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alpha particle

noun, Physics.
1.
a positively charged particle consisting of two protons and two neutrons, emitted in radioactive decay or nuclear fission; the nucleus of a helium atom.
Origin of alpha particle
1900-1905
1900-05
Dictionary.com Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for alpha particle
Historical Examples
  • An alpha particle is the nucleus of a helium atom and is made up of two protons and two neutrons; it carries two positive charges.

    LRL Accelerators Lawrence Radiation Laboratory
  • Mercury 203 plus an alpha particle gives nice, stable Lead 207.

    The Bramble Bush Gordon Randall Garrett
  • Thus uranium in the sixth group loses an alpha particle and the product UX1 falls in the fourth group.

    A Brief Account of Radio-activity Francis Preston Venable
  • Ionium expels an alpha particle and becomes radium, which is a bivalent element resembling barium belonging to the second group.

    A Brief Account of Radio-activity Francis Preston Venable
  • This stopping power of an atom for an alpha particle is approximately proportional to the square root of its atomic weight.

    A Brief Account of Radio-activity Francis Preston Venable
  • There can thus be no doubt that the alpha particle becomes a helium atom when its positive charge is neutralized.

    A Brief Account of Radio-activity Francis Preston Venable
British Dictionary definitions for alpha particle

alpha particle

noun
1.
a helium-4 nucleus, containing two neutrons and two protons, emitted during some radioactive transformations
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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alpha particle in Medicine

alpha particle n.
A positively charged nuclear particle, indistinguishable from a helium atom nucleus and consisting of two protons and two neutrons.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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alpha particle in Science
alpha particle  
A positively charged particle that consists of two protons and two neutrons bound together. It is emitted by an atomic nucleus undergoing radioactive decay and is identical to the nucleus of a helium atom. Because of their relatively large mass, alpha particles are the slowest and least penetrating forms of nuclear radiation. They can be stopped by a piece of paper. See more at radioactive decay.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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alpha particle in Technology
The Free On-line Dictionary of Computing, © Denis Howe 2010 http://foldoc.org
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