1. |
- Schael, S., et al.
(author)
-
Electroweak measurements in electron positron collisions at W-boson-pair energies at LEP
- 2013
-
In: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 532:4, s. 119-244
-
Research review (peer-reviewed)abstract
- Electroweak measurements performed with data taken at the electron positron collider LEP at CERN from 1995 to 2000 are reported. The combined data set considered in this report corresponds to a total luminosity of about 3 fb(-1) collected by the four LEP experiments ALEPH, DELPHI, 13 and OPAL, at centre-of-mass energies ranging from 130 GeV to 209 GeV. Combining the published results of the four LEP experiments, the measurements include total and differential cross-sections in photon-pair, fermion-pair and four-fermion production, the latter resulting from both double-resonant WW and ZZ production as well as singly resonant production. Total and differential cross-sections are measured precisely, providing a stringent test of the Standard Model at centre-of-mass energies never explored before in electron positron collisions. Final-state interaction effects in four-fermion production, such as those arising from colour reconnection and Bose Einstein correlations between the two W decay systems arising in WW production, are searched for and upper limits on the strength of possible effects are obtained. The data are used to determine fundamental properties of the W boson and the electroweak theory. Among others, the mass and width of the W boson, m(w) and Gamma(w), the branching fraction of W decays to hadrons, B(W -> had), and the trilinear gauge-boson self-couplings g(1)(Z), K-gamma and lambda(gamma), are determined to be: m(w) = 80.376 +/- 0.033 GeV Gamma(w) = 2.195 +/- 0.083 GeV B(W -> had) = 67.41 +/- 0.27% g(1)(Z) = 0.984(-0.020)(+0.018) K-gamma - 0.982 +/- 0.042 lambda(gamma) = 0.022 +/- 0.019. (C) 2013 Elsevier B.V. All rights reserved.
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2. |
- Schael, S, et al.
(author)
-
Precision electroweak measurements on the Z resonance
- 2006
-
In: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
-
Research review (peer-reviewed)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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3. |
- Adriani, O., et al.
(author)
-
Measurements of quasi-trapped electron and positron fluxes with PAMELA
- 2009
-
In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 114, s. A12218-
-
Journal article (peer-reviewed)abstract
- This paper presents precise measurements of the differential energy spectra of quasi-trapped secondary electrons and positrons and their ratio between 80 MeV and 10 GeV in the near-equatorial region (altitudes between 350 km and 600 km). Latitudinal dependences of the spectra are analyzed in detail. The results were obtained from July until November 2006 onboard the Resurs-DK satellite by the PAMELA spectrometer, a general purpose cosmic ray detector system built around a permanent magnet spectrometer and a silicon-tungsten calorimeter.
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4. |
- Adriani, O., et al.
(author)
-
Time Dependence Of The Proton Flux Measured By Pamela During The 2006 July-2009 December Solar Minimum
- 2013
-
In: Astrophysical Journal. - : IOP Publishing. - 0004-637X .- 1538-4357. ; 765:2, s. 91-
-
Journal article (peer-reviewed)abstract
- 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.
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5. |
- Mayorov, A. G., et al.
(author)
-
Antiprotons of galactic cosmic radiation in the PAMELA experiment
- 2013
-
In: Bulletin of the Russian Academy of Sciences: Physics. - 1062-8738. ; 77:5, s. 602-605
-
Journal article (peer-reviewed)abstract
- A method for antiproton selection against a background of electrons, based on a mathematical model of data classification using variations in interparticle interaction in a calorimeter, and a method for excluding events accompanied by scattering in the inner detectors of a tracking system (which result in errors in the measured trajectory's curvature and charge sign) from analysis are discussed in this paper. Antiproton spectra and antiproton/proton flux ratio at energies of 0.06 to 350 GeV with statistics of events surpassing those in [1] are obtained. The results can be used to create models for the generation and distribution of particles in the Galaxy, and for searching and studying the nature of hypothetical dark matter particles.
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6. |
- Mikhailov, V., et al.
(author)
-
Cosmic ray electron and positron spectra measured with PAMELA
- 2013
-
In: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 409:1, s. 012035-
-
Journal article (peer-reviewed)abstract
- The PAMELA experiment is carried out on board of the satellite Resurs DK1 launched on June 15th 2006 on polar orbit (the inclination is 70, the altitude is 350-600 km). The instrument which consists of magnetic spectrometer, silicon-tungsten imaging electromagnetic calorimeter gives a possibility to measure electron and positron fluxes over wide energy range from hundreds MeVs to hundreds GeVs. Measurements made in June 2006- January 2010 are presented and compared with other results and models. Positron spectrum appears to be harder than standard diffusive propagation models predict.
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7. |
- Munini, R., et al.
(author)
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Evidence of Energy and Charge Sign Dependence of the Recovery Time for the 2006 December Forbush Event Measured by the PAMELA Experiment
- 2018
-
In: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 853:1
-
Journal article (peer-reviewed)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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8. |
- Munini, R., et al.
(author)
-
Short-term variation in the galactic cosmic ray intensity measured with the PAMELA experiment
- 2017
-
In: Proceedings of Science. - : Sissa Medialab Srl.
-
Conference paper (peer-reviewed)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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9. |
- Adriani, O., et al.
(author)
-
Cosmic-Ray Electron Flux Measured by the PAMELA Experiment between 1 and 625 GeV
- 2011
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 106:20, s. 201101-
-
Journal article (peer-reviewed)abstract
- 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 (> 30 GeV). 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.
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10. |
- Adriani, O., et al.
(author)
-
Cosmic-Ray Positron Energy Spectrum Measured by PAMELA
- 2013
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 111:8, s. 081102-
-
Journal article (peer-reviewed)abstract
- 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.
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11. |
- Adriani, O., et al.
(author)
-
Measurement of the flux of primary cosmic ray antiprotons with energies of 60 MeV to 350 GeV in the PAMELA experiment
- 2013
-
In: JETP Letters. - 0021-3640 .- 1090-6487. ; 96:10, s. 621-627
-
Journal article (peer-reviewed)abstract
- It is interesting to measure the antiproton galactic component in cosmic rays in order to study the mechanisms by which particles and antiparticles are generated and propagate in the Galaxy and to search for new sources of, e.g., annihilation or decay of dark matter hypothetical particles. The antiproton spectrum and the ratio of the fluxes of primary cosmic ray antiprotons to protons with energies of 60 MeV to 350 GeV found from the data obtained from June 2006 to January 2010 in the PAMELA experiment are presented. The usage of the advanced data processing method based on the data classification mathematical model made it possible to increase statistics and analyze the region of higher energies than in the earlier works.
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12. |
- Adriani, O., et al.
(author)
-
Measurement of the isotopic composition of hydrogen and helium nuclei in cosmic rays with the PAMELA experiment
- 2013
-
In: Astrophysical Journal. - : IOP Publishing. - 0004-637X .- 1538-4357. ; 770:1, s. 2-
-
Journal article (peer-reviewed)abstract
- The satellite-borne experiment PAMELA has been used to make new measurements of cosmic ray H and He isotopes. The isotopic composition was measured between 100 and 600 MeV /n for hydrogen and between 100 and 900 MeV /n for helium isotopes over the 23rd solar minimum from 2006 July to 2007 December. The energy spectrum of these components carries fundamental information regarding the propagation of cosmic rays in the galaxy which are competitive with those obtained from other secondary to primary measurements such as B/C.
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13. |
- Adriani, O., et al.
(author)
-
Pamela's measurements of magnetospheric effects on high-energy solar particles
- 2015
-
In: Astrophysical Journal Letters. - 2041-8205 .- 2041-8213. ; 801:1
-
Journal article (peer-reviewed)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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14. |
- Adriani, O., et al.
(author)
-
The gamma-400 space observatory : Status and perspectives
- 2014
-
In: Proceedings of Science. - : Sissa Medialab Srl.
-
Conference paper (peer-reviewed)abstract
- The present design of the new space observatory GAMMA-400 is presented in this paper. The instrument has been designed for the optimal detection of gamma rays in a broad energy range (from ∼100 MeV up to 3 TeV), with excellent angular and energy resolution. The observatory will also allow precise and high statistic studies of the electron component in the cosmic rays up to the multi TeV region, as well as protons and nuclei spectra up to the knee region. The GAMMA-400 observatory will allow to address a broad range of science topics, like search for signatures of dark matter, studies of Galactic and extragalactic gamma-ray sources, Galactic and extragalactic diffuse emission, gamma-ray bursts and charged cosmic rays acceleration and diffusion mechanism up to the knee.
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15. |
- Adriani, O., et al.
(author)
-
Time Dependence of the Electron and Positron Components of the Cosmic Radiation Measured by the PAMELA Experiment between July 2006 and December 2015
- 2016
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 116:24
-
Journal article (peer-reviewed)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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16. |
- Bazilevskaya, G. A., et al.
(author)
-
Solar proton events at the end of the 23rd and start of the 24th solar cycle recorded in the PAMELA experiment
- 2013
-
In: Bulletin of the Russian Academy of Sciences: Physics. - 1062-8738. ; 77:5, s. 493-496
-
Journal article (peer-reviewed)abstract
- The PAMELA magnetic spectrometer was launched into a near-Earth orbit on board the Resurs-DK1 satellite in June 2006; in December 2006, it recorded the last strong solar high-energy particle event of the 23rd solar cycle. A deficit was thereafter observed in solar energetic particle events because of the lengthy solar activity minimum and the weak evolution of the next (24th) solar cycle. As a result, only a few solar events involving protons with energies of more than 100 MeV were recorded between 2010 and 1012. This work presents the preliminary results from measurements of charged particle fluxes in these events, recorded by the Pamela spectrometer.
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17. |
- Bruno, A., et al.
(author)
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Geomagnetically trapped, albedo and solar energetic particles : Trajectory analysis and flux reconstruction with PAMELA
- 2017
-
In: Advances in Space Research. - : Elsevier. - 0273-1177 .- 1879-1948. ; 60:4, s. 788-795
-
Journal article (peer-reviewed)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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18. |
- Bruno, A., et al.
(author)
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Solar energetic particle events : Trajectory analysis and flux reconstruction with PAMELA
- 2015
-
In: Proceedings of Science. - : Proceedings of science.
-
Conference paper (peer-reviewed)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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19. |
- Di Felice, V., et al.
(author)
-
Solar modulation of galactic hydrogen and helium over the 23rd solar minimum with the PAMELA experiment
- 2013
-
In: Proceedings of the 33rd International Cosmic Rays Conference, ICRC 2013. - : Sociedade Brasileira de Fisica. - 9788589064293
-
Conference paper (peer-reviewed)abstract
- PAMELA has been orbiting the Earth for more than six years, gathering data on solar, galactic and trapped cosmic rays during the time of the last solar minimum. The apparatus comprises a time-of-flight system, a silicon-microstrip magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail catcher scintillator and a neutron detector. The combination of these devices allows charged particle and antiparticle identification over a wide energy range and with an unprecedented precision. The quasi-polar orbit of the instrument, with an inclination of 70 degrees, makes it possible to measure low energy particles starting from about 100 MeV/n. In this work we present the time and rigidity dependence of the galactic proton and helium fluxes over the first 4 years of operation during the A < 0 solar minimum of solar cycle 23.
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20. |
- Koldobskiy, S. A., et al.
(author)
-
Galactic deuteron spectrum measured in PAMELA experiment
- 2013
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In: 23Rd European Cosmic Ray Symposium (And 32Nd Russian Cosmic Ray Conference). - : IOP Publishing.
-
Conference paper (peer-reviewed)abstract
- Results of galactic deuteron spectrum measurement by means of PAMELA apparatus are described. PAMELA is an international experiment developed for antimatter search and measurement of p, He, electron and positron spectra in wide energy range. In addition, PAMELA allows to identify and measure deuteron spectrum at low energies. In this paper deuteron-to-proton ratio and deuteron spectrum are presented.
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21. |
- Koldobskiy, S. A., et al.
(author)
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Measurement of galactic cosmic-ray deuteron spectrum in the PAMELA experiment
- 2013
-
In: Bulletin of the Russian Academy of Sciences: Physics. - : Allerton Press. - 1062-8738. ; 77:5, s. 606-608
-
Journal article (peer-reviewed)abstract
- This work presents the results of measuring the deuteron spectrum of Galactic cosmic rays (GCRs) with the PAMELA experiment. The PAMELA is an international experiment. Its main objectives are to search for antimatter and measure proton, helium nuclei, electron, and positron spectra over a wide range of energies. In addition, the experimental setup allows the detection of deuterons and the reconstruction of their spectra at low energies. Cosmic ray deuteron spectrum and the deuteron-proton ratio measured in the PAMELA experiment in the energy range of 50-650 MeV/nucleon are presented below.
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22. |
- Leonov, A. A., et al.
(author)
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Separation of electrons and protons in the GAMMA-400 gamma-ray telescope
- 2015
-
In: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 56:7, s. 1538-1545
-
Journal article (peer-reviewed)abstract
- The GAMMA-400 telescope will measure the fluxes of gamma rays and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV. These measurements will allow it to achieve the following scientific objectives: search for signatures of dark matter, investigation of gamma-ray point-like and extended sources, study of the energy spectrum of the Galactic and extragalactic diffuse emission, study of gamma-ray bursts and gamma-ray emission from the active Sun, together with high-precision measurements of the high-energy electrons and positrons spectra, protons and nuclei up to the knee. The bulk of cosmic rays are protons and helium nuclei, whereas the lepton component in the total flux is similar to 10(-3) at high energy. In the present paper, the simulated capability of the GAMMA-400 telescope to distinguish electrons and positrons from protons in cosmic rays is addressed. The individual contribution to the proton rejection from each detector system of GAMMA-400 is studied separately. The use of the combined information from all detectors allows us to reach a proton rejection of the order of similar to 4 x 10(5) for vertical incident particles and similar to 3 x 10(5) for particles with initial inclination of 30 degrees in the electron energy range from 50 GeV to 1 TeV. (C) 2015 COSPAR.
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23. |
- Leonov, A. A., et al.
(author)
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The GAMMA-400 gamma-ray telescope characteristics. Angular resolution and electrons/protons separation
- 2014
-
In: Proceedings of Science. - : Sissa Medialab Srl.
-
Conference paper (peer-reviewed)abstract
- The measurements of gamma-ray fluxes and cosmic-ray electrons and positrons in the energy range from 100 MeV to several TeV, which will be realized by the specially designed GAMMA-400 gamma-ray telescope, concern with the following broad range of scientific topics. Search for signatures of dark matter, surveying the celestial sphere in order to study point and extended sources of gamma-rays, measuring the energy spectra of Galactic and extragalactic diffuse gamma-ray emission, study of gamma-ray bursts and gamma-ray emission from the Sun, as well as high precision measurements of spectra of high-energy electrons and positrons, protons and nuclei up to the knee. To clarify these scientific problems with the new experimental data the GAMMA-400 gamma-ray telescope possesses unique physical characteristics comparing with previous and present experiments. For gamma-ray energies more than 100 GeV GAMMA-400 provides the energy resolution ~1% and angular resolution better than 0.02 deg. The methods, developed to reconstruct the direction of incident gamma photon, are presented in this paper, as well as, the capability of the GAMMA-400 gamma-ray telescope to distinguish electrons and positrons from protons in cosmic rays is investigated. The first point concerns with the space topology of high-energy gamma photon interaction in the matter of GAMMA-400. Multiple secondary particles, generated inside gamma-ray telescope, produce significant problems to restore the direction of initial gamma photon. Also back-splash particles, i.e., charged particles and gamma photons generated in calorimeter and moved upward, mask the initial tracks of electron/positron pair from conversion of incident gamma photon. The processed methods allow us to reconstruct the direction of electromagnetic shower axis and extract the electron/positron trace. As a result, the direction of incident gamma photon with the energy of 100 GeV is calculated with an accuracy of better than 0.02 deg. The main components of cosmic rays are protons and helium nuclei, whereas the part of lepton component in the total flux is ~10 -3 for high energies. The separate contribution in proton rejection is studied for each detector system of the GAMMA-400 gamma-ray telescope. Using combined information from all detector systems allow us to provide the rejection from protons with a factor of ~4 10 5 for vertical incident particles and ~3 10 5 for particle with initial inclination of 30 deg. Science with the New Generation of High Energy Gamma-ray experiments, 10th Workshop (Scineghe2014) 04-06 June 2014 Lisbon - Portugal.
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24. |
- Martucci, M., et al.
(author)
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Magnetospheric effects on high-energy solar particles during the 2012 May 17th event measured with the PAMELA experiment
- 2015
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In: Proceedings of Science. - : Proceedings of Science (PoS).
-
Conference paper (peer-reviewed)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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25. |
- Martucci, M., et al.
(author)
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Proton Fluxes Measured by the PAMELA Experiment from the Minimum to the Maximum Solar Activity for Solar Cycle 24
- 2018
-
In: Astrophysical Journal Letters. - : Institute of Physics Publishing (IOPP). - 2041-8205 .- 2041-8213. ; 854:1
-
Journal article (peer-reviewed)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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26. |
- Mayorov, A. G., et al.
(author)
-
Solar modulation of galactic cosmic rays during 2006-2015 based on PAMELA and ARINA data
- 2017
-
In: International Conference On Particle Physics And Astrophysics. - : Institute of Physics Publishing (IOPP).
-
Conference paper (peer-reviewed)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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27. |
- Menn, W., et al.
(author)
-
Lithium and beryllium isotopes in the pamela-experiment
- 2015
-
In: Proceedings of Science. - : Proceedings of Science (PoS).
-
Conference paper (peer-reviewed)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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28. |
- Menn, W., et al.
(author)
-
Measurement of the isotopic composition of hydrogen and helium nuclei in cosmic rays with the pamela-experiment
- 2015
-
In: Proceedings of Science. - : Proceedings of Science (PoS).
-
Conference paper (peer-reviewed)abstract
- The cosmic-ray hydrogen and helium (1H,2H,3He,4He) isotopic composition between 100 MeV/n and 1.4 GeV/n has been measured with the satellite-borne experiment PAMELA, which was launched into low-Earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. The rare isotopes 2H and 3He in cosmic rays are believed to originate mainly from the interaction of high energy protons and helium with the galactic interstellar medium. The energy spectrum of these components carries fundamental information regarding the propagation of cosmic rays in the galaxy which are competitive with those obtained from other secondary to primary measurements such as B/C. The isotopic composition was measured between 100 and 1100 MeV/n for hydrogen and between 100 and 1400 MeV/n for helium isotopes using two different detector systems over the 23rd solar minimum from July 2006 to December 2007.
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29. |
- Menn, W., et al.
(author)
-
The PAMELA space experiment
- 2013
-
In: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 51:2, s. 209-218
-
Journal article (peer-reviewed)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 is comprised of a time-of-flight system, a silicon-microstrip magnetic spectrometer, a silicon-tungsten electromagnetic calorimeter, an anticoincidence system, a shower tail counter scintillator and a neutron detector. The combination of these devices allows precision studies of the charged cosmic radiation to be conducted over a wide energy range (100 MeV to 100's GeV) with high statistics. The primary scientific goal is the measurement of the antiproton and positron energy spectra in order to search for exotic sources, such as dark matter particle annihilations. PAMELA is also searching for primordial antinuclei (anti-helium), and testing cosmic-ray propagation models through precise measurements of the antiparticle energy spectrum and precision studies of light nuclei and their isotopes. Moreover, PAMELA is investigating phenomena connected with solar and earth physics. After 4 years of operation in flight, PAMELA is now delivering coherent results about spectra and chemical composition of the charged cosmic radiation, allowing scenarios of production and propagation of cosmic rays to be fully established and understood.
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30. |
- Mikhailov, V. V., et al.
(author)
-
Sharp increasing of positron to electron fluxes ratio below 2 GV measured by the PAMELA
- 2017
-
In: Journal of Physics, Conference Series. - : Institute of Physics Publishing (IOPP). - 1742-6588 .- 1742-6596. ; 798:1
-
Journal article (peer-reviewed)abstract
- Magnetic spectrometer PAMELA was launched onboard a satellite Resurs-DK1 into low-Earth polar orbit with altitude 350-600 km to study cosmic ray antiparticle fluxes in a wide energy range from ∼ 100 MeV to hundreds GeV. This paper presents the results of observations of temporal variations of the positron and electron fluxes in the 2006-2015. The ratio of the positron and electron fluxes below 2 GV shows sharp increasing since 2014 due to changing of the polarity of the solar magnetic field.
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31. |
- Munini, R., et al.
(author)
-
Solar modulation of galactic cosmic ray electrons and positrons over the 23rd solar minimum with the PAMELA experiment
- 2015
-
In: Proceedings of Science. - : Proceedings of Science (PoS).
-
Conference paper (peer-reviewed)abstract
- The satellite-borne PAMELA experiment has been continuously collecting data since 15th June 2006, when it was launched from the Baikonur cosmodrome to detect the charged component of cosmic rays over a wide energy range and with unprecedented statistics. The apparatus design is particularly suited for particle and antiparticle identification. The PAMELA experiment has measured the time variation of electron and positron spectrum at Earth in great detail, extending the measurement down to 70 MeV and 200 MeV respectively. The spectra have been evaluated with data collected from July 2006 to December 2009, i.e. during the A<0 solar minimum of solar cycle 23, over six-months intervals. These spectra provide important information for the study of CR propagation inside the heliosphere and the investigation of the charge-dependent solar modulation.
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32. |
- Munini, R., et al.
(author)
-
Solar modulation of galactic cosmic rays electrons and positrons over the 23rd solar minimum with the pamela experiment
- 2013
-
In: Proceedings of the 33rd International Cosmic Rays Conference, ICRC 2013. - : Sociedade Brasileira de Fisica. - 9788589064293
-
Conference paper (peer-reviewed)abstract
- The satellite-borne PAMELA experiment has been continuously collecting data since 15th June 2006, when it was launched from the Baikonur cosmodrome to detect the charged component of cosmic rays over a wide energy range and with an unprecedented statistics. The apparatus design is particularly suited for particle and antiparticle identification. The satellite quasi-polar orbit, with an inclination of 70 degrees, allows particles to be measure down to 100 MeV/n. This makes the instrument suited for the investigation of phenomena related to galactic cosmic ray solar modulation in the inner heliosphere. Data for oppositely charged particles were collected from 2006 to 2009, during the A< 0 solar minimum of solar cycle 23. The time and rigidity dependence of galactic cosmic ray electron and positron fluxes were measured. These fluxes provide important information for the study of charge dependent solar modulation effects.
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33. |
- Munini, R., et al.
(author)
-
Solar modulation of GCR electrons over the 23rd solar minimum with PAMELA
- 2015
-
In: 24TH EUROPEAN COSMIC RAY SYMPOSIUM (ECRS). - : IOP Publishing.
-
Conference paper (peer-reviewed)abstract
- The satellite-borne PAMELA experiment has been continuously collecting data since 15th June 2006, when it was launched from the Baikonur cosmodrome to detect the charged component of cosmic rays over a wide energy range and with unprecedented statistics. The apparatus design is particularly suited for particle and antiparticle identification. The PAMELA experiment has measured the electron spectrum at Earth in great detail, extending up to about 100 GeV and down to about 200 MeV. The galactic cosmic ray electron spectra for 2007 and 2009, i.e. measured during the A<0 solar minimum of solar cycle 23, are presented. These fluxes provide important information for the study of charge dependent solar modulation effects.
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34. |
- Munini, R., et al.
(author)
-
Ten years of positron and electron solar modulation measured by the PAMELA experiment
- 2017
-
In: Proceedings of Science. - : Sissa Medialab Srl.
-
Conference paper (peer-reviewed)abstract
- The satellite-borne PAMELA experiment was launched on the 15th June 2006 from the Baikonur cosmodrome. Till January 2016 PAMELA has detected the charged component of cosmic-rays (CRs) over a wide energy range. Due to its long flight duration PAMELA represents an ideal detector for cosmic-ray solar modulation studies. Moreover, the capability to measure particles of the same mass with opposite charge allows to investigate the charge-sign dependent solar modulation. The results on the positron and electron intensity variation at Earth over the 23rd solar minimum (July 2006 - January 2009) till the middle of the 24rd solar maximum (December 2015), will be presented. The positron to electron ratio shows a clear time variation interpreted as solar modulation sign-charge dependence introduced by particle drifts. The effect of the polarity reversal of the heliospheric magnetic field, which took place between 2013 and 2014, is also distinctly visible from the PAMELA data. These results provide the first clear indication of how drift effects unfold with time during different phases of the solar activity and their dependence on the particle rigidity and the cyclic polarity of the solar magnetic field.
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35. |
- Papini, P., et al.
(author)
-
Latest results from PAMELA
- 2009
-
Conference paper (peer-reviewed)abstract
- The PAMELA experiment is a satellite-borne apparatus designed to study charged particles in the cosmic radiation, with a particular focus on antiparticles. The detector is housed on the Resurs-DK1 satellite and it is taking data since June 2006. The main parts of the apparatus are a magnetic spectrometer, which is equipped with a silicon-microstrip tracking system and which is used to measure the rigidity and the charge of particles, and a silicon/tungsten electromagnetic calorimeter which provides particle identification. The main results about the antiparticles component of cosmic rays obtained during the first 500 days of data taking are summarized here.
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36. |
- Topchiev, N. P., et al.
(author)
-
The GAMMA-400 experiment : Status and prospects
- 2015
-
In: Bulletin of the Russian Academy of Sciences: Physics. - 1062-8738. ; 79:3, s. 417-420
-
Journal article (peer-reviewed)abstract
- The development of the GAMMA-400 γ-ray telescope continues. The GAMMA-400 is designed to measure fluxes of γ-rays and the electron-positron cosmic-ray component possibly associated with annihilation or decay of dark matter particles; and to search for and study in detail discrete γ-ray sources, to measure the energy spectra of Galactic and extragalactic diffuse γ-rays, and to study γ-ray bursts and γ-rays from the active Sun. The energy range for measuring γ-rays and electrons (positrons) is from 100 MeV to 3000 GeV. For 100-GeV γ-rays, the γ-ray telescope has an angular resolution of ∼0.01°, an energy resolution of ∼1%, and a proton rejection factor of ∼5 × 105. The GAMMA-400 will be installed onboard the Russian Space Observatory.
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37. |
- Vannuccini, E., et al.
(author)
-
Measurement of Lithium and Beryllium cosmic-ray abundances by the PAMELA experiment
- 2015
-
In: Proceedings of Science. - : Proceedings of Science (PoS).
-
Conference paper (peer-reviewed)abstract
- The PAMELA experiment is collecting particles along a low Earth semi-polar orbit on board of Resurs-DK1 satellite since June 2006. The combined information of a silicon tracking system and a scintillator hodoscope provides redundant light-element identification capabilities, via multiple ionization energy-loss measurements. The instrument design is not optimized for nuclei detection, whose high ionization signal progressively saturates the detectors. However, Li and Be nuclei can still be identified by using the full set of information, which allows to efficiently select the two elements against the background of more abundant elements. The main issues of the analysis aiming to optimize the Li and Be selection are discussed in this paper. Preliminary results on the elemental abundances will be presented at the conference.
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38. |
- Zhang, S. -N, et al.
(author)
-
Introduction to the high energy cosmic-radiation detection (HERD) facility onboard China's future space station
- 2017
-
In: Proceedings of Science. - : Sissa Medialab Srl.
-
Conference paper (peer-reviewed)abstract
- The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads onboard China's Space Station, which is planned for operation starting around 2025 for about 10 years. The main scientific objectives of HERD are searching for signals of dark matter annihilation products, precise cosmic electron (plus positron) spectrum and anisotropy measurements up to 10 TeV, precise cosmic ray spectrum and composition measurements up to the knee energy, and high energy gamma-ray monitoring and survey. HERD is composed of a 3-D cubic calorimeter (CALO) surrounded by microstrip silicon trackers (STKs) from five sides except the bottom. CALO is made of about 7,500 cubes of LYSO crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction lengths, respectively. The top STK microstrips of six X-Y layers are sandwiched with tungsten converters to make precise directional measurements of incoming electrons and gamma-rays. In the baseline design, each of the four side STKs is made of only three layers microstrips. All STKs will also be used for measuring the charge and incoming directions of cosmic rays, as well as identifying back scattered tracks. With this design, HERD can achieve the following performance: energy resolution of 1% for electrons and gamma-rays beyond 100 GeV and 20% for protons from 100 GeV to 1 PeV; electron/proton separation power better than 10-5; effective geometrical factors of >3 m2sr for electron and diffuse gamma-rays, >2 m2sr for cosmic ray nuclei. R&D is under way for reading out the LYSO signals with optical fiber coupled to image intensified IsCMOS and CALO prototype of 250 LYSO crystals.
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39. |
- Adriani, O., et al.
(author)
-
A statistical procedure for the identification of positrons in the PAMELA experiment
- 2010
-
In: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 34:1, s. 1-11
-
Journal article (peer-reviewed)abstract
- The PAMELA satellite experiment has measured the cosmic-ray positron fraction between 1.5 GeV and 100 GeV. The need to reliably discriminate between the positron signal and proton background has required the development of an ad hoc analysis procedure. In this paper, a method for positron identification is described and its stability and capability to yield a correct background estimate is shown. The analysis includes new experimental data, the application of three different fitting techniques for the background sample and an estimate of systematic uncertainties due to possible inaccuracies in the background selection. The new experimental results confirm both solar modulation effects on cosmic-rays with low rigidities and an anomalous positron abundance above 10 GeV. (c) 2010 Elsevier B.V. All rights reserved.
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40. |
- Adriani, O., et al.
(author)
-
Antiprotons in primary cosmic radiation with PAMELA experiment
- 2013
-
In: Proceedings of the 33rd International Cosmic Rays Conference, ICRC 2013. - : Sociedade Brasileira de Fisica. - 9788589064293
-
Conference paper (peer-reviewed)abstract
- The latest measurements of antiprotons spectrum and antiproton-to-proton ratio in primary cosmic rays with PAMELA experiment are presented. They are in good agreement with model of secondary production of antiprotons in Galaxy, but they do not completely rule other sources at the high-energies.
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41. |
- Adriani, O., et al.
(author)
-
Latest results from the Pamela experiment
- 2009
-
In: Proceedings of Science. ; , s. 1-6
-
Conference paper (peer-reviewed)abstract
- In this paper we present the latest results of the Pamela satellite experiment, focusing in particular on the p̄/p and the e +/(e+ +e-) ratios.
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42. |
- Adriani, O., et al.
(author)
-
Measurement of Boron and Carbon Fluxes in Cosmic Rays with the Pamela Experiment
- 2014
-
In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 791:2, s. 93-
-
Journal article (peer-reviewed)abstract
- The propagation of cosmic rays inside our galaxy plays a fundamental role in shaping their injection spectra into those observed at Earth. One of the best tools to investigate this issue is the ratio of fluxes for secondary and primary species. The boron-to-carbon (B/C) ratio, in particular, is a sensitive probe to investigate propagation mechanisms. This paper presents new measurements of the absolute fluxes of boron and carbon nuclei as well as the B/C ratio from the PAMELA space experiment. The results span the range 0.44-129 GeV/n in kinetic energy for data taken in the period 2006 July to 2008 March.
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43. |
- Adriani, O., et al.
(author)
-
MEASUREMENTS OF COSMIC-RAY HYDROGEN AND HELIUM ISOTOPES WITH THE PAMELA EXPERIMENT
- 2016
-
In: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 818:1
-
Journal article (peer-reviewed)abstract
- The cosmic-ray hydrogen and helium (H-1, H-2, He-3, He-4) isotopic composition has been measured with the satellite-borne experiment PAMELA, which was launched into low-Earth orbit on board the Resurs-DK1 satellite on 2006 June 15. The rare isotopes H-2 and He-3 in cosmic rays are believed to originate mainly from the interaction of high-energy protons and helium with the galactic interstellar medium. The isotopic composition was measured between 100 and 1100 MeV/n for hydrogen and between 100 and 1400 MeV/n for helium isotopes using two different detector systems over the 23rd solar minimum from 2006 July to 2007 December.
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44. |
- Adriani, O., et al.
(author)
-
Measurements of cosmic-ray proton and helium spectra with the PAMELA calorimeter
- 2013
-
In: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 51:2, s. 219-226
-
Journal article (peer-reviewed)abstract
- We present a new measurement of the cosmic ray proton and helium spectra by the PAMELA experiment performed using the "thin" (in terms of nuclei interactions) sampling electromagnetic calorimeter. The described method, optimized by using Monte Carlo simulation, beam test and experimental data, allows the spectra to be measured up to 10 TeV, thus extending the PAMELA observational range based on the magnetic spectrometer measurement.
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45. |
- Adriani, O., et al.
(author)
-
OBSERVATIONS OF THE 2006 DECEMBER 13 AND 14 SOLAR PARTICLE EVENTS IN THE 80 MeV n(-1)-3 GeV n(-1) RANGE FROM SPACE WITH THE PAMELA DETECTOR
- 2011
-
In: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 742:2, s. 102-
-
Journal article (peer-reviewed)abstract
- We present the space spectrometer PAMELA observations of proton and helium fluxes during the 2006 December 13 and 14 solar particle events. This is the first direct measurement of the solar energetic particles in space with a single instrument in the energy range from similar to 80 MeV n(-1) up to similar to 3 GeV n(-1). For the December 13 event, measured energy spectra of solar protons and helium are compared with results obtained by neutron monitors and other detectors. Our measurements show a spectral behavior different from those derived from the neutron monitor network. No satisfactory analytical fitting was found for the energy spectra. During the first hours of the December 13 event, solar energetic particles spectra were close to the exponential form, demonstrating rather significant temporal evolution. Solar He with energy up to 1 GeV n(-1) was recorded on December 13. For the December 14 event, energy of solar protons reached 600 MeV, whereas the maximum energy of He was below 100 MeV n(-1). The spectra were slightly bent in the lower energy range and preserved their form during the second event. Differences in the particle flux appearance and temporal evolution of these two events may argue for special conditions leading to the acceleration of solar particles up to relativistic energies.
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46. |
- Adriani, O., et al.
(author)
-
PAMELA Measurements of Cosmic-Ray Proton and Helium Spectra
- 2011
-
In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 332:6025, s. 69-72
-
Journal article (peer-reviewed)abstract
- Protons and helium nuclei are the most abundant components of the cosmic radiation. Precise measurements of their fluxes are needed to understand the acceleration and subsequent propagation of cosmic rays in our Galaxy. We report precision measurements of the proton and helium spectra in the rigidity range 1 gigavolt to 1.2 teravolts performed by the satellite-borne experiment PAMELA (payload for antimatter matter exploration and light-nuclei astrophysics). We find that the spectral shapes of these two species are different and cannot be described well by a single power law. These data challenge the current paradigm of cosmic-ray acceleration in supernova remnants followed by diffusive propagation in the Galaxy. More complex processes of acceleration and propagation of cosmic rays are required to explain the spectral structures observed in our data.
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47. |
- Adriani, O., et al.
(author)
-
PAMELA Results on the Cosmic-Ray Antiproton Flux from 60 MeV to 180 GeV in Kinetic Energy
- 2010
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 105:12, s. 121101-
-
Journal article (peer-reviewed)abstract
- The satellite-borne experiment PAMELA has been used to make a new measurement of the cosmic-ray antiproton flux and the antiproton-to-proton flux ratio which extends previously published measurements down to 60 MeV and up to 180 GeV in kinetic energy. During 850 days of data acquisition approximately 1500 antiprotons were observed. The measurements are consistent with purely secondary production of antiprotons in the Galaxy. More precise secondary production models are required for a complete interpretation of the results.
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48. |
- Adriani, O., et al.
(author)
-
Positrons and electrons in primary cosmic rays as measured in the PAMELA experiment
- 2009
-
In: Bulletin of the Russian Academy of Sciences: Physics. - 1062-8738. ; 73:5, s. 568-570
-
Journal article (peer-reviewed)abstract
- The PAMELA experiment is being carried out on board the Russian satellite Resurs DK1 placed in the near-earth near-polar orbit on June 15, 2006. The apparatus comprising a silicon-strip magnetic spectrometer and an electromagnetic calorimeter allows measurement of electron and positron fluxes in cosmic rays in a wide energy interval from ∼100 MeV to hundreds of GeV. The high-energy electron and positron separation technique is discussed and the data on positron-to-electron ratio in primary cosmic rays up to E ≃ 10 GeV from the 2006 - 2007 measurements are reported in this work.
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49. |
- Adriani, O., et al.
(author)
-
Reentrant albedo proton fluxes measured by the PAMELA experiment
- 2015
-
In: Journal of Geophysical Research - Space Physics. - 2169-9380 .- 2169-9402. ; 120:5, s. 3728-3738
-
Journal article (peer-reviewed)abstract
- We present a precise measurement of downward going albedo proton fluxes for kinetic energy above similar to 70 MeV performed by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA) experiment at an altitude between 350 and 610 km. On the basis of a trajectory tracing simulation, the analyzed protons were classified into quasi-trapped, concentrating in the magnetic equatorial region, and untrapped spreading over all latitudes, including both short-lived (precipitating) and long-lived (pseudotrapped) components. In addition, features of the penumbra region around the geomagnetic cutoff were investigated in detail. PAMELA results significantly improve the characterization of the high-energy albedo proton populations at low-Earth orbits.
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50. |
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