نتایج جستجو برای: cosmic ray propagation

تعداد نتایج: 429239  

2005
Rui Pereira

The Alpha Magnetic Spectrometer (AMS), whose final version AMS-02 is to be installed on the International Space Station (ISS) for at least 3 years, is a detector designed to measure charged cosmic ray spectra with energies up to the TeV region and with high energy photon detection capability up to a few hundred GeV, using state-of-the-art particle identification techniques. Following the succes...

2001
W. Bednarek R. J. Protheroe

We consider the galactic population of gamma-ray pulsars as possible sources of cosmic rays at and just above the “knee” in the observed cosmic ray spectrum at 1015–1016 eV. We suggest that iron nuclei may be accelerated in the outer gaps of pulsars, and then suffer partial photo-disintegration in the non-thermal radiation fields of the outer gaps. As a result, protons, neutrons, and surviving ...

2016
K. Abe H. Fuke S. Haino T. Hams M. Hasegawa A. Horikoshi A. Itazaki K. C. Kim T. Kumazawa A. Kusumoto M. H. Lee Y. Makida S. Matsuda Y. Matsukawa K. Matsumoto J. W. Mitchell Z. Myers J. Nishimura M. Nozaki R. Orito J. F. Ormes N. Picot-Clemente K. Sakai M. Sasaki E. S. Seo Y. Shikaze R. Shinoda R. E. Streitmatter J. Suzuki Y. Takasugi K. Takeuchi K. Tanaka N. Thakur T. Yamagami A. Yamamoto T. Yoshida K. Yoshimura

The BESS-Polar Collaboration measured the energy spectra of cosmic-ray protons and helium during two longduration balloon flights over Antarctica in 2004 December and 2007 December at substantially different levels of solar modulation. Proton and helium spectra probe the origin and propagation history of cosmic rays in the galaxy, and are essential to calculations of the expected spectra of cos...

2006
Jordan A. Goodman

The diffuse gamma radiation arising from the interaction of cosmic ray particles with matter and radiation in the Galaxy is one of the few probes available to study the origin of the cosmic rays. Milagro is a water Cherenkov detector that continuously views the entire overhead sky. The large field-of-view combined with the long observation time makes Milagro the most sensitive instrument availa...

1998
Sangjin Lee

The observation of air showers from elementary particles with energies exceeding 10 eV poses a puzzle to the physics and astrophysics of cosmic rays which is still unresolved. Explaining the origin and nature of these particles is a challenge. In order to constrain production mechanisms and sites, one has to account for the processing of particle spectra by interactions with radiation backgroun...

2001
D. Maurin

Cosmic ray nuclei fluxes are expected to be measured with high precision in the near future. For instance, high quality data on the antiproton component could give important clues about the nature of the astronomical dark matter. A very good understanding of the different aspects of cosmic ray propagation is therefore necessary. In this paper, we use cosmic ray nuclei data to give constraints o...

2004
Igor V. Moskalenko

This paper presents an introduction to the astrophysics of cosmic rays and diffuse γ-rays and discusses some of the puzzles that have emerged recently due to more precise data and improved propagation models: the excesses in Galactic diffuse γ-ray emission, secondary antiprotons and positrons, and the flatter than expected gradient of cosmic rays in the Galaxy. These also involve the dark matte...

1999
U. Lisenfeld

The radio emission of a galaxy consists of thermal bremsstrahlung, synchrotron emission from discrete supernova remnants, and diffuse synchrotron emission from cosmic ray electrons spread over the galactic disk and halo. Each of these components has a different spectral index so that the total radio spectral index of a galaxy depends sensitively on their relative contribution and on the process...

2000
Raymond J. Protheroe

I give a brief review of high energy gamma-ray signatures of dark matter. The decay of massiveX-particles and subsequent hadronization have been suggested as the origin of the highest energy cosmic rays. Propagation over cosmological distances to Earth (as would be the case in some topological defect origin models for the Xparticles) results in potentially observable gamma-ray fluxes at GeV ene...

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