Element 114 Confirmed

Ten years after scientists in Dubna, Russia, first reported synthesizing nuclei of element 114 in a high-energy accelerator, researchers at Lawrence Berkeley National Laboratory have independently confirmed those results, according to a study published in Physical Review Letters (2009, 103, 132502). Reproducing experimental results is the bedrock of the scientific method. Yet the extremely low probability of making superheavy nuclei, which in the case of element 114 was done by firing ⁴⁸Ca ions into a plutonium target, presented formidable challenges to successfully reproducing the Dubna results. As explained by Kenneth E. Gregorich, who co-led the Berkeley team with Heino Nitsche, eight days of almost continuously bombarding the target with ⁴⁸Ca ions yielded just two atoms of element 114. The nuclei, ²⁸⁶114 and ²⁸⁷114, which survived for about 0.1 and 0.5 seconds, respectively, before disintegrating, were identified by tracking a series of α-particle emission and fission events that were correlated in time and position in the Berkeley team’s detector. These lifetimes, which are relatively long for superheavy isotopes, are viewed by the scientists as evidence in support of the so-called island of stability—a region on the chart of nuclides where certain proton-neutron combinations may lead to long-lived superheavy isotopes.