近垒重离子诱发裂变反应机制研究

Nuclear fission is a complex process with the involvement of large-scale nucleon transfer and rearrangement. It is an important and hot topic with both academic significance and realistic applications. The relevant physical mechanism is still not yet well understood up to now. To understand the fission mechanism, this project will develop a detector array with high mass resolution for the fission fragments and a large-solid-angle detector array with high granularity for the light-charged-particles (LCP), and develop a new multi-parameter correlation measurement method of double time-of-flight (TOF) plus double kinetic energy. This detector array will be used for the first time to study the mass-energy-angle multi-parameter correlation of fission fragments and fission-LCP, to obtain the high-precision experimental data of mass, kinetic energy and angular distributions for the fission fragments. At the same time, for accurately describing the potential energy surface of fission/quasi-fission systems and understanding the fission mechanism, we will improve a series of theoretical models, such as the improved quantum molecular dynamics model, the macroscopic-microscopic model and the Skyrme energy density functional approach, with the pairing, shell correction and isospin effects being taken into account. Together with the measured data, we will obtain the temperature and deformations before the scission-point, and as well as the fission timescale, which is of great importance to understand the fission dynamics from the compound-nucleus to the saddle-point and then to scission-point.

原子核裂变涉及大规模核子迁移和重组的复杂过程，是一个兼具学术意义和现实应用价值的重要前沿基础课题，相关的物理机制至今仍未被很好地理解。基于此，本项目将研制高质量分辨的裂变碎片探测阵列和大立体角覆盖高颗粒度的轻带电粒子探测器阵列，建立和发展双飞行时间+双动能的多参数关联测量新技术，首次开展裂变碎片之间以及碎片与轻带电粒子之间质量-动能-角度的多重关联测量，获得高精度的质量、动能、角度分布等裂变碎片特征的实验数据。同时，从理论上深入了解原子核裂变的微观机制，考虑对关联、壳效应和同位旋效应等，发展并完善一整套理论模型，包括量子分子动力学模型、宏观-微观模型以及能量密度泛函方法等，准确计算裂变体系势能曲面。结合高质量的实验数据，准确获得裂变核断前的温度、形变和裂变时标等裂变源的关键信息，较全面理解从复合核到鞍点再到断点的裂变反应动力学。

原子核裂变涉及大规模核子迁移和重组的复杂过程，是一个兼具学术意义和现实应用价值的重要前沿基础课题，相关的物理机制至今仍未被很好地理解。基于此，本项目成功研制了高质量分辨的裂变碎片探测阵列和大立体角覆盖高颗粒度的轻带电粒子探测器阵列，建立和发展了双飞行时间+双动能的多参数关联测量新技术，为裂变碎片之间以及碎片与轻带电粒子之间质量-动能-角度的多重关联测量，获取高精度裂变碎片特征的实验数据打下坚实基础。同时，从理论上深入探索了原子核裂变的微观机制，特别是对关联、壳效应和同位旋效应等对于裂变体系势能曲面以及裂变碎片电荷分布的影响，成功描述了碎片电荷分布的奇偶效应。发展并完善了宏观-微观模型以及能量密度泛函方法，基于这些理论模型系统研究了重离子熔合-裂变核核相互作用势垒以及熔合机制。