Deep inside stars, light nuclei fuse, giving birth to helium and streams of neutrons. On Earth, we recreate this process by combining deuterium and tritium — special isotopes of hydrogen. When they merge, neutrons are born, which, like a philosopher’s stone, turn stable elements into precious radioactive isotopes — the basis for cancer diagnosis and therapy. These transformations follow the Standard Model of physics.

The method leaves no long-lived waste, and the desired isotope is extracted chemically. The idea traces back to the experiments of Enrico Fermi and Ernest Rutherford, who nearly a hundred years ago first altered atomic nuclei with neutrons. Astonishingly, to meet the global demand for technetium-99m (30 million procedures annually), the neutrons from a desk-sized device would suffice. Moreover, the technology doesn’t use weapons-grade materials, eliminating the proliferation risk.