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  2. Half-life - Wikipedia

    en.wikipedia.org/wiki/Half-life

    In this situation it is generally uncommon to talk about half-life in the first place, but sometimes people will describe the decay in terms of its "first half-life", "second half-life", etc., where the first half-life is defined as the time required for decay from the initial value to 50%, the second half-life is from 50% to 25%, and so on.

  3. Samarium-147 - Wikipedia

    en.wikipedia.org/wiki/Samarium-147

    Samarium-147 is used in samarium–neodymium dating.The method of isochron dating is used to find the date at which a rock (or group of rocks) are formed. [4] The Sm-Nd isochron plots the ratio of radiogenic 143 Nd to non-radiogenic 144 Nd against the ratio of the parent isotope 147 Sm to the non-radiogenic isotope 144 Nd.

  4. Isotopes of nitrogen - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_nitrogen

    It has a short half-life of about 7.1 s, [4] but its decay back to 16 O produces high-energy gamma radiation (5 to 7 MeV). [ 4 ] [ 10 ] Because of this, access to the primary coolant piping in a pressurised water reactor must be restricted during reactor power operation. [ 10 ]

  5. 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 ...

  6. Isotopes of phosphorus - Wikipedia

    en.wikipedia.org/wiki/Isotopes_of_phosphorus

    The longest-lived radioactive isotopes are 33 P with a half-life of 25.34 days and 32 P with a half-life of 14.268 days. [3] [4] All others have half-lives of under 2.5 minutes, most under a second. The least stable known isotope is 47 P, with a half-life of 2 milliseconds.

  7. 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.

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  9. Uranium-232 - Wikipedia

    en.wikipedia.org/wiki/Uranium-232

    Uranium-232 (232 U) is an isotope of uranium.It has a half-life of around 69 years and is a side product in the thorium cycle.It has been cited as an obstacle to nuclear proliferation using 233 U as the fissile material, because the intense gamma radiation emitted by 208 Tl (a daughter of 232 U, produced relatively quickly) makes the 233 U contaminated with it more difficult to handle.