Laser spectroscopy determines shape of fermium-255 nucleus

Scientists have, for the first time, mapped the precise shape of the actinide nucleus of fermium‑255 (Fm‑255) and measured its internal structure with unprecedented accuracy. Using advanced high‑resolution spectroscopy and state‑of‑the‑art detectors, the team was able to resolve the subtle deformations of the nucleus that had eluded previous investigations. The findings represent a significant step forward in the understanding of heavy‑element nuclear physics, where experimental data are scarce and theoretical models often rely on indirect assumptions.

The research, conducted at a leading national laboratory, employed a combination of gamma‑ray tracking arrays and ion‑beam techniques to probe the excited states of Fm‑255. By analyzing the emitted radiation patterns and decay pathways, the team reconstructed the nucleus’s shape, revealing a pronounced prolate deformation that aligns with predictions from modern nuclear‑structure theories. The high‑precision measurements also provide critical benchmarks for refining models that predict the behavior of superheavy elements, which are essential for exploring the limits of the periodic table and for applications ranging from nuclear medicine to energy research.

These results mark a milestone in experimental nuclear science, offering the first direct observation of the shape of an actinide nucleus at such high precision. The data will be incorporated into global nuclear databases, aiding future studies of fission dynamics and the synthesis of new elements. The study underscores the importance of continued investment in high‑resolution experimental facilities to unlock the remaining mysteries of the atomic nucleus.