Positron emission
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Positron emission is a type of beta decay, sometimes referred to as "beta plus" (β+). In beta plus decay, a proton is converted to a neutron via the weak nuclear force and a beta plus particle (a positron) and a neutrino are emitted. Isotopes which emit positrons include Carbon-11, Nitrogen-13, Oxygen-15 and Fluorine-18; for example:
- <math>
{}^{11}\hbox{C}\;\to\;^{11}\hbox{B}\;+\;e^+\;+\;\nu_e. </math> These isotopes are used in positron emission tomography, a technique used for medical imaging.
Electron capture is a competing decay mode in this process and is energetically favoured, but as the energy difference goes up so does the branching ratio towards positron emission.
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