Wednesday, August 28, 2013

The elusive element 115?

"Have scientists discovered a new element?"

The periodic table might get a new addition. Scientists in Germany say they have replicated a decade-old Russian experiment that created dozens of short-lived atoms with 115 protons.


Megan Gannon

August 27th, 2013

The Christian Science Monitor

Scientists say they've created a handful of atoms of the elusive element 115, which occupies a mysterious corner of the periodic table.

The super-heavy element has yet to be officially named, but it is temporarily called ununpentium, roughly based on the Latin and Greek words for the digits in its atomic number, 115. 

The atomic number is the number of protons an element contains. The heaviest element commonly found in nature is uranium, which has 92 protons, but scientists can load even more protons into an atomic nucleus and make heavier elements through nuclear fusion reactions.

Scientists hope that by creating heavier and heavier elements, they will find a theoretical "island of stability," an undiscovered region in the periodic table where stable super-heavy elements with as yet unimagined practical uses might exist.

In experiments in Dubna, Russia about 10 years ago, researchers reported that they created atoms with 115 protons. Their measurements have now been confirmed in experiments at the GSI Helmholtz Centre for Heavy Ion Research in Germany.

To make ununpentium in the new study, a group of researchers shot a super-fast beam of calcium (which has 20 protons) at a thin film of americium, the element with 95 protons. When these atomic nuclei collided, some fused together to create short-lived atoms with 115 protons.

"We observed 30 in our three-week-long experiment," study researcher Dirk Rudolph, a professor of atomic physics at Lund University in Sweden, said in an email. Rudolph added that the Russian team had detected 37 atoms of element 115 in their earlier experiments.

"The results are by and large compatible,"
Rudolph said.

Super-heavy elements are generally unstable and most last only a fraction of a second before they start to decay. The scientists had to use special detectors to look for the energy signatures for the X-ray radiation predicted to be given off by element 115 as it quickly degrades.

A committee from the International Union of Pure and Applied Chemistry (IUPAC), which governs chemical nomenclature, will review the new findings to decide whether more experiments are necessary before element 115 gets an official name.

Some of element 115's neighbors have already been christened. Last year, the man-made elements 114 and 116 were named flerovium (Fl) and livermorium (Lv).

The new experiments will be detailed in The Physical Review Letters.

"Made in Lab, Fleeting Element May Join Periodic Table"


Kenneth Chang

August 27th, 2013

The New York Times

Scientists may be adding a new element to the periodic table, but don’t expect to see it anytime soon: created in a laboratory, it exists for less than a second.

The new superheavy chemical element has 115 protons and would fill a gap in the periodic table, taking its place between the two elements, 114 and 116, which were added just last year. The newcomer, as yet unnamed, was first discovered a decade ago by Russian and American scientists, but the official organizations of chemists and physicists that act as gatekeepers for the periodic table wanted another laboratory to repeat the experiment before they would officially add it.

A Swedish university announced Tuesday that that had finally happened. The new work, led by physicists at Lund University in Sweden and performed at an accelerator in Darmstadt, Germany, duplicated the earlier experiment and observed the similar patterns of debris. The new findings will be published Thursday in the journal Physical Review Letters.

“Everything is perfect,” said Krzysztof Rykaczewski, a scientist at Oak Ridge National Laboratory in Tennessee who was a member of the confirmation team.

The experiment also provided additional confirmation of earlier claims for element 113, which also has not yet been added to the periodic table, Dr. Rykaczewski said. In the first decay, element 115 turned into element 113 while emitting a chunk known as an alpha particle.

The Russian-American team had already replicated its own results, but, “it’s always better when someone else does it,” Dr. Rykaczewski said.

To create the element, calcium nuclei were fired into a target containing americium atoms. Occasionally, a calcium and an americium merged together, creating a new atom with 115 protons in its nucleus. Then, in less than a second, it fell apart. The researchers deduced its existence from the pieces of debris.

In addition, for the first time, the researchers observed an X-ray “fingerprint” emitted during the decay, which provided more direct evidence that the initial atom contained 115 protons.

Dirk Rudolph, a professor of nuclear physics at Lund University, said he was “most satisfied” that the team had created the element. “Mother Nature has not been as kind as she could have been,” he said.

The number of observed X-rays — just two — was too few to be definitive, but “we obviously show the feasibility of such experiments,” he said.

If the new data proves convincing, the Russian and American scientists who made the original discovery would be given the opportunity to name the element, a process that would take months.

Just last year, the overseers of the periodic table acceded to the addition of elements 114 and 116 as flerovium and livermorium, more than a decade after they were first made. The elements 117 and 118 have also been claimed, but not yet confirmed.

The study of superheavy atoms — which are unstable chemical elements with atomic numbers greater than 92 — help scientists better understand the basic forces that hold matter together.

Proposed names for the two new elements

No comments: