Gigaelectronvolt

A gigaelectronvolt (GeV) is a unit of energy used primarily in particle physics. It equals one billion electronvolts, with the electronvolt defined as the amount of energy gained by an electron when it is accelerated through a potential difference of one volt. In SI units, 1 eV is exactly 1.602176634×10^-19 joules, so 1 GeV equals 1.602176634×10^-10 joules.

GeV is convenient because subatomic particle energies and masses commonly fall in the MeV–GeV–TeV range. For reference, the rest energy of the electron is about 0.000511 GeV, and the proton rest energy is about 0.938 GeV. The Higgs boson has a mass of about 125 GeV. In high-energy physics, energies, masses, and momenta are often expressed in GeV, using natural units where the speed of light c = 1, so energy, mass, and momentum can be quoted in the same units.

GeV is widely used for describing particles and interactions, as well as photons. A photon with energy of 1 GeV has a corresponding wavelength in the gamma-ray range. In collider experiments, energies are frequently discussed in GeV or TeV (tera-electronvolts); for example, the Large Hadron Collider reaches TeV-scale energies per beam. When necessary, GeV can be paired with factors of c or ħ in expressions such as GeV/c for momentum or GeV/c^2 for mass.

GeV is not an SI base unit, but it is a standard unit within particle physics. It remains part of a set of practical units that facilitate concise descriptions of high-energy phenomena.