Systematic Study of Stability of Super Heavy Nuclei

A systematic overview on the characteristics of super heavy nuclei from Z = 101 to Z = 130 based on the data by P. Moller et al. is presented. The nuclei which have the biggest mean binding energy in each of their isotope chain show systematic regular behavior, indicating that the mean binding energy is a good criterion to classify super heavy nuclei by their stabilities. Further investigation on the nuclear data at and after Z=127 has been suggested.

LUNARINFO: A Data Archiving and Retrieving System for the Circumlunar Explorer Based on XML/Web Services

It is essential to build a modern information management system to store and manage data of our circumlunar explorer in order to realize the scientific objectives. It is difficult for an information system based on traditional distributed technology to communicate information and work together among heterogeneous systems in order to meet the new requirement of Internet development. XML and Web Services, because of their open standards and self-containing properties, have changed the mode of information organization and data management. Now they can provide a good solution for building an open, extendable, and compatible information management system, and facilitate interchanging and transferring of data among heterogeneous systems. On the basis of the three-tiered browse/server architectures and the Oracle 9i Database as an information storage platform, we have designed and implemented a data archiving and retrieval system for the circumlunar explorer-LUNARINFO. We have also successfully realized the integration between LUNARINFO and the cosmic dust database system. LUNARINFO consists of five function modules for data management, information publishing, system management, data retrieval, and interface integration. Based on XML and Web Services, it not only is an information database system for archiving, long-term storing, retrieving and publication of lunar reference data related to the circumlunar explorer, but also provides data web Services which can be easily developed by various expert groups and connected to the common information system to realize data resource integration.

Total Nuclear Reaction Cross Section Induced by Halo Nuclei and Stable Nuclei

We develop a method for calculation of the total reaction cross sections induced by the halo nuclei and stable nuclei. This approach is based on the Glauber theory, which is valid for nuclear reactions at high energies. It is extended for nuclear reactions at low energies and intermediate energies by including both the quantum correction and Coulomb correction under the assumption of the effective nuclear density distribution. The calculated results of the total reaction cross section induced by stable nuclei agree well with 30 experimental data within 10 percent accuracy.The comparison between the numerical results and 20 experimental data for the total nuclear reaction cross section induced by the neutron halo nuclei and the proton halo nuclei indicates a satisfactory agreement after considering the halo structure of these nuclei, which implies quite digerent mean fields for the nuclear reactions induced by halo nuclei and stable nuclei. The halo nucleon distributions and the root-mean-square radii of these nuclei can be extracted from the above comparison based on the improved Glauber model, which indicates clearly the halo structures of these nuclei. Especially,it is clear to see that the medium correction of the nucleon-nucleon collision has little effect on the total reaction cross sections, induced by the halo nuclei due to the very weak binding and the very extended density distribution.

Study of Survival Probability of Super Heavy Nuclei

The survival probability of super heavy nuclei produced in cold fusion reactions is studied by using the standard Fermi gas level density formula and analyzed with fission and neutron evaporation characteristics predicted in different theoretical models. The level density formula used in this letter suppresses the ratio of neutron emission width to fission width, Гn/Гf. The dependence of Гn/Гf on the saddle point level density parameter and excitation energy is also investigated.

Spin—Polarized States of Nuclear Matter

The equations of state of spin-polarized nuclear matter and pure neutron matter are studied in the framework of the Brueckner–Hartree–Fock theory including a three-body force. The energy per nucleon EA(δ) calculated in the full range of spin polarization for symmetric nuclear matter and pure neutron matter fulfills a parabolic law. In both the cases the spin-symmetry energy is calculated as a function of the baryonic density along with the related quantities such as the magnetic susceptibility and the Landau parameter G0. The main effect of the three-body force is to strongly reduce the degenerate Fermi gas magnetic susceptibility even more than the value with only two-body force. The equation of state is monotonically increasing with the density for all spin-aligned configurations studied here so that no any signature is found for a spontaneous transition to a ferromagnetic state.

Chemical Classification of Space Debris

Space debris, here referring to all non-operating orbital objects, has steadily increased in number so that it has become a potential barrier to the exploration of space. The ever-increasing number of space debris pieces in space has created an increasingly threatening hazard to all on-the-orbit spacecraft, and all future space exploration activities have to be designed and operated with respect to the increasing threat posed by space debris. Generally, space debris is classified as large, medium and small debris pieces based on their sizes. The large debris piece is easily catalogued, but medium to small debris pieces are very difficult to track and also quite different in damage mechanisms from the large ones. In this paper, a scheme of chemical classification of space debris is developed. In our scheme, the first-order classification is employed to divide space debris into two groups: natural micrometeoroids and artificial space debris. The second-order classification is based on their chemical patterns and compositions. The natural micrometeoroids are further divided into three types, namely mafic, metal and phyllosilicate micrometeorites, while the artificial space debris is divided into seven types, which are polymers, non-metal debris, metals and their alloys, oxides, sulphides and their analogs, halides and carbides. Of the latter seven types, some can also be further divided into several sub-types. Chemical classification of space debris is very useful for the study of the chemical damage mechanism of small debris pieces, and also is of great significance in constraining the origin and source of space debris and assessing their impact on spacecraft and human space activities.

Three—Body Force Effects on EOS of Asymmetric Nuclear Matter and Proton Fraction in Neutron Star Matter

The three-body force effects on the equation of state and its iso-spin dependence of asymmetric nuclear matter and on the proton fraction in neutron star matter have been investigated within Brueckner-Hartree-Fock approach by using a microscopic three-body force. It is shown that, even in the presence of the three-body force, the empirical parabolic law of the energy per nucleon vs. isospin asymmetry is fulfilled in the whole asymmetry range and also up to high density. The three-body force provides a strong enhancement of symmetry energy at high density in agreement with relativistic approaches. It also shows that the three-body force leads to a much more rapid increasing of symmetry energy with density in relatively high density region and to a much lower threshold density for the direct URCA process to occur in a neutron star as compared to the predictions adopting only pure two-body force.

A non-perturbation approach in temperature Green function theory

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Three-body Force Effect on Proton Fraction in Neutron Star Matter

The three-body force ( TBF ) effect on the proton fraction in the β-stable neutron star matter has been investigated within the iso-spin dependent Brueckner Hartree-Fock ( BHF ) framework, by adopting the microscopic TBF based on a meson-exchange current model of interaction mediated by the excitation of NN couples and low-lying nucleon resonances The calculated proton fraction vs. baryon density is displayed

Potential Energy Surface in Deformed Di-Nuclear System

In DNS model, a key point is the calculation of PES because it governs the fusion dynamics and thus determines the optimum excitation energy of the compound nucleus and the optimum bombarding energy. Furthermore, it gives the information about the optimum projectile-target combination leading to a certain super-heavy nucleus.

Evaporation Residue Cross-sections of Super-heavy Nuclear Production

To synthesize new superheavy nuclei a better understanding of the physics conception on the production mechanism is very important. Several theoretical models have been developed to describe the reaction dynamical mechanism. Among them Adamian et al.have investigated the reaction mechanism of the superheavy element (SHE) formation in the concept of a dinuclear system (DNS) which is proved to be a powerful tool

Proton and Neutron Mean Free Paths in Asymmetric Nuclear Matter and Effect of Ground State Correlations

Within the isospin-dependent extended Brueckner-Hartree-Fock ( IEBHF ) framework, the proton and neutron mean free paths in isospin asymmetric nuclear matter and their isospin dependence have been investigated. It is found that as increasing the isospin asymmetry, the proton mean free path decreases while the neutron one increases. This implies that the surface of a neutron-rich nuclei near drip-line will be much

Equation of State of Spin-polarized Neutron Matter from BHF Approach

Within the spin-dependent Brueckner-Hatree-Fock framework, the equation of state ( EOS ) of the spin-polarized neutron matter has been investigated by adopting the realistic nucleon-nucleon interaction AV18 supplemented with the microscopic three-body force ( TBF ) based on the meson-exchange current method. The related physical quantities such as spin-symmetry energy, magnetic susceptibility and the Landau param-

Optimal Excitation Energy of Superheavy Compound Nuclei Produced in Heavy Ion Fusion Reactions

So far super heavy elements are synthesized by cold fusion of heavy ions with Pb and Bi targets, or hot fusion reaction using 232Th, 238U and 242>244Pu targets. Further heavier synthesizing could be very difficult. The study of the fusion mechanism will hopefully propose optimal experimental conditions for the formation of the super heavy elements.

Survival Probability of Super Heavy Nuclei

The survival probability of the excited compound nucleus is considered as one of the crucial factors for producing SHE. The competition between the neutron emission and the fission during the de-excitation process is the main mechanism to determine the survival probability. The form of level density formula, the level

Three-body Force Effects on Nuclear Pairing

In the present work, the influence of three-body force(TBF) on the 1S0 pairing in symmetric nuclear matter and pure neutron matter has been investigated. The energy gap is calculated within the standard BCS scheme. The AV18 force is adopted as the two-body realistic nucleon-nucleon interaction. The microscopic three-body force adopted in the present calculations is constructed from a meson-exchange current