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出典:『Wikipedia』 (2011/02/17 22:09 UTC 版)

英語による解説

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Plutonium-244 (²⁴⁴Pu) is an isotope of plutonium that has a halflife of 80 million years. This is longer than any of the other isotopes of plutonium and longer than any actinide except for the three naturally abundant ones uranium-235 (700my), uranium-238, and thorium-232. It is also longer than any other known radioactive isotopes except samarium-146 (103my), potassium-40 (1.25by), and a number of nearly stable isotopes with half-lives much longer than the age of the universe, such as bismuth-209 (19 quintillion years).