A pioneering breakthrough in nuclear physics has emerged from an international consortium of researchers, unveiling a cutting-edge model that predicts the critical energy barriers dictating heavy-ion fusion reactions with unprecedented accuracy. This innovative approach, detailed in the forthcoming issue of Nuclear Science and Techniques, leverages the synergy between the Skyrme energy density functional and nuclear reaction Q-values to craft an effective nucleus-nucleus potential. By harmonizing these theoretical frameworks, the model transcends previous limitations, successfully replicating experimental fusion barrier data across an extensive array of over 440 fusion systems.
Heavy-ion fusion reactions lie at the heart of modern nuclear science, offering pathways to synthesize superheavy nuclei whose properties challenge the boundaries of the periodic table. They enable deep exploration into the quantum mechanics of nuclear matter and present practical avenues for advancing nuclear energy and medical isotope production. Yet, a persistent obstacle has been the reliable prediction of fusion barrier heights—the energy thresholds that nuclei must surmount to combine into a compound system. Traditional models frequently falter, especially for reactions involving deformed nuclei such as uranium-238, due to their intricate internal dynamics and shape-dependent interactions.
The new model ingeniously addresses these challenges by incorporating the dynamical effects that emerge in heavy-ion fusion processes. Unlike lighter-particle fusion, where the nucleus-nucleus potential can often be approximated by the frozen density assumption, heavy systems experience notable shape rearrangements and energy dissipation during fusion. By moving beyond static assumptions, the researchers have introduced a calculated distribution of barrier heights rather than a singular value, yielding a comprehensive view that mirrors the complex realities of nuclear fusion. This conceptual advancement is crucial for refining capture cross-section predictions—an essential metric for understanding the likelihood of successful fusion events.
Integral to this development is the coupling of the effective potential with the Siwek-Wilczynski formula, a sophisticated expression for capture cross sections that incorporates barrier distributions. Such integration enables the model not only to fit the fusion barrier data with a remarkable root-mean-square deviation of 1.53 MeV but also to closely reproduce capture cross sections for both spherical and extensively deformed nuclear systems. For instance, in fusion reactions between calcium-48 and uranium-238, the model accurately accounts for observed cross sections, providing critical insights into experimentally challenging scenarios.
Beyond replication of known data, the model sheds light on subtle phenomena influencing heavy-ion fusion. The researchers identify distinctive features in heavy systems, such as shallow capture pockets and comparatively smaller barrier radii, factors which hinder the formation of compound nuclei by promoting quasi-fission. Quasi-fission is a rapid re-separation process that competes with fusion, reducing the probability of creating new superheavy elements. Understanding these mechanisms allows experimental physicists to optimize reaction conditions, selecting projectile-target combinations and energies that mitigate quasi-fission effects and maximize compound nucleus formation.
Superheavy nuclei synthesis is a cornerstone objective in nuclear physics, underpinning efforts to discover new elements beyond current limits. Facilities such as the Superheavy Element Factory rely heavily on theoretical predictions to guide expensive and time-consuming experiments. The advent of this predictive model promises to streamline such endeavors by providing reliable energy barrier estimates and reaction probabilities, thus conserving resources and accelerating discoveries in the field. This capability is especially pivotal for exploring elements with atomic numbers 119 and 120, which remain at the frontier of experimental nuclear science.
The model’s foundation on the Skyrme energy density functional—a versatile tool reflecting the nuclear many-body problem—and experimentally derived Q-values underscores its blend of rigorous theory and empirical grounding. This approach fosters a nuanced understanding of the interplay between nuclear forces, shapes, and energy landscapes during fusion, encompassing a broad spectrum of isotopic combinations. The demonstrated computational efficiency ensures that extensive surveys of fusion probabilities across thousands of reaction systems are feasible, advancing systematic studies and enabling parametric explorations previously unattainable.
Remarkably, the model’s utility extends beyond terrestrial laboratories. Given the universality of nuclear fusion processes, it holds potential applications in astrophysics, where heavy-ion fusion reactions are hypothesized to occur during extreme cosmic events such as neutron star mergers and supernovae. Accurate modeling of fusion barriers in these environments could illuminate nucleosynthesis pathways responsible for the generation of heavy elements in the universe, bridging terrestrial nuclear physics with astrophysical phenomena.
Furthermore, the implications for nuclear energy research are profound. Enhanced predictive capacity for fusion barriers and capture cross sections could inform the design of fusion-based reactors and guide isotope production for medical therapies. The ability to tailor reaction parameters to optimize desirable nuclear outcomes promises advancements in energy production efficiency and the availability of medically important isotopes, reinforcing the societal value of this scientific advancement.
The development of this model demonstrates the power of interdisciplinary collaboration, integrating expertise from Guangxi Normal University and associated institutions. Their concerted efforts not only address a longstanding challenge in nuclear physics but also provide accessible data and detailed methodologies to the global scientific community. This openness encourages validation, refinement, and innovative applications, embodying the collaborative ethos essential for progress in fundamental science.
As Prof. Ning Wang, the lead author, emphasizes, “Our approach bridges the gap between theoretical predictions and experimental data. It provides a reliable tool for designing experiments, particularly the optimal incident energy aimed at creating new elements.” Complementing this perspective, co-author Prof. Min Liu remarks, “This work not only deepens our understanding of nuclear interactions but also opens doors to exploring uncharted regions of the periodic table.” Their collective insights reflect the transformative potential of this model in reshaping nuclear reaction research.
The model’s validation across a wide selection of heavy-ion systems, its adaptability to various nuclear shapes and sizes, and its integration with established theoretical frameworks signify a paradigm shift in predicting fusion reactions. This achievement paves the way for future studies to delve into complex reaction mechanisms, explore exotic nuclear configurations, and refine our comprehension of nuclear matter under diverse conditions.
Funding from the National Natural Science Foundation of China and the Guangxi Natural Science Foundation has been instrumental in supporting this ambitious research. The commitment to data transparency and resource sharing, embodied in the study’s open-access datasets and visualization tools, fosters an inclusive environment for advancing nuclear science worldwide.
The full details of the study, including comprehensive datasets, computational methods, and detailed visualizations illustrating nucleus-nucleus potentials and barrier distributions, are accessible via DOI: 10.1007/s41365-024-01625-9. These resources enable researchers globally to harness the findings for their theoretical investigations and experimental designs, promoting accelerated progress in this dynamic field.
In summary, this groundbreaking model marks a significant leap forward in the predictive capabilities for heavy-ion fusion reactions. By capturing the intricate dynamics that govern fusion barriers and reaction probabilities, the research not only enhances our fundamental understanding of nuclear physics but also drives tangible advancements in superheavy element synthesis, astrophysics, nuclear energy, and medical isotope production. The profound implications of this work herald a new era of precision and efficiency in nuclear science.
Subject of Research: Not applicable
Article Title: Effective nucleus-nucleus potentials for heavy-ion fusion reactions
News Publication Date: 10-Jan-2025
Web References: http://dx.doi.org/10.1007/s41365-024-01625-9
Image Credits: Ning Wang
Keywords
Heavy-Ion Fusion Reactions; Nucleus-Nucleus Potential; Superheavy Nuclei; Capture Cross Sections; Skyrme Energy Density Functional; Fusion Barriers; Nuclear Physics
Tags: deformed nuclei interactionsenergy barrier prediction modelexperimental fusion barrier dataheavy-ion fusion reactionsHuman-AI Collaboration.medical isotope productionnuclear energy advancementsnuclear physics breakthroughnucleus-nucleus potential developmentquantum mechanics of nuclear matterSkyrme energy density functionalsuperheavy nuclei synthesis
