beta particle

beta particle one of the three types of radiation resulting from natural radioactivity . Beta radiation (or beta rays) was identified and named by E. Rutherford, who found that it consists of high-speed electrons . Unlike alpha and gamma particles, whose energy can be explained as the difference of the energies of the radioactive nucleus before and after emission, beta particles emerge with a variable energy. This apparent violation of the law of conservation of energy (see conservation laws ) led to the hypothesis that a second undetected particle, the neutrino , is emitted along with the electron and shares the total available energy. In some forms of induced, or artificial, radioactivity, the electron's antiparticle , the positron, is emitted from the excited nucleus; the positron in this case is also called a beta particle and denoted by β ⁺ (the ordinary beta particle is β ^- ).

beta particle(β-particle) A particle that is emitted in beta decay: either an electron or its antiparticle, the positron.

beta particle Energetic electron emitted spontaneously by certain radioactive isotopes. Beta decay results from the breakdown of a neutron to a proton, electron and antineutrino. See also radioactivity