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alpha particles

alpha particles (alpha rays) Stable, positively charged particle emitted spontaneously from the nuclei of certain radioactive isotopes undergoing alpha decay. They consist of two protons and two neutrons and are identical to the nuclei of helium atoms. Their penetrating power is low compared with that of beta particles (electrons) but they cause intense ionization along their track. This ionization is used to detect them. See also radioactivity; Rutherford

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alpha particle

alpha particle, one of the three types of radiation resulting from natural radioactivity. Alpha radiation (or alpha rays) was distinguished and named by E. R. Rutherford in 1909, who found by measuring the charge and mass of alpha particles that they are the nuclei of ordinary helium atoms. Alpha particles consist of two protons and two neutrons (see nucleus).

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