Editing Unbinilium (section)

===Nuclear stability and isotopes===
[[File:Island of Stability derived from Zagrebaev.svg|thumb|upright=2.5|alt=A 2D graph with rectangular cells colored in black-and-white colors, spanning from the llc to the urc, with cells mostly becoming lighter closer to the latter|A chart of nuclide stability as used by the Dubna team in 2010. Characterized isotopes are shown with borders. Beyond element 118 (oganesson, the last known element), the line of known nuclides is expected to rapidly enter a region of instability. The elliptical region encloses the predicted location of the island of stability.{{sfn|Zagrebaev|Karpov|Greiner|2013}}]]

[[File:Next proton shell.svg|class=skin-invert-image|thumb|upright=1.2|Orbitals with high [[azimuthal quantum number]] are raised in energy, eliminating what would otherwise be a gap in orbital energy corresponding to a closed proton shell at element 114, as shown in the left diagram which does not take this effect into account. This raises the next proton shell to the region around element 120, as shown in the right diagram, potentially increasing the half-lives of element 119 and 120 isotopes.<ref name="Kratz">{{cite conference |last1=Kratz |first1=J. V. |date=5 September 2011 |title=The Impact of Superheavy Elements on the Chemical and Physical Sciences |url=http://tan11.jinr.ru/pdf/06_Sep/S_1/02_Kratz.pdf |conference=4th International Conference on the Chemistry and Physics of the Transactinide Elements |access-date=27 August 2013}}</ref>]]
The stability of nuclei decreases greatly with the increase in atomic number after [[curium]], element 96, whose half-life is four orders of magnitude longer than that of any currently known higher-numbered element. All isotopes with an atomic number above [[mendelevium|101]] undergo [[radioactive decay]] with half-lives of less than 30 hours. No elements with atomic numbers above 82 (after [[lead]]) have stable isotopes.<ref>{{cite journal |last1=de Marcillac |first1=Pierre |last2=Coron |first2=Noël |last3=Dambier |first3=Gérard |last4=Leblanc |first4=Jacques |last5=Moalic |first5=Jean-Pierre |display-authors=3 |date=2003 |title=Experimental detection of α-particles from the radioactive decay of natural bismuth |journal=Nature |volume=422 |pages=876–878 |pmid=12712201 |doi=10.1038/nature01541 |issue=6934 |bibcode=2003Natur.422..876D |s2cid=4415582 }}</ref> Nevertheless, because of reasons not yet well understood, there is a slight increase of nuclear stability around atomic numbers [[darmstadtium|110]]–[[flerovium|114]], which leads to the appearance of what is known in nuclear physics as the "[[island of stability]]". This concept, proposed by [[University of California, Berkeley|University of California]] professor [[Glenn Seaborg]], explains why superheavy elements last longer than predicted.<ref>{{cite book |title=Van Nostrand's scientific encyclopedia |first1=Glenn D. |last1=Considine |first2=Peter H. |last2=Kulik |publisher=Wiley-Interscience |date=2002 |edition=9th |isbn=978-0-471-33230-5 |oclc=223349096 }}</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|author=Chowdhury, P. Roy|author2=Samanta, C.|author3=Basu, D. N.|name-list-style=amp |doi=10.1103/PhysRevC.77.044603|bibcode=2008PhRvC..77d4603C |issue=4|arxiv=0802.3837|s2cid=119207807}}</ref><ref name="sciencedirect1">{{cite journal |author=Chowdhury |first=P. Roy |author2=Samanta |first2=C. |author3=Basu |first3=D. N. |name-list-style=amp |year=2008 |title=Nuclear half-lives for α -radioactivity of elements with 100 ≤ Z ≤ 130 |journal=[[Atomic Data and Nuclear Data Tables]] |volume=94 |issue=6 |pages=781–806 |arxiv=0802.4161 |bibcode=2008ADNDT..94..781C |doi=10.1016/j.adt.2008.01.003 |s2cid=96718440}}</ref> In a [[quantum tunneling]] model with mass estimates from a macroscopic-microscopic model, the [[alpha decay|alpha-decay]] half-lives of several unbinilium [[isotope]]s (<sup>292–304</sup>Ubn) have been predicted to be around 1–20 microseconds.<ref name="prc08ADNDT08" /><ref name="half-lifesall">{{cite journal|journal=Phys. Rev. C|volume=73 |issue=1|at=014612|date=2006|title=α decay half-lives of new superheavy elements|author=Chowdhury, P. Roy |author2=Samanta, C.|author3=Basu, D. N.|name-list-style=amp |doi=10.1103/PhysRevC.73.014612 |bibcode=2006PhRvC..73a4612C |arxiv=nucl-th/0507054|s2cid=118739116 }}</ref><ref>{{cite journal| journal=Nucl. Phys. A |volume=789|issue=1–4|pages=142–154|date=2007| title=Predictions of alpha decay half lives of heavy and superheavy elements |author=Samanta, C.|author2=Chowdhury, P. Roy|author3=Basu, D.N.|name-list-style=amp |doi=10.1016/j.nuclphysa.2007.04.001|bibcode=2007NuPhA.789..142S |arxiv=nucl-th/0703086|s2cid=7496348}}</ref><ref name="sciencedirect1"/> Some heavier isotopes may be more stable; Fricke and Waber predicted <sup>320</sup>Ubn to be the most stable unbinilium isotope in 1971.<ref name="Fricke1971" /> Since unbinilium is expected to decay via a cascade of alpha decays leading to [[spontaneous fission]] around [[copernicium]], the total half-lives of unbinilium isotopes are also predicted to be measured in microseconds.<ref name="Haire" /><ref name="Hofmann" /> This has consequences for the synthesis of unbinilium, as isotopes with half-lives below one microsecond would decay before reaching the detector.<ref name="Haire" /><ref name="Hofmann" /> Nevertheless, new theoretical models show that the expected gap in energy between the [[nuclear shell model|proton orbitals]] 2f<sub>7/2</sub> (filled at element 114) and 2f<sub>5/2</sub> (filled at element 120) is smaller than expected, so that element 114 no longer appears to be a stable spherical closed nuclear shell, and this energy gap may increase the stability of elements 119 and 120. The next [[doubly magic]] nucleus is now expected to be around the spherical <sup>306</sup>Ubb (element 122), but the expected low half-life and low production [[cross section (physics)|cross section]] of this nuclide makes its synthesis challenging.<ref name="Kratz" />

Given that element 120 fills the 2f<sub>5/2</sub> proton orbital, much attention has been given to the compound nucleus <sup>302</sup>Ubn* and its properties. Several experiments have been performed between 2000 and 2008 at the Flerov Laboratory of Nuclear Reactions in Dubna studying the fission characteristics of the compound nucleus <sup>302</sup>Ubn*. Two nuclear reactions have been used, namely <sup>244</sup>Pu+<sup>58</sup>Fe and <sup>238</sup>U+<sup>64</sup>Ni. The results have revealed how nuclei such as this fission predominantly by expelling closed shell nuclei such as <sup>132</sup>[[tin|Sn]] (''[[atomic number|Z]]''&nbsp;=&nbsp;50, ''[[neutron number|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>{{cite web |url=http://www1.jinr.ru/Reports/Reports_eng_arh.html |title=JINR Publishing Department: Annual Reports (Archive) |author=JINR |date=1998–2014 |website=jinr.ru |publisher=JINR |access-date=23 September 2016}}</ref>

In 2008, the team at [[Grand Accélérateur National d'Ions Lourds|GANIL]], France, described the results from a new technique which attempts to measure the fission [[half-life]] of a compound nucleus at high excitation energy, since the yields are significantly higher than from neutron evaporation channels. It is also a useful method for probing the effects of shell closures on the survivability of compound nuclei in the super-heavy region, which can indicate the exact position of the next proton shell (''Z''&nbsp;=&nbsp;114, 120, 124, or 126). The team studied the nuclear fusion reaction between uranium ions and a target of natural nickel:<ref name="Natowitz" /><ref name="Morjean" />

:{{nuclide|U|238}} + {{nuclide|Ni|nat}} → {{nuclide|Ubn|296,298,299,300,302}}* → fission

The results indicated that nuclei of unbinilium were produced at high (≈70&nbsp;MeV) excitation energy which underwent fission with measurable half-lives just over 10<sup>−18</sup> s.<ref name="Natowitz" /><ref name="Morjean" /> Although very short (indeed insufficient for the element to be considered by [[IUPAC]] to exist, because a compound nucleus has no internal structure and its nucleons have not been arranged into shells until it has survived for 10<sup>−14</sup>&nbsp;s, when it forms an electronic cloud),<ref>{{cite web |title=Kernchemie |url=http://www.kernchemie.de/Transactinides/Transactinide-2/transactinide-2.html |access-date=23 September 2016|language=de|trans-title=Nuclear Chemistry}}</ref> the ability to measure such a process indicates a strong shell effect at ''Z''&nbsp;=&nbsp;120. At lower excitation energy (see neutron evaporation), the effect of the shell will be enhanced and ground-state nuclei can be expected to have relatively long half-lives. This result could partially explain the relatively long half-life of <sup>294</sup>Og measured in experiments at Dubna. Similar experiments have indicated a similar phenomenon at [[unbiquadium|element 124]] but not for [[flerovium]], suggesting that the next proton shell does in fact lie beyond element 120.<ref name="Natowitz">{{cite journal |doi=10.1103/Physics.1.12|title=How stable are the heaviest nuclei?|date=2008|author=Natowitz, Joseph |journal=Physics|volume=1|pages=12|bibcode = 2008PhyOJ...1...12N |doi-access=}}</ref><ref name="Morjean">{{cite journal|journal=Phys. Rev. Lett. |volume=101|issue=7|date=2008 |at=072701|title=Fission Time Measurements: A New Probe into Superheavy Element Stability|doi=10.1103/PhysRevLett.101.072701|pmid=18764526|bibcode=2008PhRvL.101g2701M |last1=Morjean|first1=M.|last2=Jacquet|first2=D. |last3=Charvet |first3=J. |display-authors=etal |url=http://hal.in2p3.fr/in2p3-00289928/document}}</ref> In September 2007, the team at RIKEN began a program utilizing <sup>248</sup>Cm targets and have indicated future experiments to probe the possibility of 120 being the next proton magic number (and 184 being the next neutron magic number) using the aforementioned nuclear reactions to form <sup>302</sup>Ubn*, as well as <sup>248</sup>Cm+<sup>54</sup>Cr. They also planned to further chart the region by investigating the nearby compound nuclei <sup>296</sup>Og*, <sup>298</sup>Og*, <sup>306</sup>Ubb*, and <sup>308</sup>Ubb*.<ref>{{cite web |title=Future Plan of the Experimental Program on Synthesizing the Heaviest Element at RIKEN |last1=Morita |first1=K. |date=28 September 2007 |url=http://www-win.gsi.de/tasca07/contributions/TASCA07_Contribution_Morita.pdf |access-date=23 September 2016 |url-status=dead |archive-url=https://web.archive.org/web/20150403120113/http://www-win.gsi.de/tasca07/contributions/TASCA07_Contribution_Morita.pdf |archive-date=3 April 2015 }}</ref>

The most likely isotopes of unbinilium to be synthesised in the near future are <sup>295</sup>Ubn through <sup>299</sup>Ubn, because they can be produced in the 3n and 4n channels of the <sup>249–251</sup>Cf+<sup>50</sup>Ti, <sup>245</sup>Cm+<sup>54</sup>Cr, and <sup>248</sup>Cm+<sup>54</sup>Cr reactions.<ref name=jinr2024>{{Cite web |url=https://indico.jinr.ru/event/4343/contributions/28663/attachments/20748/36083/U%20+%20Cr%20AYSS%202024.pptx |title=Synthesis and study of the decay properties of isotopes of superheavy element Lv in Reactions <sup>238</sup>U + <sup>54</sup>Cr and <sup>242</sup>Pu + <sup>50</sup>Ti |last=Ibadullayev |first=Dastan |date=2024 |website=jinr.ru |publisher=[[Joint Institute for Nuclear Research]] |access-date=2 November 2024 |quote=}}</ref>