基于HIAF的超重元素和核素研究

Research program of superheavy elements and nuclides based on HIAF

原子核是由质子和中子构成的量子多体系统.超重核素是指考虑了壳效应才存在的原子核.探索原子核存在的电荷数和质量数极限始终是核物理研究的前沿和热点.迄今,在实验上合成和鉴别了百余种超重核素,将化学元素周期表从92号扩展至118号元素,完成了周期表上第七周期元素的填充.强流重离子加速器装置(High Intensity heavy-ion Accelerator Facility, HIAF)将于2025年建成并投入运行,超重元素和核素研究是其重要研究目标之一. HIAF的超导直线加速器能够提供能量可调的强流重离子束流,将为合成超重新元素和探索理论预言的超重核稳定岛提供重大机遇.本文介绍了基于HIAF的超重元素和核素研究计划,对超重核研究的现状和意义进行了综述,重点描述了基于重离子诱发的熔合反应和多核子转移反应的电磁谱仪以及实验测量装置.本文针对超重新元素和核素的合成研究、超重核结构和性质研究、超重核素产生机制研究、超重原子结构和元素化学性质研究分别进行了研究计划的介绍,最后对超重核研究的发展规划进行了总结.

Atomic nuclei are many-body quantum systems composed of protons and neutrons. The nuclides, whose existence is attributed to the nuclear shell effects, are referred to as superheavy nuclides. The exploration of the limit to the existence of nuclides with regard to the proton and mass numbers is at the frontier of nuclear physics research. So far, superheavy elements with an atomic number of up to 118 and hundreds of superheavy nuclides have been experimentally synthesized and identified in various laboratories, resulting in the completion of the seventh period of the periodic table of elements.The High Intensity heavy-ion Accelerator Facility(HIAF) is now under construction and is scheduled to be commissioned in 2025. The study on superheavy elements and nuclei is one of the main research goals of HIAF. Intense heavy-ion beams can be extracted from around the middle point of linac, and the beam energies can be finely adjusted around the Coulomb barriers of nuclear reactions. Therefore, HIAF will provide great opportunities for the synthesis of new superheavy elements and to explore the superheavy island of stability, which was theoretically predicted long ago via fusion and multi-nucleon transfer reactions, respectively. This paper presents the research program of superheavy elements and nuclides based on HIAF, provides an overview of the research on superheavy nuclei, and describes the electromagnetic spectrometers and experimental measurement systems associated with fusion and multi-nucleon transfer reactions. The HIAF physics goals,including the synthesis of new superheavy elements and nuclides, the study on the nuclear structure of superheavy nuclei,the reaction mechanism of producing superheavy nuclides, and the atomic structure and chemical properties of the heaviest elements, are illustrated in detail. Lastly, the future research plan for superheavy elements and nuclides is summarized.