The nucleus of an atom, composed of protons and neutrons, is organized in a layered structure, or 'shells', very similar to that of electrons around the nucleus. This structure presents 'magic numbers' that mark the major energy jumps, or 'gaps', between the layers. Scientists have recently discovered that in some radioactive nuclei with an excess of neutrons, these 'magic numbers' and their stability can disappear. Essentially, neutrons change their usual arrangement and 'jump' across the energy gap. Reorganizing to make the nucleus more bound, they gain correlation energy and thus generate 'Islands of Inversion'.

The research, published in Nature Communications, focused on Molybdenum isotopes, particularly 84Mo and 86Mo. The researchers found a sudden and sharp structural change between the two. This abrupt change defines the edge of a region identified as a new Island of Inversion, but with a special characteristic. While previously known islands have an excess of neutrons, this one is generated by symmetric excitations of both protons and neutrons. For this reason, it has been named the 'Isospin-Symmetric Island of Inversion'.
The experiment, conducted in the laboratories of Michigan State University in the United States by an international collaboration including scientists from Italy, South Korea, France, Spain, and the United Kingdom, was coordinated by Professor F. Recchia of the Department of Physics and Astronomy at the University of Padua and the National Institute of Nuclear Physics, Padua section.