Abrupt structural transition in exotic molybdenum isotopes unveils an isospin-symmetric island of inversion.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 41309569.
- Also identified by DOI 10.1038/s41467-025-65621-2 and PMC identifier 12661037.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Like electrons in atoms, protons and neutrons in nuclei occupy orbitals in a shell structure with energy gaps at magic numbers. Radioactive-beam experiments revealed the disappearance of magic numbers in some neutron-rich isotopes. In these nuclei, configurations involving particles excited across the shell gap gain correlation energy, becoming the ground state. Neutron-rich regions of the nuclear chart that exhibit this property are known as "Islands of Inversion". Here we present the lifetime measurement of the first 2<sup>+</sup> states in <sup>84</sup>Mo (N = Z) and <sup>86</sup>Mo (N = Z + 2) revealing an unexpected sharp structural change between them defining the edge of the region of deformation around <sup>80</sup>Zr. Similarly to the neutron-rich N = 40 Island of Inversion near <sup>64</sup>Cr where cross-shell excitations dominate, we identify this region as an Island of Inversion with symmetrical proton and neutron excitations that we term "Isospin-Symmetric Island of Inversion". Three-nucleon forces are suggested to drive Mo isotope structural changes.