viernes, 30 de agosto de 2013

Super-heavy weight element confirmed

ORIGINAL: ABC-Science Australia
28 August 2013 Darren Osborne

The finding could strengthen the case for formally adding element 115 to the periodic table - and giving it a name (Source: Brian Cantoni/Flickr)

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If you struggle remembering more than a dozen elements on the periodic table, your task just got harder with the discovery of chemical element 115.

An international team of researchers, led by physicists from Lund University, have found evidence of the new, super-heavy element, as part of an experiment at GSI research facility in Germany.

It confirms earlier experiments by scientists at Russia's Joint Institute for Nuclear Research and the US Lawrence Livermore National Laboratory almost a decade ago.

The finding, to be published in the scientific journal The Physical Review, could strengthen the case for adding element 115 to the periodic table.

"This was a very successful experiment and is one of the most important in the field in recent years", says Professor Dirk Rudolph from the Division of Nuclear Physics at Lund University.

Commentating on the latest discovery, Dr Liz Williams, a nuclear physicist at the Australian National University (ANU) says making super-heavy elements is extremely challenging.

"We typically smash lighter atoms into a thin foil of much heavier atoms and hope that some tiny fraction of these collisions actually produces the element we are interested in creating," says Williams, who is part of an Australian team working with researchers at the collaboration at GSI.

Short-lived existence

To create element 115, scientists bombarded a thin film of americium with calcium ions. But they don't last long. In almost an instant they decay into smaller atoms, releasing photons and alpha particles at the same time. Measurements of the photon energy levels show the new atom has the expected energies for x-ray radiation expected for element 115.

According to Williams, these experiments typically produce only one or two atoms at a time and there is little room for error when it comes to creating and measuring them.

"These atoms live for only a very short time, so we have to do all of this very quickly and carefully," she says.

Williams adds this latest finding will strengthen element 115's case for being added to the periodic table.

"It's really important to confirm the existence of new super-heavy elements at multiple labs before they are added to the periodic table."

In the near future, a committee comprising members of the international unions of pure and applied physics and chemistry will meet to decide whether further experiments are needed. For now it will remain known by its temporary name ununpentium (Uup), or one-one-five.

More to come?

Williams believes this isn't the end of the line for super-heavy elements - which already includes element 116 (livermorium) - but admits it isn't going to be easy creating them.

"We are reaching the end of what we can do with current methods," she says. "Part of the work we do here at the ANU is aimed at exploring better ways to form super-heavy elements, and all I can tell you right now is that it is not an easy task."

And while it may take a lot of time, effort and energy, the information gained from these experiments is worthwhile.

"Every time we discover a new super-heavy element, we learn more about the matter that makes up our visible universe," says Williams. "Each new super-heavy element gives us new insight into how the atomic world works."

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