Isotopes of oganesson

Oganesson (118Og) is a synthetic element created in particle accelerators, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first and only isotope to be synthesized was 294Og in 2002 and 2005; it has a half-life of 0.7 milliseconds.

List of isotopes

Nucleosynthesis

Target-projectile combinations leading to Z=118 compound nuclei

The below table contains various combinations of targets and projectiles that could be used to form compound nuclei with Z=118.

Cold fusion

208Pb(86Kr,xn)294-xOg

In 1999, a team led by Victor Ninov at the Lawrence Berkeley National Laboratory performed this experiment, as a 1998 calculation by Robert Smolańczuk suggested a promising outcome. After eleven days of irradiation, three events of 293Og and its alpha decay products were reported in this reaction; this was the first reported discovery of element 118 and then-unknown element 116.

The following year, they published a retraction after researchers at other laboratories were unable to duplicate the results and the Berkeley lab could not duplicate them either. In June 2002, the director of the lab announced that the original claim of the discovery of these two elements had been based on data fabricated by principal author Victor Ninov. Newer experimental results and theoretical predictions have confirmed the exponential decrease in cross-sections with lead and bismuth targets as the atomic number of the resulting nuclide increases.

Hot fusion

249Cf(48Ca,xn)297-xOg (x=3)

Following successful experiments utilizing calcium-48 projectiles and actinide targets to generate elements 114 and 116, the search for element 118 was first performed at the Joint Institute for Nuclear Research (JINR) in 2002.