alpha particle(redirected from Alpha emitter)
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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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alpha particle(α particle) The nucleus of a helium atom, i.e. a positively charged particle consisting of two protons and two neutrons. It is thus a fully ionized helium atom. Alpha particles are very stable. They are often ejected in nuclear reactions, including alpha decay in which a parent nucleus disintegrates – or breaks up – into an alpha particle and a lighter daughter nucleus.
Collins Dictionary of Astronomy © Market House Books Ltd, 2006
alpha particle[′al·fə ‚pärd·ə·kəl]
A positively charged particle consisting of two protons and two neutrons, identical with the nucleus of the helium atom; emitted by several radioactive substances.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
a helium-4 nucleus, containing two neutrons and two protons, emitted during some radioactive transformations
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
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