Absolute Differential Cross Sections for Elastic Scattering of Electrons from CO at Intermediate and High Energies

The additivity rule model together with the complex optical model potential correlated by the concept of bonded atoms, which considers the overlapping effect of electron clouds between two atoms in a molecule, is firstly employed to calculate the absolute differential cross sections for electrons scattered by carbon monoxide at intermediate and high energies at the Hartree-Fock level. A comparison of elastic differential cross section results, obtained by using the correlated complex optical model potential, with the available experimental data,shows a significant improvement over the uncorrelated ones. The differential cross sections obtained by using thecorrelated complex optical model potential are in very good agreement with the experimental data. It is shown that the additivity rule model together with the correlated complex optical model potential is suitable for the calculations of the absolute differential cross sections of e-CO scattering.     

Differential, elastic integral and moment transfer cross sections for electron scattering from N2 at intermediate- and high-energies

A complex optical model potential modified by incorporating the concept of bonded atom, with the overlapping effect of electron clouds between two atoms in a molecule taken into consideration, is firstly employed to calculate the differential cross sections, elastic integral cross sections, and moment transfer cross sections for electron scattering from molecular nitrogen over the energy range 300—1000eV by using additivity rule model at Hartree—Fock level. The bonded-atom concept is used in the study of the complex optical model potential composed of static, exchange, correlation polarization and absorption contributions. The calculated quantitative molecular differential cross sections, elastic integral cross sections, and moment transfer cross sections are compared with the experimental and theoretical ones wherever available, and they are found to be in good agreement with each other. It is shown that the additivity rule model together with the complex optical model potential modified by incorporating the concept of bonded atom is completely suitable for the calculations of differential cross section, elastic integral cross section and moment transfer cross section over the intermediate- and high-energy ranges.     

Hadro- and photo-production of η′ in quasi-free proton and neutron processes

The η′ photoproduction process on quasi-free proton and neutron and the reaction NN→ η′NN are investigated within a relativistic effective Lagrangian approach to hadronic interactions. Resonances with spins 1/2 and 3/2 are considered together with the nucleonic and t-channel meson-exchange current contributions. In photoproduction processes, the S11 resonance is found to be responsible for the sharp rise of the cross sections near threshold. In pp → η′pp, it is found that the S11 resonance dominates the total cross section over the entire energy region considered. The spin observables, in particular the beam and target asymmetries, are shown to be very sensitive to the reaction mechanism and will help impose more stringent constraints on the model parameters.     

Effect of Polarization in （e, 2e） Ionization of Argon

The triple differential cross section of the Ar 2p orbital in a highly asymmetric geometry is calculated by using a modified distorted wave Born approximation method. A short-range polarization potential via density-functional theory is included in our calculations. It is shown that polarization potential is particularly important for calculations of the triple differential cross section.     

Electron-Helium Scattering in Free-Free Transitions in a Bichromatic Laser Field

Theoretical calculation of the differential cross section （DCS） for elastic electron-helium scattering in the presence of a bichromatic CO2 laser field is carried out in the first Born approximation with a simple screening electric potential. The two components of the laser field have the frequencies w and 2w, which are out of phase by an arbitrary scale φ. The variations of the differential cross section as a function of the phase angle φ in the domain 0°≤ φ ≤360° are presented. We discuss the influence of the number of photons exchanged on the phase-dependee effect. Moreover, for different scattering angles and incident electron energies, the DCS has outstanding ditferences. These illustrate that the two parameters have important effects on the differential cross section and the screening electric potential is effective.     

Electron scattering by O2 at intermediate and high energies

A complex optical model potential correlated by the concept of bonded atoms, which considers the overlapping effect of electron clouds between two atoms in a molecule, is firstly employed to calculate the absolute differential cross sections, the integrated and momentum transfer cross sections for electrons scattered by O2 at intermediate and high energies by using additivity rule model at Hartree-Fock level. In the study,the complex optical model potential is composed of static, exchange, correlation polarization plus absorption contributions. The quantitative absolute differential cross sections, the integrated and momentum transfer cross sections are obtained. Compared with available experimental data, this approach presents good results. It is shown that the additivity rule model together with the complex optical model potential correlated by the concept of bonded atoms is completely suitable for the calculations of the absolute differential cross sections, the integrated and momentum transfer cross sections.     

A Study of Intermediate Energy Proton-^16O Elastic Scattering Based on the α-Particle Model

In the framework of KMT multiple scattering theory, an optical potential for the intermediate energy proton-160 elastic scattering is presented based on the α particle model of 160. The differential cross sections, the analyzing powers, and the total cross sections of the intermediate energy proton-160 scattering have been calculated by using the obtained optical potential. The main features of the measured angular distributions of the cross section and the analyzing power can be well described. The calculated total cross sections are in good agreement with the experimental data at energies below 0.7 GeV and underestimate the data about 8% at higher energies.     

The effect of dynamical screening on helium （e, 2e） fully differential cross-sections

This paper presents the fully differential cross sections (FDCS) for 102eV electron impact single ionization of helium for both the coplanar and perpendicular plane asymmetric geometries within the framework of dynamically screened three-Coulomb-wave theory. Comparisons are made with the experimental data and those of the three-Coulomb wave function model and second-order distorted-wave Born method. The angular distribution and relative heights of the present FDCS is found to be in very good agreement with the experimental data in the perpendicular plane geometry. It is shown that dynamical screening effects are significant in this geometry. Three-body coupling is expected to be weak in the coplanar geometry, although the precise absolute value of the cross section is still sensitive to the interaction details.     

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.     

Isospin Effect of Coulomb Interaction on Momentum Dissipation in Intermediate Energy Heavy Ion Collisions

We investigate the isospin effect of Coulomb interaction on the momentum dissipation or nuclear stopping in the intermediate energy heavy ion collisions by using the isospin-dependent quantum molecular dynamics model. The calculated results show that the Coulomb interaction induces obviously the reductions of the momentum dissipation. We also find that the variation amplitude of momentum dissipation induced by the Coulomb interaction depends sensitively on the form and strength of symmetry potential. However, the isospin effect of Coulomb interaction on the momentum dissipation is less than that induced by the in-medium nucleon-nucleon cross section.In this case, Coulomb interaction does not change obviously the isospin effect of momentum dissipation induced by the in-medium two-body collision. In particular, the Coulomb interaction is preferable for standing up the isospin effect of in-medium nucleon-nucleon cross section on the momentum dissipation and reducing the isospin effect of symmetry potential on it, which is important for obtaining the feature about the sensitive dependence of momentum dissipation on the in-medium nucleon-nucleon cross section and weakly on the symmetry potential.     

Study on the shadowing effect for optical wave scattering from randomly rough surface

Based on the Kirchhoff approximation for rough surface scattering and by calculating the shadowing function of the rough surface, the formula of the scattering cross section of the dielectric rough surface is presented with consideration of the shadowing effect for the optical wave incidence. It is obtained that in comparison with the conventional Kirchhoff solution, the shadowing effect should not be neglected for the optical wave scattering from the rough surface. The influence of the shadowing effect for different incidence angle, surface root mean square slope, and surface roughness on the scattering cross section is discussed in detail.     

In-medium NN→NΔ cross section and its dependence on effective Lagrange parameters in isospin-asymmetric nuclear matter

The in-medium NN→N△ cross sections and its differential cross sections in isospin asymmetric nuclear medium are investigated in the framework of the one-boson exchange model by including isovector mesons, i.e., δand p mesons. Our results show that the in-medium NN→N△ cross sections are suppressed when the density increases, and the differential cross sections become isotropic with an increase in the density around the △ threshold energy. The isospin splitting on the medium correction factor, R =σ_(NN→N△)~*/σ_(NN→N△)~(free) is observed for different channels of NN→N△, especially around the threshold energy for all the effective Lagrangian parameters. By analyzing the selected effective Lagrangian parameters, our results show that the larger effective mass is, the weaker medium correction R is.     

Electron-Helium Atom Collisions in the Presence of a Bichromatic Laser Field

The differential cross section （DCS） for electron-helium atom collisions in the presence of a bichromatic CO2 laser field is investigated as a function of the scattering angle θ by employing first-Born approximation （FBA） with a simple screening electric potential. We discuss in detail the influence of the scattering geometry, the photon energy and the number of photons exchanged on the DCSs. These illustrate that the three factors have important effects on the elastic scattering and the screening electric potential is effective.     

A theoretical study of halo structure using elastic proton-nucleus scattering

Elastic proton scattering from Be, C, and O isotopes has been investigated in the relativistic impulse approximation （RIA）. In the calculations, the nucleon-nucleus optical potentials are obtained using ground state nuclear matter densities, which are computed using the relativistic mean field model with the FSU parameter set. The scattering observables, including differential cross section, analyzing power, and spin-rotation function, are analyzed. It is found that the scattering observables for O isotopic chains display a clear mass dependence, for instance, the minimum analyzing power shifts to a low scattering angle with increasing mass number. While for the Be isotopic chain, the emergence of a neutron halo in ¹⁴ Be breaks this trend, i.e., the minimum analyzing powers for ¹² Be and ¹⁴ Be are almost the same as each other.     

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.     

Variation of photoabsorption cross section of atomic silver from isolated to condensed conditions

The influence of the local-field on the photoabsorption cross section of the atomic silver is studied in detail by using the Clausius--Mossotti (CM) model and the Onsager model separately. The variations of the photoabsorption cross section of atomic silver with number density and radius of the environmental interaction cavity are studied systematically by using more general expressions for the photoabsorption cross sections, proposed by Sun et al recently. It has proved to be reasonable to model the optical response properties of bulky material by coupling the property of isolated atom with the environmental effects in the present work.     

Absolute differential, elastic integrated and moment transfer cross sections for electron--OCS collisions at intermediate and high energies

A complex optical model potential modified by incorporating the concept of bonded atom, which takes into consideration the overlapping effect of electron clouds between atoms in a molecule, is firstly employed to calculate the absolute differential, elastic integrated and moment transfer cross sections for electron scattering by OCS over the incident energy range from 200 to 1000\,eV using the additivity rule model at Hartree--Fock level. The calculated results are compared with those obtained by experiment and other theories wherever available, and good agreement is obtained over a wide energy range. It is shown that the additivity rule model together with the modified potential is completely suitable for calculating the absolute differential, elastic integrated and moment transfer cross sections of electron scattering by molecules such as OCS.     

Cross sections for charmonia dissociation in collisions with pions, rhos and kaons

We calculate the unpolarized cross sections for dissociation reactions of charmonia in collisions with π, ρ and K in a potential that is derived from QCD. The reactions are governed by the quark-interchange processes. The mesonic quark-antiquark relative-motion wave functions are determined by the central spin-independent terms of the potential. The numerical wave functions and cross sections are parametrized. The difference of transition amplitudes in the prior form and in the post form is explored by deriving and examining the transition amplitudes of the one-gluon-exchange spin-spin term of the potential in the two forms. We find that the post-prior discrepancy in meson-meson elastic scattering that is governed by quark-interchange processes depends on the difference of quark or antiquark masses and of quark-antiquark spatial distributions of the two mesons.     

Electron Correlation in the Final Continuum of Ionization Hydrogen by 150-eV Electron Impact

Electron correlation in triple differential cross sections for ionization of atomic hydrogen by electron impact is analysed for the case of coplanar asymmetric geometry within the framework of the two-potential formulae. Based on the approximations of projectile and faster-electron plane wave, the transition matrix element is analytically expressed to be a product of two factors: the correlation factor of two electrons in the final channel and the structure-scattering factor. The contribution of both the factors to the angular distribution of the triple differential cross section is calculated. The present results are compared with the experimental data and the other theoretical calculations for the incident energy of 150eV.     

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.