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Welcome back element 118 (ununoctium)

Experiments conducted at the Flerov Laboratory of Nuclear Reactions (Joint Institute for Nuclear Research) at Dubna in Russia indicate that element 118 (ununoctium, Uuo) was produced. Not too much though, one atom in the spring of 2002 and two more in 2005.1,2

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 294118Uuo.

24998Cf + 4820Ca → 294118Uuo + 31n

This ununoctium isotope loses three alpha particles in rapid succesion:

294118Uuo → 290116Uuh + 42He (1.29 milliseconds)

290116Uuh → 286114Uuq + 42He (14.4 milliseconds)

286114Uuq → 282112Uub + 42He (230 milliseconds)

The 282112Uub species then undergoes spontaneous fragmentation (denoted SF) to other species. It took a few years to carry out enough research to properly characterize the decompoition products.

In 2005 a similar experiment but with more sensitive detectors and a total beam dose of 1.6 x 1019 calcium ions resulted in the detection of two further events arising from the formation of 294118Uuo.

This work is particularly significant given the scandal associated with the first report (now withdrawn) of element 118.

Element 118 discovery retracted

The team of Berkeley Lab scientists that announced two years ago (1999) the observation of what appeared to be Element 118 (heaviest undiscovered transuranic element at the time) has retracted its original paper after several confirmation experiments failed to reproduce the results. This means that the pages for element 118 and parts of the data for element 116 are wrong.

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