The creation of the lightest uranium atom ever gives scientists a better understanding of a fundamental type of radioactive decay.
All elements have one or more isotopes, which differ from each other in the number of neutrons in their nuclei. Almost all naturally occurring uranium atoms contain either 143 or 146 neutrons.
Zai-Guo Gan at the Chinese Academy of Sciences in Lanzhou and his colleagues have produced a uranium isotope with only 122 neutrons by firing a beam of argon at a tungsten target until atoms of each element fused together — an extremely rare event that formed uranium atoms. The team then extracted the 122-neutron isotope using a magnetic device called a separator.
All uranium isotopes undergo α-decay, a process whereby an atom loses two protons and two neutrons. Unexpectedly, the authors found that their ultralight isotope and a previously detected uranium isotope containing 124 neutrons decay more easily than do light isotopes of other elements. This suggests that interactions between protons and neutrons in atomic nuclei can have a greater role in α-decay than previously thought.