| 51. |
- Munini, R., et al.
(författare)
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Short-term variation in the galactic cosmic ray intensity measured with the PAMELA experiment
- 2017
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Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
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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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| 52. |
- Munini, R., et al.
(författare)
-
Ten years of positron and electron solar modulation measured by the PAMELA experiment
- 2017
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Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
-
Konferensbidrag (refereegranskat)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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| 53. |
- Panico, B., et al.
(författare)
-
Time dependence of the helium flux measured by pamela
- 2017
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Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- The last solar cycle has presented a peculiarly long quiet phase with consequent minimum modulation conditions for cosmic rays. The proton and electron spectra were measured from July 2006 to December 2009 by PAMELA experiment, providing fundamental information about the transport and modulation of cosmic rays inside the heliosphere. These studies allow to obtain a more complete description of the cosmic radiation. In this picture the time dependence of the helium spectrum become very important to constrain parameters of the actual solar modulation model. The crucial point for this analysis is the selection of a dataset of helium events which ensure high statistics with a very low contamination. In this paper the definition of the selection criteria for helium events with data taken from July 2006 to June 2014 by PAMELA experiment is reported.
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| 54. |
- Panico, B., et al.
(författare)
-
Time dependence of the proton and helium flux measured by PAMELA
- 2017
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Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
-
Konferensbidrag (refereegranskat)abstract
- The energy spectra of galactic cosmic rays carry fundamental information regarding their origin and propagation, but, near Earth, cosmic rays are significantly affected by the solar magnetic field which changes over time. The time dependence of proton and electron spectra were measured from July 2006 to December 2009 by PAMELA experiment, that is a ballooon-borne experiment collecting data since 15 June 2006. These studies allowed to obtain a more complete description of the cosmic radiation, providing fundamental information about the transport and modulation of cosmic rays inside the heliosphere. In this talk the study of the time dependence of the cosmic-ray protons and helium nuclei from the unusual 23rd solar minimum through the following period of solar maximum activity is presented.
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| 55. |
- Ricci, M., et al.
(författare)
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Effect of the Jupiter magnetosphere on the cosmic ray protons measured with the PAMELA experiment
- 2017
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Ingår i: Proceedings of Science. - : Sissa Medialab Srl.
-
Konferensbidrag (refereegranskat)abstract
- The very intense Jovian magnetic field produces a magnetosphere where high-energy charged particles are trapped, allowing the possibility for acceleration mechanism that could inject those particles in the open space. In the last decades, accelerated electrons from the Jupiter magnetosphere have been detected and studied in the interplanetary space.This work investigated whether the proton data obtained by the PAMELA space-borne detector between July 9th, 2006 to August 31th, 2014 shows signatures that arise from Jupiter. In this proceeding the basis of the analysis of cosmic ray protons by PAMELA are described and results will be shown at the conference.
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| 56. |
- Leonov, A. A., et al.
(författare)
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Separation of electrons and protons in the GAMMA-400 gamma-ray telescope
- 2015
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Ingår i: Advances in Space Research. - : Elsevier BV. - 0273-1177 .- 1879-1948. ; 56:7, s. 1538-1545
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Tidskriftsartikel (refereegranskat)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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| 57. |
- Panico, B., et al.
(författare)
-
Study on CRE arrival distributions with PAMELA experiment
- 2015
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Ingår i: Proceedings of Science. - : Proceedings of Science (PoS).
-
Konferensbidrag (refereegranskat)abstract
- From 2009, several experiments, like PAMELA, FERMI and AMS, have shown a rise in the fraction of positrons versus electrons+positrons. One of the most probable explanation is due to the presence of nearby sources, like SNRs or pulsars. PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) is a ballooon-borne experiment and is collecting data since 15 June 2006. Its quasi-polar orbit permits to perform a survey in each direction of the sky. The study of the arrival distribution of cosmic ray electrons and positrons from different regions allows the exploration of different origins for the excess.
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| 58. |
- Topchiev, N. P., et al.
(författare)
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GAMMA-400 gamma-ray observatory
- 2015
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Ingår i: Proceedings of Science. - : Proceedings of Science (PoS).
-
Konferensbidrag (refereegranskat)abstract
- The GAMMA-400 gamma-ray telescope with excellent angular and energy resolutions is designed to search for signatures of dark matter in the fluxes of gamma-ray emission and electrons+ positrons.Precision investigations of gamma-ray emission fromGalactic Center, Crab, Vela, Cygnus, Geminga, and other regions will be performed, as well asdiffuse gamma-rayemission,along with measurements of high-energy electron + positron and nuclei fluxes. Furthermore, it will studygamma-ray bursts and gamma-ray emission from the Sun during periods of solar activity. The energy range of GAMMA-400 is expected to be from ∼20 MeV up to TeV energies for gamma rays, up to 10 TeV for electrons + positrons, and up to 1015eV for cosmic-ray nuclei. For high-energy gamma rays with energy from 10 to 100 GeV, the GAMMA-400 angular resolution improves from 0.1° to ∼0.01° and energy resolution from 3% to ∼1%; the proton rejection factor is ∼5x105. GAMMA-400 will be installed onboardthe Russian space observatory.
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| 59. |
- Topchiev, N. P., et al.
(författare)
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The GAMMA-400 experiment : Status and prospects
- 2015
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Ingår i: Bulletin of the Russian Academy of Sciences: Physics. - 1062-8738. ; 79:3, s. 417-420
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Tidskriftsartikel (refereegranskat)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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