Editing Copernicium (section)

===Discovery===
Copernicium was [[discovery of the chemical elements|first created]] on 9 February 1996, at the [[Gesellschaft für Schwerionenforschung]] (GSI) in [[Darmstadt]], Germany, by [[Sigurd Hofmann]], [[Victor Ninov]] et al.<ref name="96Ho01" /> This element was created by firing accelerated [[zinc]]-70 nuclei at a target made of [[lead]]-208 nuclei in a heavy [[ion accelerator]]. A single atom of copernicium was produced with a [[mass number]] of 277. (A second was originally reported, but was found to have been based on data fabricated by Ninov, and was thus retracted.)<ref name="96Ho01">
{{cite journal
|last1=Hofmann |first1=S.
|year=1996
|title=The new element 112
|journal=[[Zeitschrift für Physik A]]
|volume=354 |issue=1 |pages=229–230
|bibcode=1996ZPhyA.354..229H
|doi=10.1007/BF02769517
|s2cid=119975957
|display-authors=etal}}</ref>

:{{su|p=208|b=82|a=r}}Pb + {{su|p=70|b=30}}Zn → {{su|p=278|b=112}}Cn* → {{su|p=277|b=112}}Cn + {{su|p=1|b=0}}n

In May 2000, the GSI successfully repeated the experiment to synthesize a further atom of copernicium-277.<ref>{{cite journal
|last1           = Hofmann
|first1          = S.
|year            = 2000
|title           = New Results on Element 111 and 112
|journal = European Physical Journal A
|volume = 14
|issue = 2
|pages = 147–157
|url             = https://www.gsi.de/informationen/wti/library/scientificreport2000/Nuc_St/7/ar-2000-z111-z112.pdf
|publisher       = [[Gesellschaft für Schwerionenforschung]]
|display-authors = etal
|access-date      = 2 March 2008
|archive-url     = https://web.archive.org/web/20080227134031/https://www.gsi.de/informationen/wti/library/scientificreport2000/Nuc_St/7/ar-2000-z111-z112.pdf
|archive-date    = 27 February 2008
|url-status      = dead
|bibcode = 2002EPJA...14..147H
|doi = 10.1140/epja/i2001-10119-x
|s2cid = 8773326
}}</ref>
This reaction was repeated at [[RIKEN]] using the Search for a Super-Heavy Element Using a Gas-Filled Recoil Separator set-up in 2004 and 2013 to synthesize three further atoms and confirm the decay data reported by the GSI team.<ref name="japan">
{{cite conference
|last1=Morita |first1=K.
|year=2004
|title=Decay of an Isotope <sup>277</sup>112 produced by <sup>208</sup>Pb + <sup>70</sup>Zn reaction
|editor1-last=Penionzhkevich |editor1-first=Yu. E.
|editor2-last=Cherepanov |editor2-first=E. A.
|book-title=Exotic Nuclei: Proceedings of the International Symposium
|pages=188–191
|publisher=[[World Scientific]]
|doi=10.1142/9789812701749_0027
}}</ref><ref>{{Cite journal | doi=10.7566/JPSJ.82.024202|title = New Result on the Production of277Cn by the208Pb +70Zn Reaction| journal=Journal of the Physical Society of Japan| volume=82| issue=2| pages=024202|year = 2013|last1 = Sumita|first1 = Takayuki| last2=Morimoto| first2=Kouji| last3=Kaji| first3=Daiya| last4=Haba| first4=Hiromitsu| last5=Ozeki| first5=Kazutaka| last6=Sakai| first6=Ryutaro| last7=Yoneda| first7=Akira| last8=Yoshida| first8=Atsushi| last9=Hasebe| first9=Hiroo| last10=Katori| first10=Kenji| last11=Sato| first11=Nozomi| last12=Wakabayashi| first12=Yasuo| last13=Mitsuoka| first13=Shin-Ichi| last14=Goto| first14=Shin-Ichi| last15=Murakami| first15=Masashi| last16=Kariya| first16=Yoshiki| last17=Tokanai| first17=Fuyuki| last18=Mayama| first18=Keita| last19=Takeyama| first19=Mirei| last20=Moriya| first20=Toru| last21=Ideguchi| first21=Eiji| last22=Yamaguchi| first22=Takayuki| last23=Kikunaga| first23=Hidetoshi| last24=Chiba| first24=Junsei| last25=Morita| first25=Kosuke|bibcode = 2013JPSJ...82b4202S}}</ref> This reaction had also previously been tried in 1971 at the [[Joint Institute for Nuclear Research]] in [[Dubna]], [[Russia]] to aim for <sup>276</sup>Cn (produced in the 2n channel), but without success.<ref>{{cite web |url=https://newuc.jinr.ru/img_sections/file/Practice2016/EU/2016-07%20AGP_SHE.pdf |title=Synthesis of superheavy elements |last=Popeko |first=Andrey G. |date=2016 |website=jinr.ru |publisher=[[Joint Institute for Nuclear Research]] |access-date=4 February 2018 |archive-url=https://web.archive.org/web/20180204124109/https://newuc.jinr.ru/img_sections/file/Practice2016/EU/2016-07%20AGP_SHE.pdf |archive-date=4 February 2018 |url-status=dead }}</ref>

The [[IUPAC/IUPAP Joint Working Party]] (JWP) assessed the claim of copernicium's discovery by the GSI team in 2001<ref>{{cite journal
|last1=Karol
|first1=P. J.
|last2=Nakahara
|first2=H.
|last3=Petley
|first3=B. W.
|last4=Vogt
|first4=E.
|year=2001
|title=On the Discovery of the Elements 110–112
|url=https://www.iupac.org/publications/pac/2001/pdf/7306x0959.pdf
|journal=[[Pure and Applied Chemistry]]
|volume=73
|issue=6
|pages=959–967
|doi=10.1351/pac200173060959
|s2cid=97615948
|access-date=9 January 2008
|archive-url=https://web.archive.org/web/20180309212208/https://www.iupac.org/publications/pac/2001/pdf/7306x0959.pdf
|archive-date=9 March 2018
|url-status=dead
}}</ref> and 2003.<ref>{{cite journal
|last1=Karol
|first1=P. J.
|last2=Nakahara
|first2=H.
|last3=Petley
|first3=B. W.
|last4=Vogt
|first4=E.
|year=2003
|title=On the Claims for Discovery of Elements 110, 111, 112, 114, 116 and 118
|url=https://www.iupac.org/publications/pac/2003/pdf/7510x1601.pdf
|journal=[[Pure and Applied Chemistry]]
|volume=75
|issue=10
|pages=1061–1611
|doi=10.1351/pac200375101601
|s2cid=95920517
|access-date=9 January 2008
|archive-url=https://web.archive.org/web/20160822073903/https://www.iupac.org/publications/pac/2003/pdf/7510x1601.pdf
|archive-date=22 August 2016
|url-status=dead
}}</ref> In both cases, they found that there was insufficient evidence to support their claim. This was primarily related to the contradicting decay data for the known [[nuclide]] rutherfordium-261. However, between 2001 and 2005, the GSI team studied the reaction <sup>248</sup>Cm(<sup>26</sup>Mg,5n)<sup>269</sup>Hs, and were able to confirm the decay data for [[hassium-269]] and [[rutherfordium-261]]. It was found that the existing data on rutherfordium-261 was for an [[Nuclear isomer|isomer]],<ref>
{{cite web
|last1=Dressler
|first1=R.
|last2=Türler
|first2=A.
|year=2001
|title=Evidence for Isomeric States in <sup>261</sup>Rf
|url=https://lch.web.psi.ch/files/anrep01/B-02heavies.pdf
|work=Annual Report
|publisher=[[Paul Scherrer Institute]]
|url-status=dead
|archive-url=https://web.archive.org/web/20110707001918/https://lch.web.psi.ch/files/anrep01/B-02heavies.pdf
|archive-date=2011-07-07
}}</ref> now designated rutherfordium-261m.

In May 2009, the JWP reported on the claims of discovery of element&nbsp;112 again and officially recognized the GSI team as the discoverers of element 112.<ref name="GSINewElement">{{cite web
|date         = 10 June 2009
|title        = A New Chemical Element in the Periodic Table
|url          = https://www.gsi.de/portrait/Pressemeldungen/10062009_e.html
|publisher    = [[Gesellschaft für Schwerionenforschung]]
|access-date   = 14 April 2012
|archive-url  = https://web.archive.org/web/20090823022637/https://www.gsi.de/portrait/Pressemeldungen/10062009_e.html
|archive-date = 23 August 2009
|url-status   = dead
}}</ref> This decision was based on the confirmation of the decay properties of daughter nuclei as well as the confirmatory experiments at RIKEN.<ref name="fusion">{{cite journal
|last1=Barber
|first1=R. C.
|year=2009
|title=Discovery of the element with atomic number 112
|journal=[[Pure and Applied Chemistry]]
|volume=81
|issue=7
|page=1331
|doi=10.1351/PAC-REP-08-03-05
|s2cid=95703833
|url=https://pac.iupac.org/publications/pac/pdf/2009/pdf/8107x1331.pdf
|display-authors=etal
|access-date=2022-02-22
|archive-date=2012-11-28
|archive-url=https://web.archive.org/web/20121128020041/http://pac.iupac.org/publications/pac/pdf/2009/pdf/8107x1331.pdf
|url-status=dead
}}</ref>

Work had also been done at the [[Joint Institute for Nuclear Research]] in [[Dubna]], Russia from 1998 to synthesise the heavier isotope <sup>283</sup>Cn in the hot fusion reaction <sup>238</sup>U(<sup>48</sup>Ca,3n)<sup>283</sup>Cn; most observed atoms of <sup>283</sup>Cn decayed by spontaneous fission, although an alpha decay branch to <sup>279</sup>Ds was detected. While initial experiments aimed to assign the produced nuclide with its observed long half-life of 3&nbsp;minutes based on its chemical behaviour, this was found to be not mercury-like as would have been expected (copernicium being under mercury in the periodic table),<ref name="fusion" /> and indeed now it appears that the long-lived activity might not have been from <sup>283</sup>Cn at all, but its [[electron capture]] daughter <sup>283</sup>Rg instead, with a shorter 4-second half-life associated with <sup>283</sup>Cn. (Another possibility is assignment to a [[meta state|metastable isomeric state]], <sup>283m</sup>Cn.)<ref name="EXON">{{cite conference |title=Remarks on the Fission Barriers of SHN and Search for Element 120 |first1=S. |last1=Hofmann |first2=S. |last2=Heinz |first3=R. |last3=Mann |first4=J. |last4=Maurer |first5=G. |last5=Münzenberg |first6=S. |last6=Antalic |first7=W. |last7=Barth |first8=H. G. |last8=Burkhard |first9=L. |last9=Dahl |first10=K. |last10=Eberhardt |first11=R. |last11=Grzywacz |first12=J. H. |last12=Hamilton |first13=R. A. |last13=Henderson |first14=J. M. |last14=Kenneally |first15=B. |last15=Kindler |first16=I. |last16=Kojouharov |first17=R. |last17=Lang |first18=B. |last18=Lommel |first19=K. |last19=Miernik |first20=D. |last20=Miller |first21=K. J. |last21=Moody |first22=K. |last22=Morita |first23=K. |last23=Nishio |first24=A. G. |last24=Popeko |first25=J. B. |last25=Roberto |first26=J. |last26=Runke |first27=K. P. |last27=Rykaczewski |first28=S. |last28=Saro |first29=C. |last29=Schneidenberger |first30=H. J. |last30=Schött |first31=D. A. |last31=Shaughnessy |first32=M. A. |last32=Stoyer |first33=P. |last33=Thörle-Pospiech |first34=K. |last34=Tinschert |first35=N. |last35=Trautmann |first36=J. |last36=Uusitalo |first37=A. V. |last37=Yeremin |year=2016 |conference=Exotic Nuclei |editor1-first=Yu. E. |editor1-last=Peninozhkevich |editor2-first=Yu. G. |editor2-last=Sobolev |book-title=Exotic Nuclei: EXON-2016 Proceedings of the International Symposium on Exotic Nuclei |pages=155–164 |isbn=9789813226555}}</ref> While later cross-bombardments in the <sup>242</sup>Pu+<sup>48</sup>Ca and <sup>245</sup>Cm+<sup>48</sup>Ca reactions succeeded in confirming the properties of <sup>283</sup>Cn and its parents <sup>287</sup>Fl and <sup>291</sup>Lv, and played a major role in the acceptance of the discoveries of [[flerovium]] and [[livermorium]] (elements 114 and 116) by the JWP in 2011, this work originated subsequent to the GSI's work on <sup>277</sup>Cn and priority was assigned to the GSI.<ref name="fusion" />