Beta decay
In nuclear physics, beta decay is a type of radioactive decay where a beta particle (an electron or a positron) is made and sent away, or emitted. When it is an electron, it is called beta minus, and changes a neutron into a proton. When it is a positron, it is beta plus and changes a proton into a neutron. The weak force makes beta decay possible.
In regular matter†, as the neutron becomes a proton, but the number of nucleons stays the same, the atomic mass will change by 0, but the atomic number will increase by +1. In effect, we can say the β particle has an atomic number of "-1".[math]\ce{ ^{16}_{6}C -> ^{16}_{7}N + ^{0}_{-1}\beta }[/math](† - see Antimatter)
Beta Decay Media
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 boson.
A beta spectrum, showing a typical division of energy between electron and antineutrino
The leading-order Feynman diagram for decay of a neutron into a proton, electron, and electron antineutrino via a virtual boson. For higher-order diagrams see
The leading-order Feynman diagram for ' decay of a proton into a neutron, positron, and electron neutrino via an intermediate virtual boson
The leading-order Feynman diagrams for electron capture decay. An electron interacts with an up quark in the nucleus via a W boson to create a down quark and electron neutrino. Two diagrams comprise the leading (second) order, though as a virtual particle, the type (and charge) of the W-boson is indistinguishable.
Beta spectrum of 210Bi. Emax = Q = 1.16 MeV is the maximum energy
icon for the live chart of nuclides application at the IAEA Nuclear Data Section
