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Sesto Fiorentino, Italy
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Adriani O.,University of Florence | Adriani O.,National Institute of Nuclear Physics, Italy | Barbarino G.C.,University of Naples Federico II | Barbarino G.C.,National Institute of Nuclear Physics, Italy | And 74 more authors.
Physical Review Letters | Year: 2013

Precision measurements of the positron component in the cosmic radiation provide important information about the propagation of cosmic rays and the nature of particle sources in our Galaxy. The satellite-borne experiment PAMELA has been used to make a new measurement of the cosmic-ray positron flux and fraction that extends previously published measurements up to 300 GeV in kinetic energy. The combined measurements of the cosmic-ray positron energy spectrum and fraction provide a unique tool to constrain interpretation models. During the recent solar minimum activity period from July 2006 to December 2009, approximately 24 500 positrons were observed. The results cannot be easily reconciled with purely secondary production, and additional sources of either astrophysical or exotic origin may be required. © 2013 American Physical Society.


Adriani O.,University of Florence | Adriani O.,National Institute of Nuclear Physics, Italy | Barbarino G.C.,University of Naples Federico II | Barbarino G.C.,National Institute of Nuclear Physics, Italy | And 78 more authors.
Physics Reports | Year: 2014

On the 15th of June 2006, the PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) satellite-borne experiment was launched onboard the Russian Resurs-DK1 satellite by a Soyuz rocket from the Baikonur space centre. The satellite was placed in a quasi-polar 70°inclination orbit at an altitude varying between 350 km and 600 km.New results on the antiparticle component of the cosmic radiation were obtained. The positron energy spectrum and positron fraction were measured from 400 MeV up to 200 GeV revealing a positron excess over the predictions of commonly used propagation models. This can be interpreted either as evidence that the propagation models should be revised or in terms of dark matter annihilation or a pulsar contribution. The antiproton spectrum was measured over the energy range from 60 MeV to 350 GeV. The antiproton spectrum is consistent with secondary production and significantly constrains dark matter models.The energy spectra of protons and helium nuclei were measured up to 1.2 TV. The spectral shapes of these two species are different and cannot be described well by a single power law. For the first time the electron spectrum was measured up to 600 GeV complementing the information obtained from the positron data. Nuclear and isotopic composition was obtained with unprecedented precision.The variation of the low energy proton, electron and positron energy spectra was measured from July 2006 until December 2009 accurately sampling the unusual conditions of the most recent solar minimum activity period (2006-2009). Low energy particle spectra were accurately measured also for various solar events that occurred during the PAMELA mission.The Earth's magnetosphere was studied measuring the particle radiation in different regions of the magnetosphere. Energy spectra and composition of sub-cutoff and trapped particles were obtained. For the first time a belt of trapped antiprotons was detected in the South Atlantic Anomaly region. The flux was found to exceed that for galactic cosmic-ray antiprotons by three order of magnitude. © 2014 Elsevier B.V.


Adriani O.,University of Florence | Adriani O.,National Institute of Nuclear Physics, Italy | Barbarino G.C.,University of Naples Federico II | Barbarino G.C.,National Institute of Nuclear Physics, Italy | And 71 more authors.
Astrophysical Journal | Year: 2013

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 2006 July to 2009 December 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. © 2013. The American Astronomical Society. All rights reserved..


Mecklenburg S.,European Space Agency | Drusch M.,European Space Agency | Kaleschke L.,University of Hamburg | Rodriguez-Fernandez N.,CNRS Center for the Study of the Biosphere from Space | And 18 more authors.
Remote Sensing of Environment | Year: 2016

The Soil Moisture and Ocean Salinity (SMOS) mission, launched in November 2009, is the European Space Agency's (ESA) second Earth Explorer Opportunity mission. The scientific objectives of the SMOS mission directly respond to the need for global observations of soil moisture and ocean salinity, two key variables used in predictive hydrological, oceanographic and atmospheric models. SMOS observations also provide information on vegetation, in particular plant available water and water content in a canopy, drought index and flood risks, surface ocean winds in storms, freeze/thaw state and sea ice and its effect on ocean-atmosphere heat fluxes and dynamics affecting large-scale processes of the Earth's climate system.Significant progress has been made over the course of the now 6-year life time of the SMOS mission in improving the ESA provided level 1 brightness temperature and level 2 soil moisture and sea surface salinity data products. The main emphasis of this paper is to review the status of the mission and provide an overview and performance assessment of SMOS data products, in particular with a view towards operational applications, and using SMOS products in data assimilation.SMOS is in excellent technical condition with no limiting factors for operations beyond 2017. The instrument performance fulfils the requirements. The radio-frequency interference (RFI) contamination originates from man-made emitters on ground, operating in the protected L-band and adding signal to the natural radiation emitted by the Earth. RFI has been detected worldwide and has been significantly reduced in Europe and the Americas but remains a constraint in Asia and the Middle East. The mission's scientific objectives have been reached over land and are approaching the mission objectives over ocean.This review paper aims to provide an introduction and synthesis to the papers published in this RSE special issue on SMOS. © 2015 Elsevier Inc.


Adriani O.,University of Florence | Adriani O.,National Institute of Nuclear Physics, Italy | Barbarino G.C.,University of Naples Federico II | Barbarino G.C.,National Institute of Nuclear Physics, Italy | And 73 more authors.
Physical Review Letters | Year: 2011

Precision measurements of the electron component in the cosmic radiation provide important information about the origin and propagation of cosmic rays in the Galaxy. Here we present new results regarding negatively charged electrons between 1 and 625 GeV performed by the satellite-borne experiment PAMELA. This is the first time that cosmic-ray e- have been identified above 50 GeV. The electron spectrum can be described with a single power-law energy dependence with spectral index -3.18±0.05 above the energy region influenced by the solar wind (>30GeV). No significant spectral features are observed and the data can be interpreted in terms of conventional diffusive propagation models. However, the data are also consistent with models including new cosmic-ray sources that could explain the rise in the positron fraction. © 2011 American Physical Society.


PubMed | National Research Nuclear University MEPhI, IFAC, University of Bari, University of Florence and 8 more.
Type: Journal Article | Journal: Physical review letters | Year: 2015

In this work we present results of a direct search for strange quark matter (SQM) in cosmic rays with the PAMELA space spectrometer. If this state of matter exists it may be present in cosmic rays as particles, called strangelets, having a high density and an anomalously high mass-to-charge (A/Z) ratio. A direct search in space is complementary to those from ground-based spectrometers. Furthermore, it has the advantage of being potentially capable of directly identifying these particles, without any assumption on their interaction model with Earths atmosphere and the long-term stability in terrestrial and lunar rocks. In the rigidity range from 1.0 to 1.010^{3}GV, no such particles were found in the data collected by PAMELA between 2006 and 2009. An upper limit on the strangelet flux in cosmic rays was therefore set for particles with charge 1Z8 and mass 4A1.210^{5}. This limit as a function of mass and as a function of magnetic rigidity allows us to constrain models of SQM production and propagation in the Galaxy.

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