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Retracted. A report 2 years ago of element 118 was incorrect, scientists now say.

Now You See Element 118, Now You Don't

It appears that the superheavy element 118 has one exotic property that nobody predicted: the ability to vanish into thin air. The team of physicists who had claimed to have created the most massive chemical element have retracted their claim in a short statement submitted 27 July to Physical Review Letters.

Two years ago, scientists at the Lawrence Berkeley National Laboratory in California presented evidence that they had created element 118, as well as a slightly lighter one, element 116 (ScienceNOW, 7 June 1999). The news came as a shock to many scientists in the field, who thought that the fusion method used by the Berkeley team wouldn't produce element 118 in detectable quantities. But in the face of the experimental data--a chain of alpha particle decays that seemed to indicate the existence of a new superheavy element--teams across the world attempted to replicate the results.

Those attempts, at the Institute for Heavy Ion Research (GSI) in Darmstadt, Germany; at the Great National Heavy Ion Accelerator (GANIL) in Caen, France; and at the Institute of Physical and Chemical Research (RIKEN) in Japan, all came to naught, but the extreme rarity of the new nuclei made it possible that a slight difference in the experimental setup or even a statistical fluke could be responsible for the failed replication attempts. So the Berkeley team tried, last year and this year, to repeat their own experiment. They failed. In the wake of that failure, Berkeley researchers went back and reanalyzed their original data. "Those analyses showed that the chains reported are not there," says Kenneth Gregorich, a member of the Berkeley team.

Gregorich has little idea what caused the false readings. "The problem we have now is that none of the [possible explanations] looks very likely." In the meantime, nuclear physicist Sigurd Hofmann of the GSI praises the Berkeley team for their candor, and, along with the rest of the heavy-ion community, awaits a fuller accounting so they can understand what went wrong.

Related sites

The Berkeley team's Web site
The GSI home page
The GANIL home page
The RIKEN home page