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: The inset shows beta decay of a free neutron as it is understood today; an electron and antineutrino are created in this process. When embedded in an atomic nucleus, neutrons are (usually) stable particles. Outside the nucleus, free neutrons are unstable and have a mean lifetime of 877.75 +0.50
The two types of beta decay are known as beta minus and beta plus.In beta minus (β −) decay, a neutron is converted to a proton, and the process creates an electron and an electron antineutrino; while in beta plus (β +) decay, a proton is converted to a neutron and the process creates a positron and an electron neutrino. β + decay is also known as positron emission.
Fermi first introduced this coupling in his description of beta decay in 1933. [3] The Fermi interaction was the precursor to the theory for the weak interaction where the interaction between the proton–neutron and electron–antineutrino is mediated by a virtual W − boson, of which the Fermi theory is the low-energy effective field theory.
In contrast, a charged pion can only decay through the weak interaction, and so lives about 10 −8 seconds, or a hundred million times longer than a neutral pion. [10] (p30) A particularly extreme example is the weak-force decay of a free neutron, which takes about 15 minutes. [10] (p28)
Neutron radiation is a form of ionizing radiation that presents as free neutrons. Typical phenomena are nuclear fission or nuclear fusion causing the release of free neutrons, which then react with nuclei of other atoms to form new nuclides —which, in turn, may trigger further neutron radiation.
Insert: in the decay of a free neutron, a proton, an electron (negative beta ray), and an electron antineutrino are produced. An unstable atomic nucleus with an excess of neutrons may undergo β − decay, where a neutron is converted into a proton, an electron, and an electron antineutrino (the antiparticle of the neutrino): n → p + e − + ν e
Outside the nucleus, free neutrons undergo beta decay with a mean lifetime of about 14 minutes, 38 seconds, [24] corresponding to a half-life of about 10 minutes, 11 s. The mass of the neutron is greater than that of the proton by 1.293 32 MeV/ c 2 , [ 25 ] hence the neutron's mass provides energy sufficient for the creation of the proton ...
In nuclear physics, neutron decay may refer to: Neutron emission by an atomic nucleus; Free neutron decay; Beta decay of a neutron inside an atomic nucleus; Baryon decay, as predicted by grand unified theories, also involves neutron decay