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  2. Half-life - Wikipedia

    en.wikipedia.org/wiki/Half-life

    The term "half-life" is almost exclusively used for decay processes that are exponential (such as radioactive decay or the other examples above), or approximately exponential (such as biological half-life discussed below). In a decay process that is not even close to exponential, the half-life will change dramatically while the decay is happening.

  3. Exponential decay - Wikipedia

    en.wikipedia.org/wiki/Exponential_decay

    For example, if the initial population of the assembly, N(0), is 1000, then the population at time , (), is 368. A very similar equation will be seen below, which arises when the base of the exponential is chosen to be 2, rather than e. In that case the scaling time is the "half-life".

  4. Radioactive decay - Wikipedia

    en.wikipedia.org/wiki/Radioactive_decay

    For example, carbon-14, a radioactive nuclide with a half-life of only 5700(30) years, [27] is constantly produced in Earth's upper atmosphere due to interactions between cosmic rays and nitrogen. Nuclides that are produced by radioactive decay are called radiogenic nuclides, whether they themselves are stable or not.

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

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

    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 make it difficult to measure half-lives between approximately 10 −19 and 10 −10 seconds.

  6. Alpha decay - Wikipedia

    en.wikipedia.org/wiki/Alpha_decay

    As an extreme example, the half-life of the isotope bismuth-209 is 2.01 × 10 19 years. The isotopes in beta-decay stable isobars that are also stable with regards to double beta decay with mass number A = 5, A = 8, 143 ≤ A ≤ 155, 160 ≤ A ≤ 162, and A ≥ 165 are theorized to undergo alpha decay.

  7. Decay scheme - Wikipedia

    en.wikipedia.org/wiki/Decay_scheme

    The decay scheme of a radioactive substance is a graphical presentation of all the transitions occurring in a decay, and of their relationships. Examples are shown below. It is useful to think of the decay scheme as placed in a coordinate system, where the vertical axis is energy, increasing from bottom to top, and the horizontal axis is the proton number, increasing from left to right.

  8. Commonly used gamma-emitting isotopes - Wikipedia

    en.wikipedia.org/wiki/Commonly_used_gamma...

    It has a half-life of 30 years, and decays by beta decay without gamma ray emission to a metastable state of barium-137 (137m Ba). Barium-137m has a half-life of a 2.6 minutes and is responsible for all of the gamma ray emission in this decay sequence. The ground state of barium-137 is stable. The photon energy (energy of a single gamma ray) of ...

  9. Beta decay - Wikipedia

    en.wikipedia.org/wiki/Beta_decay

    Another example is the decay of hydrogen-3 into helium-3 with a half-life of about 12.3 years: 3 1 H → 3 2 He + e − + ν e. An example of positron emission (β + decay) is the decay of magnesium-23 into sodium-23 with a half-life of about 11.3 s: 23 12 Mg → 23 11 Na + e + + ν e