Editing Nihonium (section)

== History ==
{{See also|Discoveries of the chemical elements}}

=== Early indications ===
The syntheses of elements [[bohrium|107]] to [[copernicium|112]] were conducted at the [[GSI Helmholtz Centre for Heavy Ion Research]] in [[Darmstadt]], Germany, from 1981 to 1996. These elements were made by cold fusion{{efn|[[Transactinide element]]s, such as nihonium, are produced by [[nuclear fusion]]. These fusion reactions can be divided into "hot" and "cold" fusion, depending on the excitation energy of the compound nucleus produced. "Cold fusion" in the context of superheavy element synthesis is a distinct concept from the idea that nuclear fusion can be achieved under room temperature conditions.<ref>{{cite journal |doi=10.1016/0022-0728(89)80006-3 |title=Electrochemically induced nuclear fusion of deuterium |date=1989 |last1=Fleischmann |first1=Martin |last2=Pons |first2=Stanley |journal=Journal of Electroanalytical Chemistry and Interfacial Electrochemistry |volume=261 |issue=2 |pages=301–308}}</ref> In hot fusion reactions, light, high-energy projectiles are accelerated towards heavy targets ([[actinide]]s), creating compound nuclei at high excitation energy (~40–50&nbsp;[[electronvolt|MeV]]) that may fission, or alternatively emit several (3 to 5) neutrons.<ref name="fusion">{{cite journal |last1=Barber |first1=Robert C. |last2=Gäggeler |first2=Heinz W. |last3=Karol |first3=Paul J. |last4=Nakahara |first4=Hiromichi |last5=Vardaci |first5=Emanuele |last6=Vogt |first6=Erich |title=Discovery of the element with atomic number 112 (IUPAC Technical Report) |journal=Pure and Applied Chemistry |volume=81 |issue=7 |page=1331 |date=2009 |doi=10.1351/PAC-REP-08-03-05|doi-access=free }}</ref> Cold fusion reactions use heavier projectiles, typically from the [[period 4 element|fourth period]], and lighter targets, usually [[lead]] and [[bismuth]]. The fused nuclei produced have a relatively low excitation energy (~10–20&nbsp;MeV), which decreases the probability that they will undergo fission reactions. As the fused nuclei cool to the [[ground state]], they emit only one or two neutrons. Hot fusion produces more neutron-rich products because actinides have the highest neutron-to-proton ratios of any elements, and is currently the only method to produce the superheavy elements from [[flerovium]] (element 114) onwards.<ref name="AM89">{{Cite journal |first1=Peter |last1=Armbruster |first2=Gottfried |last2=Munzenberg |title=Creating superheavy elements |journal=Scientific American |volume=34 |pages=36–42 |date=1989}}</ref>}} reactions, in which targets made of [[lead]] and [[bismuth]], which are around the [[nuclear shell model|stable configuration]] of 82 protons, are bombarded with heavy ions of [[period 4 element]]s. This creates fused nuclei with low excitation energies due to the stability of the targets' nuclei, significantly increasing the yield of [[superheavy element]]s. Cold fusion was pioneered by [[Yuri Oganessian]] and his team in 1974 at the [[Joint Institute for Nuclear Research]] (JINR) in [[Dubna]], Soviet Union. Yields from cold fusion reactions were found to decrease significantly with increasing atomic number; the resulting nuclei were severely neutron-deficient and short-lived. The GSI team attempted to synthesise element 113 via cold fusion in 1998 and 2003, bombarding bismuth-209 with [[zinc]]-70; both attempts were unsuccessful.<ref name="Chapman" /><ref>{{cite conference |url=https://www.epj-conferences.org/articles/epjconf/pdf/2016/26/epjconf-NS160-06001.pdf |title=The discovery of elements 107 to 112 |last1=Hofmann |first1=Sigurd |date=2016 |conference=Nobel Symposium NS160 – Chemistry and Physics of Heavy and Superheavy Elements |doi=10.1051/epjconf/201613106001|doi-access=free }}</ref>

Faced with this problem, [[Yuri Oganessian|Oganessian]] and his team at the [[Joint Institute for Nuclear Research|JINR]] turned their renewed attention to the older hot fusion technique, in which heavy [[actinide]] targets were bombarded with lighter ions. [[Calcium-48]] was suggested as an ideal projectile, because it is very neutron-rich for a light element (combined with the already neutron-rich actinides) and would minimise the neutron deficiencies of the nuclides produced. Being [[doubly magic]], it would confer benefits in stability to the fused nuclei. In collaboration with the team at the [[Lawrence Livermore National Laboratory]] (LLNL) in [[Livermore, California]], United States, they made an attempt on [[flerovium|element 114]] (which was predicted to be a [[magic number (physics)|magic number]], closing a proton shell, and more stable than element 113).<ref name="Chapman" />

In 1998, the JINR–LLNL collaboration started their attempt on element 114, bombarding a target of [[plutonium-244]] with ions of calcium-48:<ref name="Chapman" />

:{{nuclide|plutonium|244}} + {{nuclide|calcium|48}} → <sup>292</sup>114* → <sup>290</sup>114 + 2 {{SubatomicParticle|neutron}} + e<sup>−</sup> → <sup>290</sup>113 + [[electron neutrino|ν<sub>e</sub>]] ?

A single [[atom]] was observed which was thought to be the isotope <sup>289</sup>114: the results were published in January 1999.<ref name="99Og01">{{cite journal |last1=Oganessian |first1=Yu. Ts. |display-authors=etal |date=1999 |title=Synthesis of Superheavy Nuclei in the <sup>48</sup>Ca + <sup>244</sup>Pu Reaction |url=http://flerovlab.jinr.ru/linkc/flnr_presentations/articles/synthesis_of_Element_114_1999.pdf |journal=[[Physical Review Letters]] |volume=83 |issue=16 |page=3154 |bibcode=1999PhRvL..83.3154O |doi=10.1103/PhysRevLett.83.3154 |access-date=5 April 2017 |archive-date=30 July 2020 |archive-url=https://web.archive.org/web/20200730232521/http://flerovlab.jinr.ru/linkc/flnr_presentations/articles/synthesis_of_Element_114_1999.pdf |url-status=dead }}</ref> Despite numerous attempts to repeat this reaction, an isotope with these decay properties has never again been found, and the exact identity of this activity is unknown.<ref name="04OgJINRPP">{{cite journal |last=Oganessian |first=Yu. Ts. |display-authors=etal |date=2004 |title=Measurements of cross sections and decay properties of the isotopes of elements 112, 114, and 116 produced in the fusion reactions <sup>233,238</sup>U, <sup>242</sup>Pu, and <sup>248</sup>Cm + <sup>48</sup>Ca |url=http://www.jinr.ru/publish/Preprints/2004/160(E7-2004-160).pdf |journal=[[Physical Review C]] |volume=70 |issue=6 |page=064609 |bibcode=2004PhRvC..70f4609O |doi=10.1103/PhysRevC.70.064609 |url-status=dead |archive-url=https://web.archive.org/web/20080528130343/http://www.jinr.ru/publish/Preprints/2004/160%28E7-2004-160%29.pdf |archive-date=28 May 2008 }}</ref> A 2016 paper by [[Sigurd Hofmann]] et al. considered that the most likely explanation of the 1998 result is that two neutrons were emitted by the produced compound nucleus, leading to <sup>290</sup>114 and [[electron capture]] to <sup>290</sup>113, while more neutrons were emitted in all other produced chains. This would have been the first report of a decay chain from an isotope of element 113, but it was not recognised at the time, and the assignment is still uncertain.<ref name="Hofmann2016" /> A similar long-lived activity observed by the JINR team in March 1999 in the <sup>242</sup>Pu + <sup>48</sup>Ca reaction may be due to the electron-capture daughter of <sup>287</sup>114, <sup>287</sup>113; this assignment is also tentative.<ref name="EXON" />

=== JINR–LLNL collaboration ===
The now-confirmed discovery of element 114 was made in June 1999 when the JINR team repeated the first <sup>244</sup>Pu + <sup>48</sup>Ca reaction from 1998;<ref name="00Og01">{{cite journal |last1=Oganessian |first1=Yu. Ts. |display-authors=etal |date=2000 |title=Synthesis of superheavy nuclei in the <sup>48</sup>Ca + <sup>244</sup>Pu reaction: <sup>288</sup>114 |journal=[[Physical Review C]] |volume=62 |issue=4 |page=041604 |bibcode=2000PhRvC..62d1604O |doi=10.1103/PhysRevC.62.041604}}</ref><ref name="04Og01">{{cite journal |last1=Oganessian |first1=Yu. Ts. |display-authors=etal |date=2004 |title=Measurements of cross sections for the fusion-evaporation reactions <sup>244</sup>Pu(<sup>48</sup>Ca,xn)<sup>292−x</sup>114 and <sup>245</sup>Cm(<sup>48</sup>Ca,xn)<sup>293−x</sup>116 |journal=[[Physical Review C]] |volume=69 |issue=5 |page=054607 |bibcode=2004PhRvC..69e4607O |doi=10.1103/PhysRevC.69.054607|url=http://link.aps.org/abstract/PRC/V69/E054607/ |doi-access=free }}</ref> following this, the JINR team used the same hot fusion technique to synthesize elements [[livermorium|116]] and [[oganesson|118]] in 2000 and 2002 respectively via the <sup>248</sup>[[curium|Cm]] + <sup>48</sup>Ca and <sup>249</sup>[[californium|Cf]] + <sup>48</sup>Ca reactions. They then turned their attention to the missing odd-numbered elements, as the odd protons and possibly neutrons would hinder decay by [[spontaneous fission]] and result in longer decay chains.<ref name="Chapman" /><ref name="03Og01" />

The first report of element 113 was in August 2003, when it was identified as an [[alpha decay]] product of [[moscovium|element 115]]. Element 115 had been produced by bombarding a target of [[americium]]-243 with calcium-48 projectiles. The [[Joint Institute for Nuclear Research|JINR]]–[[Lawrence Livermore National Laboratory|LLNL]] collaboration published its results in February 2004<!-- the 1st -->:<ref name="03Og01">{{cite journal |title=Experiments on the synthesis of element 115 in the reaction <sup>243</sup>Am(<sup>48</sup>Ca,xn)<sup>291−x</sup>115 |doi=10.1103/PhysRevC.69.021601 |date=2004 |author=Oganessian, Yu. Ts. |journal=Physical Review C |volume=69 |pages=021601 |last2=Utyonkoy |first2=V. |last3=Lobanov |first3=Yu. |last4=Abdullin |first4=F. |last5=Polyakov |first5=A. |last6=Shirokovsky |first6=I. |last7=Tsyganov |first7=Yu. |last8=Gulbekian |first8=G. |last9=Bogomolov |first9=S. |first10=A. N. |last10=Mezentsev |first11=S. |last11=Iliev |first12=V. G. |last12=Subbotin |first13=A. M. |last13=Sukhov |first14=A. A. |last14=Voinov |first15=G. V. |last15=Buklanov |first16=K. |last16=Subotic |first17=V. I. |last17=Zagrebaev |first18=M. G. |last18=Itkis |first19=J. B. |last19=Patin |first20=K. J. |last20=Moody |first21=J. F. |last21=Wild |first22=M. A. |last22=Stoyer |first23=N. J. |last23=Stoyer |first24=D. A. |last24=Shaughnessy |first25=J. M. |last25=Kenneally |first26=R. W. |last26=Lougheed |issue=2 |bibcode=2004PhRvC..69b1601O |display-authors=10 |url=http://lt-jds.jinr.ru/record/7440/files/178%28E7-2003-178%29.pdf |access-date=13 December 2019 |archive-date=7 March 2020 |archive-url=https://web.archive.org/web/20200307233820/http://lt-jds.jinr.ru/record/7440/files/178%28E7-2003-178%29.pdf |url-status=dead }}</ref>

:{{nuclide|link=no|Americium|243}} + {{nuclide|link=no|Calcium|48}} → <sup>291</sup>115* → <sup>288</sup>115 + 3 {{SubatomicParticle|link=no|neutron}} → <sup>284</sup>113 + {{SubatomicParticle|link=no|alpha}}
:{{nuclide|Americium|243}} + {{nuclide|Calcium|48}} → <sup>291</sup>115* → <sup>287</sup>115 + 4 {{SubatomicParticle|link=no|neutron}} → <sup>283</sup>113 + {{SubatomicParticle|link=no|alpha}}

Four further alpha decays were observed, ending with the [[spontaneous fission]] of isotopes of element 105, [[dubnium]].<ref name="03Og01" />

=== Riken ===
While the JINR–LLNL collaboration had been studying fusion reactions with <sup>48</sup>Ca, a team of Japanese scientists at the [[Riken]] Nishina Center for Accelerator-Based Science in [[Wakō, Saitama|Wakō]], Japan, led by [[Kōsuke Morita]] had been studying cold fusion reactions. Morita had previously studied the synthesis of superheavy elements at the JINR before starting his own team at Riken. In 2001, his team confirmed the GSI's discoveries of elements [[hassium|108]], [[darmstadtium|110]], [[roentgenium|111]], and 112. They then made a new attempt on element 113, using the same <sup>209</sup>Bi + <sup>70</sup>Zn reaction that the GSI had attempted unsuccessfully in 1998. Despite the much lower yield expected than for the JINR's hot fusion technique with calcium-48, the Riken team chose to use cold fusion as the synthesised isotopes would alpha decay to known daughter nuclides and make the discovery much more certain, and would not require the use of radioactive targets.<ref>{{cite web |url=https://www.youtube.com/watch?v=kGVkkVMgvOg | archive-url=https://ghostarchive.org/varchive/youtube/20211114/kGVkkVMgvOg| archive-date=14 November 2021 | url-status=live|title=Q & A session |last=Morita |first=Kōsuke |date=5 February 2016 |publisher=The Foreign Correspondents' Club of Japan |via=YouTube |access-date=28 April 2017}}{{cbignore}}</ref> In particular, the isotope <sup>278</sup>113 expected to be produced in this reaction would decay to the known <sup>266</sup>Bh, which had been synthesised in 2000 by a team at the [[Lawrence Berkeley National Laboratory]] (LBNL) in Berkeley.<ref name="JWP" />

The bombardment of <sup>209</sup>Bi with <sup>70</sup>Zn at Riken began in September 2003<!--the 5th-->.<ref name="RudolphForsberg2013">{{cite journal |last1=Rudolph |first1=D. |last2=Forsberg |first2=U. |last3=Golubev |first3=P. |last4=Sarmiento |first4=L. G. |last5=Yakushev |first5=A. |last6=Andersson |first6=L.-L. |last7=Di Nitto |first7=A. |last8=Düllmann |first8=Ch. E. |last9=Gates |first9=J. M.|last10=Gregorich|first10=K. E. |last11=Gross |first11=C. J. |last12=Heßberger |first12=F. P. |last13=Herzberg |first13=R.-D. |last14=Khuyagbaatar |first14=J. |last15=Kratz |first15=J. V. |last16=Rykaczewski |first16=K. |last17=Schädel |first17=M. |last18=Åberg |first18=S. |last19=Ackermann |first19=D.|last20=Block|first20=M. |last21=Brand |first21=H. |last22=Carlsson |first22=B. G. |last23=Cox |first23=D. |last24=Derkx |first24=X. |last25=Eberhardt |first25=K. |last26=Even |first26=J. |last27=Fahlander |first27=C. |last28=Gerl |first28=J. |last29=Jäger |first29=E.|last30=Kindler|first30=B. |last31=Krier |first31=J. |last32=Kojouharov |first32=I. |last33=Kurz |first33=N. |last34=Lommel |first34=B. |last35=Mistry |first35=A. |last36=Mokry |first36=C. |last37=Nitsche |first37=H. |last38=Omtvedt |first38=J. P. |last39=Papadakis |first39=P.|last40=Ragnarsson|first40=I. |last41=Runke |first41=J. |last42=Schaffner |first42=H. |last43=Schausten |first43=B. |last44=Thörle-Pospiech |first44=P. |last45=Torres |first45=T. |last46=Traut |first46=T. |last47=Trautmann |first47=N. |last48=Türler |first48=A. |last49=Ward |first49=A.|last50=Ward|first50=D. E. |last51=Wiehl |first51=N. |title=Spectroscopy of Element 115 Decay Chains |journal=Physical Review Letters |volume=111 |issue=11 |pages=112502 |year=2013 |issn=0031-9007 |doi=10.1103/PhysRevLett.111.112502 |pmid=24074079 |url=http://lup.lub.lu.se/record/4002358 |type=Submitted manuscript|bibcode=2013PhRvL.111k2502R|s2cid=3838065 }}</ref> The team detected a single atom of <sup>278</sup>113 in July 2004<!--the 23rd--> and published their results that September<!--the 28th-->:<ref name="04Mo01">{{cite journal |title=Experiment on the Synthesis of Element 113 in the Reaction <sup>209</sup>Bi(<sup>70</sup>Zn,n)<sup>278</sup>113 |year=2004 |journal=Journal of the Physical Society of Japan |volume=73 |issue=10 |pages=2593–2596 |doi=10.1143/JPSJ.73.2593 |bibcode=2004JPSJ...73.2593M |last1=Morita |first1=Kosuke |last2=Morimoto |first2=Kouji |last3=Kaji |first3=Daiya |last4=Akiyama |first4=Takahiro |last5=Goto |first5=Sin-ichi |last6=Haba |first6=Hiromitsu |first7=Eiji |last7=Ideguchi |first8=Rituparna |last8=Kanungo |first9=Kenji |last9=Katori|first10=Hiroyuki |last10=Koura |first11=Hisaaki |last11=Kudo |first12=Tetsuya |last12=Ohnishi |first13=Akira |last13=Ozawa |first14=Toshimi |last14=Suda |first15=Keisuke |last15=Sueki |first16=HuShan |last16=Xu |first17=Takayuki |last17=Yamaguchi |first18=Akira |last18=Yoneda |first19=Atsushi |last19=Yoshida|first20=YuLiang |last20=Zhao|doi-access=free }}</ref>

:{{nuclide|link=no|Bismuth|209}} + {{nuclide|link=no|Zinc|70}} → <sup>279</sup>113* → <sup>278</sup>113 + {{SubatomicParticle|link=no|neutron}}

The [[Riken]] team observed four alpha decays from <sup>278</sup>113, creating a decay chain passing through <sup>274</sup>Rg, <sup>270</sup>Mt, and <sup>266</sup>Bh before terminating with the spontaneous fission of <sup>262</sup>Db.<ref name="04Mo01" /> The decay data they observed for the alpha decay of <sup>266</sup>Bh matched the 2000 data, lending support for their claim. [[Spontaneous fission]] of its daughter <sup>262</sup>Db had not been previously known; the American team had observed only alpha decay from this nuclide.<ref name="JWP" />

=== Road to confirmation ===
When the discovery of a new element is claimed, the [[IUPAC/IUPAP Joint Working Party|Joint Working Party]] (JWP) of the [[International Union of Pure and Applied Chemistry]] (IUPAC) and the [[International Union of Pure and Applied Physics]] (IUPAP) assembles to examine the claims according to their criteria for the discovery of a new element, and decides [[scientific priority]] and naming rights for the elements. According to the JWP criteria, a discovery must demonstrate that the element has an atomic number different from all previously observed values. It should also preferably be repeated by other laboratories, although this requirement has been waived where the data is of very high quality. Such a demonstration must establish properties, either physical or chemical, of the new element and establish that they are those of a previously unknown element. The main techniques used to demonstrate atomic number are cross-reactions (creating claimed [[Nuclide|nuclides]] as parents or daughters of other nuclides produced by a different reaction) and anchoring decay chains to known daughter nuclides. For the JWP, priority in confirmation takes precedence over the date of the original claim. Both teams set out to confirm their results by these methods.<ref name="Karol" />
[[File:Element 113 decay chains.svg|thumb|upright=3|center|Summary of decay chains passing through isotopes of element 113, ending at [[mendelevium]] (element 101) or earlier. The two chains with bold-bordered nuclides were accepted by the JWP as evidence for the discoveries of element 113 and its parents, elements 115 and 117. Data is presented as known in 2015 (before the JWP's conclusions were published).]]

==== 2004–2008 ====
In June 2004 and again in December 2005, the JINR–LLNL collaboration strengthened their claim for the discovery of element 113 by conducting chemical experiments on <sup>268</sup>[[Dubnium|Db]], the final [[decay product]] of <sup>288</sup>115. This was valuable as none of the nuclides in this decay chain were previously known, so that their claim was not supported by any previous experimental data, and chemical experimentation would strengthen the case for their claim, since the chemistry of dubnium is known. <sup>268</sup>Db was successfully identified by extracting the final decay products, measuring [[spontaneous fission]] (SF) activities and using chemical identification techniques to confirm that they behave like a [[group 5 element]] (dubnium is known to be in group 5).<ref name="Haire" /><ref name="e115" /> Both the half-life and decay mode were confirmed for the proposed <sup>268</sup>Db which lends support to the assignment of the parent and [[daughter isotope|daughter nuclei]] to elements 115 and 113 respectively.<ref name="e115">{{cite journal |title=Chemical identification of dubnium as a decay product of element 115 produced in the reaction <sup>48</sup>Ca+<sup>243</sup>Am |first1=S. N. |last1=Dmitriev |first2=Yu. Ts. |last2=Oganessyan |first3=V. K. |last3=Utyonkov |first4=S. V. |last4=Shishkin |first5=A. V. |last5=Yeremin |first6=Yu. V. |last6=Lobanov |first7=Yu. S. |last7=Tsyganov |first8=V. I. |last8=Chepygin |first9=E. A. |last9=Sokol |first10=G. K. |last10=Vostokin |first11=N. V. |last11=Aksenov |first12=M. |last12=Hussonnois |first13=M. G. |last13=Itkis |first14=H. W. |last14=Gäggeler |first15=D. |last15=Schumann |first16=H. |last16=Bruchertseifer |first17=R. |last17=Eichler |first18=D. A. |last18=Shaughnessy |first19=P. A. |last19=Wilk |first20=J. M. |last20=Kenneally |first21=M. A. |last21=Stoyer |first22=J. F. |last22=Wild |journal=Mendeleev Communications |volume=15 |issue=1 |date=2005 |pages=1–4 |doi=10.1070/MC2005v015n01ABEH002077|s2cid=98386272 }}</ref><ref>{{cite journal |title=Synthesis of elements 115 and 113 in the reaction <sup>243</sup>Am + <sup>48</sup>Ca |doi=10.1103/PhysRevC.72.034611 |date=2005 |author=Oganessian, Yu. Ts. |journal=Physical Review C |volume=72 |pages=034611 |last2=Utyonkov |first2=V. |last3=Dmitriev |first3=S. |last4=Lobanov |first4=Yu. |last5=Itkis |first5=M. |last6=Polyakov |first6=A. |last7=Tsyganov |first7=Yu. |last8=Mezentsev |first8=A. |last9=Yeremin |first9=A.|first10=A. A. |last10=Voinov |first11=E. A. |last11=Sokol |first12=G. G. |last12=Gulbekian |first13=S. L. |last13=Bogomolov |first14=S. |last14=Iliev |first15=V. G. |last15=Subbotin |first16=A. M. |last16=Sukhov |first17=G. V. |last17=Buklanov |first18=S. V. |last18=Shishkin |first19=V. I. |last19=Chepygin|first20=G. K. |last20=Vostokin |first21=N. V. |last21=Aksenov |first22=M. |last22=Hussonnois |first23=K. |last23=Subotic |first24=V. I. |last24=Zagrebaev |first25=K. J. |last25=Moody |first26=J. B. |last26=Patin |first27=J. F. |last27=Wild |first28=M. A. |last28=Stoyer |first29=N. J. |last29=Stoyer|first30=D. A. |last30=Shaughnessy |first31=J. M. |last31=Kenneally |first32=P. A. |last32=Wilk |first33=R. W. |last33=Lougheed |first34=H. W. |last34=Gäggeler |first35=D. |last35=Schumann |first36=H. |last36=Bruchertseifer |first37=R. |last37=Eichler |issue=3 |bibcode=2005PhRvC..72c4611O|display-authors=10|url=https://www.dora.lib4ri.ch/psi/islandora/object/psi%3A13194}}</ref> Further experiments at the JINR in 2005 confirmed the observed decay data.<ref name="JWP" />

In November and December 2004, the Riken team studied the <sup>205</sup>Tl + <sup>70</sup>Zn reaction, aiming the zinc beam onto a [[thallium]] rather than a bismuth target, in an effort to directly produce <sup>274</sup>Rg in a cross-bombardment as it is the immediate daughter of <sup>278</sup>113. The reaction was unsuccessful, as the thallium target was [[Strength of materials|physically weak]] compared to the more commonly used lead and bismuth targets, and it deteriorated significantly and became non-uniform in thickness. The reasons for this weakness are unknown, given that thallium has a higher melting point than bismuth.<ref name="Morimoto2016" /> The Riken team then repeated the original <sup>209</sup>Bi + <sup>70</sup>Zn reaction and produced a second atom of <sup>278</sup>113 in April 2005<!--the 2nd-->, with a decay chain that again terminated with the spontaneous fission of <sup>262</sup>Db. The decay data were slightly different from those of the first chain: this could have been because an [[alpha particle]] escaped from the detector without depositing its full energy, or because some of the intermediate decay products were formed in [[metastable state|metastable isomeric states]].<ref name="JWP" />

In 2006, a team at the Heavy Ion Research Facility in [[Lanzhou]], China, investigated the <sup>243</sup>Am + <sup>26</sup>Mg reaction, producing four atoms of <sup>266</sup>Bh. All four chains started with an alpha decay to <sup>262</sup>Db; three chains ended there with spontaneous fission, as in the <sup>278</sup>113 chains observed at Riken, while the remaining one continued via another alpha decay to <sup>258</sup>Lr, as in the <sup>266</sup>Bh chains observed at LBNL.<ref name="Karol" />

In June 2006, the JINR–LLNL collaboration claimed to have synthesised a new isotope of element 113 directly by bombarding a [[neptunium]]-237 target with accelerated calcium-48 nuclei:

:{{nuclide|link=no|Neptunium|237}} + {{nuclide|link=no|Calcium|48}} → <sup>285</sup>113* → <sup>282</sup>113 + 3 {{SubatomicParticle|link=no|neutron}}

Two atoms of <sup>282</sup>113 were detected. The aim of this experiment had been to synthesise the isotopes <sup>281</sup>113 and <sup>282</sup>113 that would fill in the gap between isotopes produced via hot fusion (<sup>283</sup>113 and <sup>284</sup>113) and cold fusion (<sup>278</sup>113). After five alpha decays, these nuclides would reach known isotopes of [[lawrencium]], assuming that the decay chains were not terminated prematurely by spontaneous fission. The first decay chain ended in fission after four alpha decays, presumably originating from <sup>266</sup>Db or its electron-capture daughter <sup>266</sup>Rf. [[Spontaneous fission]] was not observed in the second chain even after four alpha decays. A fifth alpha decay in each chain could have been missed, since <sup>266</sup>Db can theoretically undergo alpha decay, in which case the first decay chain would have ended at the known <sup>262</sup>Lr or <sup>262</sup>No and the second might have continued to the known long-lived <sup>258</sup>Md, which has a half-life of 51.5&nbsp;days, longer than the duration of the experiment: this would explain the lack of a spontaneous fission event in this chain. In the absence of direct detection of the long-lived [[Alpha decay|alpha decays]], these interpretations remain unconfirmed, and there is still no known link between any superheavy nuclides produced by hot fusion and the well-known main body of the chart of nuclides.<ref name="07Og01">{{cite journal |url=http://nrv.jinr.ru/pdf_file/PhysRevC_76_011601.pdf |title=Synthesis of the isotope <sup>282</sup>113 in the <sup>237</sup>Np + <sup>48</sup>Ca fusion reaction |last1=Oganessian |first1=Yu. Ts. |journal=Physical Review C |volume=76 |issue=1 |page=011601(R) |year=2007 |doi=10.1103/PhysRevC.76.011601 |last2=Utyonkov |first2=V. |last3=Lobanov |first3=Yu. |last4=Abdullin |first4=F. |last5=Polyakov |first5=A. |last6=Sagaidak |first6=R. |last7=Shirokovsky |first7=I. |last8=Tsyganov |first8=Yu. |last9=Voinov |first9=A. |last10=Gulbekian |first10=Gulbekian |last11=Bogomolov |first11=Bogomolov |last12=Gikal |first12=Gikal |last13=Mezentsev |first13=Mezentsev |last14=Subbotin |first14=Subbotin |last15=Sukhov |first15=Sukhov |last16=Subotic |first16=Subotic |last17=Zagrebaev |first17=Zagrebaev |last18=Vostokin |first18=Vostokin |last19=Itkis |first19=Itkis |last20=Henderson |first20=Henderson |last21=Kenneally |first21=Kenneally |last22=Landrum |first22=Landrum |last23=Moody |first23=Moody |last24=Shaughnessy |first24=Shaughnessy |last25=Stoyer |first25=Stoyer |last26=Stoyer |first26=Stoyer |last27=Wilk |first27=Wilk |bibcode=2007PhRvC..76a1601O |display-authors=10}}</ref>

==== 2009–2015 ====
The JWP published its report on elements 113–116 and 118 in 2011. It recognised the JINR–LLNL collaboration as having discovered elements 114 and 116, but did not accept either team's claim to element 113 and did not accept the JINR–LLNL claims to elements 115 and 118. The JINR–LLNL claim to elements 115 and 113 had been founded on chemical identification of their daughter dubnium, but the JWP objected that current theory could not distinguish between superheavy [[group 4 element|group 4]] and group 5 elements by their chemical properties with enough confidence to allow this assignment.<ref name="JWP">{{cite journal |author=Barber, Robert C. |author2=Karol, Paul J |author3=Nakahara, Hiromichi |author4=Vardaci, Emanuele |author5=Vogt, Erich W. |title=Discovery of the elements with atomic numbers greater than or equal to 113 (IUPAC Technical Report) |doi=10.1351/PAC-REP-10-05-01 |journal=Pure Appl. Chem. |date=2011 |volume=83 |issue=7 |page=1485|doi-access=free }}</ref> The decay properties of all the nuclei in the decay chain of element 115 had not been previously characterised before the JINR experiments, a situation which the JWP generally considers "troublesome, but not necessarily exclusive", and with the small number of atoms produced with neither known daughters nor cross-reactions the JWP considered that their criteria had not been fulfilled.<ref name="JWP" /> The JWP did not accept the Riken team's claim either due to inconsistencies in the decay data, the small number of atoms of element 113 produced, and the lack of unambiguous anchors to known isotopes.<ref name="JWP" />

In early 2009, the Riken team synthesised the decay product <sup>266</sup>Bh directly in the <sup>248</sup>Cm + <sup>23</sup>Na reaction to establish its link with <sup>278</sup>113 as a cross-bombardment. They also established the branched decay of <sup>262</sup>Db, which sometimes underwent spontaneous fission and sometimes underwent the previously known alpha decay to <sup>258</sup>Lr.<ref>{{cite journal |last1=Morita |first1=Kosuke |last2=Morimoto |first2=Kouji |first3=Daiya |last3=Kaji |first4=Hiromitsu |last4=Haba |first5=Kazutaka |last5=Ozeki |first6=Yuki |last6=Kudou |first7=Nozomi |last7=Sato |first8=Takayuki |last8=Sumita |first9=Akira |last9=Yoneda |first10=Takatoshi |last10=Ichikawa |first11=Yasuyuki |last11=Fujimori |first12=Sin-ichi |last12=Goto |first13=Eiji |last13=Ideguchi |first14=Yoshitaka |last14=Kasamatsu |first15=Kenji |last15=Katori |first16=Yukiko |last16=Komori |first17=Hiroyuki |last17=Koura |first18=Hisaaki |last18=Kudo |first19=Kazuhiro |last19=Ooe |first20=Akira |last20=Ozawa |first21=Fuyuki |last21=Tokanai |first22=Kazuaki |last22=Tsukada |first23=Takayuki |last23=Yamaguchi |first24=Atsushi |last24=Yoshida |date=25 May 2009 |title=Decay Properties of <sup>266</sup>Bh and <sup>262</sup>Db Produced in the <sup>248</sup>Cm + <sup>23</sup>Na Reaction |journal=Journal of the Physical Society of Japan |volume=78 |issue=6 |pages=064201–1–6 |doi=10.1143/JPSJ.78.064201 |arxiv=0904.1093 |bibcode=2009JPSJ...78f4201M|s2cid=16415500 }}</ref><ref name="morimoto">{{cite web |url=http://www.kernchemie.uni-mainz.de/downloads/che_7/presentations/morimoto.pdf |title=Production and Decay Properties of <sup>266</sup>Bh and its daughter nuclei by using the <sup>248</sup>Cm(<sup>23</sup>Na,5n)<sup>266</sup>Bh Reaction |last1=Morimoto |first1=Kouji |first2=K. |last2=Morita |first3=D. |last3=Kaji |first4=H. |last4=Haba |first5=K. |last5=Ozeki |first6=Y. |last6=Kudou |first7=N. |last7=Sato |first8=T. |last8=Sumita |first9=A. |last9=Yoneda |first10=T. |last10=Ichikawa |first11=Y. |last11=Fujimori |first12=S. |last12=Goto |first13=E. |last13=Ideguchi |first14=Y. |last14=Kasamatsu |first15=K. |last15=Katori |first16=Y. |last16=Komori |first17=H. |last17=Koura |first18=H. |last18=Kudo |first19=K. |last19=Ooe |first20=A. |last20=Ozawa |first21=F. |last21=Tokanai |first22=K. |last22=Tsukada |first23=T. |last23=Yamaguchi |first24=A. |last24=Yoshida |date=October 2009 |via=[[University of Mainz]] |access-date=28 April 2017 |archive-url=https://web.archive.org/web/20170921193318/http://www.kernchemie.uni-mainz.de/downloads/che_7/presentations/morimoto.pdf |archive-date=21 September 2017 |url-status=dead}}</ref>

In late 2009, the JINR–LLNL collaboration studied the <sup>249</sup>Bk + <sup>48</sup>Ca reaction in an effort to produce [[tennessine|element 117]], which would decay to elements 115 and 113 and bolster their claims in a cross-reaction. They were now joined by scientists from [[Oak Ridge National Laboratory]] (ORNL) and [[Vanderbilt University]], both in [[Tennessee]], United States,<ref name="Chapman" /> who helped procure the rare and highly radioactive [[berkelium]] target necessary to complete the JINR's calcium-48 campaign to synthesise the heaviest elements on the periodic table.<ref name="Chapman" /> Two isotopes of element 117 were synthesised, decaying to element 115 and then element 113:<ref name="e117">{{cite journal |last1=Oganessian |first1=Yuri Ts. |last2=Abdullin |first2=F. Sh. |last3=Bailey |first3=P. D. |last4=Benker |first4=D. E. |last5=Bennett |first5=M. E. |last6=Dmitriev |first6=S. N. |last7=Ezold |first7=J. G. |last8=Hamilton |first8=J. H. |last9=Henderson |first9=R. A. | first10=M. G. |last10=Itkis |first11=Yuri V. |last11=Lobanov |first12=A. N. |last12=Mezentsev |first13=K. J. |last13=Moody |first14=S. L. |last14=Nelson |first15=A. N. |last15=Polyakov |first16=C. E. |last16=Porter |first17=A. V. |last17=Ramayya |first18=F. D. |last18=Riley |first19=J. B. |last19=Roberto | first20=M. A. |last20=Ryabinin |first21=K. P. |last21=Rykaczewski |first22=R. N. |last22=Sagaidak |first23=D. A. |last23=Shaughnessy |first24=I. V. |last24=Shirokovsky |first25=M. A. |last25=Stoyer |first26=V. G. |last26=Subbotin |first27=R. |last27=Sudowe |first28=A. M. |last28=Sukhov |first29=Yu. S. |last29=Tsyganov | first30=Vladimir K. |last30=Utyonkov |first31=A. A. |last31=Voinov |first32=G. K. |last32=Vostokin |first33=P. A. |last33=Wilk |title=Synthesis of a New Element with Atomic Number ''Z''=117 |date=9 April 2010 |journal=Physical Review Letters |volume=104 |issue=14 |pages=142502 |doi=10.1103/PhysRevLett.104.142502 |pmid=20481935 |bibcode=2010PhRvL.104n2502O |url=https://www.researchgate.net/publication/44610795|doi-access=free }}</ref>

:{{nuclide|link=no|Berkelium|249}} + {{nuclide|link=no|Calcium|48}} → <sup>297</sup>117* → <sup>294</sup>117 + 3 {{SubatomicParticle|link=no|neutron}} → <sup>290</sup>115 + α → <sup>286</sup>113 + α
:{{nuclide|link=no|Berkelium|249}} + {{nuclide|link=no|Calcium|48}} → <sup>297</sup>117* → <sup>293</sup>117 + 4 {{SubatomicParticle|link=no|neutron}} → <sup>289</sup>115 + α → <sup>285</sup>113 + α

The new isotopes <sup>285</sup>113 and <sup>286</sup>113 produced did not overlap with the previously claimed <sup>282</sup>113, <sup>283</sup>113, and <sup>284</sup>113, so this reaction could not be used as a cross-bombardment to confirm the 2003 or 2006 claims.<ref name="Karol" />

In March 2010, the Riken team again attempted to synthesise <sup>274</sup>Rg directly through the <sup>205</sup>Tl + <sup>70</sup>Zn reaction with upgraded equipment; they failed again and abandoned this cross-bombardment route.<ref name="Morimoto2016">{{cite web |url=http://www.physics.adelaide.edu.au/cssm/workshops/inpc2016/talks/Morimoto_Mon_HallL_0930.pdf |title=The discovery of element 113 at RIKEN |last=Morimoto |first=Kouji |date=2016 |publisher=26th International Nuclear Physics Conference |access-date=14 May 2017}}</ref>

After 450 more days of irradiation of bismuth with zinc projectiles, Riken produced and identified another <sup>278</sup>113 atom in August 2012<!--the 12th-->.<ref name="six-alpha">{{cite journal |journal=Journal of the Physical Society of Japan |volume=81 |pages=103201 |date=2012 |title=New Results in the Production and Decay of an Isotope, <sup>278</sup>113, of the 113th Element |author=K. Morita |doi=10.1143/JPSJ.81.103201 |last2=Morimoto |first2=Kouji |last3=Kaji |first3=Daiya |last4=Haba |first4=Hiromitsu |last5=Ozeki |first5=Kazutaka |last6=Kudou |first6=Yuki |last7=Sumita |first7=Takayuki |last8=Wakabayashi |first8=Yasuo |last9=Yoneda |first9=Akira|first10=Kengo |last10=Tanaka |first11=Sayaka |last11=Yamaki |first12=Ryutaro |last12=Sakai |first13=Takahiro |last13=Akiyama |first14=Shin-ichi |last14=Goto |first15=Hiroo |last15=Hasebe |first16=Minghui |last16=Huang |first17=Tianheng |last17=Huang |first18=Eiji |last18=Ideguchi |first19=Yoshitaka |last19=Kasamatsu|first20=Kenji |last20=Katori |first21=Yoshiki |last21=Kariya |first22=Hidetoshi |last22=Kikunaga |first23=Hiroyuki |last23=Koura |first24=Hisaaki |last24=Kudo |first25=Akihiro |last25=Mashiko |first26=Keita |last26=Mayama |first27=Shin-ichi |last27=Mitsuoka |first28=Toru |last28=Moriya |first29=Masashi |last29=Murakami|first30=Hirohumi |last30=Murayama |first31=Saori |last31=Namai |first32=Akira |last32=Ozawa |first33=Nozomi |last33=Sato |first34=Keisuke |last34=Sueki |first35=Mirei |last35=Takeyama |first36=Fuyuki |last36=Tokanai |first37=Takayuki |last37=Yamaguchi |first38=Atsushi |last38=Yoshida |issue=10|display-authors=10 |arxiv=1209.6431 |bibcode=2012JPSJ...81j3201M|s2cid=119217928 }}</ref> Although electricity prices had soared since the [[2011 Tōhoku earthquake and tsunami]], and Riken had ordered the shutdown of the accelerator programs to save money, Morita's team was permitted to continue with one experiment, and they chose their attempt to confirm their synthesis of element 113.<ref name="podcast">{{cite web |url=https://www.chemistryworld.com/podcasts/nihonium/3008633.article |title=Nihonium |last=Chapman |first=Kit |date=8 February 2018 |website=Chemistry World |publisher=[[Royal Society of Chemistry]] |access-date=20 March 2018}}</ref> In this case, a series of six alpha decays was observed, leading to an isotope of [[mendelevium]]:

:<sup>278</sup>113 → {{nuclide|link=no|Roentgenium|274}} + {{SubatomicParticle|link=no|alpha}} → {{nuclide|link=no|Meitnerium|270}} + {{SubatomicParticle|link=no|alpha}} → {{nuclide|link=no|Bohrium|266}} + {{SubatomicParticle|link=no|alpha}} → {{nuclide|link=no|Dubnium|262}} + {{SubatomicParticle|link=no|alpha}} → {{nuclide|link=no|Lawrencium|258}} + {{SubatomicParticle|link=no|alpha}} → {{nuclide|link=no|Mendelevium|254}} + {{SubatomicParticle|link=no|alpha}}

This decay chain differed from the previous observations at Riken mainly in the decay mode of <sup>262</sup>Db, which was previously observed to undergo spontaneous fission, but in this case instead alpha decayed; the alpha decay of <sup>262</sup>Db to <sup>258</sup>Lr is [[isotopes of dubnium|well-known]]. The team calculated the probability of accidental [[mathematical coincidence|coincidence]] to be 10<sup>−28</sup>, or totally negligible.<ref name="six-alpha" /> The resulting <sup>254</sup>Md atom then underwent [[electron capture]] to <sup>254</sup>[[fermium|Fm]], which underwent the seventh alpha decay in the chain to the long-lived <sup>250</sup>[[californium|Cf]], which has a half-life of around thirteen years.<ref>{{cite web |url=http://cyclotron.tamu.edu/she2015/assets/pdfs/presentations/Morita_SHE_2015_TAMU.pdf |title=SHE Research at RIKEN/GARIS |first=Kosuke |last=Morita |date=2015 |access-date=4 September 2018 |via=Texas A&M University Cyclotron Institute}}</ref>

The <sup>249</sup>Bk + <sup>48</sup>Ca experiment was repeated at the JINR in 2012 and 2013 with consistent results, and again at the GSI in 2014.<ref name="Karol" /> In August 2013, a team of researchers at [[Lund University]] in [[Lund]], Sweden, and at the GSI announced that they had repeated the 2003 <sup>243</sup>Am + <sup>48</sup>Ca experiment, confirming the findings of the JINR–LLNL collaboration.<ref name="RudolphForsberg2013" /><ref>{{cite news |url=http://www.lunduniversity.lu.se/article/existence-of-new-element-confirmed |agency=Lund University |title=Existence of new element confirmed |date=27 August 2013 |access-date=10 April 2016}}</ref> The same year, the 2003 experiment had been repeated at the JINR, now also creating the isotope <sup>289</sup>115 that could serve as a cross-bombardment for confirming their discovery of the [[tennessine|element 117]] isotope <sup>293</sup>117, as well as its daughter <sup>285</sup>113 as part of its decay chain.<ref name="Karol" /> Confirmation of <sup>288</sup>115 and its daughters was published by the team at the LBNL in August 2015.<ref>{{cite journal |doi=10.1103/PhysRevC.92.021301 |title=Decay spectroscopy of element 115 daughters: <sup>280</sup>Rg→<sup>276</sup>Mt and <sup>276</sup>Mt→Bh |journal=Physical Review C |volume=92 |issue=2 |pages=021301 |bibcode=2015PhRvC..92b1301G |year=2015 |last1=Gates |first1=J. M. |last2=Gregorich |first2=K. E. |last3=Gothe |first3=O. .R |last4=Uribe |first4=E. C. |last5=Pang |first5=G. K. |last6=Bleuel |first6=D. L. |last7=Block |first7=M. |last8=Clark |first8=R. M. |last9=Campbell |first9=C. M.|last10=Crawford|first10=H. L. |last11=Cromaz |first11=M. |last12=Di Nitto |first12=A. |last13=Düllmann |first13=Ch. E. |last14=Esker |first14=N. E. |last15=Fahlander |first15=C. |last16=Fallon |first16=P. |last17=Farjadi |first17=R. M. |last18=Forsberg |first18=U. |last19=Khuyagbaatar |first19=J.|last20=Loveland|first20=W. |last21=MacChiavelli |first21=A. O. |last22=May |first22=E. M. |last23=Mudder |first23=P. R. |last24=Olive |first24=D. T. |last25=Rice |first25=A. C. |last26=Rissanen |first26=J. |last27=Rudolph |first27=D. |last28=Sarmiento |first28=L. G. |last29=Shusterman |first29=J. A.|last30=Stoyer|first30=M. A.|display-authors=29|doi-access=free }}</ref>

=== Approval of discoveries ===
In December 2015, the conclusions of a new JWP report were published by IUPAC in a press release, in which element 113 was awarded to Riken; elements 115, 117, and 118 were awarded to the collaborations involving the JINR.<ref name="huffingtonpost" /> A joint 2016 announcement by IUPAC and IUPAP had been scheduled to coincide with the publication of the JWP reports, but IUPAC alone decided on an early release because the news of Riken being awarded credit for element 113 had been leaked to Japanese newspapers.<ref name="McKellar" /> For the first time in history, a team of Asian physicists would name a new element.<ref name="huffingtonpost">{{cite web |url=http://www.huffingtonpost.com/2012/09/26/element-113-created-synthetically-japan_n_1916253.html |title=Element 113: Ununtrium Reportedly Synthesised In Japan |website=Huffington Post |date=September 2012 |access-date=22 April 2013}}</ref> The JINR considered the awarding of element 113 to Riken unexpected, citing their own 2003 production of elements 115 and 113, and pointing to the precedents of elements [[lawrencium|103]], [[rutherfordium|104]], and [[dubnium|105]] where IUPAC had awarded joint credit to the JINR and LBNL. They stated that they respected IUPAC's decision, but reserved determination of their position for the official publication of the JWP reports.<ref name="reaction">{{cite web |url=http://www.jinr.ru/posts/discovery-of-the-new-chemical-elements-with-numbers-113-115-117-and-118-2/ |title=Discovery of the new chemical elements with numbers 113, 115, 117 and 118 |date=6 January 2016 |publisher=[[Joint Institute for Nuclear Research]] |access-date=14 January 2018}}</ref>

The full JWP reports were published on 21 January 2016. The JWP recognised the discovery of element 113, assigning priority to Riken. They noted that while the individual decay energies of each nuclide in the decay chain of <sup>278</sup>113 were inconsistent, their sum was now confirmed to be consistent, strongly suggesting that the initial and final states in <sup>278</sup>113 and its daughter <sup>262</sup>Db were the same for all three events. The decay of <sup>262</sup>Db to <sup>258</sup>Lr and <sup>254</sup>Md was previously known, firmly anchoring the decay chain of <sup>278</sup>113 to known regions of the chart of nuclides. The JWP considered that the JINR–LLNL collaborations of 2004 and 2007, producing element 113 as the daughter of element 115, did not meet the discovery criteria as they had not convincingly determined the atomic numbers of their nuclides through cross-bombardments, which were considered necessary since their decay chains were not anchored to previously known nuclides. They also considered that the previous JWP's concerns over their chemical identification of the dubnium daughter had not been adequately addressed. The JWP recognised the JINR–LLNL–ORNL–Vanderbilt collaboration of 2010 as having discovered elements 117 and 115, and accepted that element 113 had been produced as their daughter, but did not give this work shared credit.<ref name="Karol">{{cite journal |last1=Karol |first1=Paul J. |last2=Barber |first2=Robert C. |last3=Sherrill |first3=Bradley M. |last4=Vardaci |first4=Emanuele |last5=Yamazaki |first5=Toshimitsu |date=22 December 2015 |title=Discovery of the elements with atomic numbers Z = 113, 115 and 117 (IUPAC Technical Report) |journal=Pure Appl. Chem. |volume=88 |issue=1–2 |pages=139–153 |doi=10.1515/pac-2015-0502|doi-access=free }}</ref><ref name="Morimoto2016" /><ref name="namingiupac">{{cite web |url=http://www.iupac.org/news/news-detail/article/discovery-and-assignment-of-elements-with-atomic-numbers-113-115-117-and-118.html |title=Discovery and Assignment of Elements with Atomic Numbers 113, 115, 117 and 118. |publisher=IUPAC |date=30 December 2015 |access-date=8 September 2018 |archive-date=31 December 2015 |archive-url=https://web.archive.org/web/20151231074712/http://www.iupac.org/news/news-detail/article/discovery-and-assignment-of-elements-with-atomic-numbers-113-115-117-and-118.html |url-status=dead }}</ref>

After the publication of the JWP reports, Sergey Dimitriev, the lab director of the Flerov lab at the JINR where the discoveries were made, remarked that he was happy with IUPAC's decision, mentioning the time Riken spent on their experiment and their good relations with Morita, who had learnt the basics of synthesising superheavy elements at the JINR.<ref name="Chapman">{{cite news |url=https://www.chemistryworld.com/what-it-takes-to-make-a-new-element/1017677.article |title=What it takes to make a new element |last=Chapman |first=Kit |date=30 November 2016 |magazine=Chemistry World |publisher=Royal Society of Chemistry |access-date=3 December 2016}}</ref><ref name="reaction" />

The sum argument advanced by the JWP in the approval of the discovery of element 113 was later criticised in a May 2016 study from Lund University and the GSI, as it is only valid if no [[gamma decay]] or [[internal conversion]] takes place along the decay chain, which is not likely for odd nuclei, and the uncertainty of the alpha decay energies measured in the <sup>278</sup>113 decay chain was not small enough to rule out this possibility. If this is the case, similarity in lifetimes of intermediate daughters becomes a meaningless argument, as different isomers of the same nuclide can have different half-lives: for example, the ground state of <sup>180</sup>Ta has a half-life of hours, but an excited state [[isotopes of tantalum|<sup>180m</sup>Ta]] has never been observed to decay. This study found reason to doubt and criticise the IUPAC approval of the discoveries of elements 115 and 117, but the data from Riken for element 113 was found to be congruent, and the data from the JINR team for elements 115 and 113 to probably be so, thus endorsing the IUPAC approval of the discovery of element 113.<ref>{{cite journal |last1=Forsberg |first1=U. |last2=Rudolph |first2=D. |first3=C. |last3=Fahlander |first4=P. |last4=Golubev |first5=L. G. |last5=Sarmiento |first6=S. |last6=Åberg |first7=M. |last7=Block |first8=Ch. E. |last8=Düllmann |first9=F. P. |last9=Heßberger |first10=J. V. |last10=Kratz |first11=A. |last11=Yakushev |date=9 July 2016 |title=A new assessment of the alleged link between element 115 and element 117 decay chains |url=http://portal.research.lu.se/portal/files/9762047/PhysLettB760_293_2016.pdf |journal=Physics Letters B |volume=760 |issue=2016 |pages=293–296 |doi=10.1016/j.physletb.2016.07.008 |access-date=2 April 2016 |bibcode=2016PhLB..760..293F|doi-access=free }}</ref><ref>{{cite conference |url=http://www.epj-conferences.org/articles/epjconf/pdf/2016/26/epjconf-NS160-02003.pdf |title=Congruence of decay chains of elements 113, 115, and 117 |last1=Forsberg |first1=Ulrika |last2=Fahlander |first2=Claes |last3=Rudolph |first3=Dirk |date=2016 |conference=Nobel Symposium NS160 – Chemistry and Physics of Heavy and Superheavy Elements |doi=10.1051/epjconf/201613102003|doi-access=free }}</ref> Two members of the JINR team published a journal article rebutting these criticisms against the congruence of their data on elements 113, 115, and 117 in June 2017.<ref>{{cite journal |last1=Zlokazov |first1=V. B. |last2=Utyonkov |first2=V. K. |date=8 June 2017 |title=Analysis of decay chains of superheavy nuclei produced in the <sup>249</sup>Bk + <sup>48</sup>Ca and <sup>243</sup>Am + <sup>48</sup>Ca reactions |journal=Journal of Physics G: Nuclear and Particle Physics |volume=44 |issue=75107 |pages=075107 |doi=10.1088/1361-6471/aa7293 |bibcode=2017JPhG...44g5107Z|doi-access=free }}</ref>

=== Naming ===
[[File:Kosuke Morita and Hiroshi Matsumoto cropped Hideto Enyo Kosuke Morita Koji Morimoto and Hiroshi Matsumoto 20161201.jpg|thumb|[[Kōsuke Morita]] and [[Hiroshi Matsumoto (engineer)|Hiroshi Matsumoto]], celebrating the naming on 1 December 2016.|alt=Lead researcher Kosuke Morita and Riken president Hiroshi Matsumoto from Riken showing "Nh" being added to the periodic table]]

Using [[Mendeleev's predicted elements|Mendeleev's nomenclature for unnamed and undiscovered elements]], nihonium would be known as ''eka-thallium''. In 1979, IUPAC published recommendations according to which the element was to be called ''ununtrium'' (with the corresponding symbol of ''Uut''),<ref name="iupac">{{cite journal |author=Chatt, J. |journal=Pure Appl. Chem. |date=1979 |volume=51 |pages=381–384 |title=Recommendations for the Naming of Elements of Atomic Numbers Greater than 100 |doi=10.1351/pac197951020381 |issue=2|doi-access=free }}</ref> a [[systematic element name]] as a [[placeholder name|placeholder]], until the discovery of the element is confirmed and a name is decided on. The recommendations were widely used in the chemical community on all levels, from chemistry classrooms to advanced textbooks, but were mostly ignored among scientists in the field, who called it "element 113", with the symbol of ''E113'', ''(113)'', or even simply ''113''.<ref name="Haire" />

Before the JWP recognition of their priority, the Japanese team had unofficially suggested various names: ''japonium'', after their home country;<ref name="aaa" /> ''nishinanium'', after Japanese physicist [[Yoshio Nishina]], the "founding father of modern physics research in Japan";<ref>{{Cite news |url=http://www.nikkei.com/article/DGXNASDG2604F_W2A920C1CR8000/ |date=27 September 2012 |newspaper=[[Nihon Keizai Shimbun]] |language=ja|script-title=ja:新元素113番、日本の発見確実に 合成に３回成功 |access-date=13 October 2012}}</ref> and ''rikenium'', after the institute.<ref name="aaa">{{cite web |url=https://www.scientificamerican.com/article/element-113-at-last/ |title=Element 113 at Last? |first=Richard Van |last=Noorden |website=[[Scientific American]] |date=27 September 2012}}</ref> After the recognition, the Riken team gathered in February 2016 to decide on a name. Morita expressed his desire for the name to honour the fact that element 113 had been discovered in Japan. ''Japonium'' was considered, making the connection to Japan easy to identify for non-Japanese, but it was rejected as ''[[Jap]]'' is considered an [[ethnic slur]]. The name ''nihonium'' was chosen after an hour of deliberation: it comes from {{nihongo||日本|[[Names of Japan#Nihon and Nippon|Nihon]]}}, one of the two Japanese pronunciations for the name of Japan.<ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |title=Proposed name for 113th element a fulfilled wish for Japanese researchers |url=https://mainichi.jp/english/articles/20160609/p2a/00m/0na/010000c |newspaper=The Mainichi |date=9 June 2016 |access-date=29 April 2018}}</ref> The discoverers also intended to reference the support of their research by the Japanese people (Riken being almost entirely government-funded),<ref>{{cite news |author=<!--Staff writer(s); no by-line.--> |date=9 June 2016 |title=Naming 113th element 'nihonium' a tribute to Japanese public support: researcher |url=https://mainichi.jp/english/articles/20160609/p2a/00m/0na/014000c |newspaper=The Mainichi |access-date=29 April 2018}}</ref> recover lost pride and trust in science among those who were affected by the [[Fukushima Daiichi nuclear disaster]],<ref name="IUPAC-June2016" /> and honour Japanese chemist [[Masataka Ogawa]]'s 1908 discovery of [[rhenium]], which he named "nipponium" with symbol Np after the other Japanese pronunciation of Japan's name.<ref name="namingiupac" /> As Ogawa's claim had not been accepted, the name "nipponium" could not be reused for a new element, and its symbol Np had since been used for [[neptunium]].{{efn|Neptunium had been first reported at Riken by Nishina and [[Kenjiro Kimura]] in 1940, who did not get naming rights because they could not chemically separate and identify their discovery.<ref name="Ikeda">{{cite journal |last1=Ikeda |first1=Nagao |date=25 July 2011 |title=The discoveries of uranium 237 and symmetric fission – From the archival papers of Nishina and Kimura |pmc=3171289 |journal=Proceedings of the Japan Academy, Series B: Physical and Biological Sciences |volume=87 |issue=7 |pages=371–376 |doi=10.2183/pjab.87.371 |pmid=21785255 |bibcode=2011PJAB...87..371I}}</ref><ref name="Enyo">{{cite web |url=https://www.ssken.gr.jp/MAINSITE/event/2017/20170526-generalmeeting/lecture-01/SSKEN_generalmeeting2017_EnyoHideto_presentation.pdf |language=ja |script-title=ja:ビックバンから １１３番元素ニホニウムまで、元素創成の１３８億年 |title=Bikkuban kara 113-ban genso nihoniumu made, genso sōsei no 138 oku-nen |trans-title=From the Big Bang to the 113th element nihonium: element creation of 13.8 billion years |last=En'yo |first=Hideto |date=26 May 2017 |access-date=28 January 2018 |archive-url=https://web.archive.org/web/20180129004320/https://www.ssken.gr.jp/MAINSITE/event/2017/20170526-generalmeeting/lecture-01/SSKEN_generalmeeting2017_EnyoHideto_presentation.pdf |archive-date=29 January 2018}}</ref>}} In March 2016, Morita proposed the name "nihonium" to IUPAC, with the symbol Nh.<ref name="namingiupac" /> The naming realised what had been a national dream in Japanese science ever since Ogawa's claim.<ref name="podcast" />

The former president of IUPAP, [[Cecilia Jarlskog]], complained at the Nobel Symposium on Superheavy Elements in [[Bäckaskog Castle]], Sweden, in June 2016 about the lack of openness involved in the process of approving new elements, and stated that she believed that the JWP's work was flawed and should be redone by a new JWP. A survey of physicists determined that many felt that the Lund–GSI 2016 criticisms of the JWP report were well-founded, but it was also generally thought that the conclusions would hold up if the work was redone. Thus the new president, [[Bruce McKellar]], ruled that the proposed names should be released in a joint IUPAP–IUPAC press release.<ref name="McKellar">{{cite web |url=http://iupap.org/wp-content/uploads/2016/09/Presidents-report-20161013-2.pdf |title=President's report to the meeting of the IUPAP Council and Commission Chairs |last=McKellar |first=Bruce |date=22–23 October 2016 |publisher=[[International Union of Pure and Applied Physics]] |access-date=14 January 2018 |archive-date=2 November 2020 |archive-url=https://web.archive.org/web/20201102094153/http://iupap.org/wp-content/uploads/2016/09/Presidents-report-20161013-2.pdf |url-status=dead }}</ref> IUPAC and IUPAP publicised the proposal of ''nihonium'' that June,<ref name="IUPAC-June2016">{{cite web |url=http://iupac.org/iupac-is-naming-the-four-new-elements-nihonium-moscovium-tennessine-and-oganesson/ |title=IUPAC Is Naming The Four New Elements Nihonium, Moscovium, Tennessine, And Oganesson |date=8 June 2016 |publisher=IUPAC |access-date=8 June 2016}}</ref> and set a five-month term to collect comments, after which the name would be formally established at a conference.<ref name="mainichi.jp">{{cite web |title=Japan scientists plan to name atomic element 113 'Nihonium' |date=8 June 2016 |newspaper=Mainichi Shimbun |url=http://mainichi.jp/english/articles/20160608/p2g/00m/0fp/060000c |quote=Japanese scientists who discovered the atomic element 113 plan to name it "Nihonium", sources close to the matter said Wednesday. |url-status=dead |archive-url=https://web.archive.org/web/20160609135534/http://mainichi.jp/english/articles/20160608/p2g/00m/0fp/060000c |archive-date=9 June 2016 }}</ref><ref name="sankei.com-2016">{{cite web |title=ニホニウム」有力 日本初の新元素名称案、国際機関が９日公表 |trans-title=Nihonium the most probable |newspaper=The Sankei Shimbun |date=6 June 2016 |language=ja |quote=Rather than initially proposed ''Japanium'' which is derived from Latin or French, Morita group leader seems to stick to his own language. |url=http://www.sankei.com/life/news/160608/lif1606080005-n1.html}}</ref> The name was officially approved on 28 November 2016.<ref name="IUPAC-Nov2016">{{cite web |url=https://iupac.org/iupac-announces-the-names-of-the-elements-113-115-117-and-118 |title=IUPAC Announces the Names of the Elements 113, 115, 117, and 118 |date=30 November 2016 |publisher=IUPAC |access-date=30 November 2016}}</ref> The naming ceremony for the new element was held in [[Tokyo]], Japan, on 14 March 2017, with [[Naruhito]], then the Crown Prince of Japan, in attendance.<ref>{{cite news |work=News on Japan |date=15 March 2017 |title=Naming ceremony held for new element 'nihonium' |url=http://newsonjapan.com/html/newsdesk/article/119326.php |access-date=28 January 2018 |archive-url=https://web.archive.org/web/20180128132830/http://newsonjapan.com/html/newsdesk/article/119326.php |archive-date=28 January 2018 |url-status=dead}}</ref>