2.3.3 Electron capture

Electron capture is sometimes included as a type of beta decay. 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.

Electron capture is a competing (simultaneous) decay process for all nuclei that can undergo β⁺ decay. The converse, however, is not true: electron capture is the only type of decay that is allowed in proton-rich nuclides that do not have sufficient energy to emit a positron and neutrino.