Chasing the elusive Element 115

New Delhi: The existence of a previously unknown chemical element, with atomic number 115, has been confirmed by researchers from Lund University in Sweden. If acknowledged after review of the committee of international unions of pure and applied physics and chemistry, the new, unnamed super-heavy element will be the newest member of the periodic table.

The experiment was conducted at the GSI research facility in Germany. The results confirm earlier measurements performed by research groups in Russia. In 2004, Yuri Oganessian and colleagues at the Joint Institute for Nuclear Research in Dubna, Russia collaborating with a team from the Lawrence Livermore National Laboratory in the US collided calcium-48 with americium-243 nuclei to produce element 115.

But the theory produced by Dubna-Livermore collaborations was declared “sufficiently uncertain” by an International Union of Pure and Applied Chemistry (IUPAC) technical report. In the past few years, nuclear physicists have created elements 110, 111, 112, 114 and 116. But Element 115 has proved to be elusive so far.NextMAds

Elements 114 and 116 were discovered by the same team in Dubna, Russia.

Researchers at Lund University discovered element 115 by bombarding a thin film of americium with calcium ions, and then measuring photons in connection with the new element’s alpha decay. fourthMAds

“Photons can be either coming from the atom (X-rays) or the atomic nuclei (gamma rays). Now, dating back to Moseley’s law from 1913, X-rays have energies which depend on the number of protons inside the nucleus, which, in turn, determines the classification as a chemical element. We have observed two such X-ray candidates along the decay chains of the isotope 288-115, that is, 115 protons and 173 neutrons,” explained Dirk Rudolph, professor at the Division of Nuclear Physics at Lund University.

The new super-heavy element is yet to be named. The new evidence for the chemical element with atomic number 115 will be presented in the scientific journal Physical Review Letters.

“Whether or not the IUPAC/IUPAP committee is going to approve element 115 or not based on our new results, or whether they in turn ask for a statistically significant proof along the lines of X-ray fingerprinting, remains to be seen,” said Rudolph.sixthMAds