ModeDefinition Example
β Negatron (electron) emission. Conversion of a neutron to a proton and emission of an electron and an antineutrino 60Co → 60Ni + e + ν¯
β+Positron emission. Conversion of a proton to a neutron and emission of an positron and an neutrino. Always in competition with EC decay. 22Na → 22Ne + e+ + ν
ECElectron capture. Capture of an atomic electron converting a proton to a neutron and emission of a neutrino. 57Co + e57Fe + ν
αAlpha (4He) emission. 238U → 231Pa + α
ITIsomeric transition. γ-ray or conversion electron emission from an long-lived metastable state. γ-ray emission from short-lived excited states frequently accompanies all decay modes. 137mBa → 137Ba + γ(662 keV)
SFSpontaneous fission. Splitting of nucleus into to lighter nuclei, usually accompanied by neutron emission. 252Cf → 137I + 112Rh + 3n
pProton emission. 145Er → 144Ho + p
nNeutron emission. 10Li → 9Li + n
ββDouble negatron emission. Conversion of two neutrons to two protons and emission of two electrons and two antinuetrinos. 128Te → 128Xe + 2e + 2ν¯
ECECDouble orbital electron capture. Conversion of two protons to two neutrons and emission of two positrons and two neutrinos. 124Xe → 124Te + 2e+ + 2ν
βxNegatron-delayed emission of x=n,2n,α,... 145Cs → 144Ba + e + ν¯ + n
ECxElectron capture emission of x=p,α,SF,... 147Dy → 146Tb + e+ + ν + p
14C14C emission. Other nuclei can also be emitted. 226Ra → 212Pb + 14C
It is generally true that a nucleus can decay by multiple alternative energetically possible decay modes. The decay branching intensities are given, when known.