Isotopes of tennessine

Tennessine is the most-recently synthesized synthetic element, and much of the data is hypothetical. As for any synthetic element, a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotopes to be synthesized were ²⁹³Ts and ²⁹⁴Ts in 2009. The longer-lived isotope is ²⁹⁴Ts with a half-life of 51 ms.

Isotopes and nuclear properties

Nucleosynthesis

Target-projectile combinations leading to Z=117 compound nuclei

The below table contains various combinations of targets and projectiles that could be used to form compound nuclei with atomic number 117.

Target	Projectile	CN	Attempt result
²⁰⁸Pb	⁸¹Br	²⁸⁹Ts
²⁰⁹Bi	⁸²Se	²⁹¹Ts
²³⁸U	⁵⁵Mn	²⁹³Ts
²⁴³Am	⁵⁰Ti	²⁹³Ts
²⁴⁹Bk	⁴⁸Ca	²⁹⁷Ts

Hot fusion

²⁴⁹Bk(⁴⁸Ca,''x''n)^297−''x''Ts (''x''=3,4)

Between July 2009 and February 2010, the team at the JINR (Flerov Laboratory of Nuclear Reactions) ran a 7-month-long experiment to synthesize tennessine using the reaction above.
The expected cross-section was of the order of 2 pb. The expected evaporation residues, ²⁹³Ts and ²⁹⁴Ts, were predicted to decay via relatively long decay chains as far as isotopes of dubnium or lawrencium.

The team published a paper in April 2010 that six atoms of the isotopes ²⁹⁴Ts and ²⁹³Ts were detected. ²⁹⁴Ts decayed by six alpha decays down as far as the new isotope ²⁷⁰Db, which underwent apparent spontaneous fission. The lighter odd-even isotope underwent just three alpha decays, as far as ²⁸¹Rg, which underwent spontaneous fission. The reaction was run at two different excitation energies, 35 MeV and 39 MeV. Initial decay data was published as a preliminary presentation on the JINR website.
A further experiment in May 2010, aimed at studying the chemistry of the granddaughter of tennessine, nihonium, identified a further two atoms of ²⁸⁶Nh from decay of ²⁹⁴Ts. The original experiment was repeated successfully by the same collaboration in 2012 and by a joint German–American team in May 2014, confirming the discovery.

Theoretical calculations

Evaporation residue cross sections

The below table contains various targets-projectile combinations for which calculations have provided estimates for cross section yields from various neutron evaporation channels. The channel with the highest expected yield is given.
DNS = Di-nuclear system; σ = cross section

Target	Projectile	CN	Channel	σ_max	Model	Ref
²⁰⁹Bi	⁸²Se	²⁹¹Ts	1n	15 fb	DNS
²⁰⁹Bi	⁷⁹Se	²⁸⁸Ts	1n	0.2 pb	DNS
²³²Th	⁵⁹Co	²⁹¹Ts	2n	0.1 pb	DNS
²³⁸U	⁵⁵Mn	²⁹³Ts	2-3n	70 fb	DNS
²⁴⁴Pu	⁵¹V	²⁹⁵Ts	3n	0.6 pb	DNS
²⁴⁸Cm	⁴⁵Sc	²⁹³Ts	4n	2.9 pb	DNS
²⁴⁶Cm	⁴⁵Sc	²⁹¹Ts	4n	1 pb	DNS
²⁴⁹Bk	⁴⁸Ca	²⁹⁷Ts	3n	2.1 pb ; 3 pb	DNS
²⁴⁷Bk	⁴⁸Ca	²⁹⁵Ts	3n	0.8, 0.9 pb	DNS

Decay characteristics

Theoretical calculations in a quantum tunneling model with mass estimates from a macroscopic-microscopic model predict the alpha-decay half-lives of isotopes of tennessine to be around 0.1–40 ms.