Isoscaling Behavior in ^48,40Ca＋^9Be Collisions at Intermediate Energy Investigated by the HIPSE Model

The fragment production cross sections for 140 Me V/nucleon ^48,40 Ca^＋9 Be reactions are calculated by the heavyion phase space exploration （HIPSE） model. Isoscaling behavior is observed. The isoscaling parameters a and β for both heavy and light fragments from the HIPSE model calculations are in good agreement with the experimental data. It is shown that the potential parameters in the HIPSE model have very little effect on the isoscaling parameters. The effect of the excitation energy and evaporation on the isoscaling behavior is also discussed.     

φElectro-production in Pomeron Exchange Model

Based on the Pomeron exchange model, elastic production of φ meson in electron-proton interaction is investigated with both linear and non-linear Pomeron trajectories. The numerical calculations of the differential cross section for e＋p→e＇ ＋p＋ φ are performed. The theoretical predictions show that the dependence of the differential cross section on virtual photon virtuality, Q^2, is of moderation, the change of the energy scale parameter so causes moderate effect on the differential cross section, and the linear trajectory is a good approximation to non-linearity of the Pomeron trajectory, in particular, at small momentum transfer region ｜t｜≤ 0.2 GeV^2.     

Charged Higgs Pair Production in a General Two Higgs Doublet Model at e^＋e^- and μ^＋μ^- Linear Colliders

In this paper, charged Higgs pair production through l^＋l^- → H^＋ H^-, where l = e or μ, is studied within the framework of a general Two Higgs Doublet Model （2HDM）. The analysis is relevant to a future e^＋e^- or μ^＋ μ^- collider operating at center of mass energy of √s = 500 GeV. Two different scenarios of small and large a values are studied. Here a is the parameter, which diagonMizes the neutral CP-even Higgs boson mass matrix. Within the Minimal Supersymmetric Standard Model （MSSM）, cross section of this process is almost the same at e＋ e- and #＋#- colliders. It is shown that at e^＋e^- eolliders within a general 2HDM, cross section is not sensitive to the mass of neutral Higgs bosons, however, it can acquire large values up to several picobarn at μ^＋μ^- colliders with the presence of heavy neutral Higgs bosons. A scan over Higgs boson mass parameter space is performed to analyze the effect of large masses of neutral Higgs bosons involved in the s-channel propagator and thus in the total cross section of this process.     

Halo Structure of Nucleus ^23Al

The recently measured reaction cross section of ^23Al is analysed in the Glauber model with an optical limit or few-body approach.It is found that the conventional fixed core-plus-nucleon model for halo nuclei is unable to explain the observed abnormally large reaction cross section of ^23Al by any selection of the halo nucleon configurations.The reaction cross section of ^23Al can be described when the core size is enlarged,although the Coulomb barrier lagely hinders the formation of a halo sturcture for proton-rich nuclei.This is consistent with the case in s-d shell neutron-rich nuclei,where an enlarged core was proposed to explain both the reaction cross section and longitudinal momentum distribution data.     

Precise measurement of the e^＋e^- →π^＋π^-（γ） cross section with the initial state radiation method at BABAR

We present a precise BABAR measurement on the cross section of the process e^＋e^- →π^＋π^-（γ） from threshold to an energy of 3 GeV with the initial state radiation （ISR） technique, using 232 fb^-1 of data collected with the BABAR detector at e^＋e^- center-of-mass energies near 10.58 GeV. The ISR luminosity is determined from a study of the leptonic process e^＋e^- →μ^＋μ^-γ（γ）. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the ππ cross section measured from threshold to 1.8 GeV is （514.1± 2.2（stat） ± 3.1（syst）） × 10^-10.     

Rayleigh Scattering for An Electromagnetic Anisotropic Medium Sphere

Based on the scales theory of electromagnetic waves, the analytical expression of electrical fields inside an anisotropic medium sphere is studied. Differential scattering cross section and radar cross section （RCS） for an anisotropic spherical target are presented. The correctness of the obtained results is tested. The simulation results show that the scattering of an anisotropic sphere has the property of a dipole radiation under the condition of Rayleigh scattering. The larger the dielectric constant is, the stronger the dipole scattering is. Anisotropy in magnetism only has an effect on differential RCS. These results provide a theoretical base for the identification of anisotropic targets.     

Isoscaling Behaviour in the Isospin-Dependent Quantum Molecular Dynamics Model

The isoscaling behaviour is investigated in a frame of isospin-dependent quantum molecular dynamics models. The isotopic yields ratio Y2/Y1 for reactions ^48Ca ^48Ca and ^40 Ca ^4oCa at different entrance channels are simulated and presented, the relationship between the isoscaling parameter and the entrance channel is analysed, the results show that a and β reduce with the rise of incident energies and increase with the impact parameter b, which can be attributed to the temperature varying of the pre-fragments in different entrance channels. The relation of a and symmetry-term coefficient Csym reveals that the chemical potential difference △μ is sensitive to thesymmetry-term coefficient Csym, and raises with the increasing Csym.     

Dependence of Isoscaling Parameters on Nucleon-Nucleon Cross Section and Momentum-Dependent Interaction

Inltuences of the isospin dependence of the in-medium nucleon-nucleon cross section and the momentum-dependent interaction （MDI） on the isotope scaling are investigated by using the isospin-dependent quantum molecular dynamics model （IQMD）. The results show that both the isospin dependence of the in-medium nucleon-nucleon cross section and the momentum-dependent interaction affect the isoscaling parameters appreciably and indepen- dently. The inltuence caused by the isospin dependence of two-body collision is relatively larger than that from the MDI in the mean tield. Aiming at exploring the implication of isoscaling behaviour, which the statistical equilibrium in the reaction is reached, the statistical properties in the mass distribution and the kinetic energy distribution of the fragments simulated by IQMD are presented.     

Calculation of Cross Section of Radiative Halo—Neutron Capture by ^12C at Stellar Energy with the Asymptotic Normalization Coefficient Method

The cross section of the direct neutron capture reaction 12C(n,γ)^13C(1/2^ ) is calculated with the asymptotic normalization coefficient method.The result is in good agreement with a recent experiment at low energy,An enormous enhancement of cross section is found for this direct neutron capture in which a p-wave neutron is captured into an 2s1/2 orbit with neutron halo.The possible effect of the neutron halo structure presented in this reaction on the s-precess in astrophysics is discussed in general.     

Probing the medium effect and isospin dependence of the in-medium nucleon--nucleon cross section in heavy ion collisions

Probing in-medium nucleon-nucleon （NN） cross section σ1/NN（α） in heavy ion collisions has been investigated by means of the isospin-dependent quantum molecular dynamics （IQMD） with the isospin- and momentum-dependent interaction （IMDI（T））. It is found that there are the very obvious medium effect and the sensitive isospin-dependence of nuclear stopping R on the in-medium NN cross section α1/NN（α） in the nuclear reactions induced by halo-neutron projectile and the same-mass stable projectile. However, R induced by the neutron-halo projectile is obviously lower than that induced by the corresponding stable projectile. In particular, there is a very obvious dependence of R on the medium effect of σ1/NN（α） in the whole beam energy region for the above two kinds of projectiles. Therefore, the comparison between the results of R＇s in the reactions induced by the neutron-halo projectile and the corresponding same-mass stable projectile is a more favourable probe for extracting the information of σ1/NN（α） because of adding a new judgement.[第一段]     

2-um emission performance of Tm^3＋-Ho^3＋ co-doped tellurite glasses

The emission properties of 2-um region fluorescence of Tm^3＋-Ho^3＋ co-doped tellurite glasses are investigated. Introducing F- ions to the composition of tellurite glasses plays a positive effect on the 2-#m emission. A maximum intensity of 2-um emission is achieved when 1.5-mol% Tm2O3 and 1-mol% Ho203 concentration are doped in the glasses. The emission cross section and gain coefficient of the ^5I8-^5I7 transition of Ho^3＋ are calculated. The emission cross section has a maximum of 1.29×10-20 cm^2 at 2048 nm wavelength. The results indicate that Tm＆3＋-Ho^3＋ co-doped tellurite glasses are suitable for 2-um application.     

Isotope Dependence of Superheavy Nucleus Formation Cross Section

The dynamical process in the superheavy nucleus synthesis is studied on the basis of the two-dimensional Smoluchowski equation. Special attention is paid to the isotope dependence of the cross section for the superheavy nucleus formation by means of making a comparison among the reaction systems of ^54Re＋204pb, ^56Re ＋206Pb, and ^58Fe＋^208Pb. It is found by this comparison that the formation cross section is very sensitive to the conditional saddle-point height and the neutron separation energy of the compound nucleus. Reaction systems with lower height of conditional saddle-point and smaller neutron separation energy are more favourable for the synthesis of the superheavy nucleus.     

A possible experimental observable for the determination of neutron skin thickness

The dependence between neutron skin thickness and neutron abrasion cross section （σnabr） for neutron-rich nuclei is investigated within the framework of the statistical abrasion ablation model. Assuming that the density distributions for proton and neutron are of Fermi-type, and adjusting the diffuseness parameter of neutron density distribution in the droplet model, we find out the good linear correlation between the neutron skin thickness and the abrasion cross section σnabr for neutron-rich nuclei. The uncertainty of neutron skin thickness determined from σnabr is very small. It is suggested that σnabr can be used as a new experimental observable to extract the neutron skin thickness for neutronrich nucleus. The scaling behaviours between neutron skin thickness and σnabr, separately, for isotopes of ^26-35Na, ^44-56Ar, ^48-60Ca, ^67-78Ni are also investigated.     

Cross Section of Heavy Ion Reaction （14.5 MeV/u） ^132Xe ＋ Bi

We investigate the cross section of the heavy ion reaction （14.5 MeV/u） ^132Xe ＋ Bi by using a CR-39 plastic track detector. The target-detector assembly is exposed at UNILAC beam facility of GSI, Germany. After etching under appropriate etching conditions, the detector is scanned for multipronged events produced as a result of interactions of projectile ions with target atoms. The elastic events are separated from binary events and used for the determination of the quarter-point angle. The quarter-point angle obtained is used to determine the total reaction cross section. The total experimental reaction cross section is determined by using statistics of inelastic events of two-pronged and higher multiplicity events. The experimental reaction cross sections determined by using elastic and inelastic data observed in the reaction under study are found to be in good agreement with the theoretically calculated value of reaction cross section using a sharp cutoff model.     

Medium Suppression of In medium Nucleon-Nucleon Cross Sections Predicted with Various Microscopic Calculations

The nucleon-nucleon cross sections in the dense nuclear matter are microscopically calculated by using Dirac- Brueckner-Hartree-Fock （DBHF） approximation with different covariant representations of the T-matrix, i.e., complete pseudo-vector （CPV）, pseudoscalar （PS） and pseudo-vector （PV） choices. Special attention is paid to the discrepancies among the cross sections calculated with these different T-matrix project choices. The results show that the medium suppression of the cross section given by DBHF in the CPV choice is not only smaller than those obtained in both PS and PV choices, but also smaller than the predictions with a nonrelativistic Brueckner-Hartree-Fock （BHF） method including three body force （3BF）. The further analysis reveals that the influence of the different choices on the cross section in the DBHF approximation is mainly determined by the state of smaller total angular momentum due to the medium effect being strongly suppressed in the higher angular momentum.     

Magnetic Field Effect on β^＋ Decay in the Crusts of Accreting Neutron Stars

Based on shell model of nuclei, the influence of a high magnetic field on β^＋ decay in the crusts of accreting neutron stars is analyzed. The magnetic field effect on 54 Mn is discussed. The results show that a weak magnetic field makes little effect on β^＋ decay but a strong magnetic field （B 〉 10^11 G） improves β^＋ decay rates obviously. The conclusion derived will benefit to develop further research on nuclear astrophysics in the future.     

Calculation of Interaction Potentials between Spherical and Deformed Nuclei

The interaction potential for spherical-deformed reaction partners is calculated. The shape, separation and orientation dependence of the interaction potential and fusion cross section of the system ^32S＋^154Sm are investigated within the double-folding model of the deformed nuclei. The effective nucleon-nucleon interaction is taken to be the M3Y-Reid potential. The density is considered for three terms of the expansion using the truncated multipole expansion method, which is a deformed Fermi shape With quadrupole and hexadecapole for the density distribution of ^154Sm. It is found for the interaction potential that the height and the position of barrier strongly depend on the deformations, the orientation angle of the deformed nucleus, and hence produce great effects on fusion cross section. The integrated fusion cross section is in good agreement with the experimental data.     

A Monte Carlo Study of Low-Energy Electron Transport in Liquid Water： Influence of the Rutherford Formula and the Mott Model

Influence of the Rutherford formula and the Mott model on the Monte Carlo simulation of low-energy electron （〈10 keV） transport in liquid water is investigated. One of the features of the constructed Monte Carlo code is the implementation of the new optical-data model from Emfietzoglou et al. in inelastic cross section based on the dielectric response theory. In addition, a novel mean elastic cross section by means of the Mott model is proposed to calculate the electron elastic scattering for high simulation efficiency. The systematical calculations of both the distribution of energy depositions and penetration parameter for low-energy electrons in liquid water are performed by using the Rutherford formula and the Mott model, respectively, for the elastic collisions in the simulations. The calculated results show that the effect of the two models is evident at energies below about 1 keV.