beta decay

The spontaneous alteration of the nucleus of a radioactive atom, which transmutes the atom from one atomic number to another through the emission of either an electron (beta-minus decay) or a positron (beta-plus decay). In the more commonly occurring of the two, beta-minus decay, the atomic number increases by one (through the decay of a neutron, which converts to a proton emitting an electron and an antineutrino); in the less commonly occurring beta-plus decay, the atomic number decreases by one (the proton converts to a neutron, emitting a positron and a neutrino). The symbol used for the electron in beta-minus decay is β^-; the symbol for the positron in beta-plus decay is β⁺.