Editing Radioactive tracer (section)

===Hydrogen===
[[Tritium]] (hydrogen-3) is produced by neutron irradiation of [[lithium|<sup>6</sup>Li]]:
:[[lithium|<sup>6</sup>Li]] + [[neutron|n]] → [[Helium|<sup>4</sup>He]] + [[tritium|<sup>3</sup>H]]
Tritium has a [[half-life]] {{val|4500|8}} days (approximately 12.32 years)<ref>{{cite journal | vauthors = Lucas LL, Unterweger MP | title = Comprehensive Review and Critical Evaluation of the Half-Life of Tritium | journal = Journal of Research of the National Institute of Standards and Technology | volume = 105 | issue = 4 | pages = 541–9 | year = 2000 | pmid = 27551621 | doi = 10.6028/jres.105.043 | url = http://nvl.nist.gov/pub/nistpubs/jres/105/4/j54luc2.pdf | archive-url = https://web.archive.org/web/20111017042101/http://nvl.nist.gov/pub/nistpubs/jres/105/4/j54luc2.pdf | url-status = dead | archive-date = 2011-10-17 | pmc=4877155}}</ref> and it decays by [[beta decay]]. The [[electron]]s produced have an average energy of 5.7&nbsp;keV. Because the emitted electrons have relatively low energy, the detection efficiency by scintillation counting is rather low. However, hydrogen atoms are present in all organic compounds, so tritium is frequently used as a tracer in [[biochemistry|biochemical]] studies.