Isotopes of unbinilium

Unbinilium (120Ubn) has not yet been synthesised, so all data would be theoretical and a standard atomic weight cannot be given. Like all synthetic elements, it would have no stable isotopes.

List of isotopes

No isotopes of unbinilium are known.

Nucleosynthesis

Target-projectile combinations leading to Z = 120 compound nuclei

The below table contains various combinations of targets and projectiles that could be used to form compound nuclei with Z=120.[1]

TargetProjectileCNAttempt result
208Pb 88Sr296UbnReaction yet to be attempted
238U 64Ni302UbnFailure to date
237Np 59Co296UbnReaction yet to be attempted
244Pu 58Fe302UbnFailure to date
244Pu 60Fe304UbnReaction yet to be attempted
243Am 55Mn298UbnReaction yet to be attempted
248Cm 54Cr302UbnFailure to date
250Cm 54Cr304UbnReaction yet to be attempted
249Bk 51V300UbnReaction yet to be attempted
249Cf 50Ti299UbnFailure to date
250Cf 50Ti300UbnReaction yet to be attempted
251Cf 50Ti301UbnReaction yet to be attempted
252Cf 50Ti302UbnReaction yet to be attempted
257Fm 48Ca305UbnReaction yet to be attempted

238U(64Ni,xn)302-xUbn

In April 2007, the team at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany attempted to create unbinilium using a 238U target and a 64Ni beam:[2]

238
92U
 + 64
28Ni
 → 302
120Ubn
* → no atoms

No atoms were detected, providing a limit of 1.6 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 fb.[2]

244Pu(58Fe,xn)302-xUbn

Following their success in obtaining oganesson by the reaction between 249Cf and 48Ca in 2006, the team at the Joint Institute for Nuclear Research (JINR) in Dubna started experiments in March–April 2007 to attempt to create unbinilium with a 58Fe beam and a 244Pu target.[3][4] Initial analysis revealed that no atoms of unbinilium were produced, providing a limit of 400 fb for the cross section at the energy studied.[5]

244
94Pu
 + 58
26Fe
 → 302
120Ubn
* → no atoms

The Russian team planned to upgrade their facilities before attempting the reaction again.[5]

248Cm(54Cr,xn)302-xUbn

In 2011, after upgrading their equipment to allow the use of more radioactive targets, scientists at the GSI attempted the rather asymmetrical fusion reaction:[6]

248
96Cm
 + 54
24Cr
 → 302
120Ubn
* → no atoms

It was expected that the change in reaction would quintuple the probability of synthesizing unbinilium,[7] as the yield of such reactions is strongly dependent on their asymmetry.[8] Although this reaction is less asymmetric than the 249Cf+50Ti reaction, it also creates more neutron-rich unbinilium isotopes that should receive increased stability from their proximity to the shell closure at N = 184.[9] Three signals were observed in May 2011; a possible assignment to 299Ubn and its daughters was considered,[10] but could not be confirmed,[11][12][9] and a different analysis suggested that what was observed was simply a random sequence of events.[13]

In March 2022, Yuri Oganessian gave a seminar at the JINR considering how one could synthesise element 120 in the 248Cm+54Cr reaction.[14]

249Cf(50Ti,xn)299-xUbn

In August–October 2011, a different team at the GSI using the TASCA facility tried a new, even more asymmetrical reaction:[6][15]

249
98Cf
 + 50
22Ti
 → 299
120Ubn
* → no atoms

Because of its asymmetry,[16] the reaction between 249Cf and 50Ti was predicted to be the most favorable practical reaction for synthesizing unbinilium, although it is also somewhat cold, and is further away from the neutron shell closure at N = 184 than any of the other three reactions attempted. No unbinilium atoms were identified, implying a limiting cross section of 200 fb.[15] Jens Volker Kratz predicted the actual maximum cross section for producing unbinilium by any of the four reactions 238U+64Ni, 244Pu+58Fe, 248Cm+54Cr, or 249Cf+50Ti to be around 0.1 fb;[17] in comparison, the world record for the smallest cross section of a successful reaction was 30 fb for the reaction 209Bi(70Zn,n)278Nh,[8] and Kratz predicted a maximum cross section of 20 fb for producing ununennium.[17] If these predictions are accurate, then synthesizing ununennium would be at the limits of current technology, and synthesizing unbinilium would require new methods.[17]

This reaction was investigated again in April to September 2012 at the GSI. This experiment used a 249Bk target and a 50Ti beam to produce element 119, but since 249Bk decays to 249Cf with a half-life of about 327 days, both elements 119 and 120 could be searched for simultaneously:

249
97Bk
 + 50
22Ti
 → 299
119Uue
* → no atoms
249
98Cf
 + 50
22Ti
 → 299
120Ubn
* → no atoms

Neither element 119 nor element 120 was observed. This implied a limiting cross section of 65 fb for producing element 119 in these reactions, and 200 fb for element 120.[18]

In May 2021, the JINR announced plans to investigate the 249Cf+50Ti reaction in their new facility.[19] The 249Cf target would be produced by the Oak Ridge National Laboratory in Oak Ridge, Tennessee, United States; the 50Ti beam would be produced by the Hubert Curien Pluridisciplinary Institute in Strasbourg, Alsace, France. If diplomatic relations between Russia and the United States make this impossible, then the 248Cm+54Cr reaction may be investigated instead, with a Russian-produced 248Cm target and a French-produced 54Cr beam, though the cross section would likely be three to ten times lower.[20]

References
  • Isotope masses from:
    • M. Wang; G. Audi; A. H. Wapstra; F. G. Kondev; M. MacCormick; X. Xu; et al. (2012). "The AME2012 atomic mass evaluation (II). Tables, graphs and references" (PDF). Chinese Physics C. 36 (12): 1603–2014. Bibcode:2012ChPhC..36....3M. doi:10.1088/1674-1137/36/12/003. S2CID 250839471.
    • Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A, 729: 3–128, Bibcode:2003NuPhA.729....3A, doi:10.1016/j.nuclphysa.2003.11.001
  1. Isospin dependence in heavy-element synthesis in fusion-evaporation reactions with neutron-rich radioactive ion-beams, A. Yakushev et al.
  2. Hoffman, S.; et al. (2008). Probing shell effects at Z = 120 and N = 184 (Report). GSI Scientific Report. p. 131.
  3. "A New Block on the Periodic Table" (PDF). Lawrence Livermore National Laboratory. April 2007. Retrieved 2008-01-18.
  4. Itkis, M. G.; Oganessian, Yu. Ts. (2007). "Synthesis of New Nuclei and Study of Nuclear Properties and Heavy-Ion Reaction Mechanisms". jinr.ru. Joint Institute for Nuclear Research. Retrieved 23 September 2016.
  5. Oganessian, Yu. Ts.; Utyonkov, V.; Lobanov, Yu.; et al. (2009). "Attempt to produce element 120 in the 244Pu+58Fe reaction". Phys. Rev. C. 79 (2). 024603. Bibcode:2009PhRvC..79b4603O. doi:10.1103/PhysRevC.79.024603.
  6. Düllmann, C. E. (20 October 2011). "Superheavy Element Research: News from GSI and Mainz". Retrieved 23 September 2016.
  7. GSI (5 April 2012). "Searching for the island of stability". www.gsi.de. GSI. Retrieved 23 September 2016.
  8. Zagrebaev, Karpov & Greiner 2013.
  9. Hofmann, S.; Heinz, S.; Mann, R.; et al. (2016). "Review of even element super-heavy nuclei and search for element 120". The European Physical Journal A. 2016 (52): 180. Bibcode:2016EPJA...52..180H. doi:10.1140/epja/i2016-16180-4. S2CID 124362890.
  10. Hofmann, S.; Heinz, S.; Mann, R.; et al. (2016). "Remarks on the Fission Barriers of SHN and Search for Element 120". In Peninozhkevich, Yu. E.; Sobolev, Yu. G. (eds.). Exotic Nuclei: EXON-2016 Proceedings of the International Symposium on Exotic Nuclei. Exotic Nuclei. pp. 155–164. ISBN 9789813226555.
  11. Adcock, Colin (2 October 2015). "Weighty matters: Sigurd Hofmann on the heaviest of nuclei". JPhys+. Journal of Physics G: Nuclear and Particle Physics. Retrieved 23 September 2016.
  12. Hofmann, Sigurd (August 2015). "Search for Isotopes of Element 120 on the Island of SHN". Exotic Nuclei: 213–224. Bibcode:2015exon.conf..213H. doi:10.1142/9789814699464_0023. ISBN 978-981-4699-45-7.
  13. Heßberger, F. P.; Ackermann, D. (2017). "Some critical remarks on a sequence of events interpreted to possibly originate from a decay chain of an element 120 isotope". The European Physical Journal A. 53 (123): 123. Bibcode:2017EPJA...53..123H. doi:10.1140/epja/i2017-12307-5. S2CID 125886824.
  14. JINR (29 March 2022). "At seminar on synthesis of element 120". jinr.ru. JINR. Retrieved 17 April 2022.
  15. Yakushev, A. (2012). "Superheavy Element Research at TASCA" (PDF). asrc.jaea.go.jp. Retrieved 23 September 2016.
  16. Siwek-Wilczyńska, K.; Cap, T.; Wilczyński, J. (April 2010). "How can one synthesize the element Z = 120?". International Journal of Modern Physics E. 19 (4): 500. Bibcode:2010IJMPE..19..500S. doi:10.1142/S021830131001490X.
  17. Kratz, J. V. (5 September 2011). The Impact of Superheavy Elements on the Chemical and Physical Sciences (PDF). 4th International Conference on the Chemistry and Physics of the Transactinide Elements. Retrieved 27 August 2013.
  18. Khuyagbaatar, J.; Yakushev, A.; Düllmann, Ch. E.; et al. (December 2020). "Search for elements 119 and 120" (PDF). Physical Review C. 102 (6): 064602. Bibcode:2020PhRvC.102f4602K. doi:10.1103/PhysRevC.102.064602. hdl:1885/289860. S2CID 229401931. Retrieved 25 January 2021.
  19. Sokolova, Svetlana; Popeko, Andrei (24 May 2021). "How are new chemical elements born?". jinr.ru. JINR. Retrieved 4 November 2021. 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.

    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.
  20. Riegert, Marion (19 July 2021). "In search of element 120 in the periodic table of elements". en.unistra.fr. University of Strasbourg. Retrieved 20 February 2022.

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