The Joint Working Party (JWP) on the priority of claims to the discovery of new elements has officially credited the research collaboration led by Sigurd Hofmann at the Gesellschaft für Schwerionenforschung (GSI) with the discovery of element 111. In addition, the four independent experts from the International Union of Pure and Applied Chemistry (IUPAC) and its physics sister the IUPAP, have officially approved the naming of element 110, also discovered by GSI, as darmstadtium (Ds).
The researchers at GSI first created element 111 in December 1994, when they bombarded a target of bismuth (209Bi) with a beam of nickel (64Ni) and observed three sets of localized alpha-decay chains, which they attributed to the decay of nuclei with 111 protons and 161 neutrons. Two of the decay chains, however, involved isotopes of bohrium and meitnerium (264Bh and 268Mt), which were then unknown. The JWP therefore decided that further results would be needed. In a repeat of the experiment in 2000, the GSI team observed further decay chains originating from element 111, bringing the total number of events to six. Due to the high quality of the data, the JWP has now accepted the results and confirmed the GSI team’s priority for the discovery of element 111.
The JWP also assessed evidence for the production of elements 112, 114 and 116 by GSI and a collaboration led by Yuri Oganessian at the Joint Institute for Nuclear Research in Dubna. Although the JWP found the evidence encouraging, they concluded that confirmation from further results is needed.
