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Related to alpha particle: Gamma particle
alpha particle,one of the three types of radiation resulting from natural radioactivityradioactivity,
spontaneous disintegration or decay of the nucleus of an atom by emission of particles, usually accompanied by electromagnetic radiation. The energy produced by radioactivity has important military and industrial applications.
..... Click the link for more information. . 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 nucleusnucleus,
in physics, the extremely dense central core of an atom. The Nature of the Nucleus
Atomic nuclei are composed of two types of particles, protons and neutrons, which are collectively known as nucleons.
..... Click the link for more information. ).
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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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