兰州大学机构库 >核科学与技术学院
原子核质量公式与自发裂变的理论研究
Alternative TitleTheoretical Studies of Nuclear Mass Formula and Nuclear Spontaneous Fission
张海飞
Thesis Advisor张海飞
2015-05-29
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Keyword原子核质量公式 对修正与壳修正 连续态 自发裂变 beta参数化
Abstract本论文的主要工作是:1)在Weizsacker-Skyrme (WS) 质量公式基础上,通过微观BCS 方法结合Strutinsky平滑处理来同时计算原子核的壳修正和对修正能。2) 在WS 质量公式的壳修正部分中考虑连续态效应,我们提出另一组WS质量公式WS+CS。另一个工作是基于推广液滴模型(GLDM),将该模型中用于描述原子核形状演化的准分子形状进行beta参数化,从而实现了原子核自发裂变路径中每一个准分子形状所对应的Strutinsky壳修正的自洽计算。基于WS+BCS质量公式,我们主要考察该质量公式在描述原子核的粗块性质(结合能、形变等)和微观结构信息(单双中子分离能、对能隙)方面的预言能力。基于WS+CS质量公式,着重讨论了在考虑连续态效应之后我们的质量公式与原来的WS公式相比,在微观结构信息描述上的改进和优越性。从而证实了考虑连续态效应对于改进原子核质量公式在微观结构描述方面的重要性。在GLDM模型的框架下实现准分子形状beta参数化需要分两种情况:对于对称裂变道,我们采用解析展开的方法(以球谐函数Yl0为基矢);对于不对称裂变道,采用数值方法(最小二乘法)。以U,Pu,Am,Cm,Cf和Fm同位素的几个不对称裂变道以及256 Fm的对称裂变道为例,计算了其自发裂变半衰期,得到的半衰期能较好地符合对应的实验值。
Other AbstractThe main topics of this thesis are: 1) Based on the Weizsacker-Skyrme (WS) nuclear mass formula, a modified WS model labeled by WS+BCS is carried out, which employed a microscopic BCS method combining a procedure similar to Strutinsky method to simultaneously evaluate shell and pairing corrections. 2) Considering the continuum state effect on the shell correction in WS-like model, a new WS model named WS+CS are performed. Another work is that in the framework of Generalized Liquid Drop Model (GLDM) we make the quasimolecular shapes beta-parameterized, which are employed to describe the nuclear deformation evolution, and thus implement the purpose of self-consistent calculations of Strutinsky shell correction of each quasimolecular shape along the spontaneous fission pathway. Based on the WS+BCS model we mainly test the predictive power of this new formula from the aspects of nuclear bulk properties (such as binding energies, deformations and so on) and the microscopic structure information (one neutron separation energy, pairing gaps), and then compare it with other mass formulas or models, and finally employ it to predict the masses of still unknown or not well-known nuclei and calculate the -decay energies of superheavy nuclei. Rooted on WS+CS model and compared with the original WS formula, besides the nuclear bulk properties (binding energies, deformations and so on) we concentrate on the improvement and superiority of them within considering continuum state e ect in describing the microscopic structure information (for example, the shell gaps, beta−decay energies). Therefore it proves the importance of considering continuum state in improving the descriptions of microscopic nuclear structure aspects.In framework of GLDM the specific implement of beta−parameterized quasimolecular shape need to be divided into two cases: For symmetric fission it is done analytically (taking the spherical harmonics Yl0 as basis), whereas for asymmetric fission it is performed in a pure numerical way (least-squares method). We substitute the beta−parameterized values of every quasimolecular shape into axial symmetry WSBETA code and calculate the corresponding shell corrections, so that the evaluations of the fission barrier are more self-consistently. Afterward, taking the asymmetric channels of U, Pu, Am, Cm, Cf, and Fm isotopes and the symmetric channel 256Fm as examples, we calculate their spontaneous fission half-lives, and as a results the theo...
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Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/211844
Collection核科学与技术学院
Recommended Citation
GB/T 7714
张海飞. 原子核质量公式与自发裂变的理论研究[D]. 兰州. 兰州大学,2015.
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