Scientists Solve a Decades-Old Mystery Inside Atomic Nuclei

A long-standing puzzle in nuclear physics finally has an answer. Researchers at the Facility for Rare Isotope Beams have identified the source of an mysterious excess of low-energy gamma rays in zinc-70 nuclei. For decades, scientists observed more gamma radiation than theoretical models predicted, but the physical origin of this phenomenon remained elusive.

By examining the decay of copper-70 into zinc-70, the team discovered that magnetic transitions inside the nucleus are responsible for this effect. The researchers used highly pure beams of two different copper-70 states to isolate the signal. This experiment relied on the Low Energy Beam and Ion Trap, a precision instrument that allowed the team to separate nuclei with minute differences in mass and energy. The findings were published in the journal Nature after a decade of investigative work involving institutions from six countries.

This resolution has practical implications for astrophysics and beyond. The low-energy enhancement influences neutron-capture reactions, which are fundamental to the creation of heavy elements during supernova explosions and neutron star mergers. By identifying that magnetic transitions drive this activity, scientists can now produce more accurate models of stellar nuclear processes and nuclear energy systems.

The project underscores the value of large-scale collaborations between national laboratories and universities. It also demonstrates how advanced experimental capabilities can bridge the gap between fundamental physics and national security applications. The study provided significant training for early-career researchers who managed the project from the initial proposal stage through to the final publication. As researchers look to apply this isomer separation technique to other nuclei, the data will continue to refine our understanding of nuclear structure.