The World’s Fastest Supercomputer Has Decoded The Decade-Long Calcium-48 Magnetic Mystery

After ten years of discussion, nuclear physicists at Oak Ridge National Laboratory (ORNL) have finally settled the magnetic characteristics of the calcium-48 nucleus, leading to a significant scientific advance. By utilizing Frontier, the fastest supercomputer in the world, scientists made progress toward solving this riddle that has baffled the field of nuclear physics for years.

Calcium-48, a special atom with a doubly magic nucleus (20 protons and 28 neutrons), exhibits strong magnetic interactions that influence how nuclei are formed and decay. Early experiments in the 1980s using protons and electrons suggested that calcium-48 had a magnetic transition strength of 4 nuclear magnetons squared. However, in 2011, experiments using gamma rays reported a transition strength nearly double that value, leading to conflicting results and years of confusion.

Using chiral effective field theory and the Frontier supercomputer’s immense power, Gaute Hagen’s team conducted highly precise simulations, revealing that the calcium-48 magnetic transition strength aligned with the gamma-ray experiments. This resolution clarifies the fundamental forces governing nuclear magnetism and illuminates how nuclei interact with their environment.

The study also sheds light on the continuum effects within the nucleus, showing that nucleon pairs (protons and neutrons) influence magnetic transitions in unexpected ways, with some interactions even enhancing the strength, contrary to prior assumptions.

This finding offers insights into astrophysics and goes beyond nuclear physics. Calcium-48 is widely distributed in supernova cores, where neutrinos are essential. Scientists can better investigate how neutrinos interact with matter and impact cosmic processes like star formation and elemental distribution by having a better understanding of its magnetic properties. This ground-breaking study lays the groundwork for future findings that will expand our knowledge of the cosmos.