Isotopes of unbinilium

Template:SHORTDESC: Unbinilium (₁₂₀Ubn) has not yet been synthesised, so there is no experimental data 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.

Target	Projectile	CN	Attempt result
208Pb	88Sr	296Ubn	Template:Unk
238U	64Ni	302Ubn	Failure to date
237Np	59Co	296Ubn	Template:Unk
244Pu	58Fe	302Ubn	Failure to date
244Pu	60Fe	304Ubn	Template:Unk
243Am	55Mn	298Ubn	Template:Unk
245Cm	54Cr	299Ubn	Template:Unk
246Cm	54Cr	300Ubn	Template:Unk
248Cm	54Cr	302Ubn	Failure to date
250Cm	54Cr	304Ubn	Template:Unk
249Bk	51V	300Ubn	Template:Unk
249Cf	50Ti	299Ubn	Failure to date
250Cf	50Ti	300Ubn	Template:Unk
251Cf	50Ti	301Ubn	Template:Unk
252Cf	50Ti	302Ubn	Template:Unk
257Fm	48Ca	305Ubn	Template:Unk

Hot fusion

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:

Template:Nuclide + Template:Nuclide → Template:Nuclide* → 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.

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. Initial analysis revealed that no atoms of unbinilium were produced, providing a limit of 400 fb for the cross section at the energy studied.

Template:Nuclide + Template:Nuclide → Template:Nuclide* → no atoms

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

²⁴⁵Cm(⁵⁴Cr,xn)^299-xUbn

There are indications that this reaction may be tried by the JINR in the future. The expected products of the 3n and 4n channels, ²⁹⁶Ubn and ²⁹⁵Ubn, could undergo five alpha decays to reach the darmstadtium isotopes ²⁷⁶Ds and ²⁷⁵Ds respectively; these darmstadtium isotopes were synthesised at the JINR in 2022 and 2023 respectively, both in the ²³²Th+⁴⁸Ca reaction.

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:

Template:Nuclide + Template:Nuclide → Template:Nuclide* → no atoms

It was expected that the change in reaction would quintuple the probability of synthesizing unbinilium, as the yield of such reactions is strongly dependent on their asymmetry. 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. Three signals were observed in May 2011; a possible assignment to ²⁹⁹Ubn and its daughters was considered, but could not be confirmed, and a different analysis suggested that what was observed was simply a random sequence of events.

In March 2022, Yuri Oganessian gave a seminar at the JINR considering how one could synthesise element 120 in the ²⁴⁸Cm+⁵⁴Cr reaction. In 2023, the director of the JINR, Grigory Trubnikov, stated that he hoped that the experiments to synthesise element 120 will begin in 2025.

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:

Template:Nuclide + Template:Nuclide → Template:Nuclide* → no atoms

Because of its asymmetry, 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. 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; in comparison, the world record for the smallest cross section of a successful reaction was 30 fb for the reaction ²⁰⁹Bi(⁷⁰Zn,n)²⁷⁸Nh, and Kratz predicted a maximum cross section of 20 fb for producing ununennium. If these predictions are accurate, then synthesizing ununennium would be at the limits of current technology, and synthesizing unbinilium would require new methods.

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:

Template:Nuclide + Template:Nuclide → Template:Nuclide* → no atoms

Template:Nuclide + Template:Nuclide → Template:Nuclide* → 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.

In May 2021, the JINR announced plans to investigate the ²⁴⁹Cf+⁵⁰Ti reaction in their new facility. The ²⁴⁹Cf target would have been 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. However, after the Russian invasion of Ukraine began in 2022, collaboration between the JINR and other institutes completely ceased due to sanctions. Thus, the JINR's plans have since shifted to the ²⁴⁸Cm+⁵⁴Cr reaction, where the target and projectile beam could both be made in Russia.

Starting from 2022, plans began to be made to use the 88-inch cyclotron in the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California, United States to attempt to make new elements using ⁵⁰Ti projectiles. The plan was to first test them on a plutonium target to create livermorium (element 116), which was successful in 2024. Thus, an attempt to make element 120 in the ²⁴⁹Cf+⁵⁰Ti reaction is now planned for 2025.