• Number 309  |
• April 12, 2010

Superheavy element 117 discovered

An international team of scientists from Russia and the United States, including DOE's Lawrence Livermore National Laboratory and Oak Ridge Laboratory, has discovered the newest superheavy element, element 117.

The team established the existence of element 117 from decay patterns observed following the bombardment of a radioactive berkelium target with calcium ions at the JINR U400 cyclotron in Dubna, Russia. The experiment depended on the availability of special detection facilities and dedicated accelerator time at Dubna, unique isotope production and separation facilities at Oak Ridge, and distinctive nuclear data analysis capabilities at Livermore.

The two-year experimental campaign began at the High Flux Isotope Reactor in Oak Ridge with a 250-day irradiation in the world's most intense neutron flux to produce 22 mg of berkelium. This was followed by 90 days of processing at Oak Ridge to separate and purify the berkelium, target preparation at Dimitrovgrad, 150 days of bombardment at one of the world's most powerful heavy ion accelerators at Dubna, data analysis at Livermore and Dubna, and assessment and review of the results by the team. The entire process was driven by the 320-day half-life of the berkelium target material. 

The experiment produced six atoms of element 117.  For each atom, the team observed the alpha decay from element 117 to 115 to 113 and so on until the nucleus fissioned, splitting into two lighter elements. [Video]

In total, 11 new "neutron-rich" isotopes were produced, bringing researchers closer to the presumed "island of stability" of superheavy elements.

Submitted by DOE's Lawrence Livermore National Laboratory