Researchers at the RIKEN Nishina Center for Accelerator-based Science have obtained the most unambiguous data to date on element 113. A chain of six consecutive α decays, produced in experiments at the RIKEN Radioisotope Beam Factory, conclusively identifies the element through connections to well known daughter nuclides.
In the experiment at the RIKEN Linear Accelerator Facility in Wako, near Tokyo, Kosuke Morita and his team fired zinc ions travelling at 10% the speed of light at a thin target of bismuth and used a custom-built gas-filled recoil ion separator coupled to a position-sensitive semiconductor detector to identify the reaction products. On 12 August they detected the production of a very heavy ion followed by a chain of six consecutive α decays, which they identified as the products of an isotope of element 113. The chain began with the decay to roentgenium-274 (element 111) and ended in mendelevium-254 (element 101).
The team previously detected element 113 in experiments conducted in 2004 and 2005, but were then able to identify only four α decays followed by spontaneous fission of dubnium-262 (element 105), which is not a well known process. The decay chain detected in the latest experiments takes an alternative route via α-decay, the data indicating that the dubnium decayed into lawrencium-258 (element 103) and finally into mendelevium-254. The decay of dubnium-262 to lawrencium-258 is well known and provides unambiguous proof that element 113 is the origin of the chain.
Further reading
K Morita et al. 2012 J. Phys. Soc. Jpn 81 103201.
