Editing Extended periodic table (section)

==Searches for undiscovered elements==
===Synthesis attempts===
Attempts have been made to synthesise the period 8 elements up to unbiseptium, except unbitrium. All such attempts have been unsuccessful. An attempt to synthesise ununennium, the first period 8 element, is ongoing {{as of|{{CURRENTYEAR}}|lc=y}}.

==== Ununennium (E119) <span class="anchor" id="Ununennium"></span> ====
{{Main|Ununennium#Synthesis attempts}}
The synthesis of element 119 ([[ununennium]]) was first attempted in 1985 by bombarding a target of einsteinium-254 with [[calcium-48]] ions at the superHILAC accelerator at Berkeley, California:

:{{nuclide|einsteinium|254}} + {{nuclide|calcium|48}} → {{sup|302}}119* → no atoms

No atoms were identified, leading to a limiting [[cross section (physics)|cross section]] of 300 [[barn (unit)|nb]].<ref>{{cite journal|title=Search for superheavy elements using <sup>48</sup>Ca + <sup>254</sup>Es<sup>g</sup> reaction|journal=Physical Review C|date=1985|pages=1760–1763|doi=10.1103/PhysRevC.32.1760|pmid=9953034|volume=32|issue=5|bibcode = 1985PhRvC..32.1760L|last1=Lougheed|first1=R.|last2=Landrum|first2=J.|last3=Hulet|first3=E.|last4=Wild|first4=J.|last5=Dougan|first5=R.|last6=Dougan|first6=A.|last7=Gäggeler|first7=H.|last8=Schädel|first8=M.|last9=Moody|first9=K.|display-authors=1}}</ref> Later calculations suggest that the cross section of the 3n reaction (which would result in {{sup|299}}119 and three neutrons as products) would actually be six hundred thousand times lower than this upper bound, at 0.5&nbsp;pb.<ref>{{cite journal|arxiv=0803.1117|doi=10.1016/j.nuclphysa.2008.11.003|title=Production of heavy and superheavy nuclei in massive fusion reactions|date=2009|author=Feng, Z|journal=Nuclear Physics A|volume=816|issue=1|page=33|last2=Jin|first2=G.|last3=Li|first3=J.|last4=Scheid|first4=W.|bibcode=2009NuPhA.816...33F|s2cid=18647291}}</ref>

From April to September 2012, an attempt to synthesize the isotopes {{sup|295}}119 and {{sup|296}}119 was made by bombarding a target of [[berkelium]]-249 with [[titanium]]-50 at the [[GSI Helmholtz Centre for Heavy Ion Research]] in [[Darmstadt]], Germany.<ref name="economist">[http://www.economist.com/node/21554502 Modern alchemy: Turning a line], [[The Economist]], May 12, 2012.</ref><ref name=Khuyagbaatar>[http://asrc.jaea.go.jp/soshiki/gr/chiba_gr/workshop2/&Khuyagbaatar.pdf Superheavy Element Search Campaign at TASCA]. J. Khuyagbaatar</ref> Based on the theoretically predicted cross section, it was expected that an ununennium atom would be synthesized within five months of the beginning of the experiment.<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> Moreover, as berkelium-249 decays to [[californium]]-249 (the next element) with a short half-life of 327&nbsp;days, this allowed elements 119 and 120 to be searched for simultaneously.<ref name="search">{{cite journal |last1=Khuyagbaatar |first1=J. |last2=Yakushev |first2=A. |last3=Düllmann |first3=Ch. E. |display-authors=etal |date=2020 |title=Search for elements 119 and 120 |url=https://jyx.jyu.fi/bitstream/handle/123456789/73027/2/khuyagbaatarym0812.pdf |journal=Physical Review C |volume=102 |issue=6 |at=064602 |doi=10.1103/PhysRevC.102.064602 |bibcode=2020PhRvC.102f4602K |hdl=1885/289860 |s2cid=229401931 |access-date=25 January 2021}}</ref>

:{{nuclide|berkelium|249}} + {{nuclide|titanium|50}} → {{sup|299}}119* → no atoms

The experiment was originally planned to continue to November 2012,<ref>{{Cite web |url=https://www-win.gsi.de/tasca12/program/contributions/TASCA12_Duellmann.pdf |title=Search for element 119: Christoph E. Düllmann for the ''TASCA E119'' collaboration |access-date=2017-04-05 |archive-url=https://web.archive.org/web/20160304094201/https://www-win.gsi.de/tasca12/program/contributions/TASCA12_Duellmann.pdf |archive-date=2016-03-04 |url-status=dead }}</ref> but was stopped early to make use of the {{sup|249}}Bk target to confirm the synthesis of [[tennessine]] (thus changing the projectiles to {{sup|48}}Ca).<ref name=Yakushev/> This reaction of {{sup|249}}Bk + {{sup|50}}Ti was predicted to be the most favorable practical reaction for formation of element 119,<ref name=Khuyagbaatar/> as it is rather asymmetrical,<ref name=Zagrebaev/> though also somewhat cold.<ref name=Yakushev/> ({{sup|254}}Es + {{sup|48}}Ca would be superior, but preparing milligram quantities of {{sup|254}}Es for a target is difficult.)<ref name=Zagrebaev/> Nevertheless, the necessary change from the "silver bullet" {{sup|48}}Ca to {{sup|50}}Ti divides the expected yield of element 119 by about twenty, as the yield is strongly dependent on the asymmetry of the fusion reaction.<ref name=Zagrebaev/>

Due to the predicted short half-lives, the GSI team used new "fast" electronics capable of registering decay events within microseconds.<ref name=Khuyagbaatar/> No atoms of element 119 were identified, implying a limiting cross section of 70&nbsp;fb.<ref name=Yakushev/> The predicted actual cross section is around 40&nbsp;fb, which is at the limits of current technology.<ref name=Zagrebaev/>

The team at RIKEN in [[Wakō, Saitama|Wakō]], Japan began bombarding [[curium]]-248 targets with a [[vanadium]]-51 beam in January 2018<ref name=sakai22>{{cite journal |last1=Sakai |first1=Hideyuki |last2=Haba |first2=Hiromitsu |first3=Kouji |last3=Morimoto |first4=Naruhiko |last4=Sakamoto |date=9 December 2022 |title=Facility upgrade for superheavy-element research at RIKEN |journal=The European Physical Journal A |volume=58 |issue=238 |page=238 |doi=10.1140/epja/s10050-022-00888-3 |pmid=36533209 |pmc=9734366 |bibcode=2022EPJA...58..238S }}</ref> to search for element 119. Curium was chosen as a target, rather than heavier berkelium or californium, as these heavier targets are difficult to prepare.<ref name="sakai">{{cite web |url=http://www0.mi.infn.it/~colo/slides_27_2_19/2019-2_Milano-WS_sakai.pdf |title=Search for a New Element at RIKEN Nishina Center |last=Sakai |first=Hideyuki |date=27 February 2019 |website=infn.it |access-date=17 December 2019}}</ref> The {{sup|248}}Cm targets were provided by [[Oak Ridge National Laboratory]]. RIKEN developed a high-intensity vanadium beam.<ref name=usprogram>{{cite journal |url=https://www.osti.gov/servlets/purl/1896856 |title=The Status and Ambitions of the US Heavy Element Program |first1=J. |last1=Gates |first2=J. |last2=Pore |first3=H. |last3=Crawford |first4=D. |last4=Shaughnessy |first5=M. A. |last5=Stoyer |date=25 October 2022 |website=osti.gov |publisher= |access-date=13 November 2022 |doi=10.2172/1896856 |osti=1896856 |s2cid=253391052 |quote=}}</ref> The experiment began at a cyclotron while RIKEN upgraded its linear accelerators; the upgrade was completed in 2020.<ref>{{Cite web|url=https://www.nishina.riken.jp/about/greeting_e.html|title = Greeting &#124; RIKEN Nishina Center|quote=With the completion of the upgrade of the linear accelerator and BigRIPS at the beginning of 2020, the RNC aims to synthesize new elements from element 119 and beyond.|date=1 April 2020|first=Hiroyoshi|last=Sakurai}}</ref> Bombardment may be continued with both machines until the first event is observed; the experiment is currently running intermittently for at least 100 days a year.<ref name="ball19">{{cite journal |last=Ball |first=P. |title=Extreme chemistry: experiments at the edge of the periodic table |date=2019 |journal=Nature |volume=565 |issue=7741 |pages=552–555 |issn=1476-4687 |doi=10.1038/d41586-019-00285-9|pmid=30700884 |bibcode=2019Natur.565..552B |s2cid=59524524 |doi-access=free |url=https://www.nature.com/magazine-assets/d41586-019-00285-9/d41586-019-00285-9.pdf |quote="We started the search for element 119 last June," says RIKEN researcher Hideto En'yo. "It will certainly take a long time — years and years — so we will continue the same experiment intermittently for 100 or more days per year, until we or somebody else discovers it."}}</ref><ref name="sakai"/> The RIKEN team's efforts are being financed by the [[Emperor of Japan]].<ref>{{cite web |url=https://eic.rsc.org/feature/the-hunt-is-on/3008580.article |title=The hunt is on |last1=Chapman |first1=Kit |last2=Turner |first2=Kristy |date=13 February 2018 |website=Education in Chemistry |publisher=Royal Society of Chemistry |access-date=28 June 2019 |quote=The hunt for element 113 was almost abandoned because of lack of resources, but this time Japan’s emperor is bankrolling Riken’s efforts to extend the periodic table to its eighth row.}}</ref> The team at the JINR plans to attempt synthesis of element 119 in the future, probably via the {{sup|243}}Am + {{sup|54}}Cr reaction, but a precise timeframe has not been publicly released.<ref>{{cite web |url=http://www.jinr.ru/posts/jinr-presented-largest-periodic-table-to-dubna/ |title=JINR presented largest Periodic Table to Dubna |author=Joint Institute for Nuclear Research |date=24 July 2021 |website=jinr.ru |publisher=Joint Institute for Nuclear Research |access-date=27 January 2022}}</ref><ref>{{cite web |url=http://www.jinr.ru/posts/superheavy-element-factory-overview-of-obtained-results/ |title=Superheavy Element Factory: overview of obtained results |author=<!--Not stated--> |date=24 August 2023 |website= |publisher=Joint Institute for Nuclear Research |access-date=7 December 2023 |quote=}}</ref>

==== Unbinilium (E120) <span class="anchor" id="Unbinilium"></span> ====
Following their success in obtaining [[oganesson]] by the reaction between [[californium-249|<sup>249</sup>Cf]] and [[calcium-48|<sup>48</sup>Ca]] in 2006, the team at the [[Joint Institute for Nuclear Research]] (JINR) in [[Dubna]] started similar experiments in March–April 2007, in hope of creating [[unbinilium|element 120]] (unbinilium) from nuclei of [[iron-58|<sup>58</sup>Fe]] and [[plutonium-244|<sup>244</sup>Pu]].<ref>{{cite news|url=https://www.llnl.gov/str/April07/pdfs/04_07.4.pdf|title=A New Block on the Periodic Table|date=April 2007|publisher=Lawrence Livermore National Laboratory|access-date=2008-01-18|archive-url=https://web.archive.org/web/20080528130457/https://www.llnl.gov/str/April07/pdfs/04_07.4.pdf|archive-date=2008-05-28|url-status=dead}}</ref><ref>{{cite web |url=http://wwwinfo.jinr.ru/plan/ptp-2007/e751004.htm |title=Synthesis of New Nuclei and Study of Nuclear Properties and Heavy-Ion Reaction Mechanisms |last1=Itkis |first1=M. G. |last2=Oganessian |first2=Yu. Ts. |date=2007 |website=jinr.ru |publisher=Joint Institute for Nuclear Research |access-date=23 September 2016}}</ref> Isotopes of unbinilium are predicted to have alpha decay half-lives of the order of [[microsecond]]s.<ref name=prc08ADNDT08>{{cite journal|journal=Physical Review C|volume=77|page=044603|year=2008|title=Search for long lived heaviest nuclei beyond the valley of stability|first1=P. Roy |last1=Chowdhury |first2=C. |last2=Samanta |first3= D. N. |last3=Basu|doi=10.1103/PhysRevC.77.044603|bibcode = 2008PhRvC..77d4603C|issue=4|arxiv = 0802.3837 |s2cid=119207807}}</ref><ref name="sciencedirect1">{{cite journal|journal=[[Atomic Data and Nuclear Data Tables]] |volume=94|pages=781–806|year=2008|title=Nuclear half-lives for α -radioactivity of elements with 100 ≤ Z ≤ 130|author=Chowdhury, R. P.|author2=Samanta, C.|author3=Basu, D.N.|doi=10.1016/j.adt.2008.01.003|bibcode = 2008ADNDT..94..781C|issue=6|arxiv = 0802.4161 |s2cid=96718440}}</ref> Initial analysis revealed that no atoms of element 120 were produced, providing a limit of 400&nbsp;[[barn (unit)|fb]] for the [[cross section (physics)|cross section]] at the energy studied.<ref name=Oganessian120>{{cite journal|journal=Phys. Rev. C|volume=79|page=024603|date=2009|title=Attempt to produce element 120 in the <sup>244</sup>Pu+<sup>58</sup>Fe reaction|doi=10.1103/PhysRevC.79.024603|last1=Oganessian|first1=Yu. Ts.|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.|issue=2 |bibcode = 2009PhRvC..79b4603O|display-authors=8 }}</ref>

:{{nuclide|plutonium|244}} + {{nuclide|iron|58}} → <sup>302</sup>120* → no atoms

The Russian team planned to upgrade their facilities before attempting the reaction again.<ref name=Oganessian120/>

In April 2007, the team at the [[GSI Helmholtz Centre for Heavy Ion Research]] in [[Darmstadt]], Germany, attempted to create element 120 using [[uranium]]-238 and [[nickel]]-64:<ref name=GSI08>{{cite report|last=Hoffman|first=S.|display-authors=etal|title=Probing shell effects at Z=120 and N=184|date=2008|publisher=GSI Scientific Report|page=131}}</ref>

:{{nuclide|uranium|238}} + {{nuclide|nickel|64}} → <sup>302</sup>120* → no atoms

No atoms were detected, providing a limit of 1.6&nbsp;[[barn (unit)|pb]] for the cross section at the energy provided. The GSI repeated the experiment with higher sensitivity in three separate runs in April–May 2007, January–March 2008, and September–October 2008, all with negative results, reaching a cross section limit of 90&nbsp;fb.<ref name=GSI08/>

In June–July 2010, and again in 2011, after upgrading their equipment to allow the use of more radioactive targets, scientists at the GSI attempted the more asymmetrical fusion reaction:<ref name=Hofmann2016/>

:{{nuclide|curium|248}} + {{nuclide|chromium|54}} → <sup>302</sup>120 → no atoms

It was expected that the change in reaction would quintuple the probability of synthesizing element 120,<ref>{{cite web |url=https://www.gsi.de/de/work/forschung/nustarenna/nustarenna_divisions/she_physik/research/super_heavy_elements/future_projects.htm |title=Searching for the island of stability |author=GSI |date= 2012-04-05|website=gsi.de |publisher=GSI |access-date=23 September 2016}}</ref> as the yield of such reactions is strongly dependent on their asymmetry.<ref name=Zagrebaev/> Three correlated signals were observed that matched the predicted alpha decay energies of <sup>299</sup>120 and its [[decay product|daughter]] <sup>295</sup>Og, as well as the experimentally known decay energy of its granddaughter <sup>291</sup>[[livermorium|Lv]]. However, the lifetimes of these possible decays were much longer than expected, and the results could not be confirmed.<ref name=Hoffman>{{cite web |url=https://jphysplus.iop.org/2015/10/02/weighty-matters-sigurd-hofmann-on-the-heaviest-of-nuclei/ |title=Weighty matters: Sigurd Hofmann on the heaviest of nuclei |last1=Adcock |first1=Colin |date=2 October 2015 |website=JPhys+ |access-date=23 September 2016 |archive-date=18 July 2023 |archive-url=https://web.archive.org/web/20230718025533/https://jphysplus.iop.org/2015/10/02/weighty-matters-sigurd-hofmann-on-the-heaviest-of-nuclei/ |url-status=dead }}</ref><ref>{{Citation |last=Hofmann |first=S. |title=Search for isotopes of element 120 on the island of shn |date=2015-05-12 |url=https://www.worldscientific.com/doi/abs/10.1142/9789814699464_0023 |work=Exotic Nuclei |pages=213–224 |publisher=WORLD SCIENTIFIC |doi=10.1142/9789814699464_0023 |bibcode=2015exon.conf..213H |isbn=978-981-4699-45-7 |access-date=2022-02-27|url-access=subscription }}</ref><ref name=Hofmann2016>{{cite journal |last1=Hofmann |first1=S. |last2=Heinz |first2=S. |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=Scheidenberger |first30=H. J. |last30=Schött |first31=D. A. |last31=Shaughnessy |first32=M. A. |last32=Stoyer |first33=P. |last33=Thörle-Popiesch |first34=K. |last34=Tinschert |first35=N. |last35=Trautmann |first36=J. |last36=Uusitalo |first37=A. V. |last37=Yeremin |date=2016 |title=Review of even element super-heavy nuclei and search for element 120 |journal=The European Physical Journal A |volume=2016 |issue=52 |pages=180 |doi=10.1140/epja/i2016-16180-4|bibcode=2016EPJA...52..180H |s2cid=124362890 |url=https://zenodo.org/record/897926 }}</ref>

In August–October 2011, a different team at the GSI using the TASCA facility tried a new, even more asymmetrical reaction:<ref name=Duellmann>{{cite web |url=http://www.yumpu.com/en/document/view/7293741/superheavy-element-research-superheavy-element-research |title=Superheavy Element Research: News from GSI and Mainz |last1=Düllmann |first1=C. E. |date=20 October 2011 |access-date=23 September 2016}}</ref><ref name=Yakushev/>

:{{nuclide|californium|249}} + {{nuclide|titanium|50}} → <sup>299</sup>120* → no atoms

This was also tried unsuccessfully the next year during the aforementioned attempt to make element 119 in the <sup>249</sup>Bk+<sup>50</sup>Ti reaction, as <sup>249</sup>Bk decays to <sup>249</sup>Cf. Because of its asymmetry,<ref>{{cite journal |last1=Siwek-Wilczyńska |first1=K. |last2=Cap |first2=T. |last3=Wilczyński |first3=J. |date=April 2010 |title=How can one synthesize the element ''Z'' = 120? |journal=International Journal of Modern Physics E |volume=19 |issue=4 |pages=500 |doi=10.1142/S021830131001490X|bibcode=2010IJMPE..19..500S }}</ref> the reaction between <sup>249</sup>Cf and <sup>50</sup>Ti was predicted to be the most favorable practical reaction for synthesizing unbinilium, although it is also somewhat cold. No unbinilium atoms were identified, implying a limiting cross-section of 200&nbsp;fb.<ref name=Yakushev>{{cite web |url=http://asrc.jaea.go.jp/soshiki/gr/chiba_gr/workshop3/&Yakushev.pdf |title=Superheavy Element Research at TASCA |last1=Yakushev |first1=A. |date=2012 |website=asrc.jaea.go.jp |access-date=23 September 2016}}</ref> Jens Volker Kratz predicted the actual maximum cross-section for producing element 120 by any of these reactions to be around 0.1&nbsp;fb;<ref name=Kratz/> in comparison, the world record for the smallest cross section of a successful reaction was 30&nbsp;fb for the reaction <sup>209</sup>Bi(<sup>70</sup>Zn,n)<sup>278</sup>[[nihonium|Nh]],<ref name=Zagrebaev/> and Kratz predicted a maximum cross-section of 20&nbsp;fb for producing the neighbouring element 119.<ref name=Kratz/> If these predictions are accurate, then synthesizing element 119 would be at the limits of current technology, and synthesizing element 120 would require new methods.<ref name=Kratz/>

In May 2021, the JINR announced plans to investigate the <sup>249</sup>Cf+<sup>50</sup>Ti reaction in their new facility. However, the <sup>249</sup>Cf target would have had to be made by the [[Oak Ridge National Laboratory]] in the United States,<ref>{{cite web |url=http://www.jinr.ru/posts/how-are-new-chemical-elements-born/ |title=How are new chemical elements born? |last1=Sokolova |first1=Svetlana |last2=Popeko |first2=Andrei |date=24 May 2021 |website=jinr.ru |publisher=JINR |access-date=4 November 2021 |quote=Previously, we worked mainly with calcium. This is element 20 in the Periodic Table. It was used to bombard the target. And the heaviest element that can be used to make a target is californium, 98. Accordingly, 98 + 20 is 118. That is, to get element 120, we need to proceed to the next particle. This is most likely titanium: 22 + 98 = 120.<br/><br/>There is still much work to adjust the system. I don't want to get ahead of myself, but if we can successfully conduct all the model experiments, then the first experiments on the synthesis of element 120 will probably start this year.}}</ref> and after the [[Russian invasion of Ukraine]] began in February 2022, collaboration between the JINR and other institutes completely ceased due to sanctions.<ref name=ft>{{cite news |last=Ahuja |first=Anjana |date=18 October 2023 |title=Even the periodic table must bow to the reality of war |url=https://www.ft.com/content/6b6b0afc-39b2-4955-af5a-d0ea6b4d8306 |work=Financial Times |location= |access-date=20 October 2023}}</ref> Consequently, the JINR now plans to try the <sup>248</sup>Cm+<sup>54</sup>Cr reaction instead. A preparatory experiment for the use of <sup>54</sup>Cr projectiles was conducted in late 2023, successfully synthesising <sup>288</sup>Lv in the <sup>238</sup>U+<sup>54</sup>Cr reaction,<ref name=Lv288>{{cite news |url=http://www.jinr.ru/posts/v-lyar-oiyai-vpervye-v-mire-sintezirovan-livermorij-288/ |title=В ЛЯР ОИЯИ впервые в мире синтезирован ливерморий-288 |trans-title=Livermorium-288 was synthesized for the first time in the world at FLNR JINR |language=ru |date=23 October 2023 |publisher=Joint Institute for Nuclear Research |access-date=18 November 2023}}</ref> and the hope is for experiments to synthesise element 120 to begin by 2025.<ref>{{cite news |last=Mayer |first=Anastasiya |date=31 May 2023 |language=ru |title="Большинство наших партнеров гораздо мудрее политиков" |trans-title=Most of our partners are much wiser than politicians |url=https://www.vedomosti.ru/technology/characters/2023/05/31/977789-bolshinstvo-nashih-partnerov-mudree-politikov |work=[[Vedomosti]] |location= |access-date=15 August 2023 |quote=В этом году мы фактически завершаем подготовительную серию экспериментов по отладке всех режимов ускорителя и масс-спектрометров для синтеза 120-го элемента. Научились получать высокие интенсивности ускоренного хрома и титана. Научились детектировать сверхтяжелые одиночные атомы в реакциях с минимальным сечением. Теперь ждем, когда закончится наработка материала для мишени на реакторах и сепараторах у наших партнеров в «Росатоме» и в США: кюрий, берклий, калифорний. Надеюсь, что в 2025 г. мы полноценно приступим к синтезу 120-го элемента.}}</ref>

Starting from 2022,<ref name=usprogram/> plans have also been made to use 88-inch cyclotron in the [[Lawrence Berkeley National Laboratory]] (LBNL) in [[Berkeley, California]], United States to attempt to make new elements using <sup>50</sup>Ti projectiles.<ref>{{cite news |last=Chapman |first=Kit |date=10 October 2023 |title=Berkeley Lab to lead US hunt for element 120 after breakdown of collaboration with Russia |url=https://www.chemistryworld.com/news/berkeley-lab-to-lead-us-hunt-for-element-120-after-breakdown-of-collaboration-with-russia/4018207.article |work=Chemistry World |location= |access-date=20 October 2023}}</ref><ref>{{cite web |url=https://physicalsciences.lbl.gov/2023/10/16/berkeley-lab-to-test-new-approach-to-making-superheavy-elements/ |title=Berkeley Lab to Test New Approach to Making Superheavy Elements |last=Biron |first=Lauren |date=16 October 2023 |website=lbl.gov |publisher=[[Lawrence Berkeley National Laboratory]] |access-date=20 October 2023 |quote=}}</ref> First, the <sup>244</sup>Pu+<sup>50</sup>Ti reaction was tested, successfully creating two atoms of <sup>290</sup>Lv in 2024. Since this was successful, an attempt to make element 120 in the <sup>249</sup>Cf+<sup>50</sup>Ti reaction is planned to begin in 2025.<ref>{{cite web |url=https://newscenter.lbl.gov/2024/07/23/a-new-way-to-make-element-116-opens-the-door-to-heavier-atoms/ |title=A New Way to Make Element 116 Opens the Door to Heavier Atoms |last=Biron |first=Lauren |date=23 July 2024 |website=lbl.gov |publisher=Lawrence Berkeley National Laboratory |access-date=24 July 2024 |quote=}}</ref><ref>{{cite journal |last1=Bourzac |first1=Katherine |date=23 July 2024 |title=Heaviest element yet within reach after major breakthrough |url=https://www.nature.com/articles/d41586-024-02416-3 |journal=Nature |volume= |issue= |pages= |doi=10.1038/d41586-024-02416-3 |access-date=24 July 2024|url-access=subscription }}</ref><ref>{{cite news |last=Service |first=Robert F. |date=23 July 2024 |title=U.S. back in race to forge unknown, superheavy elements |url=https://www.science.org/content/article/u-s-back-race-forge-unknown-superheavy-elements |work=Science |location= |access-date=24 July 2024}}</ref> The [[Lawrence Livermore National Laboratory]] (LLNL), which previously collaborated with the JINR, will collaborate with the LBNL on this project.<ref>{{cite journal |last1=Nelson |first1=Felicity |date=15 August 2024 |title=How Japan Took the Lead in the Race to Discover Element 119 |url=https://pubs.acs.org/doi/10.1021/acscentsci.4c01266 |journal=ACS Central Science |volume= |issue= |pages= |doi=10.1021/acscentsci.4c01266 |access-date=13 September 2024|doi-access=free |pmc=11539895 }}</ref>

==== Unbiunium (E121) <span class="anchor" id="Unbiunium"></span> ====
The synthesis of [[unbiunium|element 121]] (unbiunium) was first attempted in 1977 by bombarding a target of [[uranium-238]] with [[copper]]-65 ions at the [[Gesellschaft für Schwerionenforschung]] in [[Darmstadt]], Germany:
:{{nuclide|uranium|238}} + {{nuclide|copper|65}} → <sup>303</sup>121* → no atoms
No atoms were identified.<ref name=beyonduranium>{{cite book |last=Hofmann |first=Sigurd |date=2002 |title=On Beyond Uranium |publisher=Taylor & Francis |page=[https://archive.org/details/onbeyonduraniumj0000hofm/page/105 105] |isbn=978-0-415-28496-7 |url=https://archive.org/details/onbeyonduraniumj0000hofm/page/105 }}</ref>

==== Unbibium (E122) <span class="anchor" id="Unbibium"></span> ====
The first attempts to synthesize [[unbibium|element 122]] (unbibium) were performed in 1972 by [[Georgy Flerov|Flerov]] et al. at the [[Joint Institute for Nuclear Research]] (JINR), using the heavy-ion induced hot fusion reactions:<ref name="emsley"/>

:{{nuclide|uranium|238}} + {{nuclide|zinc|66,68}} → <sup>304, 306</sup>122* → no atoms

These experiments were motivated by early predictions on the existence of an [[island of stability]] at ''N''&nbsp;=&nbsp;184 and ''Z''&nbsp;>&nbsp;120. No atoms were detected and a yield limit of 5&nbsp;[[Barn (unit)|nb]] (5,000&nbsp;[[barn (unit)|pb]]) was measured. Current results (see [[flerovium]]) have shown that the sensitivity of these experiments were too low by at least 3 orders of magnitude.<ref name=superlourds>{{cite journal|last1=Epherre|first1=M.|last2=Stephan|first2=C.|date=1975|title=Les éléments superlourds|language=fr|journal=Le Journal de Physique Colloques|volume=11|issue=36|pages=C5–159–164|url=https://core.ac.uk/download/pdf/46775464.pdf|doi=10.1051/jphyscol:1975541}}</ref>

In 2000, the [[Gesellschaft für Schwerionenforschung]] (GSI) Helmholtz Center for Heavy Ion Research performed a very similar experiment with much higher sensitivity:<ref name="emsley">{{cite book|last=Emsley|first=John|title=Nature's Building Blocks: An A-Z Guide to the Elements|edition=New|year=2011|publisher=Oxford University Press|location=New York, NY|isbn=978-0-19-960563-7|page=588}}</ref>

:{{nuclide|uranium|238}} + {{nuclide|zinc|70}} → <sup>308</sup>122* → no atoms

These results indicate that the synthesis of such heavier elements remains a significant challenge and further improvements of beam intensity and experimental efficiency is required. The sensitivity should be increased to 1&nbsp;[[barn (unit)|fb]] in the future for better quality results.

Another unsuccessful attempt to synthesize element 122 was carried out in 1978 at the GSI Helmholtz Center, where a natural [[erbium]] target was bombarded with [[xenon-136]] ions:<ref name="emsley"/>

:{{nuclide|erbium|''nat''}} + {{nuclide|xenon|136}} → <sup>298, 300, 302, 303, 304, 306</sup>122* → no atoms

In particular, the reaction between <sup>170</sup>Er and <sup>136</sup>Xe was expected to yield alpha-emitters with half-lives of microseconds that would decay down to isotopes of [[flerovium]] with half-lives perhaps increasing up to several hours, as flerovium is predicted to lie near the center of the [[island of stability]]. After twelve hours of irradiation, nothing was found in this reaction. Following a similar unsuccessful attempt to synthesize element 121 from <sup>238</sup>U and <sup>65</sup>Cu, it was concluded that half-lives of superheavy nuclei must be less than one microsecond or the cross sections are very small.<ref name=EndPT>{{cite book|last=Hofmann|first=Sigurd|title=On Beyond Uranium: Journey to the End of the Periodic Table|year=2014|publisher=CRC Press|isbn=978-0415284950|page=[https://archive.org/details/onbeyonduraniumj0000hofm/page/105 105]|url=https://archive.org/details/onbeyonduraniumj0000hofm/page/105}}</ref> More recent research into synthesis of superheavy elements suggests that both conclusions are true.<ref name=Zagrebaev/><ref name=Karpov>{{cite web |url=http://cyclotron.tamu.edu/she2015/assets/pdfs/presentations/Karpov_SHE_2015_TAMU.pdf |title=Superheavy Nuclei: which regions of nuclear map are accessible in the nearest studies |last1=Karpov |first1=A |last2=Zagrebaev |first2=V |last3=Greiner |first3=W |date=2015 |website=cyclotron.tamu.edu |publisher=Texas A & M University |access-date=30 October 2018}}</ref> The two attempts in the 1970s to synthesize element 122 were both propelled by the research investigating whether superheavy elements could potentially be naturally occurring.<ref name="emsley"/>

Several experiments studying the fission characteristics of various superheavy compound nuclei such as <sup>306</sup>122* were performed between 2000 and 2004 at the [[Flerov Laboratory of Nuclear Reactions]]. Two nuclear reactions were used, namely <sup>248</sup>Cm + <sup>58</sup>Fe and <sup>242</sup>Pu + <sup>64</sup>Ni.<ref name="emsley"/> The results reveal how superheavy nuclei fission predominantly by expelling [[nuclear shell model|closed shell]] nuclei such as <sup>132</sup>Sn (''Z''&nbsp;=&nbsp;50, ''N''&nbsp;=&nbsp;82). It was also found that the yield for the fusion-fission pathway was similar between <sup>48</sup>Ca and <sup>58</sup>Fe projectiles, suggesting a possible future use of <sup>58</sup>Fe projectiles in superheavy element formation.<ref name="www1.jinr.ru">see Flerov lab annual reports 2000–2004 inclusive http://www1.jinr.ru/Reports/Reports_eng_arh.html</ref>

==== Unbiquadium (E124) <span class="anchor" id="Unbiquadium"></span> ====
{{Further|Unbiquadium}}
Scientists at [[GANIL]] (Grand Accélérateur National d'Ions Lourds) attempted to measure the direct and delayed fission of compound nuclei of elements with ''Z'' = 114, 120, and 124 in order to probe [[nuclear shell|shell]] effects in this region and to pinpoint the next spherical proton shell. This is because having complete nuclear shells (or, equivalently, having a [[magic number (physics)|magic number]] of [[proton]]s or [[neutron]]s) would confer more stability on the nuclei of such superheavy elements, thus moving closer to the [[island of stability]]. In 2006, with full results published in 2008, the team provided results from a reaction involving the bombardment of a natural [[germanium]] target with uranium ions:

:{{nuclide|uranium|238}} + {{nuclide|germanium|''nat''}} → <sup>308, 310, 311, 312, 314</sup>124* → ''fission''

The team reported that they had been able to identify compound nuclei fissioning with half-lives > 10<sup>−18</sup> s. This result suggests a strong stabilizing effect at ''Z'' = 124 and points to the next proton shell at ''Z'' > 120, not at ''Z'' = 114 as previously thought. A compound nucleus is a loose combination of [[nucleon]]s that have not arranged themselves into nuclear shells yet. It has no internal structure and is held together only by the collision forces between the target and projectile nuclei. It is estimated that it requires around 10<sup>−14</sup>&nbsp;s for the nucleons to arrange themselves into nuclear shells, at which point the compound nucleus becomes a [[nuclide]], and this number is used by [[IUPAC]] as the minimum [[half-life]] a claimed isotope must have to potentially be recognised as being discovered. Thus, the GANIL experiments do not count as a discovery of [[element 124]].<ref name="emsley"/>

The fission of the compound nucleus <sup>312</sup>124 was also studied in 2006 at the tandem ALPI heavy-ion accelerator at the [[Laboratori Nazionali di Legnaro]] (Legnaro National Laboratories) in Italy:<ref name="thomas">{{cite journal|last1=Thomas|first1=R.G.|last2=Saxena|first2=A.|last3=Sahu|first3=P.K. |last4=Choudhury|first4=R.K.|last5=Govil|first5=I.M.|last6=Kailas|first6=S. |last7=Kapoor|first7=S.S.|last8=Barubi|first8=M.|last9=Cinausero|first9=M. |last10=Prete|first10=G.|last11=Rizzi|first11=V.|last12=Fabris|first12=D. |last13=Lunardon|first13=M.|last14=Moretto|first14=S.|last15=Viesti|first15=G. |last16=Nebbia|first16=G.|last17=Pesente|first17=S.|last18=Dalena|first18=B. |last19=D'Erasmo|first19=G.|last20=Fiore|first20=E.M.|last21=Palomba|first21=M. |last22=Pantaleo|first22=A.|last23=Paticchio|first23=V.|last24=Simonetti|first24=G. |last25=Gelli|first25=N.|last26=Lucarelli|first26=F.|date=2007|title=Fission and binary fragmentation reactions in <sup>80</sup>Se+<sup>208</sup>Pb and <sup>80</sup>Se+<sup>232</sup>Th systems|journal=Physical Review C|volume=75|issue=2|pages=024604–1–024604–9|doi=10.1103/PhysRevC.75.024604|hdl=2158/776924|hdl-access=free}}</ref>

:{{nuclide|thorium|232}} + {{nuclide|selenium|80}} → <sup>312</sup>124* → ''fission''

Similarly to previous experiments conducted at the JINR ([[Joint Institute for Nuclear Research]]), [[fission product|fission fragments]] clustered around [[doubly magic]] nuclei such as <sup>132</sup>Sn (''Z'' = 50, ''N'' = 82), revealing a tendency for superheavy nuclei to expel such doubly magic nuclei in fission.<ref name="www1.jinr.ru"/> The average number of neutrons per fission from the <sup>312</sup>124 compound nucleus (relative to lighter systems) was also found to increase, confirming that the trend of heavier nuclei emitting more neutrons during fission continues into the superheavy mass region.<ref name=thomas/>

==== Unbipentium (E125) <span class="anchor" id="Unbipentium"></span> ====
The first and only attempt to synthesize element 125 (unbipentium) was conducted in Dubna in 1970{{endash}}1971 using [[zinc]] ions and an [[americium-243]] target:<ref name=superlourds/>

:{{nuclide|americium|243}} + {{nuclide|zinc|66, 68}} → <sup>309, 311</sup>125* → no atoms

No atoms were detected, and a cross section limit of 5 nb was determined. This experiment was motivated by the possibility of greater stability for nuclei around ''Z''&nbsp;~&nbsp;126 and ''N''&nbsp;~&nbsp;184,<ref name=superlourds/> though more recent research suggests the island of stability may instead lie at a lower atomic number (such as [[copernicium]], ''Z'' = 112), and the synthesis of heavier elements such as element 125 will require more sensitive experiments.<ref name=Zagrebaev/>

==== Unbihexium (E126) <span class="anchor" id="Unbihexium"></span> ====
{{Further|Unbihexium}}
The first and only attempt to synthesize [[unbihexium|element 126]] (unbihexium), which was unsuccessful, was performed in 1971 at [[CERN]] (European Organization for Nuclear Research) by René Bimbot and John M. Alexander<!--don't link; the article titled "John M. Alexander" goes to a different John M. Alexander--> using the hot fusion reaction:<ref name="emsley"/>

:{{nuclide|thorium|232}} + {{nuclide|krypton|84}} → <sup>316</sup>126* → no atoms

[[decay energy|High-energy]] (13–15&nbsp;[[MeV]]) [[alpha particles]] were observed and taken as possible evidence for the synthesis of element 126. Subsequent unsuccessful experiments with higher sensitivity suggest that the 10&nbsp;[[barn (unit)|mb]] sensitivity of this experiment was too low; hence, the formation of element 126 nuclei in this reaction is highly unlikely.<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 |publisher=Imperial College Press|date=2000|isbn=978-1-86094-087-3}}</ref>

==== Unbiseptium (E127) <span class="anchor" id="Unbiseptium"></span> ====
The first and only attempt to synthesize element 127 (unbiseptium), which was unsuccessful, was performed in 1978 at the [[UNILAC]] accelerator at the GSI Helmholtz Center, where a natural [[tantalum]] target was bombarded with [[xenon]]-136 ions:<ref name="emsley"/>

:{{nuclide|tantalum|''nat''}} + {{nuclide|xenon|136}} → <sup>316, 317</sup>127* → no atoms

===Searches in nature===
A study in 1976 by a group of American researchers from several universities proposed that [[primordial element|primordial]] superheavy elements, mainly [[livermorium]], elements 124, 126, and 127, could be a cause of unexplained radiation damage (particularly [[radiohalos]]) in minerals.<ref name=Transuraniumppl/> This prompted many researchers to search for them in nature from 1976 to 1983. A group led by Tom Cahill<!--don't link, this Tom Cahill does not have an article-->, a professor at the [[University of California, Davis|University of California at Davis]], claimed in 1976 that they had detected [[alpha particle]]s and [[X-ray]]s with the right energies to cause the damage observed, supporting the presence of these elements. In particular, the presence of long-lived (on the order of 10<sup>9</sup> years) nuclei of elements 124 and 126, along with their decay products, at an abundance of 10<sup>−11</sup> relative to their possible [[congener (chemistry)|congeners]] [[uranium]] and [[plutonium]], was conjectured.<ref name=symposium>{{cite book |editor1-last=Lodhi |editor1-first=M.A.K. |title=Superheavy Elements: Proceedings of the International Symposium on Superheavy Elements |location= Lubbock, Texas |publisher=Pergamon Press |date=March 1978 |isbn=978-0-08-022946-1}}</ref> Others claimed that none had been detected, and questioned the proposed characteristics of primordial superheavy nuclei.<ref name=Transuraniumppl/> In particular, they cited that any such superheavy nuclei must have a closed neutron shell at ''N''&nbsp;=&nbsp;184 or ''N''&nbsp;=&nbsp;228, and this necessary condition for enhanced stability only exists in neutron deficient isotopes of livermorium or neutron rich isotopes of the other elements that would not be [[beta-decay stable isobars|beta-stable]]<ref name=Transuraniumppl/> unlike most naturally occurring isotopes.<ref name=nubase>{{cite journal|last1=Audi|first1=G.|last2=Kondev|first2=F.G.|last3=Wang|first3=M.|last4=Huang|first4=W.J.| last5=Naimi|first5=S.|title=The NUBASE2016 evaluation of nuclear properties|url=http://amdc.in2p3.fr/nubase/2017Audi03.pdf|journal=Chinese Physics C|volume=41|issue=3|date=2017|pages=030001|doi=10.1088/1674-1137/41/3/030001|bibcode=2017ChPhC..41c0001A}}</ref> This activity was also proposed to be caused by nuclear transmutations in natural [[cerium]], raising further ambiguity upon this claimed observation of superheavy elements.<ref name=Transuraniumppl/>

On April 24, 2008, a group led by [[Amnon Marinov]] at the [[Hebrew University of Jerusalem]] claimed to have found single atoms of <sup>292</sup>122 in naturally occurring [[thorium]] deposits at an abundance of between 10<sup>−11</sup> and 10<sup>−12</sup> relative to thorium.<ref name=arxiv/> The claim of Marinov et al. was criticized by a part of the scientific community. Marinov claimed that he had submitted the article to the journals ''[[Nature (journal)|Nature]]'' and ''[[Nature Physics]]'' but both turned it down without sending it for peer review.<ref>[[Royal Society of Chemistry]], "[http://rsc.org/chemistryworld/News/2008/May/02050802.asp Heaviest element claim criticised] {{Webarchive|url=https://web.archive.org/web/20160304042449/http://rsc.org/chemistryworld/News/2008/May/02050802.asp |date=2016-03-04 }}", Chemical World.</ref> The <sup>292</sup>122 atoms were claimed to be [[superdeformation|superdeformed]] or [[hyperdeformation|hyperdeformed]] [[nuclear isomer|isomers]], with a half-life of at least 100 million years.<ref name="emsley"/>

A criticism of the technique, previously used in purportedly identifying lighter [[thorium]] isotopes by [[mass spectrometry]],<ref name="thorium">{{cite journal |journal=Phys. Rev. C |title=Existence of long-lived isomeric states in naturally-occurring neutron-deficient Th isotopes |year=2007 |volume=76 |page=021303(R) |doi=10.1103/PhysRevC.76.021303 |first1=A. |last1=Marinov |first2=I. |last2=Rodushkin |first3=Y. |last3=Kashiv |first4=L. |last4=Halicz |first5=I. |last5=Segal |first6=A. |last6=Pape |first7=R. V. |last7=Gentry |first8=H. W. |last8=Miller |first9= D. |last9=Kolb |first10=R. |last10=Brandt |arxiv = nucl-ex/0605008 |bibcode = 2007PhRvC..76b1303M |issue=2 |s2cid=119443571 }}</ref> was published in ''[[Physical Review C]]'' in 2008.<ref>{{cite journal |journal=Phys. Rev. C |title=Comment on 'Existence of long-lived isomeric states in naturally-occurring neutron-deficient Th isotopes' |year=2009 |volume=79 |pages=049801 |doi=10.1103/PhysRevC.79.049801 |author1=R. C. Barber |author2=J. R. De Laeter |bibcode = 2009PhRvC..79d9801B |issue=4 }}</ref> A rebuttal by the Marinov group was published in ''Physical Review C'' after the published comment.<ref>{{cite journal |journal=Phys. Rev. C |title=Reply to "Comment on 'Existence of long-lived isomeric states in naturally-occurring neutron-deficient Th isotopes'" |year=2009 |volume=79 |pages=049802 |doi=10.1103/PhysRevC.79.049802 |author1=A. Marinov |author2=I. Rodushkin |author3=Y. Kashiv |author4=L. Halicz |author5=I. Segal |author6=A. Pape |author7=R. V. Gentry |author8=H. W. Miller |author9=D. Kolb |author10=R. Brandt |bibcode = 2009PhRvC..79d9802M |issue=4 }}</ref>

A repeat of the thorium experiment using the superior method of [[Accelerator mass spectrometry|Accelerator Mass Spectrometry]] (AMS) failed to confirm the results, despite a 100-fold better sensitivity.<ref>{{cite journal |journal=Phys. Rev. C |title=Search for long-lived isomeric states in neutron-deficient thorium isotopes |year=2008 |volume=78 |page= 064313 |doi=10.1103/PhysRevC.78.064313 |author1=J. Lachner |author2=I. Dillmann |author3=T. Faestermann |author4=G. Korschinek |author5=M. Poutivtsev |author6=G. Rugel |bibcode = 2008PhRvC..78f4313L |issue=6 |arxiv = 0907.0126 |s2cid=118655846 }}</ref> This result throws considerable doubt on the results of the Marinov collaboration with regard to their claims of long-lived isotopes of [[thorium]],<ref name="thorium"/> [[roentgenium]]<ref name="roentgenium">{{cite journal |last1=Marinov |first1=A. |last2=Rodushkin |first2=I. |last3=Pape |first3=A. |last4=Kashiv |first4=Y. |last5=Kolb |first5=D. |last6=Brandt |first6=R. |last7=Gentry |first7=R. V. |last8=Miller |first8=H. W. |last9=Halicz |first9=L. |first10=I. |last10=Segal |year=2009 |title=Existence of Long-Lived Isotopes of a Superheavy Element in Natural Au |journal=[[International Journal of Modern Physics E]] |volume=18 |number=3 |pages=621–629 |doi=10.1142/S021830130901280X |url=http://www.phys.huji.ac.il/~marinov/publications/Au_paper_IJMPE_73.pdf |access-date=February 12, 2012 |arxiv=nucl-ex/0702051 |bibcode=2009IJMPE..18..621M |s2cid=119103410 |url-status=dead |archiveurl=https://web.archive.org/web/20140714210340/http://www.phys.huji.ac.il/~marinov/publications/Au_paper_IJMPE_73.pdf |archive-date=July 14, 2014 }}</ref> and element 122.<ref name=arxiv>{{cite journal |last=Marinov |first=A. |author2=Rodushkin, I. |author3=Kolb, D. |author4=Pape, A. |author5=Kashiv, Y. |author6=Brandt, R. |author7=Gentry, R. V. |author8= Miller, H. W. |title=Evidence for a long-lived superheavy nucleus with atomic mass number A=292 and atomic number Z=~122 in natural Th |journal= International Journal of Modern Physics E|year=2010 |arxiv=0804.3869 |bibcode = 2010IJMPE..19..131M |doi = 10.1142/S0218301310014662 |volume=19 |issue=1 |pages=131–140 |s2cid=117956340 }}</ref> It is still possible that traces of unbibium might only exist in some thorium samples, although this is unlikely.<ref name="emsley"/>

The possible extent of primordial superheavy elements on Earth today is uncertain. Even if they are confirmed to have caused the radiation damage long ago, they might now have decayed to mere traces, or even be completely gone.<ref name="emsley2">{{cite book|last=Emsley|first=John|title=Nature's Building Blocks: An A–Z Guide to the Elements |edition=New |year=2011 |publisher=Oxford University Press|location=New York |isbn=978-0-19-960563-7|page=592}}</ref> It is also uncertain if such superheavy nuclei may be produced naturally at all, as [[spontaneous fission]] is expected to terminate the [[r-process]] responsible for heavy element formation between mass number 270 and 290, well before elements beyond 120 may be formed.<ref>{{cite journal|last1=Petermann |first1=I|last2=Langanke|first2=K.|last3=Martínez-Pinedo|first3=G.|last4=Panov|first4=I.V |last5=Reinhard|first5=P.G.|last6=Thielemann|first6=F.K.|date=2012|title=Have superheavy elements been produced in nature?|journal=European Physical Journal A|volume=48|issue=122|page=122|url=https://www.researchgate.net/publication/229156774|doi=10.1140/epja/i2012-12122-6|arxiv=1207.3432|bibcode=2012EPJA...48..122P|s2cid=119264543}}</ref>

A recent hypothesis tries to explain the spectrum of [[Przybylski's Star]] by naturally occurring [[flerovium]] and element 120.<ref name=Isotope1>{{cite web|url=https://sites.psu.edu/astrowright/2017/03/16/przybylskis-star-iii-neutron-stars-unbinilium-and-aliens/|title=Przybylski's Star III: Neutron Stars, Unbinilium, and aliens|author=Jason Wright|date=16 March 2017|access-date=31 July 2018}}</ref><ref name=Isotope2>{{Cite journal|title=Isotope shift and search for metastable superheavy elements in astrophysical data|journal = Physical Review A|volume = 95|issue = 6|pages = 062515|author1=V. A. Dzuba|author2=V. V. Flambaum|author3=J. K. Webb|arxiv=1703.04250|doi = 10.1103/PhysRevA.95.062515|year = 2017|bibcode=2017PhRvA..95f2515D|s2cid = 118956691}}</ref><ref name=SciShowSpace>Archived at [https://ghostarchive.org/varchive/youtube/20211211/XKD0pFYewu4 Ghostarchive]{{cbignore}} and the [https://web.archive.org/web/20190605060157/https://www.youtube.com/watch?v=XKD0pFYewu4 Wayback Machine]{{cbignore}}: {{cite web|url=https://www.youtube.com/watch?v=XKD0pFYewu4|title=This Star Might Be Hiding Undiscovered Elements. Przybylski's Star|author=SciShow Space|website=youtube.com|date=31 July 2018|access-date=31 July 2018}}{{cbignore}}</ref>