Japanese Scientists Become First From Asia to Name a New Element

On New Year's Eve, a team of researchers at RIKEN Nishina Center for Accelerator-Based Science in Japan were notified by the International Union of Pure and Applied Chemistry (IUPAC) that they would have the honor of naming element 113. The news came almost 12 years after the RIKEN team first synthesized the element in a lab, and three years after they conclusively demonstrated its decay chain. It will be the first element named by an Asian research institution.

"To scientists, this is of greater value than an Olympic gold medal," said Ryoji Noyori, former RIKEN president and Nobel laureate in chemistry.

Element 113, provisionally known as ununtrium (Latin for 'one one three', signifying its atomic number) is a highly radioactive element that isn't found in nature. It is located in the wild west of the periodic table, home to recently-synthesized superheavy synthetic elements which have no real practical purpose due to their incredibly short half-lives. Here, ununtrium can be found nestled between elements copernicium and flerovium.

A group of researchers at RIKEN headed by Kosuke Morita began working to synthesize ununtrium in 2003, using a linear accelerator to bombard bismuth with zinc ions traveling at about 10 percent the speed of light. The idea was that if they bombarded the bismuth enough times, some bismuth and zinc atoms' nuclei would eventually fuse, creating an atom of element 113. Although the idea made sense in theory, actually producing an atom of element 113 proved to be a difficult task given the extremely short half-lives of the element 113 isotopes produced by RIKEN, which amount to roughly 1/1000 of a second.

The RIKEN group first synthesized an atom of element 113 in July of 2004, only 10 months after starting their initial experiments. In April of 2005, the group synthesized a second atom of element 113, which they observed to decay in exactly the same way as the first atom. Still, according to a 2011 report by a Joint Working Group established by the IUPAC, these initial results, while promising, were not considered to be enough evidence to award the discovery of element 113 to the RIKEN group because of "the paucity of events [and] the absence of firm connections to known nuclides."

This decision was carried out in accordance with a IUPAC working group document from the early 90s, which outlined the complicated criteria that must be met to be credited with the discovery of a new element.

At the same time the RIKEN group was experiencing its initial successes, a number of other laboratories around the world were also working on synthesizing element 113, including the US-based Lawrence Livermore National Laboratory and the Joint Institute for Nuclear Research in Dubna, Russia. The Dubna team had announced that it had successfully synthesized element 113 in 2003, and initially published its results in collaboration with the Livermore lab in early 2004. The group had discovered element 113 decays from element 115, another new element they had synthesized in 2003.

Although it appeared as though the Dubna-Livermore team had beaten RIKEN to the punch, the former was also denied discovery credit for the same reason as the RIKEN group. A race was now on to demonstrate a more complete alpha decay chain for element 113—whoever was the first to do so would receive credit for the discovery of a new element and the naming rights that go with it. Yet despite the initially promising results from both the RIKEN and Dubna-Livermore groups, it would be years before either was able to successfully demonstrate conclusive evidence for element 113's existence with a proper decay chain.

"For over seven years we continued to search for data conclusively identifying element 113, but we just never saw another event," said Morita. "I was not prepared to give up, however, as I believed that one day, if we persevered, luck would fall upon us again."

Then, in August of 2012, the RIKEN group saw the decay chain they were looking for. After the zinc and bismuth nuclei fused, the atom of element 113 that resulted underwent four initial alpha decays, but rather than undergoing spontaneous fission at that point (as happened in the 2004 and 2005 experiments), the dubinium-262 (element 105) that resulted from the alpha decays continued to decay into lawrencium-258 (element 103) and then finally mendelevium-254 (element 101). This was the evidence that the RIKEN team was looking for, proving that element 113 was the result of a decay chain.

This demonstration earned them discovery status for element 113 from the IUPAC, an honor that comes with naming rights. Although the Dubna-Livermore team was also vying for discovery credit, the IUPAC announced on Thursday that Dubna-Livermore teams would receive discovery credit and naming rights for elements 118, in addition to sharing naming/discovery credit with the US Oak Ridge National Laboratory for elements 115 and 117.

Morita has yet to decide on a name for element 113, although he has considered Japonium. According to Morita, after their success with element 113, the RIKEN team has no intention of slowing their work.

"Now that we have conclusively demonstrated the existence of element 113 we plan to look to the uncharted territory of element 119 and beyond," said Morita. "[We aim] to examine the chemical properties of the elements in the seventh and eighth rows of the periodic table, and someday to discover the island of stability."