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Cosmogenic nuclide
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<h2 id="cosmogenic-nuclides">Cosmogenic nuclides</h2> <p>Here is a list of radioisotopes formed by the action of <a href="/facts/Cosmic_rays/uxCVdTKd">cosmic rays</a>; the list also contains the production mode of the isotope.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> Most cosmogenic nuclides are formed in the atmosphere, but some are formed in situ in soil and rock exposed to cosmic rays, notably calcium-41 in the table below. </p> Isotopes formed by the action of <a href="/facts/Cosmic_rays/uxCVdTKd">cosmic rays</a><table><tbody><tr><th>Isotope</th><th>Mode of formation</th><th>half life</th></tr><tr><th><a href="/facts/Tritium/HWSa6EHy">3H (tritium)</a></th><td>14N(n,12C)T</td><td>12.3 y</td></tr><tr><th><a href="/facts/Isotopes_of_beryllium/bNvHB5xg">7Be</a></th><td><a href="/facts/Cosmic_ray_spallation/gSlq9VEP">Spallation</a> (N and O)</td><td>53.2 d</td></tr><tr><th><a href="/facts/Beryllium-10/oz3rQBLB">10Be</a></th><td>Spallation (N and O)</td><td>1,387,000 y</td></tr><tr><th><a href="/facts/Carbon-11/K1LfqDNj">11C</a></th><td>Spallation (N and O)</td><td>20.3 min</td></tr><tr><th><a href="/facts/Carbon-14/Ut8SBNNa">14C</a></th><td>14N(n,p)14C</td><td>5,730 y</td></tr><tr><th><a href="/facts/Fluorine-18/4VpH1NYh">18F</a></th><td>18O(p,n)18F and Spallation (Ar)</td><td>110 min</td></tr><tr><th><a href="/facts/Sodium-22/dGhdEPWX">22Na</a></th><td>Spallation (Ar)</td><td>2.6 y</td></tr><tr><th><a href="/facts/Isotopes_of_sodium/dGhdEPWX">24Na</a></th><td>Spallation (Ar)</td><td>15 h</td></tr><tr><th><a href="/facts/Isotopes_of_magnesium/pv5hSrhW">28Mg</a></th><td>Spallation (Ar)</td><td>20.9 h</td></tr><tr><th><a href="/facts/Aluminium-26/INwQYapg">26Al</a></th><td>Spallation (Ar)</td><td>717,000 y</td></tr><tr><th><a href="/facts/Isotopes_of_silicon/8NzaY3wR">31Si</a></th><td>Spallation (Ar)</td><td>157 min</td></tr><tr><th><a href="/facts/Isotopes_of_silicon/8NzaY3wR">32Si</a></th><td>Spallation (Ar)</td><td>153 y</td></tr><tr><th><a href="/facts/Isotopes_of_phosphorus/vE2sGdt2">32P</a></th><td>Spallation (Ar)</td><td>14.3 d</td></tr><tr><th><a href="/facts/Isotopes_of_phosphorus/vE2sGdt2">33P</a></th><td>Spallation (Ar)</td><td>25.3 d</td></tr><tr><th><a href="/facts/Isotopes_of_chlorine/fdtzH9YF">34mCl</a></th><td>Spallation (Ar)</td><td>34 min</td></tr><tr><th><a href="/facts/Isotopes_of_sulfur/08Qs8w3o">35S</a></th><td>Spallation (Ar)</td><td>87.5 d</td></tr><tr><th><a href="/facts/Chlorine-36/IqR2WJxp">36Cl</a></th><td>35Cl (n,γ)36Cl</td><td>301,000 y</td></tr><tr><th><a href="/facts/Isotopes_of_argon/BhxtyJGu">37Ar</a></th><td>37Cl (p,n)37Ar</td><td>35 d</td></tr><tr><th><a href="/facts/Isotopes_of_chlorine/fdtzH9YF">38Cl</a></th><td>Spallation (Ar)</td><td>37 min</td></tr><tr><th><a href="/facts/Isotopes_of_argon/BhxtyJGu">39Ar</a></th><td>40Ar (n,2n)39Ar</td><td>269 y</td></tr><tr><th><a href="/facts/Isotopes_of_chlorine/fdtzH9YF">39Cl</a></th><td>40Ar (n,np)39Cl & spallation (Ar)</td><td>56 min</td></tr><tr><th><a href="/facts/Isotopes_of_argon/BhxtyJGu">41Ar</a></th><td>40Ar (n,γ)41Ar</td><td>110 min</td></tr><tr><th><a href="/facts/Isotopes_of_calcium/YhuBa6LI">41Ca</a></th><td>40Ca (n,γ)41Ca</td><td>102,000 y</td></tr><tr><th><a href="/facts/Isotopes_of_krypton/8hRKYepJ">81Kr</a></th><td>80Kr (n,γ) 81Kr</td><td>229,000 y</td></tr><tr><th><a href="/facts/Isotopes_of_iodine/HxgH1yJD">129I</a></th><td>Spallation (Xe)</td><td>15,700,000 y</td></tr></tbody></table> <h3>Applications in geology listed by isotope</h3> Commonly measured long lived cosmogenic isotopes<table><tbody><tr><th><a href="/facts/Chemical_element/0jducgWD">element</a></th><th><a href="/facts/Atomic_mass/J1FJY9MV">mass</a></th><th><a href="/facts/Half-life/kGVH8BAB">half-life</a> (years)</th><th>typical application</th></tr><tr><td><a href="/facts/Beryllium/dv295voP">beryllium</a></td><td>10</td><td>1,387,000</td><td>exposure dating of rocks, soils, ice cores</td></tr><tr><td><a href="/facts/Aluminium/7wmR8jYE">aluminium</a></td><td>26</td><td>720,000</td><td>exposure dating of rocks, sediment</td></tr><tr><td><a href="/facts/Chlorine/y27UwYBM">chlorine</a></td><td>36</td><td>308,000</td><td>exposure dating of rocks, <a href="/facts/Groundwater/JYM2IDS2">groundwater</a> tracer</td></tr><tr><td><a href="/facts/Calcium/hf252CC0">calcium</a></td><td>41</td><td>103,000</td><td>exposure dating of <a href="/facts/Carbonate_rock/pKYTxRkM">carbonate rocks</a></td></tr><tr><td><a href="/facts/Iodine/JlfMecMf">iodine</a></td><td>129</td><td>15,700,000</td><td>groundwater tracer</td></tr><tr><td><a href="/facts/Carbon/ukrgQexo">carbon</a></td><td>14</td><td>5730</td><td><a href="/facts/Radiocarbon_dating/qjNglhKP">radiocarbon dating</a></td></tr><tr><td><a href="/facts/Sulfur/IK0amTfM">sulfur</a></td><td>35</td><td>0.24</td><td>water residence times</td></tr><tr><td><a href="/facts/Sodium/eYuSPu2V">sodium</a></td><td>22</td><td>2.6</td><td>water residence times</td></tr><tr><td><a href="/facts/Tritium/HWSa6EHy">tritium</a></td><td>3</td><td>12.32</td><td>water residence times</td></tr><tr><td><a href="/facts/Argon/QX6NRH6d">argon</a></td><td>39</td><td>269</td><td>groundwater tracer</td></tr><tr><td><a href="/facts/Krypton/llkNlCke">krypton</a></td><td>81</td><td>229,000</td><td>groundwater tracer</td></tr></tbody></table> <h2 id="use-in-geochronology">Use in geochronology</h2> <p>As seen in the table above, there are a wide variety of useful cosmogenic nuclides which can be measured in soil, rocks, groundwater, and the atmosphere.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> These nuclides all share the common feature of being absent in the host material at the time of formation. These nuclides are chemically distinct and fall into two categories. The nuclides of interest are either <a href="/facts/Noble_gases/j0yHMEAE">noble gases</a> which due to their inert behavior are inherently not trapped in a crystallized mineral or has a short enough half-life such that it has decayed since <a href="/facts/Nucleosynthesis/F9MIeADF">nucleosynthesis</a>, but a long enough half-life such that it has built up measurable concentrations. The former includes measuring abundances of 81Kr and 39Ar whereas the latter includes measuring abundances of 10Be, 14C, and 26Al. </p><p>Three types of cosmic-ray reactions can occur once a cosmic ray strikes matter which in turn produce the measured cosmogenic nuclides.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p> <ul><li><a href="/facts/Cosmic_ray_spallation/gSlq9VEP">cosmic ray spallation</a>, which is the most common reaction on the near-surface (typically 0 to 60 cm below) the Earth and can create secondary particles which can cause additional reaction upon interaction with another nuclei called a <a href="/facts/Collision_cascade/jdMWJzhM">collision cascade</a>.</li> <li><a href="/facts/Muon_capture/BEdvDAeL">muon capture</a>, which pervades at depths a few meters below the subsurface because muons are inherently less reactive; in some cases, high-energy muons can reach greater depths<a class="footnote-ref" id="fnref:8" href="#fn:8"><sup>8</sup></a></li> <li><a href="/facts/Neutron_capture/elsFpM12">neutron capture</a>, which due to the neutron's low energy are captured into a nucleus, most commonly by water, but this process is highly dependent on snow, soil moisture and trace element concentrations.</li></ul> <h3>Corrections for cosmic-ray fluxes</h3> <p>Since the Earth bulges at the equator and mountains and deep oceanic trenches allow for deviations of several kilometers relative to a uniformly smooth spheroid, cosmic rays bombard the Earth's surface unevenly based on the latitude and altitude. Thus, many geographic and geologic considerations must be understood in order for cosmic-ray flux to be accurately determined. <a href="/facts/Atmospheric_pressure/wJLMSaVG">Atmospheric pressure</a>, for example, which varies with altitude, can change the production rate of nuclides within minerals by a factor of 30 between sea level and the top of a 5 km high mountain. Even variations in the slope of the ground can affect how far high-energy muons can penetrate the subsurface.<a class="footnote-ref" id="fnref:9" href="#fn:9"><sup>9</sup></a> Geomagnetic field strength which varies over time affects the production rate of cosmogenic nuclides though some models assume variations of the field strength are averaged out over geologic time and are not always considered. </p> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Environmental_radioactivity/z2B6mF3r">Environmental radioactivity</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 13–15. ISBN 978-0-08-037941-8. <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>"Beryllium | Properties, Uses, & Facts | Britannica". www.britannica.com. 2023-09-17. Retrieved 2023-10-19. <a href="https://www.britannica.com/science/beryllium" target="_blank">https://www.britannica.com/science/beryllium</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 13–15. ISBN 978-0-08-037941-8. <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Sapphire Lally (Jul 24, 2021). "How is gold made? The mysterious cosmic origins of heavy elements". New Scientist. <a href="https://www.newscientist.com/article/mg25133440-800-how-is-gold-made-the-mysterious-cosmic-origins-of-heavy-elements/" target="_blank">https://www.newscientist.com/article/mg25133440-800-how-is-gold-made-the-mysterious-cosmic-origins-of-heavy-elements/</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>SCOPE 50 - Radioecology after Chernobyl Archived 2014-05-13 at the Wayback Machine, the Scientific Committee on Problems of the Environment (SCOPE), 1993. See table 1.9 in Section 1.4.5.2. <a href="http://www.scopenvironment.org/downloadpubs/scope50" target="_blank">http://www.scopenvironment.org/downloadpubs/scope50</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Schaefer, Joerg M.; Codilean, Alexandru T.; Willenbring, Jane K.; Lu, Zheng-Tian; Keisling, Benjamin; Fülöp, Réka-H.; Val, Pedro (2022-03-10). "Cosmogenic nuclide techniques". Nature Reviews Methods Primers. 2 (1): 1–22. doi:10.1038/s43586-022-00096-9. ISSN 2662-8449. S2CID 247396585. <a href="https://www.nature.com/articles/s43586-022-00096-9" target="_blank">https://www.nature.com/articles/s43586-022-00096-9</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>Lal, D.; Peters, B. (1967). "Cosmic Ray Produced Radioactivity on the Earth". Kosmische Strahlung II / Cosmic Rays II. Handbuch der Physik / Encyclopedia of Physics. Vol. 9 / 46 / 2. pp. 551–612. doi:10.1007/978-3-642-46079-1_7. ISBN 978-3-642-46081-4. <a href="978-3-642-46081-4" target="_blank">978-3-642-46081-4</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> <li id="fn:8"><p>Heisinger, B.; Lal, D.; Jull, A. J. T.; Kubik, P.; Ivy-Ochs, S.; Knie, K.; Nolte, E. (30 June 2002). "Production of selected cosmogenic radionuclides by muons: 2. Capture of negative muons". Earth and Planetary Science Letters. 200 (3): 357–369. Bibcode:2002E&PSL.200..357H. doi:10.1016/S0012-821X(02)00641-6. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:8" class="footnote-back-ref">↩</a></p></li> <li id="fn:9"><p>Dunne, Jeff; Elmore, David; Muzikar, Paul (1 February 1999). "Scaling factors for the rates of production of cosmogenic nuclides for geometric shielding and attenuation at depth on sloped surfaces". Geomorphology. 27 (1): 3–11. Bibcode:1999Geomo..27....3D. doi:10.1016/S0169-555X(98)00086-5. <a href="/wiki/Bibcode_(identifier)" target="_blank">/wiki/Bibcode_(identifier)</a> <a href="#fnref:9" class="footnote-back-ref">↩</a></p></li> </ol>