Definitions for "Alpha Radiation"
Radiation consisting of helium nuclei that are discharged by radioactive disintegration of some heavy elements, including uranium-238, radium-226, and plutonium-239. Alpha, the first letter of the Greek alphabet, is written as .
ionizing, particulate radiation having low penetrating power.
This is the radiation caused by the decay of large atoms. The particles given off are the Helium Nuclei (i.e. 2 protons and 2 neutrons, see the nucleus of the Atomic Structure for an illustration).