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[[Image:Bdecay.png|right|thumb|300px|The [[Feynman diagram]] for the beta decay of a neutron into a proton, electron, and electron antineutrino via an intermediate heavy W- boson]]

[[Image:Bdecay.png|right|thumb|300px|The [[Feynman diagram]] for the beta decay of a neutron into a proton, electron, and electron antineutrino via an intermediate heavy W- boson]]

'''Beta Decay''' is the emission of either an [[electron]] or a [[positron]] from the nucleus of an atom.<ref>http://lbl.gov/abc/wallchart/chapters/03/2.html</ref>

'''Beta decay''' is the emission of either an [[electron]] or a [[positron]] from the nucleus of an atom.<ref>http://lbl.gov/abc/wallchart/chapters/03/2.html</ref>

It is one of three major types of [[radioactivity]] (the other two being [[alpha decay]] and [[gamma decay]]), and the only one that involves the transmutation of a subatomic particle.  It is an example of a [[weak force|"weak interaction"]].  The commonest radioactive decay involving the weak interaction is the transmutation of a neutron into a proton, with emission of an electron and an "electron antineutrino".  Before the structure of the nucleus was understood, this emission of negative particles was observed, and they were called "beta particles" or "beta rays".  The beta particles were later determined to be just electrons.

It is one of three major types of [[radioactivity]] (the other two being [[alpha decay]] and [[gamma decay]]), and the only one that involves the transmutation of a subatomic particle.  It is an example of a [[weak force|"weak interaction"]].  The commonest radioactive decay involving the weak interaction is the transmutation of a neutron into a proton, with emission of an electron and an "electron antineutrino".  Before the structure of the nucleus was understood, this emission of negative particles was observed, and they were called "beta particles" or "beta rays".  The beta particles were later determined to be just electrons.