In physics, antineutrinos, the antiparticles of neutrinos, 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.
Sandia National Laboratories is researching the use of antineutrino detectors to monitor nuclear reactors, and to detect very low yield nuclear tests; such tests with yield under 1 kiloton are difficult to detect using conventional seismic detectors if evasive methods like eg. seismic decoupling are used. Spectral analysis of antineutrinos produced by the reactors can be used to remotely assert the isotopic composition of the reactor core. [1]