基于俘获与存活过程系统分析的超重核合成机制研究

In the past decades, the synthesis mechanism of the superheavy nuclei have been one of the most important topics in nuclear physics studies. In recent years, due to the development of the experimental technique, the superheavy elements with Z≤118 have been discovered. It is a great challenge to synthesize superheavy nuclei with more protons. Theoretical studies of synthesis mechanism of superheavy nuclei can provide important information to help guide experimentalists. Up to now, the predictions of evaporation-residue (ER) cross sections from theoretical models have a large uncertainty because of some serious ambiguities in the reaction mechanism of fusion dynamics. Especially, the experimental measurements are nicely fitted by almost all models, while the formation probability and survival probability have large uncertainties. In this project, we will perform a step by step and systematic study of the capture process, the deexcitation process, and the fusion process, respectively. For the capture process and the deexcitation process, based on the available data of fusion and ER cross sections for the reactions without quasifission, we will develop and improve the empirical coupled-channel model and statistical model. Based on the available data of ER cross sections of the superheavy nuclei, we will extract the corresponding fusion probabilities and propose an empirical formula for these extracted fusion probabilities. This investigation will improve not only our understanding of the synthesis mechanism of superheavy nuclei, but also the reliability of theoretical descriptions. This investigation will also provide important basis for the further experimental study.

在过去数十年中，超重核合成机制研究一直是核物理研究的前沿热点问题之一。近年来，由于实验技术的发展，实验合成了质子数Z≤118的超重元素。对于合成质子数更大的超重核，实验面临着巨大的挑战。通过研究超重核合成的机制，理论能为实验提供重要参考。目前，由于熔合机制尚不十分清楚，不同理论模型对超重核合成截面的预言差别较大。特别地，大多数理论模型能很好地符合已有实验数据，但这些模型对超重核的熔合及存活概率的描述有很大的差异。本项目拟逐步地、系统地研究超重核合成的俘获过程、退激过程及熔合过程。对于俘获和退激过程，基于不涉及准裂变过程反应的熔合和蒸发剩余截面的实验数据，发展及完善描述俘获及存活过程的经验耦合道模型和统计模型。本项目将基于超重核蒸发剩余截面的实验值提取相应反应的熔合概率，并给出描述熔合概率的经验公式。此研究将有助于加深对超重核合成机制的理解，改进理论描述的可靠性，并为相关实验提供重要依据。

过去数十年中，超重核合成机制研究一直是核物理研究的前沿热点问题之一。近年来，由于实验技术的发展，实验合成了质子数Z⩽118 的超重元素。对于合成质子数更大的超重核，实验面临着巨大的挑战。通过研究超重核合成的机制，理论能为实验提供重要参考。目前，由于熔合机制尚不十分清楚，不同理论模型对超重核合成截面的预言差别较大。特别地，大多数理论模型能很好地符合已有实验数据，但这些模型对超重核的熔合及存活概率的描述有很大的差异。项目逐步地、系统地研究了重离子熔合反应的俘获过程、退激过程和熔合过程。具体成果包括：对于俘获和退激过程，基于不涉及准裂变过程反应的熔合和蒸发剩余截面的实验数据，发展及完善了描述俘获及存活过程的经验耦合道模型和统计模型；基于冷熔合反应的蒸发剩余截面的实验数据，我们提取了相应反应的熔合概率，并给出了描述熔合概率的经验公式；此研究有助于加深对超重核合成机制的理解，改进理论描述的可靠性，并为相关实验研究提供重要依据。项目发表学术论文4篇。招收硕士研究生2名。举办和承办国内学术会议2次。