200MeV以下质子-核散射的相对论微观描述

应用Dirac Brückner-Hartree-Fock方法, 采用新的G矩阵分解方式研究了核子在核介质中的同位旋相关的相对论微观光学势，采用定域密度近似得到有限核的相对论微观光学 势.讨论了有限核的相对论微观光学势及其Schrdinger等价势与入射质子能量的关系，计 算了200MeV以下质子入射40⁴⁰Ca和208²⁰⁸Pb核的弹性散射角分布 和分析本领，得到了与实验相一致的结果，并将这种方法推广用于不稳定核的研究.通过对C a同位素的计算可以看出，在相 关键词： 相对论微观光学势 Dirac Brückner-Hartree-Fock 不对称核物质 定域密度近似     

Supernovae and the nuclear equation of state at high densities

An extensive study of the shock-explosive mechanism for generating type II supernovae is made. The nuclear high-density equation of state plays an important role, moderate softening of the equation of state leading to a considerable increase in shock strength. A definition of shock energy which can be used throughout the life of the shock is introduced.     

类碳体系基态能量的相对论修正(英文)

以Breit-Pauli哈密顿的球张量形式为基础,借助不可约张量理论,将多电子原子能量的相对论修正理论拓展到了原子的拉卡波函数为多个Slater基函数的线性组合的情形,导出了此情形下多电子原子能量相对论修正(包括相对论质量修正项、单体和双体迭尔文修正项、自旋-自旋接触相互作用项)的解析表达式,完成了所有角向积分和自旋求和计算.利用所建立的理论,对类碳体系基态能量的相对论修正进行了具体计算.     

氩原子和类氩离子相对论修正

以相对论修正哈密顿(包括质量修正、单体和双体达尔文修正、自旋-自旋接触相互作用)的球张量形式为基础, 借助不可约张量理论导出了类氩体系基态能量的相对论修正的解析表达式. 在斯莱特表象中完成了所有的角向积分和自旋求和计算, 能量的相对论修正式用径向矩阵元的线性组合来表示.对类氩体系基态能量的相对论修正值进行了具体计算,相对误差均小于0.0459%     

类铝离子基态能量的相对论修正和Z相关修正

以Breit-Pauli哈密顿的球张量形式为基础,借助不可约张量理论,在拉卡表象下计算了类铝体系基态能量相对论修正(包括相对论质量修正项、单体和双体达尔文修正项、自旋-自旋接触和轨道-轨道相互作用项)。在此基础上,引入了一个与核电荷数Z相关的能量修正项,用以弥补因忽略能量的其它高阶项对原子体系能量的影响。计算结果与实验值非常接近。     

Precise determination of the ground state hyperfine splitting of135Ba+

A microwave-optical double resonance experiment has been performed on¹³⁵Ba⁺ ions, confined in a r.f. quadrupole trap. Linewidths as narrow as 0.9 Hz have been obtained on the 7.18 GHz,F=1,m=0 toF=2,m=0 transition. Shifts of the resonance frequency due to magnetic stray fields and the electric trapping field have been observed. The final result, extrapolated to zero field strengths, isΔ υ _HFS=7183340234.90(0.57) Hz.     

Relativistic equation of state of nuclear matter for supernova and neutron star

We construct the equation of state (EOS) of nuclear matter using the relativistic mean field (RMF) theory in the wide density, temperature range with various proton fractions for the use of supernova simulation and the neutron star calculations. We first construct the EOS of homogeneous nuclear matter. We use then the Thomas-Fermi approximation to describe inhomogeneous matter, where heavy nuclei are formed together with free nucleon gas. We discuss the results on free energy, pressure and entropy in the wide range of astrophysical interest. As an example, we apply the resulting EOS on the neutron star properties by using the Oppenheimer-Volkoff equation.     

On the three body contributions to the ground state energy of nuclear matter

The theory of nuclear matter is investigated by means of the method of unitary transformations in the special case of point transformations. The induced three body forces are constructed, their contributions to the ground state energy of nuclear matter are given in first order perturbation theory, and the connexion with Jastrow's procedure is shown. A first numerical estimate of the three body contributions to the energy per particle gives approximately 1 MeV in the physical density range. For higher values of the Fermi momentum (k _F ≈2 fm^?1) the contributions increase rapidly. Generally the induced three body forces cannot be neglected if one wants to calculate the correct saturation data.     

Shell-correction approach to state densities of nuclei

A consistent renormalization of ground state energy and state density as a function of deformation is presented. Renormalized state densities do not increase uniformly with deformation. Consequences for the fissionability of excited nuclei are pointed out.     

Relativistic correction to the dipole polarizability of a hydrogenic ion

The first relativistic correction of orderα ² to the dipole polarizability of a hydrogenic ion has been investigated by using mean excitation energy of the ion within the second-order perturbation theory. The density-dependent mean excitation energy is estimated via Bethe theory for the stopping cross section for a moving point charge interacting with the hydrogenic ion. In this approach only the unperturbed Dirac wavefunctions are required to evaluate the appropriate matrix elements. The first relativistic correction turns out to be − (13/12)(αZ)². This has the correct sign and is within 5% of the exact result which is −(28/27)(αZ)².     

Leptodermous expansion of nuclear ground state energies and the anomaly in the nuclear curvature energy

The leptodermous expansion of the total ground state energy of a nucleus into volume, surface, curvature and gauss curvature contributions has been studied starting from a semi-classical energy density formalism of extended Thomas Fermi type. A numerical procedure was used to obtain the surface energy and curvature energy contributions from surface moments of energy density profilesH(r) for a sequence of nuclei withN=Z and neglecting the coulomb interaction for the three Skyrme forces. A transition to the liquid drop model type expansion in increasing powers ofA ^−1/3 is then made, taking into account the dependence of the central density and the surface structure on the mass of the nucleus. It is found that there is no inconsistency between the curvature contribution to the total energy in the leptodermous expansion and theA ^−1/3 term contribution in the liquid drop model expansion. It has been shown that the earlier apparent anomaly between the above two methods arises due to the use of semi-infinite approximation and the mass dependence of the central density and the surface structure of finite nuclei.     

A study of the C(p, p′) reactions at 135 MeV

A relativistic mean field approach is used to determine and compare the single-particle Dirac potentials for nuclei and hypernuclei (Λ, Σ, Ξ). A simple model is used and the Dirac-Hartree-Fock equations are reduced to a Schrödinger-like equation. The subsequent central and spin-orbit shell-model potentials are compared to those of phenomenological approach and other recent microscopic approaches. In the case of hypernuclei the Hartree approximation works already quite well without any need of taking into account the strangeness exchange part coming from strange mesons. The influence of the anomalous magnetic moment of the baryon on the spin-orbit term is found to be rather important for both Λ- and Σ-hyperons.     

Equation of state of fluid helium at high temperatures and densities

Helium, hydrogen, and their isotopes are the simplest monoatomic and diatomic molecules. It is relatively easy to describe their properties using the basic principles of quantum mechanics. In condensed matter physics, hydrogen and helium serve as the models for the condensed matter properties at extreme conditions so that both experi- mental and theoretical physicists pay much attention to the study of their properties[1], especially the insulator-metal transition of hydrogen[2]. The aim to st…