A team of leading physicists has made a breakthrough in understanding how the shape of atomic nuclei affects the behavior of atoms.
Researchers from Germany’s Physikalisch-Technische Bundesanstalt (PTB) and the Max Planck Institute for Nuclear Physics (MPIK) worked with experts from the Technical University of Darmstadt and Leibniz University Hannover to investigate the relationship between atomic structure and nuclear properties.
Their findings, recently published in Physical Review Letters, also set new limits on the possible existence of mysterious “dark forces” that might influence matter.
For nearly a century, scientists have suspected that much of the universe is made of dark matter—an invisible substance that interacts with normal matter through gravity.
Some researchers believe that unknown “dark forces” might also be at play, influencing both visible and dark matter. If such forces exist, they could affect the structure of atoms, making precision measurements an important tool in the search for new physics.
Investigating a Mysterious Anomaly
The new research builds on an unusual discovery made in 2020 by a team at the Massachusetts Institute of Technology (MIT). When studying different versions (isotopes) of the element ytterbium, the MIT researchers found a surprising shift in electron behavior.
The shift didn’t follow expected patterns, leaving scientists wondering whether it was caused by a new force of nature or by an undiscovered property of atomic nuclei.
To investigate further, physicists at PTB and MPIK conducted extremely precise experiments on ytterbium isotopes. They measured tiny frequency differences in electron transitions using advanced optical spectroscopy at PTB.
At the same time, MPIK scientists determined isotope mass ratios using the high-precision PENTATRAP mass spectrometer. These measurements were up to 100 times more accurate than previous studies.
The results confirmed the original anomaly, but thanks to new nuclear theory calculations from researchers at TU Darmstadt, the team was able to explain it. Instead of pointing to a new dark force, the anomaly was linked to subtle changes in the shape of atomic nuclei.
In other words, the deformation of the ytterbium nucleus was affecting electron behavior in a way that had not been fully understood before.
New Insights into Atomic Nuclei and Dark Matter
By analyzing their data, the scientists also established new limits on the possible existence of dark forces between neutrons and electrons. If such forces exist, they would have influenced their measurements—but the data showed no evidence of such interactions within the current level of precision.
Additionally, the team’s findings provided direct information about how ytterbium nuclei change shape as the number of neutrons varies. This discovery offers valuable insights into the structure of heavy atomic nuclei and could help scientists better understand extreme environments, such as the matter inside neutron stars.
This research demonstrates how atomic, nuclear, and particle physics can work together to explore fundamental questions about the universe. By combining advanced experiments with theoretical modeling, scientists are not only testing the limits of our understanding of atomic structure but also searching for entirely new physics beyond the standard model.
The research findings can be found in Physical Review Letters.
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