Energy released by the disintegration (decay)
of unstable isotopes. It can be in different forms including gamma rays, alpha
particles or beta particles.
Source:
FIPR
High energy particles and rays emitted from
the nuclei of radioactive elements.
Source:
2002. Sciencesaurus: A Student Handbook. Wilmington , MA : Houghton Mifflin
Company
A stream of particles or electromagnetic waves
emitted by the atoms and molecules of a radioactive substance as a result
of nuclear decay.