Supercomputing illuminates detailed nuclear structure

Using the Frontier supercomputer at the Department of Energy’s Oak Ridge National Laboratory, researchers have developed a new technique that predicts nuclear properties in record detail.

The study revealed how the structure of a nucleus relates to the force that holds it together. This understanding could advance efforts in quantum physics and across a variety of sectors, from to energy production to national security.

“Our reliable predictions will bring new insights to the study of nuclear forces and structure,” said Zhonghao Sun of Louisiana State University, formerly of ORNL.

The team’s findings, published in the journal Physical Review X, advance knowledge of both the structure of the nucleus itself at the atomic level and the behaviors of its subatomic particles. A nucleus rotates and can have both a round and a deformed, football-like shape. Historically, building a computational model that captures a variety of these features — such as shape, the small energy of rotation, and the large binding energy that holds the nucleus together — has been a challenge.

“At very low resolution, the nucleus might be viewed as a liquid drop that rotates,” said ORNL’s Gaute Hagen. “As resolution increases, you see more details about the internal structure, and more is learned about how subatomic particles interact to build the nucleus.”

The team reached this improved understanding after modeling a variety of particle behaviors at different energy levels, where behavior changes. The steps to unite all factors into an accurate model was made possible by the computing power of Frontier. Performing at exascale, Frontier is capable of more than a quintillion calculations per second.

Results revealed that a rare nucleus known as 30-neon has both round and deformed shapes that coexist. By performing millions of computations, the team learned how the “strong nuclear force,” which hold subatomic particles together, drives this deformation. The team developed new models of nuclear properties based on these results, which required the use of Frontier for their creation but can run on laptops to enable broad future studies.

“The new techniques we introduced are truly game changers, allowing us to accurately compute the structure and behavior of a deformed nucleus,” said Sun. “This lies on the frontier of nuclear science research.”

The DOE Office of Science Office of Nuclear Physics and Office of Advanced Scientific Computing Research supported this research. Frontier is housed at the Oak Ridge Leadership Computing Facility, a DOE Office of Science user facility.

UT-Battelle manages ORNL for the DOE Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science. — Chris Driver