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Träfflista för sökning "WFRF:(Panico S.) ;pers:(Adriani O.)"

Sökning: WFRF:(Panico S.) > Adriani O.

  • Resultat 1-10 av 58
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1.
  • Munini, R., et al. (författare)
  • Evidence of Energy and Charge Sign Dependence of the Recovery Time for the 2006 December Forbush Event Measured by the PAMELA Experiment
  • 2018
  • Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 853:1
  • Tidskriftsartikel (refereegranskat)abstract
    • New results on the short-term galactic cosmic-ray (GCR) intensity variation (Forbish decrease) in 2006 December measured by the PAMELA instrument are presented. Forbush decreases are sudden suppressions of the GCR intensities, which are associated with the passage of interplanetary transients such as shocks and interplanetary coronal mass ejections (ICMEs). Most of the past measurements of this phenomenon were carried out with groundbased detectors such as neutron monitors or muon telescopes. These techniques allow only the indirect detection of the overall GCR intensity over an integrated energy range. For the first time, thanks to the unique features of the PAMELA magnetic spectrometer, the Forbush decrease, commencing on 2006 December 14 and following a CME at the Sun on 2006 December 13, was studied in a wide rigidity range (0.4-20 GV) and for different species of GCRs detected directly in space. The daily averaged GCR proton intensity was used to investigate the rigidity dependence of the amplitude and the recovery time of the Forbush decrease. Additionally, for the first time, the temporal variations in the helium and electron intensities during a Forbush decrease were studied. Interestingly, the temporal evolutions of the helium and proton intensities during the Forbush decrease were found to be in good agreement, while the low rigidity electrons (<2 GV) displayed a faster recovery. This difference in the electron recovery is interpreted as a charge sign dependence introduced by drift motions experienced by the GCRs during their propagation through the heliosphere.
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2.
  • Munini, R., et al. (författare)
  • Short-term variation in the galactic cosmic ray intensity measured with the PAMELA experiment
  • 2017
  • Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
  • Konferensbidrag (refereegranskat)abstract
    • New results on the galactic cosmic ray (GCR) short-term intensity variation associated with Forbush decrease and co-rotating interaction regions (CIRs) measured by the PAMELA instrument between November 2006 and March 2007 are presented. Most of the past measurements on Forbush decrease events were carried out with neutron monitor detector. This tecnique allows only indirect detection of the overall GCR intensity over an integrated energy range. For the first time, thanks to the unique features of the PAMELA magnetic spectrometer, the Forbush decrease associated with the December 13th coronal mass ejection (CME) was studied in a wide rigidity range (0.4 - 20 GV) and for different species of GCRs detected directly in space. Using GCR protons, the amplitude and the recovery time of the Forbush decrease were studied for ten rigidity interval with a temporal resolution of one day. For comparison the helium and the electron intensity over time were also studied. The temporal evolution of the helium and proton intensity was found in good agreement while the electrons show, on average, a faster recovery time. This was interpreted as a charge-sign dependence introduced by drift motion experienced by the low rigidity (< 5 GV) GCRs during their propagation through the heliosphere. Moreover a clear 13.5 days cyclical variation was observed in the GCR proton intensity after the Forbush decrease. This phenomena could be interpreted as an effect of prominent structures of compressed plasma in the solar wind, i.e. CIRs, or to the latitudinal gradient due to the crossing of the heliospheric current sheet (HCS). 
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3.
  • Adriani, O., et al. (författare)
  • Pamela's measurements of magnetospheric effects on high-energy solar particles
  • 2015
  • Ingår i: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 801:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The nature of particle acceleration at the Sun, whether through flare reconnection processes or through shocks driven by coronal mass ejections, is still under scrutiny despite decades of research. The measured properties of solar energetic particles (SEPs) have long been modeled in different particle-acceleration scenarios. The challenge has been to disentangle the effects of transport from those of acceleration. The Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) instrument enables unique observations of SEPs including the composition and angular distribution of the particles about the magnetic field, i.e., pitch angle distribution, over a broad energy range (>80 MeV)-bridging a critical gap between space-based and ground-based measurements. We present high-energy SEP data from PAMELA acquired during the 2012 May 17 SEP event. These data exhibit differential anisotropies and thus transport features over the instrument rigidity range. SEP protons exhibit two distinct pitch angle distributions: a low-energy population that extends to 90 degrees and a population that is beamed at high energies (>1 GeV), consistent with neutron monitor measurements. To explain a low-energy SEP population that exhibits significant scattering or redistribution accompanied by a high-energy population that reaches the Earth relatively unaffected by dispersive transport effects, we postulate that the scattering or redistribution takes place locally. We believe that these are the first comprehensive measurements of the effects of solar energetic particle transport in the Earth's magnetosheath.
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4.
  • Adriani, O., et al. (författare)
  • Time Dependence of the Electron and Positron Components of the Cosmic Radiation Measured by the PAMELA Experiment between July 2006 and December 2015
  • 2016
  • Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 116:24
  • Tidskriftsartikel (refereegranskat)abstract
    • 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) until 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.
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5.
  • Bruno, A., et al. (författare)
  • Geomagnetically trapped, albedo and solar energetic particles : Trajectory analysis and flux reconstruction with PAMELA
  • 2017
  • Ingår i: Advances in Space Research. - : Elsevier. - 0273-1177 .- 1879-1948. ; 60:4, s. 788-795
  • Tidskriftsartikel (refereegranskat)abstract
    • 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.
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6.
  • Bruno, A., et al. (författare)
  • Solar energetic particle events : Trajectory analysis and flux reconstruction with PAMELA
  • 2015
  • Ingår i: Proceedings of Science. - : Proceedings of science.
  • Konferensbidrag (refereegranskat)abstract
    • 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.
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7.
  • Martucci, M., et al. (författare)
  • Magnetospheric effects on high-energy solar particles during the 2012 May 17th event measured with the PAMELA experiment
  • 2015
  • Ingår i: Proceedings of Science. - : Proceedings of Science (PoS).
  • Konferensbidrag (refereegranskat)abstract
    • The great challenge in constraining scenarios for solar energetic particle (SEP) acceleration is due to the fact that the signatures of acceleration itself are heavily modified by transport within interplanetary space. During transport, SEPs are subject to pitch angle scattering by the turbulent magnetic field, adiabatic focusing, or reflecting magnetic structures. Ground Level Enhancements (GLEs) provide an ideal way to study acceleration with minimal transport. In this work, we present a unique high-energy SEP observation from PAMELA of the 2012 May 17 GLE and interpret the observed pitch angle distributions as a result of local scattering (1 AU) by the Earth's magnetosheath.
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8.
  • Martucci, M., et al. (författare)
  • Proton Fluxes Measured by the PAMELA Experiment from the Minimum to the Maximum Solar Activity for Solar Cycle 24
  • 2018
  • Ingår i: Astrophysical Journal Letters. - : Institute of Physics Publishing (IOPP). - 2041-8205 .- 2041-8213. ; 854:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Precise measurements of the time-dependent intensity of the low-energy (<50 GeV) galactic cosmic rays (GCRs) are fundamental to test and improve the models that describe their propagation inside the heliosphere. In particular, data spanning different solar activity periods, i.e., from minimum to maximum, are needed to achieve comprehensive understanding of such physical phenomena. The minimum phase between solar cycles 23 and 24 was peculiarly long, extending up to the beginning of 2010 and followed by the maximum phase, reached during early 2014. In this Letter, we present proton differential spectra measured from 2010 January to 2014 February by the PAMELA experiment. For the first time the GCR proton intensity was studied over a wide energy range (0.08-50 GeV) by a single apparatus from a minimum to a maximum period of solar activity. The large statistics allowed the time variation to be investigated on a nearly monthly basis. Data were compared and interpreted in the context of a state-of-the-art three-dimensional model describing the GCRs propagation through the heliosphere.
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9.
  • Mayorov, A. G., et al. (författare)
  • Solar modulation of galactic cosmic rays during 2006-2015 based on PAMELA and ARINA data
  • 2017
  • Ingår i: International Conference On Particle Physics And Astrophysics. - : Institute of Physics Publishing (IOPP).
  • Konferensbidrag (refereegranskat)abstract
    • Solar modulation of galactic protons with energies from 50 MeV up to dozens of GeV during July '06 - January '16 studied based on a data of the magnetic spectrometer PAMELA and scintillation spectrometer ARINA. This period is interesting because it covers the end of 23(rd) and current 24(th) cycles of solar activity, including the abnormally long transient period and change of the polarity of solar magnetic field.
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10.
  • Menn, W., et al. (författare)
  • Lithium and beryllium isotopes in the pamela-experiment
  • 2015
  • Ingår i: Proceedings of Science. - : Proceedings of Science (PoS).
  • Konferensbidrag (refereegranskat)abstract
    • On the 15th of June 2006, the PAMELA satellite-borne experiment was launched from the Baikonur cosmodrome and it has been collecting data since July 2006. The apparatus comprises a time-of-flight system, a silicon-microstrip magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anti-coincidence system, a shower tail counter scintillator and a neutron detector. The scientific objectives addressed by the mission are the measurement of the antiprotons and positrons spectra in cosmic rays, the hunt for antinuclei as well as the determination of light nuclei fluxes from hydrogen to oxygen in a wide energy range and with very high statistics. In this paper the identification capability for lithium and beryllium isotopes for two different techniques are presented, combining the rigidity measurement from the magnetic spectrometer with the velocity information derived either with the time-of-flight or with multiple dE/dx measurements in the calorimeter. Preliminary results of the isotopic ratios will be presented.
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  • Resultat 1-10 av 58

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