基于协变密度泛函理论的258Fm诱发裂变动力学研究  

Microscopic Study on Induced Fission Dynamics of ^(258)Fm within Covariant Density Functional Theory

作　　者：陈盛远 李泽宇 陈永静[2] 李志攀[1] CHEN Shengyuan;LI Zeyu;CHEN Yongjing;LI Zhipan(School of Physical Science and Technology,Southwest University,Chongqing 400715,China;China Nuclear Data Center,Key Laboratory of Nuclear Data,China Institute of Atomic Energy,Beijing 102413,China)

机构地区：[1]西南大学物理科学与技术学院,重庆400715 [2]中国原子能科学研究院核数据重点实验室,中国核数据中心,北京102413

出　　处：《原子能科学技术》2022年第5期869-878,共10页Atomic Energy Science and Technology

基　　金：国家自然科学基金(11790325,11875225)。

摘　　要：采用基于协变密度泛函理论的含时生成坐标方法研究了^(258)Fm低能诱发裂变动力学性质,重点探讨了裂变位能曲面、裂变碎片总动能分布和碎片质量分布等。研究表明,^(258)Fm位能曲面中存在显著的对称裂变谷,因而其低能裂变碎片总动能分布与质量分布均呈单峰结构,且随剪裂线判据Q_(n)(脖子处粒子数)从4减至1,碎片总动能分布变窄,碎片质量分布的峰值从9.88%增至10.28%。此外,随初态激发能从8.3 MeV增至17.3 MeV,碎片质量分布峰值从9.88%降至8.55%。Nuclear fission is an import object in nuclear physics and engineering due to its crucial role in the military,energy application and industry,agriculture,medical and other fields.In recent years,nuclear fission attracts more attention due to the following reasons:Nuclear fission plays a crucial role in determining the stability of super-heavy elements,and is one of the primary mechanisms that terminate nucleosynthesis and determine the abundance of the synthesized nuclides;It is also an important mechanism used to produce short-lived exotic nuclides and fission of exotic nuclei far from stability also provides a new and effective way to study exotic nuclei.Generally,heavy nucleus contains hundreds of nucleons which are coupling with each other by nucleon-nucleon many-body interaction.Due to the complication of low-energy heavy nuclear fission,it is out of reach for ab initio calculation or interacting shell-model.Modern microscopic approaches are based on the framework of nuclear energy density functionals(NEDFs)which consider the Pauli exclusion principle and nucleon-nucleon interaction simultaneously and include the shell effect and quantum many-body effect self-consistent.In our previous work,the time-dependent generator coordinator method plus Gaussian overlap approximation(TDGCM+GOA)has been implemented based on the covariant density functional theory(CDFT)and applied to describe the fission dynamics of ^(226)Th where three peaks were observed in the fragment yield distribution.In this work,the dynamics of low-energy induced fission of ^(258)Fm was analyzed by using the TDGCM+GOA based on CDFT,mainly focusing on the potential energy surface(PES),total kinetic energies(TKE)of the fragments,and fragment mass yields.A remarkable symmetric fission valley is found in the potential energy surface,and thus both the TKE distribution and fragment mass yields present a single symmetric peak structure.The scission lines show an obvious separation between the number of the nucleons in the neck Q_(n)=4,3,2,and an almost

关 键 词：核裂变 协变密度泛函理论 含时生成坐标方法 裂变碎片质量分布 

分 类 号：O571[理学—粒子物理与原子核物理]