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This is a list of radioactive nuclides (sometimes also called isotopes), ordered by half-life from shortest to longest, in seconds, minutes, hours, days and years. Current methods include jumping up and down make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds.
There is a half-life describing any exponential-decay process. For example: As noted above, in radioactive decay the half-life is the length of time after which there is a 50% chance that an atom will have undergone nuclear decay. It varies depending on the atom type and isotope, and is usually determined experimentally. See List of nuclides.
The half-life, t 1/2, is the time taken for the activity of a given amount of a radioactive substance to decay to half of its initial value. The decay constant , λ " lambda ", the reciprocal of the mean lifetime (in s −1 ), sometimes referred to as simply decay rate .
Potassium-42 has a short half life of just over half a day, so exposure to it is usually through the air, but it cannot accumulate in longer lived plants or animals. Potassium-42 is produced by the natural decay of argon-42 with a half-life time of 32.9 years. Argon-42 is in turn produced mostly from nuclear reactions between highly energetic ...
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.
The 4n decay chain of 232 Th, commonly called the "thorium series" Thorium-232 has a half-life of 14 billion years and mainly decays by alpha decay to radium-228 with a decay energy of 4.0816 MeV. [3] The decay chain follows the thorium series, which terminates at stable lead-208. The intermediates in the thorium-232 decay chain are all ...
Iodine-131 (131 I, I-131) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. [3] It has a radioactive decay half-life of about eight days.
While 238 U is minimally radioactive, its decay products, thorium-234 and protactinium-234, are beta particle emitters with half-lives of about 20 days and one minute respectively. Protactinium-234 decays to uranium-234, which has a half-life of hundreds of millennia, and this isotope does not reach an equilibrium concentration for a very long ...