Absolute partial and total ionization cross sections of carbon monoxide with electron collision from 350 eV to 8000 eV

The absolute partial and total cross sections for electron impact ionization of carbon monoxide are reported for electron energies from 350 eV to 8000 eV.The product ions(CO^(+),C^(+),O^(+),CO^(2+),C^(2+),and O^(2+))are measured by employing an ion imaging mass spectrometer and two ion-pair dissociation channels(C^(+)+O^(+)and C^(2+)+O^(+))are identified.The absolute cross sections for producing individual ions and their total,as well as for the ion-pair dissociation channels are obtained by normalizing the data of CO^(+)to that of Ar^(+)from CO-Ar mixture target with a fixed 1:1 ratio.The overall errors are evaluated by considering various kinds of uncertainties.A comprehensive comparison is made with the available data,which shows a good agreement with each other over the energy ranges that are overlapped.This work presents new cross-section data with electron energies above 1000 eV.

Dissociative ionization cross sections of CO_2 at electron impact energy of 5 keV

The dissociative ionization of CO2 induced by 5 keV electrons in two-body and three-body dissociative channels of CO2＋2 and CO3＋2 is identified by the ion-ion coincidence- method using a momentum imaging spectrometer. The partial ionization cross sections （PICSs） of different ionic fragments are measured and the results generally agree with the calculations made by a semi-empirical approach. Furthermore, the PICSs of the dissociative channels are also obtained by carefully considering the detection efficiency of the micro-channel plates and the total transmission efficiency of the time of flight system.

Preliminary Measurement of the K-Shell Ionization Cross Sections of Ti by Positron Impact in the Low Energy Region

Measurements were performed of K-shell ionization cross sections of Ti element by 10～30 keV positron impact using the thick-target method. The effects of multiple scattering of incident positron and from bremsstrahlung photons and annihilation photons with the thick-target method are discussed with the Monte Carlo code PENELOPE. Meanwhile, the Monte Carlo method is also applied to determine the detection efficiencies of X- and γ-ray detectors. Our experimental K-shell ionization cross sections for Ti element are compared with the distorted-wave Born approximation （DWBA） theoretical predictions, and it is found that the agreement of the experimental data and theoretical values is good and this indicates that the experimental method adopted in this study is applicable.

Inner-shell ionization cross sections of atoms by positron impact

The relativistic binary-encounter-Bethe model with Wannier-type threshold law is employed to obtain the inner-shell ionization cross sections of multi-electron atoms(Ni,Cu,Y,Ag,Au,Yb,Ta,and Pb)for positron impact energies from the thresholds up to 105ke V.There is good agreement between the present calculations and the experimental data.The constant in the acceleration term derived from the Wannier law is determined to be 0.2 and 0.5 for the K-and L-shells,respectively.

Calculated cross sections for the single ionization of atoms (N, Cu, As, Se, Sn, Sb, Te, I, Pb) by electron impact

By correcting some primary parameters in the semi-classical Deutsch-Mark （DM） formula, this paper calculates the absolute single electron-impact ionization cross sections of atoms N, Cu, As, Se, Sn, Sb, Te, I and Pb from threshold to 10000 eV. The calculated cross sections are compared with available experimental data and other theoretical results. An excellent agreement was achieved between the calculated and measured cross sections for these atoms over a wide range of impact energies.

MEASUREMENTS OF TOTAL CROSS SECTIONS FOR K－SHELL IONIZATION BY ELECTRON BOMBARDMENT

Cross sections for K-shell ionization have been measured at electron energies of 0.1-0.40 MeV for Cu and Sn, and of 0.30MeV for Ag. The present results have been compared with theoretical calculations and previously reported experimental values.

CORRECTION OF INFLUENCE OF SUBSTRATE ON MEASUREMENT OF INNER SHELL IONIZATION CROSS SECTIONS

The energy spectra of reflected electrons from the substrates of targets have been calculated by the bipartition model of electron transport, the contributions of the inner shen ionization events produced by the reflected electrons from the substrates in the targets to the x-ray counting in a St(Li) detector have been estimated. It has been confirmed that, by such correction to the measured data, the experimental results of inner shell ionization cross sections by electron impact with fine precision may be obtained under the condition of thick substrate.

Identifying influential spreaders in complex networks based on density entropy and community structure

In recent years,exploring the relationship between community structure and node centrality in complex networks has gained significant attention from researchers,given its fundamental theoretical significance and practical implications.To address the impact of network communities on target nodes and effectively identify highly influential nodes with strong propagation capabilities,this paper proposes a novel influential spreaders identification algorithm based on density entropy and community structure(DECS).The proposed method initially integrates a community detection algorithm to obtain the community partition results of the networks.It then comprehensively considers the internal and external density entropies and degree centrality of the target node to evaluate its influence.Experimental validation is conducted on eight networks of varying sizes through susceptible–infected–recovered(SIR)propagation experiments and network static attack experiments.The experimental results demonstrate that the proposed method outperforms five other node centrality methods under the same comparative conditions,particularly in terms of information spreading capability,thereby enhancing the accurate identification of critical nodes in networks.

Positron scattering and ionization of neon atoms—theoretical investigations

Although positron scattering with inert gas atoms has been studied in theory as well as in experiment, there are discrepancies. The present work reports all the major total cross sections of e＋-neon scattering at incident energies above ionization threshold, originating from a complex potential formalism. Elastic and cumulative inelastic scatterings are treated in the complex spherical e＋-atom potential. Our total inelastic cross section includes positronium formation together with ionization and excitation channels in Ne. Because of the Ps formation channel it is difficult to separate out ionization cross sections from the total inelastic cross sections. An approximate method similar to electron-atom scattering has been applied to bifurcate ionization and cumulative excitation cross sections at energies from threshold to 2000 eV. Comparisons of present results with available data are made. An important outcome of this work is the relative contribution of different scattering processes, which we have shown by a bar-chart at the ionization peak.

Production of projectile and target-vacancy in near-symmetric collisions of 60–100 MeV Cu^(9+) ions with thin Zn target

We report studies on both target and projectile K-shell ionization by collisions of Cu9＋ ions on the thin Zn target in the energy range of 60-100 MeV. In this work, the relative ratio for the production of the target to projectile K-vacancy is measured. The result shows that it almost remains stable over this energy range and has good consistency with the predictions by vacancy transfer via the 2po-lscr rotational coupling, which gives experimental evidence for K-vacancy sharing between two partners. Furthermore, the discussion for comparisons between the experimental ionization cross sections and the possible theoretical estimations is presented. These comparisons suggest that the experimental data agree well with those predicted by the Binary-Encounter approximation （BEA） model but are not in good agreement with the modified BEA calculations. It allows us to infer that the direct ionization （and/or excitation） is of importance to initial K-vacancy production before 2po-lso transitions in the present collision condition.