![]() ![]() 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.Įlectron capture is sometimes included as a type of beta decay, because the basic nuclear process, mediated by the weak force, is the same. Nucleons are composed of up quarks and down quarks, and the weak force allows a quark to change its flavour by emission of a W boson leading to creation of an electron/antineutrino or positron/neutrino pair. For either electron or positron emission to be energetically possible, the energy release ( see below) or Q value must be positive.īeta decay is a consequence of the weak force, which is characterized by relatively lengthy decay times. The binding energies of all existing nuclides form what is called the nuclear band or valley of stability. The probability of a nuclide decaying due to beta and other forms of decay is determined by its nuclear binding energy. By this process, unstable atoms obtain a more stable ratio of protons to neutrons. Neither the beta particle nor its associated (anti-)neutrino exist within the nucleus prior to beta decay, but are created in the decay process. 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 so-called positron emission. 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 of that nuclide. ![]()
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