Mode |
Definition |
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 |
EC |
Electron capture. Capture of an atomic electron converting a proton to a neutron and emission of a neutrino. |
57Co + e− → 57Fe + ν |
α |
Alpha (4He) emission. |
238U → 231Pa + α |
IT |
Isomeric 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) |
SF |
Spontaneous fission. Splitting of nucleus into to lighter nuclei, usually accompanied by neutron emission. |
252Cf → 137I + 112Rh + 3n |
p |
Proton emission. |
145Er → 144Ho + p |
n |
Neutron emission. |
10Li → 9Li + n |
β−β− |
Double negatron emission. Conversion of two neutrons to two protons and emission of two electrons and two antinuetrinos. |
128Te → 128Xe + 2e− + 2ν¯ |
ECEC |
Double orbital electron capture. Conversion of two protons to two neutrons and emission of two positrons and two neutrinos. |
124Xe → 124Te + 2e+ + 2ν |
β−x |
Negatron-delayed emission of x=n,2n,α,... |
145Cs → 144Ba + e− + ν¯ + n |
ECx |
Electron capture emission of x=p,α,SF,... |
147Dy → 146Tb + e+ + ν + p |
14C |
14C 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. |