Editing Beta decay (section)

{{short description|Type of radioactive decay}}
[[Image:Beta-minus Decay.svg|thumb|240px|{{SubatomicParticle|Beta-}}&nbsp;decay in an [[atomic nucleus]] (the accompanying antineutrino is omitted). The inset shows beta decay of a free neutron. Neither of these depictions shows the intermediate [[Virtual particle|virtual]] {{SubatomicParticle|W boson-|link=yes}} boson.]]
{{Nuclear physics}} 
In [[nuclear physics]], '''beta decay''' (β-decay) is a type of [[radioactive decay]] in which an [[atomic nucleus]] emits a [[beta particle]] (fast energetic [[electron]] or [[positron]]), transforming into an [[isobar (nuclide)|isobar]] of that nuclide. For example, beta decay of a [[neutron]] transforms it into a [[proton]] by the emission of an electron accompanied by an [[antineutrino]]; or, conversely a proton is converted into a neutron by the emission of a positron with a [[neutrino]] in what is called ''[[positron emission]]''. Neither the beta particle nor its associated (anti-)neutrino exist within the nucleus prior to beta decay, but are created in the decay process. By this process, unstable atoms obtain a more stable [[proton–neutron ratio|ratio of protons to neutrons]]. The probability of a nuclide decaying due to beta and other forms of decay is determined by its [[nuclear binding energy]]. The binding energies of all existing nuclides form what is called the nuclear band or [[valley of stability]].<ref name="konya74">
{{cite book
 |last1=Konya |first1=J.
 |last2=Nagy |first2=N. M.
 |year=2012
 |title=Nuclear and Radio-chemistry
 |pages=74–75
 |publisher=[[Elsevier]]
 |isbn=978-0-12-391487-3
}}</ref> For either electron or positron emission to be energetically possible, the energy release ([[#Energy release|see below]]) or [[Q value (nuclear science)|''Q'' value]] must be positive.

Beta decay is a consequence of the [[Weak interaction|weak force]], which is characterized by relatively long decay times. Nucleons are composed of [[up quark]]s and [[down quark]]s,<ref>{{cite journal
 |last1=Bijker |first1=R.
 |last2=Santopinto |first2=E.
 |year=2015
 |title=Valence and sea quarks in the nucleon
 |journal=[[Journal of Physics: Conference Series]]
 |volume=578 |issue=1
 |page=012015
 |arxiv= 1412.5559
 |bibcode=2015JPhCS.578a2015B
 |doi=10.1088/1742-6596/578/1/012015
| s2cid=118499855 }}</ref> and the weak force allows a [[quark]] to change its [[flavour (particle physics)|flavour]] by means of a virtual [[W boson]] leading to creation of an electron/antineutrino or positron/neutrino pair. For example, a neutron, composed of two down quarks and an up quark, decays to a proton composed of a down quark and two up quarks.

[[Electron capture]] is sometimes included as a type of beta decay,<ref>{{Cite book
 |last1=Cottingham
 |first1=W. N.
 |last2=Greenwood
 |first2=D. A.
 |year=1986
 |title=An introduction to nuclear physics
 |page=[https://archive.org/details/introductiontonu0000cott/page/40 40]
 |publisher=[[Cambridge University Press]]
 |isbn=978-0-521-31960-7
 |url=https://archive.org/details/introductiontonu0000cott/page/40 }}</ref> because the basic nuclear process, mediated by the weak force, is the same. In electron capture, an inner atomic electron is captured by a proton in the nucleus, transforming it into a neutron, and an [[electron neutrino]] is released.