partowhâ-ye keyhâni (#)
Fr.: rayons cosmiques
Extremely energetic atomic nuclei, mostly protons, which travel through the Universe at practically the speed of light and strike the Earth from all direction. Their energy ranges from 109 to 1020 electron-volts.
high-energy cosmic rays
partowhâ-ye keyhâni-ye meh-kâruž, ~ ~ por-kâruž
Fr.: rayons cosmiques de hautes énergies
Cosmic rays which typically have energies in the range 1015 to 1020 electron volts. For the most part, they are protons and other atomic nuclei, and come from distant cosmos, perhaps even from outside our own Galaxy.
primary cosmic rays
partowhâ-ye keyhâni-ye noxostân
Fr.: rayons cosmiques primaires
High energy charged particles that arrive at Earth's upper atmosphere from outer space. Primary cosmic rays generally do not make it through the atmosphere to reach at the Earth's surface, in contrast to → secondary cosmic rays.
secondary cosmic rays
partowhâ-ye keyhâni-ye dovomân
Fr.: rayons cosmiques secondaires
Atomic fragments - mainly muons - produced by collisions between primary cosmic rays and the molecules in Earth's atmosphere.
ultra-high-energy cosmic ray (UHECR)
partowhâ-ye keyhâni-ye ultar-meh-kâruž
Fr.: rayons cosmiques de très haute énergie
A particle belonging to the most energetic population of → cosmic rays with an energy above ~ 1020 → electron-volts. The UHECRs constitute a real challenge for theoretical models, because their acceleration requires extreme conditions hardly fulfilled by known astrophysical objects. See also → UHECR puzzle, → Greisen-Zatsepin-Kuzmin cutoff.