Helium

Isotopes


IsotopeAbundanceT½ (s)Decay
3He0.000134 %Stable-
4He99.999866 %Stable-
5He-7.04 · 10−22n
6He-0.807β-
7He-3.04 · 10−21n
8He-2.85 · 10−22β-
β- n
9He--n
10He-1.52 · 10−21n


α: alpha particle emission (4He nucleus)
β+: emission of an anti-electron and a neutrino. A proton inside the nucleus is transformed into a neutron
β-: emission of an electron and an anti-neutrino. A neutron inside the nucleus is transformed into a proton
ec: electron capture: capture of one orbital electron by the the nucleus. A proton inside the nucleus is transformed into a neutron plus a neutrino
SF: Spontaneous Fission: a nucleus spontaneously splits into fragment nuclides
IT: Isomeric Transition: a level above the ground state decays via electromagnetic process
n: neutron emission
p: proton emission
β- n (and similar): beta- decay followed by delayed neutron emission