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There are two long-lived alpha-emitters; 243 Am has a half-life of 7,370 years and is the most stable isotope, and 241 Am has a half-life of 432.2 years. The most stable nuclear isomer is 242m1 Am; it has a long half-life of 141 years. The half-lives of other isotopes and isomers range from 0.64 microseconds for 245m1 Am to 50.8 hours for 240 ...
With its half-life of 432.2 years, the americium in a smoke detector decreases and includes about 3% neptunium after 19 years, and about 5% after 32 years. The amount of americium in a typical new smoke detector is 0.29 micrograms (4.5 × 10 −6 grains) (about 1/3000 the weight of a small grain of sand) with an activity of 1 microcurie (37 kBq ...
Radioactive isotope table "lists ALL radioactive nuclei with a half-life greater than 1000 years", incorporated in the list above. The NUBASE2020 evaluation of nuclear physics properties F.G. Kondev et al. 2021 Chinese Phys. C 45 030001. The PDF of this article lists the half-lives of all known radioactives nuclides.
Americium-243 has a mass of 243.06138 g/mol and a half-life of 7,370 years, the longest lasting of all americium isotopes. It is formed in the nuclear fuel cycle by neutron capture on plutonium-242 followed by beta decay . [ 15 ]
3.1 abundance, half-life trace, synthetic, stable by keyboard code 3.2 decay mode ( β − β − ) by keyboard code 3.3 percentage abundance, decay mode formatting
Americium is stable in the +3 oxidation state, while the +4 oxidation state of plutonium can form in the human body. [20] The most common isotope americium-241 decays (half-life 432 years) to neptunium-237 which has a much longer half-life, so in the long term, the issues discussed above for neptunium apply. [21]
Americium hydroxide is a pink solid [1] which is sparingly soluble in water. [2]Due to self-irradiation, the crystal structure of 241 Am(OH) 3 decomposes within 4 to 6 months (241 Am has a half-life of 432.2 years); for 244 Cm(OH) 3 the same process takes one day (244 Cm has a half-life of 18.11 years).
At least 3,300 nuclides have been experimentally characterized [1] (see List of radioactive nuclides by half-life for the nuclides with decay half-lives less than one hour). A nuclide is defined conventionally as an experimentally examined bound collection of protons and neutrons that either is stable or has an observed decay mode .