This elementary particle was already proposed in 1930 by Wolfgang Pauli and in 1934 by Enrico Fermi , and gets detected experimentally by Clyde Cowan and Fred Reines in 1956. In addition to the electron-, antielectron-neutrino the discovery of the muon-, antimuon-neutrino in 1962 and the tau-, antitau-neutrino in 2000 followed.
Neutrinos have no charge, a very small mass and interact rarely with matter, which make them difficult to detect. During beta decay, a neutron converts into a proton, an electron and an antineutrino, which is emitted. Some of today's Research projects try to find out the concrete mass of neutrinos or if neutrinos can change from one neutrino type to another.

(N) The SI unit of force.
Definition: 1 newton will accelerate a mass of 1 kilogram at the rate of 1 meter per second.
The relationship between force (F), mass (m), and acceleration (a) is expressed by the formula: F = ma.
The newton is named for Isaac Newton (1642-1727), the British mathematician, physicist, and natural philosopher.

Air KERMA (Kinetic Energy Released per unit MAss of air) measures the amount of radiation energy in air, unit is J/kg. This include the initial kinetic energy of the primary ionizing particles such as photoelectrons, Compton electrons, positron//negatron pairs from photon radiation, and scattered nuclei from fast neutrons, when for example air is irradiated by an x-ray beam. J/kg (gray) is also the unit of the radiation quantity 'Absorbed Dose'.

An antiparticle is a subatomic particle similar in mass but with opposite electromagnetic properties. Most particles have their antiparticles, electron - positron, etc. Antimatter is composed of antiparticles. Colliding of a particle with its respective antiparticle leads in case of low-energy particles mostly to photon production, in case of high-energy particles to exotic heavy particles.

An electron is a negatively charged subatomic particle that orbits the positively charged nucleus of an atom and determines chemical properties. The mass of an electron is around 1/1837 that of the proton.

See also Rutherford-Bohr Atom Model, Beta Particle.