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

In an unprecedented move, the University of Missouri has formed a strategic consortium to spearhead the development of NextGen MURR. This coalition includes Hyundai Engineering America, the Korea Atomic Energy Research Institute (KAERI), Hyundai Engineering Company, and MPR Associates. Each member brings specialized expertise to the table: KAERI contributes deep experience in research reactor development, Hyundai Engineering offers world-class engineering and construction capabilities, and MPR Associates provides essential nuclear regulatory and licensing knowledge. Together, this international partnership exemplifies the collaborative spirit necessary to build a reactor poised to become a national strategic asset.

University of Missouri President Mun Choi heralded the project as an epochal advancement not only for the region but also for the nation’s future in nuclear science and medicine. He emphasized that NextGen MURR is not just infrastructure; it represents a commitment to life-enhancing research and a platform for producing critical medical isotopes. These isotopes are indispensable in modern precision diagnostics and targeted therapies, particularly for cancer patients. The reactor’s capabilities will elevate Missouri’s standing as a hub for scientific discovery, engineering innovation, and patient-centered healthcare advancements.

The increasing global demand for radioisotopes underscores the critical need for reliable, domestic production facilities. Current supply chains face vulnerabilities, and the establishment of NextGen MURR addresses this strategic requirement by securing a steady and scalable source of these vital materials. Radioisotopes produced by the reactor will support an array of applications, including diagnostic imaging, radiotherapy, and emerging nuclear medicine technologies, all of which have seen rapid growth due to advancements in personalized medicine.

Economic impact is a key driver behind the initiative, as the new reactor represents the largest capital investment in the university’s history. This infusion of resources supports local and national economic development by creating high-tech jobs, attracting research funding, and fostering partnerships between academia, industry, and government agencies. Todd Graves, chair of the University of Missouri Board of Curators, noted that NextGen MURR is designed to be an engine of progress, strengthening Missouri’s role in nuclear science research and medical innovation for decades to come.

Technically, the design phase—initiated by the recent $10 million agreement—will involve exhaustive programming studies and precise site evaluations. These are critical to developing a comprehensive “roadmap” that defines project scope, cost, timeline, and technical specifications. During this phase, consortium engineers and scientists will leverage advanced modeling techniques and materials science innovations to optimize reactor performance and safety. This early work will inform the preliminary design and licensing phases, ensuring the reactor adheres to stringent nuclear regulatory standards while fulfilling research and isotope production needs.

Michael Hoehn II, the program director for NextGen MURR, described the reactor as a future-facing facility engineered to integrate multiple functions: isotope production, materials testing, and workforce development. This multifunctional approach will position NextGen MURR as a versatile platform to explore advanced fuel cycles, validate materials under high neutron flux, and train the next generation of nuclear scientists and healthcare professionals. The reactor thus embodies a convergence of scientific inquiry, technical advancement, and educational mission.

Collaboration between the United States and South Korea underpins this project, highlighting international partnership in cutting-edge science. KAERI’s president, Han Gyu Joo, affirmed that this cooperation goes beyond technology transfer; it represents shared dedication to enhancing human health and advancing nuclear science globally. The exchange of knowledge and expertise across borders will facilitate not only the construction and operation of the reactor but also sustained innovation in nuclear medicine technologies.

Unlike typical power reactors, research reactors like NextGen MURR operate under specific parameters tailored for specialized applications. They produce a high neutron flux environment necessary for the creation of medical isotopes such as molybdenum-99 and others vital to diagnostic imaging. NextGen MURR will incorporate advanced cooling and shielding systems to maximize operational efficiency and safety while minimizing environmental impact. Its design is informed by lessons learned from previous reactors, including the original University of Missouri Research Reactor, which has been a reliable source of isotopes for decades.

The scale and complexity of NextGen MURR project require meticulous planning, addressing challenges such as nuclear licensing, project financing, material procurement, and community engagement. The consortium’s phased approach ensures iterative assessment and alignment with emerging regulatory frameworks. Public safety and environmental stewardship are paramount, with continuous monitoring and transparent stakeholder communication woven into the project’s governance structure.

NextGen MURR is poised to revolutionize how the United States approaches isotope production and nuclear research. Beyond medical applications, the reactor will facilitate advanced materials science, improving reactor fuels’ durability and safety, and supporting innovative research in nuclear physics. It will serve as a linchpin for collaborations across disciplines—including pharmacology, cancer research, and clinical medicine—creating a synergistic ecosystem to accelerate discovery and practical applications.

The realization of NextGen MURR represents a visionary investment in the future of nuclear technology—one that strengthens national security by reducing dependency on foreign isotope suppliers, enhances public health through novel therapies, and fuels economic vitality through research and innovation. As this large-scale initiative unfolds over the coming decade, it stands as a testament to the transformative power of science, engineering, and international cooperation forged in pursuit of common goals.

Subject of Research: Development and design of a state-of-the-art research reactor for advanced medical isotope production and nuclear science applications.

Article Title: University of Missouri Launches NextGen MURR: Pioneering America’s Future in Nuclear Medicine and Research

News Publication Date: Not specified

Web References:
https://earimediaprodweb.azurewebsites.net/Api/v1/Multimedia/304756fd-70b5-4c4f-a135-61cbb878bca6/Rendition/low-res/Content/Public

Image Credits: Nic Benner/University of Missouri

Keywords:
Discovery research, Educational institutions, Cancer treatments, Engineering, Nuclear engineering, Nuclear physics, Drug research, Clinical research, Health and medicine, Human health, Drug development, Drug design, Drug discovery, Pharmacology, Cancer medication, Medical treatments, Scientific facilities, Laboratories, Medical research facilities, Health care, Personalized medicine