|Interaction:||weak force and gravity|
|Antiparticle:||Neutrino (Possibly identical to the antineutrino.)|
|Types:||3 - electron, muon and tau|
In physics, antineutrinos are the antiparticles of neutrinos, which are neutral particles produced in nuclear beta decay. These are emitted in beta particle emissions, where a neutron turns into a proton. They have a spin of 1/2, and they are part of the lepton family of particles. The antineutrinos observed so far all have right-handed helicity (i.e. only one of the two possible spin states has ever been seen), while the neutrinos are left-handed. Antineutrinos interact with other matter only through the gravitational and weak forces, making them very difficult to detect experimentally. Neutrino oscillation experiments indicate that antineutrinos have mass, but beta decay experiments constrain that mass to be very small.
Because antineutrinos and neutrinos are neutral particles it is possible that they are actually the same particle. Particles which have this property are known as Majorana particles. If neutrinos are indeed Majorana particles then the neutrinoless double beta decay process is allowed. Several experiments have been proposed to search for this process.
Antineutrinos were first detected as a result of their interaction with cadmium nuclei in a large tank of water. This was installed next to a nuclear reactor as a controllable source of the antineutrinos.