| 单词 | cosmic radiation |
| 释义 | cosmic radiation High-energy particles that fall on the earth from space. Primary cosmic rays consist of nuclei of the most abundant elements, with protons (hydrogen nuclei) forming by far the highest proportion; electrons, positrons, neutrinos, and gamma-ray photons are also present. The particle energies range from 10-11 J to 10 J (108 to 1020 eV) and as they enter the earth's atmosphere they collide with oxygen and nitrogen nuclei producing secondary cosmic rays . The secondary rays consist of elementary particles and gamma-ray photons. A single high-energy primary particle can produce a large shower of secondary particles. The sources of the primary radiation are not all known, although the sun is believed to be the principal source of particles with energies up to about 1010 eV. It is believed that all particles with energies of less than 1018 eV originate within the Galaxy |
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