As a result, there are blanks on the periodic table where elements 115 and 113 would be — even though elements 112, 114 and 116 have been officially approved.
The latest RIKEN results seem to answer all critics, because this time their atom of dubnium did not decay by fission but instead spat out a chain of six α-particles, in well-known and previously observed reactions. “I’d say this fulfils all IUPAC’s requirements, and I’d be happy to give it to them,” says Rolf-Dietmar Herzberg, a nuclear physicist at the University of Liverpool, UK, who studies super-heavy elements.
Other researchers contacted by Nature were more equivocal. In January this year, the Dubna team reported work done between November 2010 and March 2011, including chemical analyses of the dubnium end product.
Ultimately, naming rights will depend on the committee’s decision. Paul Karol, a chemist at Carnegie Mellon University in Pittsburgh, Pennsylvania, who was on the technical committee that turned down 113 and 115 last year, says that the panel will now consider both groups’ claims. No one should get their hopes up for a speedy resolution: last year’s report took three years from experiments to decision. But Karol says that was an exceptional delay and this review will be faster.
In a 2004 newsletter that RIKEN published shortly after the team’s first claimed observation, the names ‘rikenium’ and ‘japonium’ were suggested for element 113 (temporarily called ununtrium). According to the IUPAC, elements cannot be named after an institute, so ‘japonium’ would seem to be the front-runner.
Meanwhile, Morita says that the Japanese experiment shuts down on 1 October, and the researchers will be moving on to the next undetected elements — numbers 119 and 120. Once again, the chase is on: a team at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, has spent the past five months searching for element 119, with a calculated “80–90% chance of success”, according to the project’s director Christoph Düllman.