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  2. Half-life - Wikipedia

    en.wikipedia.org/wiki/Half-life

    Instead, the half-life is defined in terms of probability: "Half-life is the time required for exactly half of the entities to decay on average". In other words, the probability of a radioactive atom decaying within its half-life is 50%. [2] For example, the accompanying image is a simulation of many identical atoms undergoing radioactive decay.

  3. Biological half-life - Wikipedia

    en.wikipedia.org/wiki/Biological_half-life

    So, for example, digoxin has a half-life (or t ⁠ 1 / 2 ⁠) of 24–36 h; this means that a change in the dose will take the best part of a week to take full effect. For this reason, drugs with a long half-life (e.g., amiodarone , elimination t ⁠ 1 / 2 ⁠ of about 58 days) are usually started with a loading dose to achieve their desired ...

  4. List of radioactive nuclides by half-life - Wikipedia

    en.wikipedia.org/wiki/List_of_radioactive...

    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.

  5. Transient equilibrium - Wikipedia

    en.wikipedia.org/wiki/Transient_equilibrium

    The activity of the daughter is given by the Bateman equation: = () + (), where and are the activity of the parent and daughter, respectively. and are the half-lives (inverses of reaction rates in the above equation modulo ln(2)) of the parent and daughter, respectively, and BR is the branching ratio.

  6. Krypton-85 - Wikipedia

    en.wikipedia.org/wiki/Krypton-85

    Krypton-85 (85 Kr) is a radioisotope of krypton.. Krypton-85 has a half-life of 10.756 years and a maximum decay energy of 687 keV. [1] It decays into stable rubidium-85.Its most common decay (99.57%) is by beta particle emission with a maximum energy of 687 keV and an average energy of 251 keV.

  7. Branching fraction - Wikipedia

    en.wikipedia.org/wiki/Branching_fraction

    For example, for decays of 132 Cs, 98.13% are ε (electron capture) or β + decays, and 1.87% are β − decays. The half-life of this isotope is 6.480 days, [2] which corresponds to a total decay constant of 0.1070 d −1. Then the partial decay constants, as computed from the branching fractions, are 0.1050 d −1 for ε/β + decays, and 2.14 ...

  8. Effective half-life - Wikipedia

    en.wikipedia.org/wiki/Effective_half-life

    Alternatively, since the radioactive decay contributes to the "physical (i.e. radioactive)" half-life, while the metabolic elimination processes determines the "biological" half-life of the radionuclide, the two act as parallel paths for elimination of the radioactivity, the effective half-life could also be represented by the formula: [1] [2]

  9. Half-life of knowledge - Wikipedia

    en.wikipedia.org/wiki/Half-life_of_knowledge

    An engineering degree went from having a half life of 35 years in ca. 1930 to about 10 years in 1960. [1] A Delphi Poll showed that the half life of psychology as measured in 2016 ranged from 3.3 to 19 years depending on the specialty, with an average of a little over 7 years. [2]