The Brueckner-Hartree-Fock Equation of State for Nuclear Matter and Neutron Skin

The equation of state for nuclear matter is presented within the Brueckner-Hartree-Fock(BHF) scheme,by using the realistic Argonne V18 or Bonn B two-nucleon potentials plus their corresponding microscopic three-nucleon forces.It is then applied to calculate the properties of finite nuclei within a simple liquid-drop model,and we compare the calculated volume,surface,and Coulomb parameters with the empirical ones from the liquid drop model.Nuclear density distributions and charge radii in good agreement with the experimental data are obtained,and we predict the neutron skin thickness of various nuclei.     

A barrier-penetration model for heavy-ion fusion,valid at all energies

We present a barrier-penetration model for heavy-ion fusion valid from the lowest energies available up to the largest energies for which the critical-radius picture is realistic. The parameters of the model are a critical radius and the parameters of a nucleus-nucleus interaction, whose form factor can be chosen freely. Fusion cross sections for a large number of systems, for which low-energy data exist, are fitted with a Woods-Saxon potential. Realistic parameters are obtained for the Coulomb barrier. Different applications and some limitations of the model are discussed.     

Study of Coulomb interaction for two diffuse spherical-deformed nuclei

The Coulomb interaction for a spherical—deformed interacting pair is derived assuming realistic nuclear charge distributions. The effect of a finite diffuseness parameter is described either by the folding product of spherical or deformed sharp-surface distribution and a spherical short-range function or by using a Fermi two-parameter distribution function. The approximate solutions obtained using these categories of charge distributions are then compared to the numerical solution obtained within the framework of the double-folding model. We found that the finite surface diffuseness parameter affects slightly the inner region of the total Coulomb potential, while it produces large errors in calculating the Coulomb form factors used frequently in nuclear reactions and fusion numerical codes. The text was submitted by the authors in English     

High energy collisions between heavy nuclei

Neglecting Coulomb effects we derive a very simple analytical result for nucleus-nucleus elastic scattering in an optical limit of the Glauber approximation which has the property that it does not diverge at large momentum transfers when the center-of-mass correlation function is retained and is more accurate and easier to apply than the commonly used expressions which involve numerical integrations. We then derive a corresponding analytical expression for the elastic scattering amplitude which includes the Coulomb effects arising from point charge incident and target nuclei.     

Study of nuclear-coulomb interference effects in inelastic deuteron scattering on 238U

The angular distributions of elastically and inelastically scattered deuterons from ²³⁸U at E = 17 MeV are compared to coupled-channel calculations. The cross sections at small scattering angles are strongly influenced by nuclear-Coulomb interference effects and allow a simultaneous extraction of nuclear (optical potential) and charge quadrupole deformation parameters. Two different deformed Coulomb potentials and the parameters of the optical model are discussed.     

柱形分布的电荷产生的电势

将无限长线电荷看成二维平面上的一个“源”,利用电势叠加原理计算了无限长柱形均匀分布的电荷产生的电势.这些柱体的截面电荷分布包括可解析表示和不可求解表示两种,后者可以通过数值计算给出结果.因此这种方法实际上可以计算任意截面柱形电荷分布的电势.通过计算,展示了各种电荷分布所产生电场的特性和共同特征.     

Systematic studies on α-decay half-lives for super heavy nuclei

Radioactive decay of super heavy nuclei via the emission of α-particles has been studied theoretically in the preformed cluster model (PCM). The nucleus-nucleus (NN) potential is obtained by double folding the density distributions of the α-particle and the daughter nucleus with a realistic effective interaction. The M3Y effective interaction, supplemented by a zero-range pseudo-potential for exchange term, is used to calculate the NN potential. The α decay half-lives for 317 nuclei at Z=102–120 are performed in the PCM framework with the theoretical Q values extracted from the Mller-Nix-Kratz and Liran-Marinov-Zeldes mass tables and are compared with the experimental data. The calculated results are also compared with those obtained by using Q values from the Muntian-Hofmann-Patyk-Sobiczewski and Myers-Swiatecki mass estimates.     

A phenomenological model of deep-inelastic collisions between complex nuclei

A simple model of heavy-ion collisions is proposed. Classical equations of motion with inclusion of a phenomenological two-body friction force are integrated numerically along trajectories. The nucleus-nucleus interaction potential which is used in the calculations includes deformation degrees of freedom in the exit channel. Both entrance and exit channel potentials are based on the boundary conditions following the liquid-drop model. The energy-angle distributions of deep-ineIastic reactions are very well reproduced by the model. The existing data on fusion cross sections are compared with the model predictions. This comparison indicates that in the nucleus-nucleus potential a repulsive core is present.     

Classical Coulomb systems: Screening and correlations revisited

From the laws of macroscopic electrostatics of conductors (in particular, the existence of screening), taken as given, one can deduce universal properties for the thermal fluctuations in a classical Coulomb system at equilibrium. The universality is especially apparent in the long-range correlations of the electrical potentials and fields. The charge fluctuations are derived from the field fluctuations. This is a convenient way to study the surface charge fluctuations on a conductor with boundaries. Explicit results are given for simple geometries. The potentials and the fields have Gaussian fluctuations, except for a short-distance cutoff.laboratory associated with the Centre National de la Recherche Scientifique.     

High momentum nucleons in the nucleus

Using Jastrow form for the nuclear wave function, single-particle distributions in the momentum space are extracted for the correlation functions corresponding to the Reid soft core, Hamada-Johnston and Ohmura-Morita-Yamada (OMY) hard core potentials. The correlations functions used for this purpose are the numerical solutions of the Schrödinger type equation for the realistic potentials and analytical form for the OMY potential. It is found that the calculated momentum distributions, with Woods-Saxon basis functions, differ significantly beyond 400 MeV/c. Comparison with the experimental proton momentum distribution from (γ, p) reaction suggests that while the OMY potential results are nearer to the experimental values, the realistic potentials do not introduce the high momentum components to the required extent.     

Dissipation and fluctuation of the relative momentum in nucleus-nucleus collisions

The dissipation of the relative momentum in nucleus-nucleus collisions is treated in terms of a Langevin equation with a fluctuating force. Equations of motion for first and second moments of the macroscopic variables are derived directly from the Langevin equation. The properties of the fluctuating force which results from random particle exchange are investigated in detail. Drift and diffusion coefficients are calculated microscopically and analytical expressions are given which can be used in any trajectory calculation. An important feature of the model is that the Einstein relation between dissipation and fluctuation turns out to be only a limiting case of a more general expression which includes nonthermal fluctuations. By treating the two nuclei as intrinsically equilibrated but not in thermal equilibrium with respect to each other, several important aspects of the dissipative behaviour, seen in heavy-ion collisions with final energies above the Coulomb barrier, can be understood.     

Proton radioactivity with a Yukawa effective interaction

The half-lives of proton radioactivity of proton emitters are investigated theoretically. Proton-nucleus interaction potentials are obtained by folding the densities of the daughter nuclei with a finite-range effective nucleon-nucleon interaction having Yukawa form. The Wood-Saxon density distributions for the nuclei used in calculating the nuclear as well as the Coulomb interaction potentials are predictions of the interaction. The quantum mechanical tunneling probability is calculated within the WKB framework. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes. The effects of neutron-proton effective mass splitting in neutron-rich asymmetric matter as well as the nuclear matter incompressibility on the decay probability are investigated.     

Localized charge inhomogeneities and phase separation near a second-order phase transition

Localized charge inhomogeneities and phase separation are described in the framework of the phenomenological theory of phase transitions. It is shown that Coulomb interaction determines the charge distribution and the characteristic size of the emerging inhomogeneities. Phase separation associated with charge segregation becomes possible because of a high dielectric constant and a low excess charge density in the localization region. The phase diagram of the system is calculated, and estimates are obtained for the gain in energy associated with the emerging state. The role of Coulomb interaction is exposed, and corresponding estimates are given.     

Parametrization of woods-saxon potential for heavy-ion systems

Several elastic scattering angular distributions of ~(12)C from target nuclei of A ≥39 are analyzed to extract the Woods-Saxon potential parameters with the fixed imaginary potential and Coulomb radius parameters.Using the best fitted diffuseness parameters,the correlations of the real part parameters with A_1~(1/3)+ A_2~(1/3) and incident energy are revealed, and the systematic Woods-Saxon potential parameters are presented for nucleus-nucleus interaction.The proposed potential parameters can reproduce not only the elastic scattering angular distributions induced by ~(12)C,but also many elastic scattering angular distributions induced by the projectiles other than ~(12)C,thus providing important inputs for the study of nuclear reactions of heavy-ion systems.     

Coulomb potentials in heavy-ion interactions

The usual point charge approximation for the Coulomb potential in heavy-ion interactions is compared with more realistic treatments. Elastic scattering and transfer reaction calculations appear to be insensitive to the form of the Coulomb potential used.     

Entrance-channel potentials in synthesis of the heaviest nuclei, muon catalysis of superheavy element formation

Entrance-channel potentials in nucleus-nucleus collisions, relevant for the synthesis of superheavy elements, are systematically studied within a semi-microscopic approach, where microscopic nuclear densities are used in semi-classical expressions of the energy-density functional. The existence of pockets in the entrance-channel potentials is crucial for heavy-ion fusion. It is shown that a muon bound with the light projectile induces the production of superheavy elements in nucleus-nucleus collisions.     

Production of exotic nuclei in peripheral nucleus-nucleus collisions below 10 A MeV

Experimental data from the literature concerning nucleus-nucleus collisions at beam energies of few A MeV above the Coulomb barrier are investigated in this work with emphasis on projectile-like fragment distributions. In peripheral collisions at beam energies below 10 A MeV, deep-inelastic transfer is shown to be the dominant reaction mechanism. In addition, the mechanism may involve an extension of the nuclear profile in the window (neck) region, observed primarily in reactions with very heavy target nuclei. Isoscaling observed at these energies can be used as a tool to predict the production rates of exotic nuclei in reactions induced by exotic secondary beams.