Mode Definition
β Negatron (electron) emission. Conversion of a neutron to a proton and emission of an electron and an antineutrino
β+ Positron emission. Conversion of a proton to a neutron and emission of an positron and an neutrino. Always in competition with EC decay.
EC Electron capture. Capture of an atomic electron converting a proton to a neutron and emission of a neutrino.
α Alpha (4He) emission.
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.
SF Spontaneous fission. Splitting of nucleus into to lighter nuclei, usually accompanied by neutron emission.
p Proton emission.
n Neutron emission.
ββ Double negatron emission. Conversion of two neutrons to two protons and emission of two electrons and two antinuetrinos.
ECEC Double orbital electron capture. Conversion of two protons to two neutrons and emission of two positrons and two neutrinos.
βx Negatron-delayed emission of x=n,2n,α,...
ECx Electron capture emission of x=p,α,SF,...
14C 14C emission. Other nuclei can also be emitted.
It is generally true that a nucleus can decay by multiple alternative energetically possible decay modes. The decay branching intensities are given, when known.