Aluminium-26

Aluminium-26
General
Symbol26Al
Namesaluminium-26
Protons (Z)13
Neutrons (N)13
Nuclide data
Natural abundancetrace (cosmogenic)
Half-life (t1/2)7.17×105 years
Spin5+
Decay modes
Decay modeDecay energy (MeV)
β+4.00414
ε4.00414
Isotopes of aluminium
Complete table of nuclides

Aluminium-26 (26Al, Al-26) is a radioactive isotope of the chemical element aluminium, decaying by either positron emission or electron capture to stable magnesium-26. The half-life of 26Al is 717,000 years. This is far too short for the isotope to survive as a primordial nuclide, but a small amount of it is produced by collisions of atoms with cosmic ray protons.

Decay of aluminium-26 also produces gamma rays and x-rays. The x-rays and Auger electrons are emitted by the excited atomic shell of the daughter 26Mg after the electron capture which typically leaves a hole in one of the lower sub-shells.

Because it is radioactive, it is typically stored behind at least 5 centimetres (2 in) of lead. Contact with 26Al may result in radiological contamination. This necessitates special tools for transfer, use, and storage.