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2024-11-02T03:48:09Z

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{{Infobox oganesson isotopes}}
[[Oganesson]] (118Og) is a [[synthetic element]] created in [[particle accelerator]]s, and thus a [[standard atomic weight]] cannot be given. Like all synthetic elements, it has no [[stable isotope]]s. The first and only [[isotope]] to be synthesized was 294Og in 2002 and 2005; it has a [[half-life]] of 0.7 milliseconds.

== List of isotopes ==
{{Anchor|Oganesson-291|Oganesson-292|Oganesson-293|Oganesson-295}}



{{Isotopes table
|symbol=Og
|refs=AME2020 II, NUBASE2020
|notes=unc(), mass#
}}

|-id=Oganesson-294
| 294Og
| style="text-align:right" | 118
| style="text-align:right" | 176
| 294.21398(59)#
| {{val|0.58|0.44|0.18|u=ms}} [{{val|0.7|(3)|u=ms}}]
| α
| [[Isotopes of livermorium|290Lv]]
| 0+

{{Isotopes table/footer}}

==Nucleosynthesis==
===Target-projectile combinations leading to Z=118 compound nuclei===
The below table contains various combinations of targets and projectiles that could be used to form compound nuclei with Z=118.{{Citation needed|date=February 2021}}

{| class="wikitable" style="text-align:center"
! Target !! Projectile !! CN !! Attempt result
|-
! 208Pb
|86Kr || 294Og || {{No|Failure to date}}
|-
! 238U
|58Fe ||296Og || {{unk|Reaction yet to be attempted}}
|-
! 244Pu
| 54Cr || 298Og || {{unk|Reaction yet to be attempted}}
|-
! 248Cm
|50Ti ||298Og || {{no|Failure to date}}
|-
! 250Cm
|50Ti ||300Og || {{unk|Reaction yet to be attempted}}
|-
! 249Cf
|48Ca ||297Og || {{Yes|Successful reaction}}
|-
! 250Cf
|48Ca ||298Og || {{No|Failure to date}}
|-
! 251Cf
|48Ca ||299Og || {{No|Failure to date}}
|-
! 252Cf
|48Ca ||300Og || {{unk|Reaction yet to be attempted}}
|}

===Cold fusion===
====208Pb(86Kr,''x''n)294-''x''Og====
In 1999, a team led by [[Victor Ninov]] at the [[Lawrence Berkeley National Laboratory]] performed this experiment, as a 1998 calculation by [[Robert Smolańczuk]] suggested a promising outcome. After eleven days of irradiation, three events of 293Og and its [[alpha decay]] products were reported in this reaction; this was the first reported discovery of element 118 and then-unknown [[livermorium|element 116]].<ref name="Transuraniumppl">{{cite book |last1=Hoffman |first1=D.C |last2=Ghiorso |first2=A. |last3=Seaborg |first3=G.T. |title=The Transuranium People: The Inside Story |pages=425–431 |publisher=Imperial College Press |date=2000 |isbn=978-1-86094-087-3}}</ref>

The following year, they published a [[retraction in academic publishing|retraction]] after researchers at other laboratories were unable to duplicate the results and the Berkeley lab could not duplicate them either.<ref>{{cite news|url=http://enews.lbl.gov/Science-Articles/Archive/118-retraction.html|publisher=Berkeley Lab|author=Public Affairs Department|title=Results of element 118 experiment retracted|date=21 July 2001|access-date=18 January 2008|url-status=dead|archive-url=https://web.archive.org/web/20080129191344/http://enews.lbl.gov/Science-Articles/Archive/118-retraction.html|archive-date=29 January 2008|df=dmy-all}}</ref> In June 2002, the director of the lab announced that the original claim of the discovery of these two elements had been based on data fabricated by principal author Victor Ninov.<ref>{{cite journal|pages=728–729|title=Misconduct: The stars who fell to Earth|journal=[[Nature (journal)|Nature]]|volume=420|doi=10.1038/420728a|date=2002|pmid=12490902|last1=Dalton| first1=R.|issue=6917|bibcode = 2002Natur.420..728D |s2cid=4398009 }}</ref><ref>[http://physicsworld.com/cws/article/news/2629 Element 118 disappears two years after it was discovered] {{Webarchive|url=https://web.archive.org/web/20071012075515/http://physicsworld.com/cws/article/news/2629 |date=2007-10-12 }}. Physicsworld.com. Retrieved on 2 April 2012.</ref> Newer experimental results and theoretical predictions have confirmed the exponential decrease in cross-sections with lead and bismuth targets as the atomic number of the resulting nuclide increases.<ref name="Zagrebaev">{{cite journal|title=Future of superheavy element research: Which nuclei could be synthesized within the next few years?|url=http://nrv.jinr.ru/pdf_file/J_phys_2013.pdf|first1=Valeriy|last1=Zagrebaev|first2=Alexander|last2=Karpov|first3=Walter |last3=Greiner|date=2013|journal=Journal of Physics|volume=420|issue=1|pages=012001|doi=10.1088/1742-6596/420/1/012001|arxiv=1207.5700|bibcode=2013JPhCS.420a2001Z|s2cid=55434734 }}</ref>

===Hot fusion===
====249Cf(48Ca,''x''n)297-''x''Og (''x''=3)====
Following successful experiments utilizing [[calcium-48]] projectiles and actinide targets to generate elements [[flerovium|114]] and 116,<ref name="shesummary">{{cite journal|last=Oganessian|first=Y.T.|date=2015|title=Super-heavy element research|url=https://www.researchgate.net/publication/273327193|journal=Reports on Progress in Physics|volume=78|issue=3|pages=036301|doi=10.1088/0034-4885/78/3/036301|pmid=25746203|bibcode=2015RPPh...78c6301O|s2cid=37779526 }}</ref> the search for element 118 was first performed at the [[Joint Institute for Nuclear Research]] (JINR) in 2002. One or two atoms of 294Og were produced in the 2002 experiment, and two more atoms were produced in a 2005 confirmation run. The discovery of element 118 was announced in 2006.<ref name="synthesis-118-116" />

Because of the very small [[fusion reaction]] probability (the fusion [[nuclear cross section|cross section]] is roughly 0.3–0.6 [[Barn (unit)|pb]]), 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=http://www.webelements.com/webelements/elements/text/Uuo/key.html|title=Ununoctium|publisher=WebElements Periodic Table|access-date=2007-12-09}}</ref>
Nevertheless, researchers were highly confident that the results were not a [[false positive]]; the chance that they were random events was estimated to be less than one part in 100,000.<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 |page=11 |doi=10.1021/cen-v084n043.p011 }}</ref>

In a 2012 experiment aimed at the confirmation of [[tennessine]], one alpha decay chain was attributed to 294Og. This synthesis event resulted from the population of 249Cf in the target as the decay product of the 249Bk target (half-life 330 days); the cross section and decays were consistent with previously reported observations of 294Og.<ref name="shesummary" />

From 1 October 2015 until 6 April 2016, the team at the JINR conducted a search for new isotopes of oganesson using a 48Ca beam and a target comprising a mixture of 249Cf (50.7%), 250Cf (12.9%), and 251Cf (36.4%). The experiment was performed at 252 MeV and 258 MeV beam energies. One event of 294Og was found at the lower beam energy, while no decays of oganesson isotopes were found at the higher beam energy; a cross section of 0.9 pb for the 249Cf(48Ca,3n) reaction was estimated.<ref name="mixedCf" />

====250,251Cf(48Ca,''x''n)298,299-''x''Og====
In the 2015–2016 experiment, these reactions were performed in a search for 295Og and 296Og. No events attributable to a reaction with the 250Cf or 251Cf portions of the target were found. A repeat of this experiment was planned for 2017–2018.<ref name="mixedCf">{{cite journal |last=Voinov |first=A.A. |display-authors=et al. |title=Study of the 249-251Cf + 48Ca reactions: recent results and outlook |date=2018 |journal=Journal of Physics: Conference Series |volume=966 |issue=1 |pages=012057 |url=https://www.researchgate.net/publication/318324354 |doi=10.1088/1742-6596/966/1/012057|bibcode=2018JPhCS.966a2057V |doi-access=free }}</ref>

====248Cm(50Ti,''x''n)298-''x''Og====
This reaction was originally planned to be tested at the JINR and [[RIKEN]] in 2017–2018, as it uses the same 50Ti projectile as planned experiments leading to elements [[ununennium|119]] and [[unbinilium|120]].<ref name="roberto">
{{cite web |url=http://cyclotron.tamu.edu/she2015/assets/pdfs/presentations/Roberto_SHE_2015_TAMU.pdf |title=Actinide Targets for Super-Heavy Element Research |last=Roberto |first=J. B. |date=31 March 2015 |website=cyclotron.tamu.edu |publisher=Texas A & M University |access-date=28 April 2017}}</ref> A search beginning in summer 2016 at RIKEN for 295Og in the 3n channel of this reaction was unsuccessful, though the study is planned to resume; a detailed analysis and cross section limit were not provided.<ref name="conseil">{{cite conference |last=Hauschild |first=K. |title=Superheavy nuclei at RIKEN, Dubna, and JYFL |date=26 June 2019 |conference=Conseil Scientifique de l'IN2P3 |url=https://in2p3.cnrs.fr/sites/institut_in2p3/files/page/2019-07/6-Pres-HAUSCHILD_-compresse%CC%81.pdf |access-date=31 July 2019}}</ref><ref name="conseil2">{{cite conference |last=Hauschild |first=K. |title=Heavy nuclei at RIKEN, Dubna, and JYFL |date=2019 |conference=Conseil Scientifique de l'IN2P3 |url=https://in2p3.cnrs.fr/sites/institut_in2p3/files/page/2019-07/6-Doc-HAUSCHILD-comp.pdf |access-date=1 August 2019}}</ref>

==Theoretical calculations==
Theoretical calculations done on the synthetic pathways for, and the half-life of, other isotopes have shown that some could be slightly more stable than the synthesized isotope 294Og, most likely 293Og, 295Og, 296Og, 297Og, 298Og, 300Og and 302Og.<ref name="half-lifes">{{cite journal |journal=Physical Review C |volume=73 |issue=1 |pages=014612 |date= January 26, 2006 |title=α decay half-lives of new superheavy elements |author=P. Roy Chowdhury |author2=C. Samanta |author3=D. N. Basu |url=http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=PRVCAN000073000001014612000001&idtype=cvips&gifs=yes |access-date=2008-01-18 |doi = 10.1103/PhysRevC.73.014612 |arxiv = nucl-th/0507054 |bibcode = 2006PhRvC..73a4612C |s2cid=118739116 }}</ref><ref>{{cite journal |journal=Nuclear Physics A |volume=789 |date= April 6, 2007 |issue=1–4 |pages=142–154 |title=Predictions of alpha decay half lives of heavy and superheavy elements |author=C. Samanta |author2=P. Roy Chowdhury |author3=D. N. Basu |doi=10.1016/j.nuclphysa.2007.04.001 |bibcode=2007NuPhA.789..142S |arxiv = nucl-th/0703086 |citeseerx=10.1.1.264.8177 |s2cid=7496348 }}</ref><ref name="odd">{{cite journal |journal=Nuclear Physics A |volume=730 |year=2004 |issue=3–4 |pages=355–376 |title=Entrance channels and alpha decay half-lives of the heaviest elements |author=G. Royer |author2=K. Zbiri |author3=C. Bonilla |doi=10.1016/j.nuclphysa.2003.11.010 |bibcode=2004NuPhA.730..355R |arxiv = nucl-th/0410048 }}</ref> Of these, 297Og might provide the best chances for obtaining longer-lived nuclei,<ref name="half-lifes" /><ref name="odd" /> and thus might become the focus of future work with this element. Some isotopes with many more neutrons, such as some located around 313Og, could also provide longer-lived nuclei.<ref>{{cite journal |title=Half-life predictions for decay modes of superheavy nuclei |year=2004 |journal=Journal of Physics G: Nuclear and Particle Physics |volume=30 |issue=10 |pages=1487–1494 |doi=10.1088/0954-3899/30/10/014 |author=S. B. Duarte |author2=O. A. P. Tavares |author3=M. Gonçalves |author4=O. Rodríguez |author5=F. Guzmán |author6=T. N. Barbosa |author7=F. García |author8=A. Dimarco |bibcode=2004JPhG...30.1487D|citeseerx=10.1.1.692.3012 }}</ref>

===Theoretical calculations on evaporation cross sections ===
The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.

DNS = Di-nuclear system; 2S = Two-step; σ = cross section

{| class="wikitable" style="text-align:center"
|-
! Target !! Projectile !! CN !! Channel (product) !! σ max !! Model !! Ref
|-
! 208Pb
| 86Kr ||294Og || 1n (293Og) ||0.1 pb ||DNS || <ref name="FengColdFusion">{{cite journal |doi=10.1103/PhysRevC.76.044606 |title=Formation of superheavy nuclei in cold fusion reactions |year=2007 |last1=Feng |first1=Zhao-Qing |journal=Physical Review C |volume=76 |issue=4 |pages=044606 |last2=Jin |first2=Gen-Ming |last3=Li |first3=Jun-Qing |last4=Scheid |first4=Werner |bibcode=2007PhRvC..76d4606F |arxiv = 0707.2588 |s2cid=711489 }}</ref>
|-
! 208Pb
| 85Kr ||293Og || 1n (292Og) ||0.18 pb ||DNS || <ref name="FengColdFusion" />
|-
! 246Cm
| 50Ti ||296Og || 3n (293Og) ||40 fb ||2S || <ref name="LiuTwoStep">{{cite journal|last1=Liu|first1=L.|last2=Shen|first2=C.|last3=Li|first3=Q.|last4=Tu|first4=Y.|last5=Wang |first5=X.|last6=Wang|first6=Y.|date=2016|title=Residue cross sections of 50Ti-induced fusion reactions based on the two-step model|journal=[[European Physical Journal A]]|volume=52|issue=35|page=35 |doi=10.1140/epja/i2016-16035-0|arxiv=1512.06504|bibcode=2016EPJA...52...35L |s2cid=254116073 }}</ref>
|-
! 244Cm
| 50Ti ||294Og || 2n (292Og) ||53 fb ||2S || <ref name="LiuTwoStep" />
|-
! 252Cf
| 48Ca ||300Og || 3n (297Og) ||1.2 pb ||DNS || <ref name="FengHotFusion">{{cite journal |doi=10.1016/j.nuclphysa.2008.11.003 |title=Production of heavy and superheavy nuclei in massive fusion reactions |year=2009 |last1=Feng |first1=Z |journal=Nuclear Physics A |volume=816 |issue=1–4 |pages=33–51 |last2=Jin |first2=G |last3=Li |first3=J |last4=Scheid |first4=W |bibcode=2009NuPhA.816...33F |arxiv = 0803.1117 |s2cid=18647291 }}</ref>
|-
! 251Cf
| 48Ca ||299Og || 3n (296Og) ||1.2 pb ||DNS || <ref name="FengHotFusion" />
|-
! 249Cf
| 48Ca ||297Og || 3n (294Og) ||0.3 pb ||DNS || <ref name="FengHotFusion" />
|}

== References ==
{{reflist}}
{{Navbox element isotopes}}

[[Category:Isotopes of oganesson| ]]
[[Category:Oganesson]]
[[Category:Lists of isotopes by element|oganesson]]

Isotopes of oganesson - Revision history

>Double sharp: /* top */ actually, symmetrise uncertainty