نتایج جستجو برای: cosmic ray meson
تعداد نتایج: 337718 فیلتر نتایج به سال:
We have developed a model which aims to reproduce observational data of many kinds related to cosmic-ray origin and propagation: direct measurements of nuclei, antiprotons, electrons and positrons, γ-rays, and synchrotron radiation. Our main results include evaluation of diffusion/convection and reacceleration models, estimates of the halo size, calculations of the interstellar positron and ant...
The ISM of active galaxy centers is exposed to a combination of cosmic ray, FUV and X-ray radiation. We apply PDR models to this ISM with both 'nor-mal' and highly elevated (5 × 10 −15 s −1) cosmic-ray rates and compare the results to those obtained for XDRs. Our existing PDR-XDR code is used to construct models over a 10 3 − 10 5 cm −3 density range and for 0.16-160 erg s −1 cm −2 im-pingent f...
The recent detection of delayed, low energy emission from Gamma-Ray Burst (GRB) sources confirmed the cosmological origin of the bursts and provided support for models where GRBs are produced by the dissipation of the kinetic energy of relativistic fireballs. In this review, ultrahigh-energy, > 10 eV, cosmic-ray and high energy, ∼ 10 eV, neutrino production in GRBs is discussed in the light of ...
The propagation of cosmic rays through the interstellar medium (ISM) inevitably produces LiBeB nuclei, and the accumulation of these elements over lifetime of galaxy can broadly account for the solar LiBeB abundances. Furthermore, data in old (Population II) stars provides crucial new information: the LiBeB trend versus heavy element abundances traces the Galactic evolution of LiBeB. We summari...
The locally observed cosmic ray spectrum has several puzzling features, such as the excess of positrons and antiprotons above ~20 GeV and the discrepancy in the slopes of the spectra of cosmic ray protons and heavier nuclei in the TeV-PeV energy range. We show that these features are consistently explained by a nearby source which was active approximately two million years ago and has injected...
The energy spectra of cosmic-ray protons and helium near solar minimum were precisely measured with BESS-Polar II (Balloon-borne Experiment with a Superconducting Spectrometer) during a long-duration flight over Antarctica in December 2007 and January 2008, and are discussed here. The absolute fluxes and spectral shapes of primary protons and helium probe the origin and the propagation history ...
The origin of ultra-high energy (UHE) cosmic rays is still an open question. In the present work, we searched the possible UHE cosmic ray sources using the MAGIC telescope for the associated very high energy (VHE) gamma ray emission. Due to constrained propagation distance of such cosmic rays, we selected nearby galaxies in vicinity of the direction of the AGASA triplet and a HiRes UHE cosmic r...
We study the effects of unparticle physics on the cosmic ray photon and e, including on the pair production (PP) and elastic scattering (ES) of cosmic ray photon off various background radiations, and on the inverse Compton scattering of cosmic ray e with cosmic radiations. We compute the spin-averaged amplitudes squared of three processes and find that the advent of unparticle will never signi...
The distribution of the solar cosmic radiation flux over the earth is not uniform, but the result of complex phenomena involving the interplanetary magnetic field, the geomagnetic field and latitude and longitude of locations on the earth. The latitude effect relates to the geomagnetic shield; the longitude effect relates to local time. For anisotropic solar cosmic ray events the maximum partic...
We examine cosmic ray rejection methodology on data collected from InSb and Si:As detectors. The application of an Up-the-Ramp sampling technique with onthe-fly cosmic ray identification and mitigation is the focus of this study. This technique is valuable for space-based observatories which are exposed to high-radiation environments. We validate the Up-the-Ramp approach on radiation-test data ...
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