Oganesson - 118Og: historical information
Experiments conducted at Dubna in Russia at the Flerov Laboratory of Nuclear Reactions (by workers from the Joint Institute for Nuclear Research in Russia and the Lawrence Livermore National Laboratory in the USA) indicate that element 118 (oganesson, Og) was produced. Not too much though, one atom in the spring of 2002 and two more in 2005.
The 2002 experiment involved firing a beam of 4820Ca at 24998Cf. The experiment took 4 months and involved a beam of 2.5 x 1019 calcium ions to produce the single event believed to be the synthesis of element 118 (ununoctium) as the 249118Uuo isotope. Three neutrons are released during this process
24998Cf + 4820Ca → 294118Og + 31n
This research was reported at an IUPAC conference in China (Yu. Ts. Oganessian, "Synthesis and decay properties of superheavy elements", Pure Appl. Chem., 2006, 78, 889-904.) in August 2006 and then more recently in Phys Rev C [Yu. Ts. Oganessian, V. K. Utyonkov, Yu. V. Lobanov, F. Sh. Abdullin, A. N. Polyakov, R. N. Sagaidak, I. V. Shirokovsky, Yu. S. Tsyganov, A. A. Voinov, G. G. Gulbekian, S. L. Bogomolov, B. N. Gikal, A. N. Mezentsev, S. Iliev, V. G. Subbotin, A. M. Sukhov, K. Subotic, V. I. Zagrebaev, G. K. Vostokin, M. G. Itkis, K. J. Moody, J. B. Patin, D. A. Shaughnessy, M. A. Stoyer, N. J. Stoyer, P. A. Wilk, J. M. Kenneally, J. H. Landrum, J. F. Wild, and R. W. Lougheed, "Synthesis of the isotopes of elements 118 and 116 in the 249Cf and 245Cm+48Ca fusion reactions", Phys. Rev. C, 2006, 74, 044602].
Earlier, a team of Berkeley Lab scientists announced in 1999 the observation of what appeared to be element 118 but retracted the claim after several confirmation experiments failed to reproduce the results. Please see this page for more details. In this work it was claimed that elements 118 and 116 were formed by accelerating a beam of krypton-86 (8636Kr) ions to an energy of 449 million electron volts and directing the beam onto targets of lead-208 (20882Pb). After 11 days work, just three atoms of the new element were identified. The production rates for element 118 are approximately one in every 1012 interactions.
20882Pb + 8636Kr → 293118Uuo + 1n
These experiments were carried out following calculations by Robert Smolanczuk (Soltan Institute for Nuclear Studies, Poland) on the fusion of atomic nucleii. His calculations suggested that it might be possible to make element 118 by fusing lead with krypton under carefully controlled conditions.