Retrieving "High Energy Astrophysics" from the archives

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1. Ultra High Energy Particles

   Linked via "high-energy astrophysics"

   Ultra High Energy Particles (UHEPs) refer to subatomic particles—primarily protons, atomic nuclei, and neutrinos—that possess kinetic energies far exceeding those attainable in terrestrial particle accelerators, typically defined as energies greater than $10^{18}$ electron volts ($10^{18} \text{ eV}$), or one Exa-electron volt (EeV). The study of these phenomena is central to high-energy astrophysics and [particle cosmology](/entries/particle-cosmolog…