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Physical Chemistry

Element 115 Detected Again

Building Blocks: Findings should bolster the case for a spot on the periodic table

by Jyllian Kemsley
August 30, 2013 | A version of this story appeared in Volume 91, Issue 35

Confirmatory evidence for the existence of element 115 has been reported by an international research team that successfully used X-ray detection methods for the first time. The new work should bolster the case for adding the element to the periodic table almost a decade after it was first spotted.

Nuclear physicist Dirk Rudolph of Lund University, in Sweden, led the team. The scientists did the experiment at the GSI heavy ion accelerator center in Darmstadt, Germany. A paper of the work has been accepted by Physical Review Letters.

Element 115 was first observed by physicists at Russia’s Joint Institute for Nuclear Research working with scientists from Lawrence Livermore National Laboratory. An international committee of chemists and physicists will decide whether to add the element to the periodic table.

Rudolph’s team created element 115 by aiming a beam of calcium ions at an americium target. Sifting through the jumble of photons, particles, and atoms that results from such an experiment, the researchers detected 𝝰-particle decay chains consistent with isotopes of element 115 decaying to isotopes of dubnium. They also identified X-ray emissions from the decay chain, a long-sought goal of the nuclear physics community because it can be another piece of supporting evidence.

Interference from other emissions makes the X-rays very hard to detect, says Dawn A. Shaughnessy, an LLNL chemist who was part of the first team to observe element 115.

“The fact that they pulled it off and got these measurements is really phenomenal,” she says of the new report.


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