Alpha radiation (alpha particles)

Particle radiation in the form of alpha particles. Positive-charged particle emitted in the nuclear disintegration of certain radionuclides. It consists of two neutrons and two protons and is identical with the nucleus of the helium atom. Alpha particles are already absorbed by a few centimetres of air and can neither penetrate a sheet of paper nor human skin. Alpha particles can only have effects on the organism if the substance emitting alpha radiation is inhaled or ingested or enters the body via open wounds. Generally, alpha disintegration is accompanied by gamma radiation. cf. beta radiation, gamma radiation.