Physicists at the Massachusetts Institute of Technology (MIT) have discovered a new method that allows researchers to examine the inside of an atom’s nucleus using a simple laboratory setup instead of large, high-energy particle accelerators.
In a study published on October 23 in Science, the scientists precisely measured the energy of electrons orbiting a radium atom that was chemically linked to a fluoride atom, resulting in radium monofluoride.
They confined the electrons of the radium atom by exploiting the molecular environment as a minuscule stand-in for a particle collider, increasing the possibility that some would pass through the nucleus briefly.
The team achieved this by creating molecules of radium monofluoride (RaF), which combine a radium atom with a fluoride atom. In these molecules, some electrons can occasionally move close enough to the nucleus to interact with it directly.
By carefully measuring subtle shifts in the electrons’ energy, the scientists confirmed that nuclear penetration had taken place. This means the molecule itself acts as a miniature particle collider, allowing the study of nuclear behaviour on a much smaller and more accessible scale.
The technique could help researchers map how magnetism is distributed within the nucleus, revealing how protons and neutrons act as tiny magnetic sources. Understanding this structure could also shed light on one of physics’ biggest mysteries — why there is more matter than antimatter in the universe.
"Our results lay the groundwork for subsequent studies aiming to measure violations of fundamental symmetries at the nuclear level," says Ronald Fernando Garcia Ruiz, co-author of the study, and a Thomas A Franck (1977) Associate Professor of Physics at MIT.
Radium is particularly useful for such experiments because its nucleus has an unusual pear-shaped asymmetry that makes it more sensitive to subtle symmetry-breaking effects.
The MIT team now plans to cool and align the RaF molecules more precisely, which will allow them to map nuclear structures in even greater detail.