TOKYO, Sept. 27, 2012 /CNW/ - The most unambiguous data to date on the
elusive 113th atomic element has been obtained by researchers at the
RIKEN Nishina Center for Accelerator-based Science (RNC). A chain of
six consecutive alpha decays, produced in experiments at the RIKEN
Radioisotope Beam Factory (RIBF), conclusively identifies the element
through connections to well-known daughter nuclides. The groundbreaking
result sets the stage for Japan to claim naming rights for the element.
The search for superheavy elements, which do not occur naturally and
must be produced through experiments, is a painstaking process. Since
the first was discovered in 1940, countries have competed to synthesize
more such elements. The Americans discovered elements 93 to 103, the
Russians and Americans discovered elements 104 to 106, the Germans
discovered elements 107 to 112, and the Russians and Americans together
discovered elements 114 and 116.
Researcher Kosuke Morita and his team at the RNC are now set to make
Japan the first Asian country to name an atomic element. For years
Morita has searched for the element using a custom-built gas-filled
recoil ion separator (GARIS) coupled to a position-sensitive
semiconductor detector to identify reaction products. On August 12, his
experiments bore fruit: zinc ions collided with a thin bismuth layer to
produce a very heavy ion followed by a chain of six consecutive alpha
decays identified as products of an isotope of the 113th element.
While Morita's team also 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). The
isotope dubnium-262 is known to also decay via alpha decay, but this
was not observed, and naming rights were not granted since the final
products were not well known nuclides at the time. The chain detected
this time takes the alternative alpha route, with data indicating that
dubnium decayed into lawrencium and finally into mendelevium. The decay
of dubnium-262 to lawrencium-258 is well known and provides unambiguous
proof that element 113 is the origin of the chain.
Combined with their earlier results, the team's groundbreaking discovery
promises to clinch their claim to naming rights for the element. "For 9
years, we have been searching for data conclusively identifying element
113, and now that at last we have it, it feels like a great weight has
been lifted from our shoulders," Morita said. "I would like to thank
all the researchers and staff involved, who persevered believing that
one day, 113 would be ours. Next we look to element 119 and beyond."
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.
For further information:
Superheavy Element Laboratory
RIKEN Nishina Center for Accelerator-Based Science
Global Relations Office