Editing Oganesson (section)

===Discovery reports===
[[File:Oganesson-294 nuclear.svg|thumb|upright=0.9|alt=Schematic diagram of oganesson-294 alpha decay, with a half-life of 0.89&nbsp;ms and a decay energy of 11.65&nbsp;MeV. The resulting livermorium-290 decays by alpha decay, with a half-life of 10.0&nbsp;ms and a decay energy of 10.80&nbsp;MeV, to flerovium-286. Flerovium-286 has a half-life of 0.16&nbsp;s and a decay energy of 10.16&nbsp;MeV, and undergoes alpha decay to copernicium-282 with a 0.7 rate of spontaneous fission. Copernicium-282 itself has a half-life of only 1.9&nbsp;ms and has a 1.0 rate of spontaneous fission.|[[Radioactive decay]] pathway of the [[isotope]] oganesson-294.<ref name="synthesis-118-116"/> The [[decay energy]] and average [[half-life]] are given for the [[parent isotope]] and each [[daughter isotope]]. The fraction of atoms undergoing [[spontaneous fission]] (SF) is given in green.]]

The first genuine decay of atoms of oganesson was observed in 2002 at the [[Joint Institute for Nuclear Research]] (JINR) in [[Dubna]], Russia, by a joint team of Russian and American scientists. Headed by [[Yuri Oganessian]], a Russian nuclear physicist of Armenian ethnicity, the team included American scientists from the [[Lawrence Livermore National Laboratory]] in California.<ref name="pp2002">{{cite journal|author=Oganessian, Yu. T.|display-authors=etal|title=Results from the first {{chem|249|Cf}}+{{chem|48|Ca}} experiment|url=https://www.jinr.ru/publish/Preprints/2002/287(D7-2002-287)e.pdf|journal=JINR Communication|date=2002|access-date=13 June 2009|archive-date=13 December 2004|archive-url=https://web.archive.org/web/20041213100709/https://www.jinr.ru/publish/Preprints/2002/287%28D7-2002-287%29e.pdf|url-status=dead}}</ref> The discovery was not announced immediately, because the decay energy of <sup>294</sup>Og matched that of [[isotopes of polonium|<sup>212m</sup>Po]], a common impurity produced in fusion reactions aimed at producing superheavy elements, and thus announcement was delayed until after a 2005 confirmatory experiment aimed at producing more oganesson atoms.<ref name="Moody"/> The 2005 experiment used a different beam energy (251&nbsp;MeV instead of 245&nbsp;MeV) and target thickness (0.34&nbsp;mg/cm<sup>2</sup> instead of 0.23&nbsp;mg/cm<sup>2</sup>).<ref name="synthesis-118-116"/> On 9 October 2006, the researchers announced<ref name="synthesis-118-116"/> that they had indirectly detected a total of three (possibly four) nuclei of oganesson-294 (one or two in 2002<ref>{{cite web|url=https://159.93.28.88/linkc/118/anno.html |title=Element 118: results from the first {{SimpleNuclide|Californium|249}} + {{SimpleNuclide|Calcium|48}} experiment |author=Oganessian, Yu. T. |display-authors=etal |publisher=Communication of the Joint Institute for Nuclear Research |date=2002 |url-status=dead |archive-url=https://web.archive.org/web/20110722060249/https://159.93.28.88/linkc/118/anno.html |archive-date=22 July 2011 }}</ref> and two more in 2005) produced via collisions of [[californium]]-249 atoms and [[calcium-48]] ions.<ref>{{cite news|title=Livermore scientists team with Russia to discover element 118|url=https://www.llnl.gov/news/newsreleases/2006/NR-06-10-03.html|publisher=Livermore press release|date=3 December 2006|access-date=18 January 2008|archive-url=https://web.archive.org/web/20111017105348/https://www.llnl.gov/news/newsreleases/2006/NR-06-10-03.html|archive-date=17 October 2011|url-status=dead}}</ref><ref>{{cite journal|author=Oganessian, Yu. T.|title=Synthesis and decay properties of superheavy elements|journal=Pure Appl. Chem.|volume=78|pages=889–904|doi=10.1351/pac200678050889|date=2006|issue=5|s2cid=55782333|doi-access=free}}</ref><ref>{{cite journal|title=Heaviest element made – again|journal=Nature News|date=2006|doi=10.1038/news061016-4|author= Sanderson, K.|s2cid=121148847}}</ref><ref>{{cite web|author=Schewe, P. |author2=Stein, B. |name-list-style=amp |title=Elements 116 and 118 Are Discovered |work=Physics News Update |publisher=[[American Institute of Physics]] |date=17 October 2006 |url=https://www.aip.org/pnu/2006/797.html |access-date=18 January 2008 |url-status=dead |archive-url=https://web.archive.org/web/20120101144201/https://www.aip.org/pnu/2006/797.html |archive-date= 1 January 2012 }}</ref><ref>{{cite news|url=https://www.washingtonpost.com/wp-dyn/content/article/2006/10/16/AR2006101601083.html|title=Scientists Announce Creation of Atomic Element, the Heaviest Yet|newspaper=The Washington Post|author=Weiss, R.|date=17 October 2006|access-date=18 January 2008}}</ref>

:{{nuclide|link=yes|Californium|249}} + {{nuclide|link=yes|Calcium|48}} → {{nuclide|link=yes|Oganesson|294}} + 3 {{SubatomicParticle|link=yes|Neutron}}.

In 2011, [[IUPAC]] evaluated the 2006 results of the Dubna–Livermore collaboration and concluded: "The three events reported for the ''Z'' = 118 isotope have very good internal
redundancy but with no anchor to known nuclei do not satisfy the criteria for discovery".<ref>{{cite journal|doi=10.1351/PAC-REP-10-05-01|title=Discovery of the elements with atomic numbers greater than or equal to 113 (IUPAC Technical Report)|date=2011|last1=Barber|first1=Robert C.|last2=Karol|first2=Paul J.|last3=Nakahara|first3=Hiromichi|last4=Vardaci|first4=Emanuele|last5=Vogt|first5=Erich W.|journal=Pure and Applied Chemistry|page=1|volume=83|issue=7|doi-access=free}}</ref>

Because of the very small [[fusion reaction]] probability (the fusion [[nuclear cross section|cross section]] is {{gaps|~|0.3–0.6|u=[[Barn (unit)|pb]]}} or {{val|p=(|3|end=–6)|e=-41|u=m2}}) the experiment took four months and involved a beam dose of {{val|2.5|e=19}} [[calcium]] ions that had to be shot at the [[californium]] target to produce the first recorded event believed to be the synthesis of oganesson.<ref name="webelements">{{cite web|url=https://www.webelements.com/oganesson/|title=Oganesson|publisher=WebElements Periodic Table|access-date=19 August 2019}}</ref> Nevertheless, researchers were highly confident that the results were not a [[false positive]], since the chance that the detections were random events was estimated to be less than one part in {{val|100000}}.<ref>{{cite journal|quote="I would say we're very confident."|url=https://pubs.acs.org/cen/news/84/i43/8443element118.html|title=Element 118 Detected, With Confidence|journal=Chemical & Engineering News|date=17 October 2006|access-date=18 January 2008|author=Jacoby, Mitch |volume=84|issue=43|pages=11|doi=10.1021/cen-v084n043.p011}}</ref>

In the experiments, the alpha-decay of three atoms of oganesson was observed. A fourth decay by direct [[spontaneous fission]] was also proposed. A [[half-life]] of 0.89&nbsp;ms was calculated: {{chem|294|Og}} decays into {{chem|link=Isotopes of livermorium#Livermorium-290|290|Lv}} by [[alpha decay]]. Since there were only three nuclei, the half-life derived from observed lifetimes has a large uncertainty: {{val|0.89|+1.07|-0.31|u=ms}}.<ref name="synthesis-118-116"/>

:{{nuclide|Oganesson|294}} → {{nuclide|livermorium|290}} + {{nuclide|link=yes|helium|4}}

The identification of the {{chem|294|Og}} nuclei was verified by separately creating the putative [[decay product|daughter nucleus]] {{chem|290|Lv}} directly by means of a bombardment of {{chem|link=curium-245|245|Cm}} with {{chem|link=calcium-48|48|Ca}} ions,

:{{nuclide|Curium|245}} + {{nuclide|Calcium|48}} → {{nuclide|livermorium|290}} + 3 {{SubatomicParticle|link=yes|Neutron}},

and checking that the {{chem|290|Lv}} decay matched the [[decay chain]] of the {{chem|294|Og}} nuclei.<ref name="synthesis-118-116"/> The daughter nucleus {{chem|290|Lv}} is very unstable, decaying with a lifetime of 14 milliseconds into {{chem|link=flerovium-286|286|Fl}}, which may experience either spontaneous fission or alpha decay into {{chem|link=copernicium-282|282|Cn}}, which will undergo spontaneous fission.<ref name="synthesis-118-116"/>