What is the physical significance or attraction of studying the structure of nuclei? If I were asked such a question, I would say that "there exist different pictures and models of nuclei, and it is interesting that they mix and compete with each other in a quantum mechanical way." I would also add, "the distinctive role of non-central interactions acting between protons and neutrons is interesting". These two answers are, in fact, closely related. In this talk, I will introduce our efforts to establish a unified picture of nuclei and the role of the non-central interactions in this process. The most standard view of nuclei is the shell structure. Protons and neutrons create their potential and move independently within it. The other view is the cluster structure. In this view, nuclei with particularly strong bonds, such as 4He (alpha-particles), constitute a subsystem. The most famous example is the second 0+ state of 12C called the Hoyle state, which plays an essential role in synthesizing 12C from three 4He in stars. We show that one of the non-central interactions, the spin-orbit interaction, breaks the cluster structure and makes the symmetry of the shell structure good. Conversely, the tensor interaction, another non-central interaction, is the source of the strong bonding of the alpha-particle and acts in the direction of supporting the cluster picture. We have developed antisymmetrized quasi cluster model (AQCM), by which we can smoothly transform the cluster model wave function to the shell model one and the competition of these two pictures can be clearly discussed. One example is 44Ti, the critical nucleus for observing supernova explosions. It should have the 40Ca+alpha cluster structure, but the cluster structure is washed out in many standard calculations. We discuss that the tensor interaction works as the salvation of the clustering in medium-heavy nuclei. It also suggests that the cluster structure is general and not confined within lighter mass region.

Prof. Itagaki is a nuclear theorist and now working at department of physics, Osaka Metropolitan University. He received his Ph.D from Hokkaido University in 1999. After that, he had professional experiences at RIKEN as Special Postdoctoral Fellow (2000-2006), at University of Tokyo as Assistant Professor (2006-2010), at Kyoto University as Associate Professor (2010-2022). During 2005-2006, he was the research fellow of Alexander Humboldt Foundation and Guest researcher of Hahn-Meitner-Institut Berlin. Prof. Itagaki received the Award for Young Scientists from Japan Physical Society in 2001 and the Prize for Young Scientists from Ministry of Education of Japan in 2011. Prof. Itagaki specializes in nuclear many-body theory, includes general description of nuclei, role of non-central interactions in nuclei, structure of neutron-rich nuclei and hyper nuclei, cluster-shell competition in nuclei, dynamical excitation modes of nuclei, and medical application of nuclei.

 主办:

复旦大学 核科学与技术系/现代物理研究所

核物理与离子束应用 教育部重点实验室

国家自然科学基金委-理论物理专款 上海核物理理论研究中心

 协办:

《Nuclear Science and Techniques》&《核技术》刊物