In pursuit of a ‘magic number’, physicists discover new uranium isotope Premium

Physicists in Japan have discovered a new uranium isotope, with mass number 241 and half-life of around 40 minutes. This is also the first discovery of a neutron-rich nuclide since 1979 and takes us a step closer to finding heavier magic-number nuclei.

While studying the atoms of heavy elements, physicists in Japan discovered a previously unknown isotope of uranium, with atomic number 92 and mass number 241, i.e. uranium-241.

The finding refines our understanding of nuclear physics. What shapes the large nuclei of heavy elements take and how often (or rarely) defines the boundaries of models that physicists use to design nuclear power plants and models of exploding stars.

“The discovery of a new neutron-rich uranium isotope is the first since 1979,” Toshitaka Niwase, a postdoctoral fellow with the KEK Wako Nuclear Science Centre (WNSC), Japan, and a member of the study, wrote in an email to The Hindu.

“This is because of the extreme difficulty of synthesising a nuclide in this region by general reaction.”

The arrangement of protons and neutrons in an atomic nucleus follows some rules. We know what these rules are based on the nuclei’s properties and structure.

“In general, an atom’s mass is slightly lower than the sum of the masses of protons, neutrons, and electrons,” Michiharu Wada, head of the WNSC and another member of the group, explained via email.

So systematically measuring the mass of “uranium and its neighbourhood elements yields essential nuclear information to understand the synthesis of such heavy elements in explosive astronomical events”.