共查询到17条相似文献,搜索用时 46 毫秒
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提出了一种从理论上检验壳效应的方法. 即在考虑了BCS近似的相对论平均场理论框架内, 通过计算粒子数的涨落, 发现涨落的大小和核的壳结构有紧密的关系, 由此从理论上证明了在滴线附近的丰中子区, 传统幻数N=28已经消失. 相似文献
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基于中子分离能的分析 ,Ozawa等提出丰中子轻核存在新幻数 N=1 6.对 N=1 6同中子素进行了形变和球形的相对论平均场计算 .相对论平均场的数值结果表明N=1 6同中子素有形状相变.这是一些丰中子核新幻数出现的可能原因. Based on the analysis of neutron-separation energies, Ozawa et al proposed a new magic number N =16 in light neutron-rich nuclei. The deformed and spherical relativistic mean-field(RMF) calculations have been carried out for N =16 isotones. The numerical relativistic mean-field results show there is a shape transition in N =16 isotones. This is the possible cause of the appearance of the new magic number in someneutron-rich nuclei. 相似文献
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利用形变约束的相对论平均场理论研究了Pt同位素偶-偶核的形状演化,比较了基态结合能和四极形变的理论计算值和实验值, 分析了这些核的位能曲线、单粒子能级及其随四极形变β2 的变化规律,发现从N=88到N=126, Pt同位素的基态变形从球形对称核经X(5)对称性核、演化为具有稳定形变的核,再演化为球形核的变化过程.其中, 166-172Pt是近球形核, 174Pt和192-196Pt位于球形和稳定形变之间,可能具有X(5)对称性, 176-190Pt具有稳定的变形, 198-202Pt是近球形核, 204Pt是球形核,这些结果与实验一致. 相似文献
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利用形变约束的相对论平均场理论系统研究了N=60同中子核素的形状演化, 给出了这些核的基态结合能、 形变、 单粒子能级以及形变激发的位能曲线。 通过比较和分析发现, 随着质子数的增加, N=60同中子核的基态形变向轴对称形变方向演化, 114Xe和116Ba位于球形U(5)和轴对称SU(3)的过渡区, 存在形状相变的临界点结构, 这些结果与实验观测一致。 The shape phase transition between spherical U(5)and axially SU(3)deformed nuclei is investigated systemically for N=60 isotonic chain by the constrained relativistic mean|field theory with the interactions NL3 and PK1. The values of bind energy and quadruple deformation β2 are calculated and a good agreement is obtained as compared with the experiments. By examining the potential energy curve and single particle spectra obtained with this microscopic approach, the possible critical point nuclei with the structure of shape phase transition are suggested to be 114Xe and 116Ba, which is favored by the experiments. 相似文献
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在球形相对论平均场模型下,采用PK1和NL3相互作用, 对N=127同中子核素的基态和低激发态进行了研究,获得了价核子的激发能及中子、 质子和最后一个中子的密度分布, 指出209Pb的3d5/2,4s1/2和3d3/2激发态可能存在一个中子晕结构,207Hg,208Tl,210Bi和211Po的3d5/2,4s1/2及3d3/2激发态也可能存在一个中子晕结构。Properties of the ground state and the excited states in N=127 isotones are investigated with relativistic mean field theory with the interactions PK1 and NL3. By analyzing the rms of proton and neutron, the single particle levels of valence nucleon and the density distributions of neutron, proton and the last neutron, it can be found that there exists a neutron halo in the excited states of 3d5/2,4s1/2 and 3d3/2. It is also predicted that there exists a neutron halo in the excited states of 3d5/2,4s1/2 and 3d3/2 in 207Hg,208Tl,210Bi and 211Po. 相似文献
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在相对论平均场理论框架下,利用粒子数守恒方法处理对关联,给出了具体的理论公式和数值细节;并以24Ne为例,用该方法研究了它的基态和低激发态性质. Particle-number conserving method is adopted to treat the pairing correlations in the relativistic mean-field theory. The formalism and numerical techniques are presented. As an example, the ground state properties and low-lying excited states in~(24)Ne are studied. 相似文献
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轻核区双中子滴线核的研究 总被引:1,自引:0,他引:1
运用形变相对论平均场(RMF)理论系统地研究了轻核区的元素O, Ne, Mg, Si, S, Ar和 Ca及Ni。 计算了这8个元素的偶 偶核基态的一些性质, 如结合能、 四极形变、 平均每核子结合能以及双中子分离能等。 计算中采用了NL3参数组, 并用BCS方法处理对关联。 限于篇幅, 文中只给出O和Mg元素的计算结果。 RMF理论计算的结果和实验值基本一致。 从双中子分离能的分析可知, RMF理论计算的各元素的双中子滴线核分别为 30O, 38Ne, 42Mg, 52Si, 54S, 60Ar, 80Ca和98Ni。 最后简单讨论了Ca和Ni同位素中的中子幻数情况。 The ground state properties of even even O, Ne, Mg, Si, S, Ar, Ca and Ni isotopes were studied with the self consistent deformed relativistic mean field theory with NL3 parameter set. The calculated results of O and Mg isotopes were presented in detail. The calculated binding energies and the two neutron separation energies were in good agreement with experimental values. By examining the two neutron separation energies, it was suggested that 30O, 38Ne, 42Mg, 52Si, 54S, 60Ar, 80Ca and 98Ni are the two neutron drip line nuclei. We also briefly discussed the possible changes of neutron magic numbers in Ca and Ni isotopes. Key words: relativistic mean field; drip line nucleus; two neutron separation energy 相似文献
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DING BinGang NING PingZhi ZHANG DaLi & LU DingHui College of Science Huzhou Teacher''''s College Huzhou China Department of Physics Nankai University Tianjin China Department of Physics Zhejiang University Hangzhou China 《中国科学G辑(英文版)》2007,50(2):231-239
Particle number fluctuations in BCS theory are studied with the relativistic mean-field theory and the shell effects of particle number fluctuations are first discovered. By analyzing the relative errors of the particle number fluctuations, we find that the particle number fluctuations are relevant with the odd-even character. We later apply this method to the examination of the new shell structure, showing that N = 184 for the neutron is indeed a new closed shell. 相似文献
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In an axially deformed relativistic mean-field calculation of single-particle energy spectra ofN = 8 (Li-Mg) andN = 14,16 (C-Mg) isotonic chain and the one- and two-neutron separation energies of various isotopes of Li-Mg, new magic numbers
are found to exist atN = 6 andN = 16 and/orN = 14, which are in addition to theN = 8 andN = 20 magic numbers. In neutron-rich nuclei, the shell gap atN = 6 is larger than atN = 8 and a large gap is observed forN = 16 or 14 for the neutron-rich andN = 14 for proton-rich nuclei. Large shell gaps are also found to exist atN = 14 and 16 orN = 16 alone for nuclei near theβ-stability line. The above results are independent of the parameter sets TM2, NL3 and NL-SH used here. Similarly, new large
shell gaps are predicted atZ = 616 and/or 14 for protons. 相似文献
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Deexcitation energies of superdeformed secondary minima of odd-odd A u and T1 isotopes are investigated with the relativistic mean field (RMF) model where the isoscalar-isovector coupling is included to change the symmetry energy. It is verified by the theoretical analysis and numerical results that the deexcitation energies of superdeformed secondary minima relative to the ground states in these heavy nuclei are sensitive to differences in the symmetry energy. In particular, the linear correlation between the deexeitation energies of odd-odd Au and T1 isotopes and the neutron skin thickness in 208Pb is established. Moreover, explorations are extended to superdeformed candidates of other mass regions. It is found that the linear correlation can even be established between the deexcitation energies and the symmetry pressure at subsaturation density. These indicate that deexcitation energies can serve as a probe to the density dependence of the symmetry energy. 相似文献
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应用严格求解的Nilsson 平均场加推广对力模型,在同时考虑质子-质子和中子-中子间对力相互作用的情况下,对稀土区的152-164Er,154-166Yb 和156-168Hf 核素的结合能、奇偶能差、低激发态转动惯量等基态性质进行系统的统一描述。通过计算结果与实验数值比较分析显示,对力相互作用在阐明以上核素能谱的基态性质中起到了关键的作用。应用拟合上述物理量所确定的模型参数,对156-162Yb 核素基态中价核子配成角动量J = 0,1,… ,12的价核子对占有率的计算结果显示,配成角动量为偶数价核子对的占有率远远高于配成角动量为奇数价核子对的占有率,其数值结果揭示了配成角动量为S,D和G的价核子对在所考虑的核素基态性质中占主导地位。The Nilsson mean-field plus extended-pairing model for deformed nuclei is applied to describe the ground-state properties of selected rare-earth nuclei. Binding energies, even-odd mass differences, moments of inertia for the ground-state band of 152-164Er, 154-166Yb, and 156-168Hf are calculated systematically in the model employing both proton-proton and neutron-neutron pairing interactions. In comparison with the corresponding experimental data, it is shown that for these rare-earth nuclei, pairing interaction is crucial in elucidating the properties of the ground state. With model parameters determined by fitting the energies of these states, ground-state occupation probabilities of valence nucleon pairs with angular momentum J =0,1, …,12 for even-even 156-162Yb are calculated. It is inferred that the occupation probabilities of valence nucleon pairs with even angular momenta are much higher than those of valence nucleon pairs with odd angular momenta. The results clearly indicate that S, D, and G valence nucleon pairs dominate in the ground state of these nuclei. 相似文献
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Using a new set of nucleon coupling constants CZ11 the properties of a proto neutron star are examined within the framework of the relativistic mean-field theory for the baryon octet system.It is found that the relative number density of Λ,Ξ-,and Ξ0 for CZ11 are all smaller than those for GL97 and for both CZ11 and GL97,Σ-,Σ0,and Σ+ do not appear.It is also found that the pressure and the maximum mass for CZ11 are all smaller than those for GL97.The maximum mass for CZ11 decreases by approximately 9 percent compared with that for GL97. 相似文献