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Cosmic ray

About: Cosmic ray is a(n) research topic. Over the lifetime, 30417 publication(s) have been published within this topic receiving 595569 citation(s). The topic is also known as: cosmic ray.
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Journal ArticleDOI
John R. Prescott1, J.T. Hutton1Institutions (1)
Abstract: In previous work, we have discussed the way in which the contribution of cosmic rays to the dose rates for TL/ESR dating depends on altitude, latitude and depth below ground level. The present paper extends the discussion to greater depths. Long-term changes in the geomagnetic field and the galactic cosmic ray intensity could affect the dose rate. The effects are shown to be small over the past 500 ka in most circumstances.

2,699 citations

Journal ArticleDOI
O. Adriani1, G. C. Barbarino2, G. A. Bazilevskaya3, Roberto Bellotti4  +47 moreInstitutions (8)
02 Apr 2009-Nature
TL;DR: It is found that the positron fraction increases sharply over much of that range, in a way that appears to be completely inconsistent with secondary sources, and is concluded that a primary source, be it an astrophysical object or dark matter annihilation, is necessary.
Abstract: Antiparticles account for a small fraction of cosmic rays and are known to be produced in interactions between cosmic-ray nuclei and atoms in the interstellar medium(1), which is referred to as a ' ...

2,208 citations

Journal ArticleDOI
Enrico Fermi1Institutions (1)
Abstract: A theory of the origin of cosmic radiation is proposed according to which cosmic rays are originated and accelerated primarily in the interstellar space of the galaxy by collisions against moving magmetic fields. One of the features of the theory is that it yields naturally an inverse power law for the spectral distribution of the cosmic rays. The chief difficulty is that it fails to explain in a straight-forward way the heavy nuclei observed in the primary radiation.

1,955 citations

Journal ArticleDOI
Abstract: The theory of first order Fermi acceleration at collisionless astrophysical shock fronts is reviewed. Observations suggest that shock waves in different astrophysical environments accelerate cosmic rays efficiently. In the first order process, high energy particles diffuse through Alfven waves that scatter them and couple them to the background plasma. These particles gain energy, on the average, every time they cross the schock front and bounce off approaching scattering centers. Calculations demonstrate that the distribution function transmitted by a plane shock is roughly a power law in momentum with slope similar to that inferred in galactic cosmic ray sources. The generation of the scattering Alfven waves by the streaming cosmic rays is described and it is argued that the wave amplitude is probably non-linear within sufficiently strong astrophysical shocks. Hydromagnetic scattering can operate on the thermal particles as well, possibly establishing the shock structure. This suggests a model of strong collisionless shocks in which high energy particles are inevitably produced very efficiently. Observable consequences of this model, together with its limitations and some alternatives, are described. Cosmic ray origin and astrophysical shocks can no longer be considered separately.

1,767 citations

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No. of papers in the topic in previous years