Positron emission

From Freepedia

Nuclear processes

Radioactive decay processes Alpha decay Beta decay Cluster decay Double beta decay Double electron capture Electron capture Gamma radiation Internal conversion Isomeric transition Neutron emission Positron emission Proton emission Spontaneous fission Nucleosynthesis Neutron Capture The R-process The S-process Proton capture: The P-process

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.

Electron capture is a competing decay mode in this process and is energetically favored, but as the energy difference goes up so does the branching ratio towards positron emission.

See also

• Beta decay