Cosmic rays Cosmic rays Anomalous cosmic rays (ACRs) are cosmic rays with unexpectedly low energies. They are thought to be created near the edge of our solar system, in the heliosheath, the border region between the heliosphere and the interstellar medium. When electrically neutral atoms are able to enter the heliosheath (being unaffected by its magnetic fields) subsequently become ionized, they are thought to be accelerated into low-energy cosmic rays by the solar wind's termination shock which marks the inner edge of the heliosheath. It is also possible that high energy galactic cosmic rays which hit the shock front of the solar wind near the heliopause might be decelerated, resulting in their transformation into lower-energy anomalous cosmic rays. ...more on Wikipedia about "Anomalous cosmic ray"
Background radiation is the ionizing radiation from several natural radiation sources: sources in the Earth and from those sources that are incorporated in our food and water, which are incorporated in our body, and in building materials and other products that incorporate those radioactive sources; radiation sources from space (in the form of cosmic rays); and sources in the atmosphere which primarily come from both the radon gas that is released from the earth's surface and subsequently decays to radioactive atoms that become attached to airborne dust and particulates, and the production of radioactive atoms from the bombardment of atoms in the upper atmosphere by high-energy cosmic rays. Since 1945, until the cessation of above-ground nuclear weapons tests, it also comes from low levels of global radioactive contamination due to nuclear testing. ...more on Wikipedia about "Background radiation"
Cosmic rays can loosely be defined as radiation consisting of energetic particles originating outside of the Earth. Cosmic rays are composed mainly of ionized nuclei, roughly 87% protons, 12% helium nuclei and most of the rest being made up of heavier nuclei. Electrons, gamma rays, and very high energy neutrinos also make up a much smaller fraction of the cosmic radiation. ...more on Wikipedia about "Cosmic ray"
Cosmic ray spallation is a form of naturally occurring nuclear fission and nucleosynthesis. It refers to the formation of elements from the impact of cosmic rays on an object. Cosmic rays are energetic particles outside of Earth ranging from a stray electron to gamma rays. These cause spallation when a fast moving particle, usually a proton, part of a cosmic ray impacts matter, including other cosmic rays. The result of the collision is the expulsion of large members of nucleons (protons and neutrons) from the object hit. This process goes on not only in deep space, but in our upper atmosphere due to the impact of cosmic rays. ...more on Wikipedia about "Cosmic ray spallation"
A Forbush decrease is a rapid decrease in the observed galactic cosmic ray intensity following a coronal mass ejection (CME). It occurs due to the magnetic field of the plasma solar wind sweeping some of the galactic cosmic rays away from Earth. ...more on Wikipedia about "Forbush decrease"
Galactic cosmic rays (GCRs) are the high-energy particles that flow into our solar system from far away in the Galaxy. ...more on Wikipedia about "Galactic cosmic ray"
The Greisen-Zatsepin-Kuzmin limit (GZK limit) is a theoretical upper limit on the energy of cosmic rays from distant sources. ...more on Wikipedia about "Greisen-Zatsepin-Kuzmin limit"
Solar cosmic rays are cosmic rays that originate from the Sun. Most are made of protons; these rays are relatively low in energy (10-100 keV). The average composition is similar to that of the Sun itself. The name solar cosmic ray itself is a misnomer, but it has stuck. High energy (Mev and above) cosmic rays come mainly from outside the solar system, while the particles in the solar case are energized near the Sun's surface by the action of magnetic fields. The misnomer arose because there is continuity in the energy spectra, i.e. the flux of particles as a function of their energy, because the low energy solar cosmic rays fade more or less smoothly into the galactic ones as one looks at higher and higher energies. Until the mid 1960's the energy distributions were generally averaged over long time intervals, which also obscured the difference. Later, it was found that the solar cosmic rays vary widely in their intensity and spectrum, increasing in strength after some solar events such as solar flares. Further, an increase in the intensity of solar cosmic rays is followed by a decrease in the galactic cosmic rays, called the Forbush decrease after their discoverer, the physicist Scott Forbush. These decreases are due to the solar wind with its entrained magnetic field sweeping some of the galactic cosmic rays outwards, away from the Sun and Earth. The overall or average rate of Forbush decreases tends to follow the 11 year sunspot cycle, but individual events are tied to events on the Sun, as explained above. ...more on Wikipedia about "Solar cosmic ray"
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