AsianScientist (Sep. 28, 2012) – A Japanese team from the RIKEN Nishina Center for Accelerator-based Science (RNC) has announced the synthesis of the elusive atomic element 113.
Reported in the Journal of Physical Society of Japan, this groundbreaking result that comes after nine years of research sets the stage for Japan to claim naming rights for the element. Japan will be the first Asian country to have this honor.
Currently known as Ununtrium, which means one-one-three, the element with 113 protons does not occur in nature.
Searching for superheavy elements is a difficult and painstaking process because they must be produced through experiments involving nuclear reactors or particle accelerators, via processes of nuclear fusion or neutron absorption.
Led by associate chief scientist Kosuke Morita, the team achieved their feat at the RIKEN Linear Accelerator Facility in Wako, a suburb of Tokyo.
Using a custom-built gas-filled recoil ion separator (GARIS) coupled to a position-sensitive semiconductor detector, Dr Morita and his team fired zinc ions travelling at 10 percent the speed of light at a thin bismuth layer.
When collided, zinc with 30 protons and bismuth with 83 produced a very heavy ion, which rapidly decayed. The products in the chain of six consecutive alpha decays were identified as those of an isotope of element 113.
While the team had already detected element 113 in experiments conducted in 2004 and 2005, earlier results identified only four decay events followed by the spontaneous fission of dubnium-262 (element 105).
In addition to spontaneous fission, dubnium-262 is known to also undergo alpha decay. But this was not observed, and naming rights were not granted because the final products were not well known nuclides at the time.
This time however, the six-step alpha decay chain detected in the latest experiments, occurred via the alternative alpha decay route, with data indicating that Dubnium decayed into lawrencium-258 (element 103) and finally into mendelevium-254 (element 101).
The decay of dubnium-262 to lawrencium-258 is well known and provides unambiguous proof that element 113 is the origin of the chain.
The two most recently named elements, 114 and 116, had been produced by cooperative work of the Russians and Americans. Looking to the cement Japan’s position on the world stage of element discovery, Dr Morita made his ambitions clear:
“For our next challenge, we look to the uncharted territory of element 119 and beyond,” he said.
Reference: Kosuke Morita et al. “New Result in the Production and Decay of an Isotope, (278)113, of the 113th Element.” Journal of Physical Society of Japan, 2012. DOI: 10.1143/JPSJ.81.103201
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Source: RIKEN.
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