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.
Precision measurements of the Z = 2 component in cosmic radiation provide crucial information about the origin and propagation of the second most abundant cosmic ray species in the Galaxy (9% of the ...total). These measurements, acquired with the PAMELA space experiment orbiting Earth, allow to study solar modulation in details. Helium modulation is compared to the modulation of protons to study possible dependencies on charge and mass. The time dependence of helium fluxes on a monthly basis measured by PAMELA has been studied for the period between July 2006 to January 2016 in the energy range from 800
MeV/n
to ~ 20
GeV/n
.
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 PAMEFA. 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.
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.
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.
A 7.24 × 12.03 cm2 sensor, Silicon Drift Detector (SDD), has been developed for the enhanced X-ray Timing and Polarimetry (eXTP) mission of the Chinese Academy of Science, with a large contribution ...by a European consortium inherited from the ESA-M3 LOFT mission study. In the frame of the project X-ray Observatories (XRO), active in the National Scientific Commission 2 of the INFN, we report the details of the qualification procedure to select from the mass production the 640 sensors that will equip the Large Area Detector (the eXTP instrument dedicated to the X-ray spectroscopy in the range 2-30 keV), with energy resolution below 240 eV FWHM at 6 keV during the entire mission duration of at least 5 years. This stringent requirement dictates the need to thoroughly verify the characteristics of each single sensor before integration in the final layout. We describe the dedicated testing facilities that have been developed. We report on the detector selection criteria and test results obtained in the pre-series production.
ABSTRACT Precision measurements of the electron component of cosmic radiation provide important information about the origin and propagation of cosmic rays in the Galaxy not accessible from the study ...of cosmic-ray nuclear components due to their differing diffusion and energy-loss processes. However, when measured near Earth, the effects of propagation and modulation of Galactic cosmic rays in the heliosphere, particularly significant for energies up to at least 30 GeV, must be properly taken into account. In this paper the electron (e−) spectra measured by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics down to 70 MeV from 2006 July to 2009 December over six-month time intervals are presented. Fluxes are compared with a state-of-the-art three-dimensional model of solar modulation that reproduces the observations remarkably well.
Light flashes are unusual visual phenomena that are observed in space and are caused by the interaction of energetic cosmic-ray particles with the human visual system. Using data gathered on board ...the Mir space station during the Sileye-2 experiment, we show here that there are two separate components of cosmic rays that cause these flashes: one due to heavy nuclei and one due to protons. This indicates that perception by an astronaut's visual apparatus could involve two complementary mechanisms.
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