147 research outputs found
Solar Energetic Particle Studies with PAMELA
The origin of the high-energy solar energetic particles (SEPs) may conceivably be found in composition signatures that reflect the elemental abundances of the low corona and chromosphere vs. the high corona and solar wind. The presence of secondaries, such as neutrons and positrons, could indicate a low coronal origin of these particles. Velocity dispersion of different species and over a wide energy range can be used to determine energetic particle release times at the Sun. Together with multi-wavelength imaging, in- situ observations of a variety of species, and coverage over a wide energy range provide a critical tool in identifying the origin of SEPs, understanding the evolution of these events within the context of solar active regions, and constraining the acceleration mechanisms at play. The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA)instrument, successfully launched in 2006 and expected to remain operational until at least the beginning of 2012, measures energetic particles in the same energy range as ground-based neutron monitors, and lower energies as well. It thus bridges the gap between low energy in-situ observations and ground-based Ground Level Enhancements (GLE) observations. It can measure the charge (up to Z=6) and atomic number of the detected particles, and it can identify and measure positrons and detect neutrons-an unprecedented array of data channels that we can bring to bear on the origin of high-energy SEPs. We present prelimiary results on the for the 2006 December 13 solar flare and GLE and the 2011 March 21 solar flare, both registering proton and helium enhancements in PAMELA. Together with multi- spacecraft contextual data and modeling, we discuss the PAMELA results in the context of the different acceleration mechanisms at play
ELO: The ELectron Observatory, an Instrument to Mea- sure High-Energy Cosmic-Ray Electrons
Abstract The ELectron Observatory (ELO) is a calorimeter designed to extend current data on the energy spectrum of cosmic-ray electrons to over 10 TeV, with the potential of detecting predicted structures imprinted on the electron flux by the acceleration process. We present a detailed description of the design and expected performance of the ELO instrument and on the plans for future implementation
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
PAMELA's measurements of geomagnetic cutoff variations during solar energetic particle events
Data from the PAMELA satellite experiment were used to measure the
geomagnetic cutoff for high-energy ( 80 MeV) protons during the solar
particle events on 2006 December 13 and 14. The variations of the cutoff
latitude as a function of rigidity were studied on relatively short timescales,
corresponding to single spacecraft orbits (about 94 minutes). Estimated cutoff
values were cross-checked with those obtained by means of a trajectory tracing
approach based on dynamical empirical modeling of the Earth's magnetosphere. We
find significant variations in the cutoff latitude, with a maximum suppression
of about 6 deg for 80 MeV protons during the main phase of the storm. The
observed reduction in the geomagnetic shielding and its temporal evolution were
compared with the changes in the magnetosphere configuration, investigating the
role of IMF, solar wind and geomagnetic (Kp, Dst and Sym-H indexes) variables
and their correlation with PAMELA cutoff results.Comment: Conference: The 34th International Cosmic Ray Conference (ICRC2015),
30 July - 6 August, 2015, The Hague, The Netherlands, Volume:
PoS(ICRC2015)28
Measurement of the flux of atmospheric muons with the CAPRICE94 apparatus
A new measurement of the momentum spectra of both positive and negative muons
as function of atmospheric depth was made by the balloon-borne experiment
CAPRICE94. The data were collected during ground runs in Lynn Lake on the
19-20th of July 1994 and during the balloon flight on the 8-9th of August 1994.
We present results that cover the momentum intervals 0.3-40 GeV/c for negative
muons and 0.3-2 GeV/c for positive muons, for atmospheric depths from 3.3 to
1000 g/cm**2, respectively. Good agreement is found with previous measurements
for high momenta, while at momenta below 1 GeV/c we find latitude dependent
geomagnetic effects. These measurements are important cross-checks for the
simulations carried out to calculate the atmospheric neutrino fluxes and to
understand the observed atmospheric neutrino anomaly.Comment: 28 pages, 13 Postscript figures, uses revtex.sty, to appear in Phys.
Rev.
Solar energetic particle events: trajectory analysis and flux reconstruction with PAMELA
The PAMELA satellite experiment is providing first direct measurements of
Solar Energetic Particles (SEPs) with energies from about 80 MeV to several GeV
in near-Earth space, bridging the low energy data by other space-based
instruments and the Ground Level Enhancement (GLE) data by the worldwide
network of neutron monitors. Its unique observational capabilities include the
possibility of measuring the flux angular distribution and thus investigating
possible anisotropies. This work reports the analysis methods developed to
estimate the SEP energy spectra as a function of the particle pitch-angle with
respect to the Interplanetary Magnetic Field (IMF) direction. The crucial
ingredient is provided by an accurate simulation of the asymptotic exposition
of the PAMELA apparatus, based on a realistic reconstruction of particle
trajectories in the Earth's magnetosphere. As case study, the results for the
May 17, 2012 event are presented.Comment: Conference: The 34th International Cosmic Ray Conference (ICRC2015),
30 July - 6 August, 2015, The Hague, The Netherlands, Volume:
PoS(ICRC2015)08
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