Ba同位素形状演化及旋称劈裂性质研究

发布时间：2018-06-17 09:28

本文选题：TRS计算 + 转动性质　；参考：《郑州大学》2017年硕士论文

【摘要】：本论文的主要工作是基于对能-形变自洽处理Total Routhian Surface(TRS)计算方法研究Ba同位素偶偶核的形状演化以及奇A核中旋称劈裂的性质。主要内容包括两部分:一、在偶偶核中沿晕线分别研究了具有四极形变和三轴形变优势的~(118-128)Ba和~(126-136)Ba同位素链的转动性质和形状演化,并讨论了质子和中子拆对顺排对长椭及三轴/扁椭形状的驱动效应;二、在奇A核中研究了117-127Ba同位素链的旋称劈裂性质,详细考察了推转频率和形变自由度对准粒子能级形变驱动的影响。对于Ba(Z=56)同位素,由于质子和中子费米面分别位于h_(2/11)壳层底部和中上部,它们对原子核形状有不同的驱动效应,导致这一区域具有丰富的形状演化现象。首先,我们研究了~(118-148)Ba同位素链基态形变随核子数填充的演化,指出~(118-128)Ba和~(126-136)Ba同位素链分别具有明显β_2和γ形变。其次,沿着晕线能级我们分别研究了~(118-128)Ba和~(126-136)Ba同位素链的转动性质和形状演化。通过形变势能曲线,角动量顺排分析了~(118-128)Ba同位素随推转频率增加,核子形变软硬和拆对顺排的关系。另外,通过Centipede-like E-GOS曲线分析了晕态带能级序列,其结果表明随自旋的增加,原子核具有γ-soft到振动到转动或γsoft-的演化性质。单粒子能级随β_2和γ的变化指出~(126-136)Ba同位素链具有明显的γ形变。角动量顺排和准粒子能级的计算表明转动轴绕着中间轴,长轴和短轴转动演化源于质子顺排v(h_(11/2))~2具有γ0的长椭形状驱动效应和中子顺排v(h_(11/2))~2具有γ0的扁椭/三轴形状驱动效应。系统研究奇A核的旋称劈裂性质可以揭示原子核形变,核子数填充对能级结构的影响。不同推转频率下的形变势能曲线表明旋称伙伴带具有不同形变软硬度,其中优先分支对γ形变的驱动力强于非优先分支。考虑堵塞效应计算显示:引起实验观测的旋称劈裂大小变化可能的原因是质子(ef)和中子(FG/EH)顺排导致原子核形状变化。我们详细讨论了不同推转频率和形变自由度(β_2,γ)等因素对旋称劈裂大小的影响。结果表明质子顺排引起旋称劈裂的减小甚至出现反转现象;中子顺排引起旋称劈裂的增大导致实验可能只观测到一个旋称分支。因此,考察原子核旋称劈裂的变化时,一个重要的前提条件是同一对旋称伙伴带能级而不能仅仅沿着晕线提取旋称劈裂信息。
[Abstract]:The main work of this thesis is to study the shape evolution of even nuclei of Ba isotopes and the properties of spin-splitting in odd A nuclei based on the calculation method of Total Routhian Surface Surface TRS. The main contents consist of two parts: first, the rotational properties and shape evolution of the isotopic chains with quadrupole deformation and triaxial deformation are studied along the halo line in the even nuclei, respectively, which have the advantages of tetrapolar deformation and triaxial deformation, and the rotation properties and shape evolution of the Ba isotopic chains with the advantage of quadrupole deformation and triaxial deformation are studied respectively. The driving effects of proton and neutron disassembly on the aligned ellipsoids and triaxial / flat ellipsoids are discussed. Secondly, the rotational splitting properties of 117-127Ba isotopic chains in odd A nuclei are studied. The effects of push frequency and deformed degrees of freedom on the deformation drive of particle energy level are investigated in detail. The proton and neutron Fermi surfaces are located at the bottom and middle upper parts of hstack 2 / 11) shell respectively, and they have different driving effects on the shape of nucleus, which leads to rich shape evolution in this region. Firstly, we have studied the evolution of ground state deformation with nucleon number filling of 118-148 Ba isotopic chains. It is pointed out that the isotopic chains of 118-128 Ba and 126-136 Ba have obvious 尾 2 and 纬 deformation, respectively. Secondly, along the halo energy levels, we have studied the rotational properties and shape evolution of the isotopic chains of 118-128 Ba and 126-136 Ba, respectively. By means of the deformation potential energy curve and angular momentum arrangement, the relationship between nucleon deformation, soft and hard deformation and disassembly is analyzed with the increasing of pushing frequency. In addition, the energy level sequence of halo band is analyzed by Centipede-like E-GOS curve. The results show that with the increase of spin, the nucleus has the properties of evolution from 纬 -soft to vibration to rotation or to 纬 soft-. The variation of single particle energy levels with 尾 _ 2 and 纬 indicates that the 126-136 Ba isotopic chain has obvious 纬 deformation. The calculation of angular momentum and quasiparticle energy levels shows that the rotation axis revolves around the intermediate axis, and the long and short axis rotation evolution results from the long ellipsoidal driving effect of proton v(h_(11/2))~2 with 纬 0 and the flat ellipse / triaxial drive effect of 纬 0 from the neutron v(h_(11/2))~2. A systematic study of the spin-splitting properties of odd A nuclei can reveal the effects of nuclear deformation and nucleon number filling on the energy level structure. The deformation potential energy curves show that the rotational partner band has different deformation hardness and soft degree, and the driving force of the preferred branch on 纬 deformation is stronger than that of the non-preferred branch. Considering the blockage effect, it is shown that the possible reasons for the variation of the rotational splitting size of the experimental observations are the proton FG / EH) and the neutron fg / EH) leading to the change of the nucleus shape. We discuss in detail the effects of different push frequencies and deformed degrees of freedom (尾 _ s _ 2, 纬) on the size of spin splitting. The results show that proton cleavage decreases or even reverses due to proton cleavage, and the increase of spin-splitting induced by neutrons may result in only one rotational branch observed in the experiment. Therefore, an important prerequisite for the investigation of the variation of nuclear spin splitting is that the energy levels of the same pair of spin partners can not be extracted only along the halo line.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O571

【相似文献】