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In my blog post the other day about element 113, I mentioned that the process of going from a successful experiment to a successful claim of discovery is tortuous. It relies on researchers convincing a joint panel of experts representing the International Union of Pure and Applied Chemistry (Iupac) and their physics counterpart, Iupap, that their evidence fulfils all the criteria for discovery of a new element.
A joint working party from Iupac and Iupap is currently considering claims relating to elements 113, 115, 117 and higher. Both the Japanese team from RIKEN and a Russian team from the Joint Institute for Nuclear Research in Dubna submitted claims relating to element 113 in May this year for the working party to consider. Kosuke Morita, the leader of the Japanese team has confirmed that they have asked the panel to take this latest paper into consideration along with their earlier results, but it will be down to the panel to decide.
Both of the claims build on earlier work that has so far failed to convince the joint working party. The two claims are quite independent of each other, Morita explains. Neither team’s data will support the other’s claim, as they involve different isotopes of the elements in the decay chains.
The Russian team’s claim revolves around an experiment designed to create element 115, which decays to element 113 by emitting an alpha particle, then continues down its decay chain, through a series of alpha decays. The advantage of the Russian group’s experiment is that they have generated many more atoms of their putative element 115 (and hence element 113), so they have a lot more data than the Japanese team. The disadvantage is that all the nuclides on the decay chain were previously unknown isotopes, so they needed to do some difficult chemical characterisation to prove their identities.
On the other hand, the Japanese team’s experiment, taking into account the latest result, has its decay chain firmly anchored in known nuclide territory. This is a distinct advantage when it comes to the strength of the claim, as it is one of the principal criteria expected by the Iupac-Iupap working party. They have also, Morita believes, gathered sufficient extra evidence supporting their previous claim to answer the joint working party’s concerns from the last review.
However, as the Japanese team only acquired this final puzzle-piece in August this year, if the panel decides that the Dubna team has done enough to characterise the nuclides in their decay chain, it could still award them priority, and possibly even a two-for-one deal including element 115 as well. If not, it looks likely that the RIKEN team has a strong enough claim to earn the first Japanese-named element.
This is by no means an easy decision to make, so both groups will be eagerly awaiting the verdict. Watch this space everyone.