Editing Cosmic ray (section)

===Changes in atmospheric chemistry===
Cosmic rays ionize nitrogen and oxygen molecules in the atmosphere, which leads to a number of chemical reactions. Cosmic rays are also responsible for the continuous production of a number of [[Radionuclide|unstable isotopes]], such as [[carbon-14]], in the Earth's atmosphere through the reaction:

{{block indent|n + <sup>14</sup>N → p + <sup>14</sup>C}}

Cosmic rays kept the level of carbon-14<ref>{{cite book|last=Trumbore|first=Susan|author-link=Susan Trumbore|title=Quaternary Geochronology: Methods and Applications|year=2000|publisher=American Geophysical Union|location=Washington, D.C.|isbn=978-0-87590-950-9|pages=41–59|url=http://www.agu.org/books/rf/v004/|editor=J. S. Noller|editor2=J. M. Sowers|editor3=W. R. Lettis|access-date=28 October 2011|archive-date=21 May 2013|archive-url=https://web.archive.org/web/20130521094616/http://www.agu.org/books/rf/v004/|url-status=dead}}</ref> in the atmosphere roughly constant (70 tons) for at least the past 100,000 years,{{citation needed|date=July 2017}} until the beginning of above-ground nuclear weapons testing in the early 1950s. This fact is used in [[radiocarbon dating]].

====Reaction products of primary cosmic rays, radioisotope half-lifetime, and production reaction====
<!-- Converting this to a table would be nice-->
{{columns-list|colwidth=30em|
* [[Hydrogen-1]] (stable): [[cosmic ray spallation|spallation]] from nitrogen and oxygen, decay of neutrons from such spallation
* [[Helium-3]] (stable): spallation or from tritium
* [[Helium-4]] (stable): spallation producing alpha rays
* [[Tritium]] (12.3 years): <sup>14</sup>N(n, <sup>3</sup>H)<sup>12</sup>C (spallation)
* Beryllium-7 (53.3 days)
* [[Beryllium-10]] (1.39 million years): <sup>14</sup>N(n,p α)<sup>10</sup>Be (spallation)
* [[Carbon-14]] (5730 years): <sup>14</sup>N(n, p)<sup>14</sup>C ([[neutron activation]])
* Sodium-22 (2.6 years)
* Sodium-24 (15 hours)
* Magnesium-28 (20.9 hours)
* Silicon-31 (2.6 hours)
* Silicon-32 (101 years)
* [[Phosphorus-32]] (14.3 days)
* Sulfur-35 (87.5 days)
* Sulfur-38 (2.84 hours)
* Chlorine-34 m (32 minutes)
* [[Chlorine-36]] (300,000 years)
* Chlorine-38 (37.2 minutes)
* Chlorine-39 (56 minutes)
* Argon-39 (269 years)
* [[Krypton-85]] (10.7 years)<ref>{{cite web|title=Natürliche, durch kosmische Strahlung laufend erzeugte Radionuklide|url=http://www.um.baden-wuerttemberg.de/servlet/is/34839/Natuerliche_durch_kosmische_Strahlung_laufend_erzeugte_Radionuklide.pdf?command=downloadContent&filename=Natuerliche_durch_kosmische_Strahlung_laufend_erzeugte_Radionuklide.pdf|access-date=11 February 2010|language=de|archive-url=https://web.archive.org/web/20100203174117/http://www.um.baden-wuerttemberg.de/servlet/is/34839/Natuerliche_durch_kosmische_Strahlung_laufend_erzeugte_Radionuklide.pdf?command=downloadContent&filename=Natuerliche_durch_kosmische_Strahlung_laufend_erzeugte_Radionuklide.pdf|archive-date=3 February 2010|url-status=dead}}</ref>
}}