
The PAMELA satellite experiment is providing comprehensive observations of
the interplanetary and magnetospheric radiation in the near-Earth environment.
Thanks to its identification capabilities and the semi-polar orbit, PAMELA is
able to precisely measure the energetic spectra and the angular distributions
of the different cosmic-ray populations over a wide latitude region, including
geomagnetically trapped and albedo particles. Its observations comprise the
solar energetic particle events between solar cycles 23 and 24, and the
geomagnetic cutoff variations during magnetospheric storms. PAMELA's
measurements are supported by an accurate analysis of particle trajectories in
the Earth's magnetosphere based on a realistic geomagnetic field modeling,
which allows the classification of particle populations of different origin and
the investigation of the asymptotic directions of arrival.Comment: Accepted for publication in Advances in Space Research, 2016. 21
pages, 7 figure
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