通过衰变研究弱束缚核的结构

Radioactive ion-beam physics is the frontier of nuclear physics, which focuses on thousands of unstable nuclei. In particular, nuclei far from the stability, due to weakly-bound property, appear with many exotic behaviors, leading to new physics mechanisms, which provides opportunities and also challenges for experimental and theoretical studies. Considering the radioactive ion-beam facilities in our country and current status of researches, we propose the research project to perform further studies on the structures and decays of weakly-bound nuclei in both experiment and theory. In experiment, we will mainly focus on light neutron-rich mass region, to study structures by the measurements of decays. PKU experimental group has established a neutron detector. By upgrading the detector associated with the domestic radioactive ion-beam facilities, we will perform experiments to measure the decays of the neutron-rich nuclei. Theoretical groups at Peking University and Nanjing University have already had very good experiences and achievements in the studies of nuclear structure and decays. We will develop our models, promote their capabilities to predict, and make the systematical calculations and analyses of the structures and decays of weakly-bound nuclei, including the weakly-bound cluster states. We will keep close collaborations between theoretical and experimental groups. Calculations can provide useful predictions and valuable explanations for related experiments, and new data obtained provide evidences to test and develop models.

放射性核束物理是当前核物理前沿领域，研究对象是几千个非稳定核素。特别是远离稳定线原子核，由于弱束缚特性，体现许多奇异性质，呈现新物理机制，这给实验和理论研究带来机遇和挑战。基于国内放射性核束装置和国内外放射性核束物理研究现状，我们提出这个理论与实验相结合的研究项目，开展进一步深入的有关弱束缚核结构与衰变性质的研究。实验主要集中于丰中子轻核区的研究，通过衰变实验研究丰中子弱束缚核的结构。北大实验组自主研发了中子探测系统，通过该系统的进一步升级改造，结合国内放射性核束装置，开展丰中子轻核衰变实验。理论上，北大和南大2个核理论组在核结构研究方面有着很好的工作经验和积累。我们将发展现有模型，提升模型的计算预言能力，将全面计算分析弱束缚核的结构与衰变，包括弱束缚态的集团结构与衰变。密切开展理论与实验合作，理论为实验提供有用预言，解释实验观察；反过来，新实验数据为检验和发展模型提供可靠的实验依据。

不稳定原子核是当前核物理研究的热点前沿，我们从理论和实验二个方面开展了不稳定核的衰变和结构研究，取得了丰硕的成果。主要的科研成果如下：1）发展了从第一性原理出发的ab initio理论与计算，使得计算更基础，结果更可，具体包括：基于手征有效场论（EFT）和CD Bonn势或其它现实核力，开创性地发展了Many-Body Perturbation Theory (MBPT)、Gamow Shell Model (GSM)、Brueckner-Hartree-Fock (BHF)、Random Phase Approximation（RPA）、In-medium Similarity Renormalization Group (IM-SRG)等理论，得到国际同行的高度认可，发表了系列文章；2）建立了基于Gogny力的壳模型，可以实现对各个核区的大规模计算，具有强大的计算能力，对实验很有帮助；3）发展了能量密度泛函理论，使得计算包含连续谱的影响，这对不稳定核是很重要的；4）发展了原子核结团模型，通过集团衰变研究原子核结构；4）发展了探测方法和技术（包括设备研发），提高测量精度，在国内外主要实验室开展了一系列衰变实验，得到了丰富的实验成果。理论配合实验，计算分析实验结果，进一步加深了对不稳定核结构性质的理解。项目实际开展的研究内容超出计划书中的内容，执行情况好于预期，取得了非常丰硕的理论与实验研究成果，共发表SCI文章88篇，其中3篇Physical Review Letters，7篇Physics Letter B，45篇Physical Review C。