Monte Carlo Simulation on Energy Deposition of Low-Energy Electrons in Liquid Water

A Monte Carlo approach to simulate the transport and energy deposition of low energy electrons (E0≤10keV) in liquid water is presented. The elastic scattering of electrons is described by Mott cross section, which is derived from the relativistic wave equation of Dirac. The inelastic scattering model of electrons is based on the dielectric response theory with exchange effect included. A new method of sampling various inelastic scattering events is proposed in the simulation. Using the approach stated, the spatial distribution of inelastic scattering events and energy deposition of electrons in liquid water are computed and the results are compared with other theoretical studies.     

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.     

Electron—impact ionization of Li^＋（ls^2） in the coplanar equal energy—sharing geometry

In this paper, the triple differential cross section for the low-energy electron impact ionization of the Li⁺ ion is considered in the coplanar equal energy-sharing kinematics at an incident energy of 114.083 eV. The emergence of structures in the calculated cross sections is explained in terms of isolated two-body final-state interactions and three-body coupling. The cross section shows two peaks originating from ′classical′ is determined by two-body final-state interactions. In addition, it is demonstrated that the signature of three-body interactions is carried by the magnitude and ratio of these two peaks. The direct and exchange amplitudes are also considered.     

CTMC Investigation of Capture and Ionization Processes in P+H(1s) Collisions in Strong Transverse Magnetic Fields

The collision processes of proton with H(1s) atoms, which is embedded in strong transverse magnetic fields perpendicular to the initial velocity of the projectile, are studied with the classical trajectory Monte Carlo method in the energy range 25 keV /u–2000 keV /u and B ～ 104 T. It is found that the charge exchange cross section is decreased while the ionization cross section is increased significantly. The physics of magnetic field effects is analyzed by the time evolution of electron energy and trajectories, and it is found that these effects are induced by the diamagnetic term in the interaction, continuum electron trapping in the target regions and the Lorentz force. The velocity distributions of the ionized electrons, significantly influenced by the applied fields, are also presented.     

Ionization of Hafnium L—Shell by Electron Impact

A lower-energy electron beam has been directed on to a hafnium thin target with thick backing to investigate the process of L-shell ionization.By using a Si(Li) detector to count the x-rays from the L-subshell,the partial and total production cross sections and mean ionization cross sections versus electron energies have been deduced simultaneously (from threshold to 36keV),The influence of the electron reflected from the backing on measurements has been corrected.The path of the electron multi-scattered in the target itself has also been calculated by using the Monte Carlo programme(EGS4).A comparison with both theoretical predictions is given.     

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.     

L-Shell X-Ray Production Cross Sections of Ta and Tm by Electron Impact near the Threshold Region

We present experimental measurements of L-shell production cross sections Lα, Lβ and Lγ for tantalum and thulium by electron impact at incident electron energies from about one to three times the threshold energy. From the experimental data, the total production cross section and mean ionization cross section are deduced. The influence of electrons reflected from the substrate is corrected by the electron transport bipartition model. Tile measured cross sections are compared with the theoretical predictions.     

Monte Carlo simulation of exposure factor

In this paper, we simulate the exposure factor by a simple model of a free-air ionization chamber with the Monte Carlo programme Geant4. Special emphasis is placed on the discussion of the exposure factor related to parameters of the chamber model. The reason for the variation in exposure factor with incident ray energy is also analysed in terms of reaction cross section for different types of reactions. The obtained results indicate that our simulation is accurate in the calculation of the exposure factor and can serve as a reference in designing air ionization chambers.     

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.     

Influence of the Choice of NN Potential Model on γd→τ~0d Observables near η-Threshold

Influence of the choice of the NN potential model governing the deuteron wave function on the observables for coherent i~0-photoproduction on the deuteron near η-threshold is investigated by using a three-body model for the intermediate ηNN system with separable two-body interactions.Results for unpolarized differential cross section and polarization observables are predicted.It is revealed that the choice of the NN potential model has a visible effect on the differential cross section and most of the polarization observables,especially in the photon energy range of 600-800 MeV and extreme backward pion angles.We find that the deviation among results obtained by using different deuteron wave functions is quite large.The use of the CD-Bonn NN potential for deuteron wave function doubles the differential cross section in this kinematic region.Compared with the experimental data from CLAS collaboration for differential cross section,sizeable discrepancies are found.     

M_(αβ) X-ray production cross sections of Pb and B iby 9–40 keV electron impact

The experimental data of Mαβ X-ray production cross sections for Pb and Bi by 9–40 keV electron impact have been given. Thin films with thick carbon substrates are used in the experiment. The effects of target structure on the Mαβ X-ray production cross sections are corrected by using the Monte Carlo method. The corrected experimental data are compared with calculated cross sections in terms of the distorted-wave Born approximation(DWBA) theory. The measured Mαβ X-ray production cross sections for Pb and Bi are lower than the DWBA calculations. The atomic relaxation parameters used in comparing the DWBA values with experimental results affect the degree of difference.     

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.     

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.     

Ionization for Hf- and W-L-shell by electron impact

Electron-induced Hf-, W-L-shell partial, total production cross sections, mean ionization cross sections and Hf-L_3-shell ionization cross sections (at two energies) have been measured as functions of electron energies (from near threshold to 36keV). The influence of electrons reflected from the backing of the thin targets on measured results was corrected using a model to relate to the electron transport process. The mean paths of electron multi-scattered in the target itself (including forward and backward scattering) were calculated by means of Monte Carlo program (EGS4) and they were used to correct measured results. A comparison with both theoretical predictions was given.     

Electron beam irradiation on novel coronavirus(COVID-19):A Monte-Carlo simulation

The novel coronavirus pneumonia triggered by COVID-19 is now raging the whole world.As a rapid and reliable killing COVID-19 method in industry,electron beam irradiation can interact with virus molecules and destroy their activity.With the unexpected appearance and quickly spreading of the virus,it is urgently necessary to figure out the mechanism of electron beam irradiation on COVID-19.In this study,we establish a virus structure and molecule model based on the detected gene sequence of Wuhan patient,and calculate irradiated electron interaction with virus atoms via a Monte Carlo simulation that track each elastic and inelastic collision of all electrons.The characteristics of irradiation damage on COVID-19,atoms’ionizations and electron energy losses are calculated and analyzed with regions.We simulate the different situations of incident electron energy for evaluating the influence of incident energy on virus damage.It is found that under the major protecting of an envelope protein layer,the inner RNA suffers the minimal damage.The damage for a^100-nm-diameter virus molecule is not always enhanced by irradiation energy monotonicity,for COVID-19,the irradiation electron energy of the strongest energy loss damage is 2 keV.     

Optical Potential Calculations of Positron-H2 Elastic Collision

We report the calculations of the elastic scattering differential cross section for positron H2 collisions with the impact energy below the positronium formation threshold. Our calculation is based on the static-exchange-optical model which has obtained great success in the case of electron scattering. The effective potential used here includes the static and optical potentials. The optical method can completely include the second-order effect arising from real and virtual excitation of target states, which is important for the scattering. A comparison is made with the available theoretical calculations.     

Mαβ X-ray production cross sections of Pb and Bi by 9-40 keV electron impactMαβ X-ray production cross sections of Pb and Bi by 9-40 keV electron impact

The experimental data of Ma/3 X-ray production cross sections for Pb and Bi by 9-40 keV electron impact have been given. Thin films with thick carbon substrates are used in the experiment. The effects of target structure on the Ma/3 X-ray production cross sections are corrected by using the Monte Carlo method. The corrected experimental data are compared with calculated cross sections in terms of the distorted-wave Born approximation （DWBA） theory. The measured Ma/3 X-ray production cross sections for Pb and Bi are lower than the DWBA calculations. The atomic relaxation parameters used in comparing the DWBA values with experimental results affect the degree of difference.     

Positron total cross sections for collisions with N2 and CO2 at 30-3000 eV

The total (elastic plus inelastic) cross sections for positron scattering from N2 and CO2 over the incident energy range from 30 to 3000eV are calculated using the additivity rule model at Hartree-Fock level.A complex optical model potential modified by incorporating the concept of bonded atom, which takes into account the overlapping effect of electron clouds between two atoms in a molecule, is employed to calculate the total cross section of positron-molecule scattering. The calculated total cross sections are in good agreement with those reported by experiments and other theories over a wide energy range.     

Total Cross Sections for Electron Scattering from the Isoelectronic （Z = 14） Molecules （C2H2, CO, HCN and N2） at 100－5000eV

A complex optical model potential correlated by the conception of bonded atom, which considers the overlapping effect of electron clouds between the two atoms in a molecule, is firstly employed to calculate the total cross sections for electron scattering from the isoelectronic (Z = 14) molecules (C2H2, CO, HCN, and N2) at 100-5000 eV using the additivity rule at the Hartree-Fock level. The difference between the bonded atom and the free one is that the overlapping effect of electron clouds of bonded atoms in molecules is considered. The quantitative molecular total cross section results are compared with the experimental data and with the other calculations wherever available and good agreement is obtained above 100 eV. It is shown that the additivity rule along with the complex optical model potential considering the overlapping effect of electron clouds can give the results better than that uncorrelated by it. The correlating calculations are much closer to the experiments than the spherical-complex-optical-potential results in the lower energy region [Phys. Rev. A 45 (1992) 202]. Therefore,considering the overlapping effect of electron clouds in the complex optical potential could be helpful for the better accuracy of the total cross section calculations of electron scattering from molecules.