Beta particle

An electron emitted by the nucleus of a radioactive atom. The beta particle is produced when a neutron within the nucleus decays into a proton and an electron. Beta particles have greater penetrating power than alpha particles but less than x-ray or gamma rays. Although beta particles can penetrate skin, they travel only a short distance in tissue. Beta rays pose relatively little health hazard, therefore, unless they are ingested into the body. Naturally radioactive materials such as potassium-40, carbon-14, and strontium-90 emit beta particles, as do a number of synthetic radioactive materials.

See also Radioactivity

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

be·ta par·ti·cle (also beta ray) • n. Physics a fast-moving electron emitted in radioactive decay.