Electron Capture
Radioactive decay in which a nucleus absorbs an inner-shell electron, converting a proton into a neutron.
Formula / equation
p + e⁻ → n + ν
Unit
MeV
In depth
Electron capture competes with positron emission in proton-rich nuclei and is the only option when the energy available is below the 1.02 MeV needed to create a positron. The vacancy left in the inner shell is filled by an outer electron, emitting a characteristic X-ray.
Examples in the real world
Potassium-40 capturing an electron to become argon-40, the basis of potassium–argon rock dating.