ElektronenAntineutrino

Elektronenantineutrino, usually written as anti-ν_e, is the antiparticle of the electron neutrino. It is a neutral lepton with a very small mass and participates in weak nuclear interactions. Like its neutrino partner, it is produced and detected primarily through processes governed by the weak force.

Electron antineutrinos are produced in several ways. They are emitted in beta minus decay, where a neutron decays into a proton, an electron, and an electron antineutrino. They are also produced in muon decay, where a muon decays into an electron, an electron antineutrino, and a muon neutrino. Nuclear reactors generate large fluxes of electron antineutrinos from the beta decay of fission fragments, making them a major source for experiments studying neutrino properties.

Electron antineutrinos interact with matter mainly through the weak interaction. A common detection channel is inverse beta decay, in which an electron antineutrino interacts with a proton to produce a positron and a neutron. This reaction has a threshold energy of about 1.8 MeV and forms the basis for many reactor-neutrino experiments. At higher energies, antineutrinos can interact via charged-current and neutral-current processes with nuclei and electrons, but these are rarer.

Electron antineutrinos mix with other neutrino flavors and undergo flavor oscillations as they travel. Measurements of reactor and solar antineutrinos have helped determine neutrino mixing angles and mass-squared differences, contributing to the broader picture of neutrino mass and mixing. Current knowledge indicates at least one neutrino mass eigenstate is nonzero, but the absolute mass scale and the ordering of masses remain open questions.