Researchers Directly Simulate the Fusion of Oxygen and Carbon Nuclei

A significantly improved description of experimental results suggests the importance of presently unaccounted for phenomena in fusion.

Top: the time evolution of a typical collision of oxygen and carbon nuclei and the shapes of the fused system. Bottom: experimental fusion probability compared to the results of thousands of simulations (black line) for a large range of energies.
Image courtesy of K. Godbey
Top: the time evolution of a typical collision of oxygen and carbon nuclei and the shapes of the fused system. Bottom: experimental fusion probability compared to the results of thousands of simulations (black line) for a large range of energies.

The Science

The fusion of two nuclei is a complex process influenced by many factors. These factors include not only the relative energy and angular momentum of the two nuclei but also how their structures evolve as they collide. The outcome of the collisions  is dramatically impacted by the quantum nature of the nuclei. The best way to handle the underlying complexities is to directly simulate how the nuclei evolve as they collide, though this constitutes a massive computational effort. In this study, the researchers performed the most comprehensive computation to-date of fusion reaction processes. The study used supercomputing facilities to perform thousands of time-dependent simulations.

The Impact

Nuclear fusion, the process of merging two nuclei into one, is important to basic science and as a potential carbon-free power source. In this study, researchers achieved an improved description of fusion by directly simulating the reaction process. The remaining differences between the simulation results and measured fusion probabilities from experiments point to phenomena that are unexplained by current theories. Scientists expect these phenomena to be more prevalent for the reactions of short-lived rare isotopes at next generation radioactive beam facilities.

Summary

This study measured the probability of fusing oxygen isotopes with carbon nuclei as a function of energy. The research found a remarkable non-smooth, oscillatory behavior in the high-resolution experimental data for the dependence of the fusion probability on the collision energy of the oxygen-carbon system. By combining advanced theoretical methods, high-performance computing, and high-resolution experimental measurements, the study offers the clearest picture to date of colliding complex nuclei.

The improved model of nuclear collisions shows great promise in describing the intricacies at play in nuclear fusion. Examining the present differences between experiment and theory will provide insights into presently unexplored factors that affect the fusion process. These unexplored factors will become more pressing as reactions of increasingly short-lived, rare isotopes become a more important research area at facilities such as the Facility for Rare Isotope Beams, a Department of Energy user facility at Michigan State University.

Contact

Contact (experiment)
Romualdo deSouza
Indiana University 
[email protected]

Contact (theory)
Kyle Godbey
Facility for Rare Isotope Beams, Michigan State University 
[email protected]

Funding

This material is based on work supported by the Department of Energy Office of Science, Office of Nuclear Physics and by the National Nuclear Security Administration’s Stewardship Science Academic Alliances program.

Publications

deSouza, R.T., et al., Search for beyond-mean-field signatures in heavy-ion fusion reactions. Physical Review C 109, L041601 (2024). [DOI: 10.1103/PhysRevC.109.L041601].

Related Links

This paper was selected as a Physical Review C Editors’ Suggestion

Highlight Categories

Program: NP

Performer: University