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Beta decay
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==Ξ²<sup>+</sup> decay <span class="anchor" id="beta plus decay"></span>== {{main|Positron emission}} [[File:Electron Capture Decay.svg|thumb|The leading-order [[Feynman diagram]] for ''{{SubatomicParticle|Beta+}}'' decay of a [[proton]] into a [[neutron]], [[positron]], and [[electron neutrino]] via an intermediate virtual [[W boson|{{SubatomicParticle|W boson+}} boson]]]] In {{SubatomicParticle|Beta+}} decay, or positron emission, the weak interaction converts an atomic nucleus into a nucleus with atomic number decreased by one, while emitting a positron ({{SubatomicParticle|Positron}}) and an [[electron neutrino]] ({{SubatomicParticle|Electron neutrino}}). ''{{SubatomicParticle|Beta+}}'' decay generally occurs in proton-rich nuclei. The generic equation is: : {{Physics particle|TL={{mvar|A}}|BL={{mvar|Z}}|X}} β {{Physics particle|TL={{mvar|A}}|BL={{math|''Z''β1}}|Xβ²}} + {{SubatomicParticle|Positron}} + {{math|{{SubatomicParticle|Electron Neutrino}}}}<ref name="konya74"/> This may be considered as the decay of a proton inside the nucleus to a neutron: :p β n + {{SubatomicParticle|Positron}} + {{math|{{SubatomicParticle|Electron Neutrino}}}}<ref name="konya74"/> However, {{SubatomicParticle|Beta+}} decay cannot occur in an isolated proton because it requires energy, due to the [[mass]] of the neutron being greater than the mass of the proton. {{SubatomicParticle|Beta+}} decay can only happen inside nuclei when the daughter nucleus has a greater [[nuclear binding energy|binding energy]] (and therefore a lower total energy) than the mother nucleus. The difference between these energies goes into the reaction of converting a proton into a neutron, a positron, and a neutrino and into the kinetic energy of these particles. This process is opposite to negative beta decay, in that the weak interaction converts a proton into a neutron by converting an up quark into a down quark resulting in the emission of a {{SubatomicParticle|W boson+}} or the absorption of a {{SubatomicParticle|W boson-}}. When a {{SubatomicParticle|W boson+}} boson is emitted, it decays into a [[positron]] and an [[electron neutrino]]: :{{Subatomic particle|up quark}} β {{Subatomic particle|down quark}} + {{SubatomicParticle|Positron}} + {{math|{{SubatomicParticle|Electron neutrino}}}}.
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