| Aluminium-26 | |
|---|---|
| General | |
| Name, symbol | Aluminium-26,26Al |
| Neutrons | 13 |
| Protons | 13 |
| Nuclide data | |
| Natural abundance | trace (cosmogenic) |
| Half-life | 7.17×105 years |
| Spin | 5+ |
| Decay mode | Decay energy |
| β+, γ, x-rays | fill in, please MeV |
| ε | fill in, please MeV |
Aluminium-26, 26Al, is a radioactive isotope of the chemical element aluminium, decaying by either of the modes beta-plus or electron capture, both resulting in the stable nuclide magnesium-26. The half-life of 26Al is 7.17×105 years. This is far too short for any but a very minute amount of the primordial atoms of the isotope to survive to the present, but small amounts of the nuclide is produced by collisions of argon atoms by cosmic ray protons.
Aluminium-26 also emits gamma rays and x-rays [1], and is one of the only radionuclides to emit x-rays. Because it is radioactive it should be stored behind at least 2 in. of lead and special tools should be used for transfer, use, and storage. Contact with 26Al may result in radiological contamination.[2]
Contents |
Aluminium-26 can be used to calculate the terrestrial age of meteorites. After the breakup of the meteorite parent body, it will be bombarded by cosmic rays, which will saturate it in aluminium-26. After falling to earth, 26Al production ceases, which means that the amount of 26Al in the sample can be used to calculate the date the meteorite fell to earth.
The gamma emission at 1809 keV was the first observed gamma emission from the galactic center. The observation was made by the HEAO-3 satellite in 1984.[3][4]
Before 1954, the measured half-life of aluminium-26 was determined to be 6.3 seconds.[5] After theoretical evidence occurred that this could be the half-life of the metastable state of aluminium-26 the ground state was produced by bombardment of magnesium-26 and magnesium-25 with deuterons in the cyclotron of the University of Pittsburgh.[6] The first half-life was determined to be in the range of 106 years.
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