检索结果-南通市图书馆

Chinese Physics B 2024年第4期33卷 459-464页

作者： Taj Wali Khan 黄伟哲王恩亮单旭陈向军 Hefei National Research Center of Physical Sciences at the Microscale and Department of Modern Physics University of Science and Technology of ChinaHefei 230026China

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.

关键词： electron impact ionization cross sections carbon monoxide ion imaging mass spectrometer

Preliminary Measurement of the K-Shell ionization cross sections of Ti by Positron Impact in the Low Energy Region

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2012年第5期14卷 434-437页

作者：田丽霞刘慢天朱敬军安竹王宝义秦秀波 Key Laboratory of Radiation Physics and Technology of Ministry of Education Institute of Nuclear Science and TechnologySichuan University East China Institute of Technology Key Laboratory of Nuclear Analysis Techniques Institute of High Energy PhysicsCAS

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.

关键词： positron impact ionization cross sections thick-target method Monte Carlosimulation

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

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第5期33卷 765-774页

作者：苏湛陈磊艾均郑雨语别娜 School of Optical-Electrical and Computer Engineering University of Shanghai for Science and Technology

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.

关键词： corrigendum electron impact ionization cross sections carbon monoxide

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

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2009年第2期18卷 553-557页

作者：侯育君程新路陈恒杰 Institute of Atomic and Molecular Physics Sichuan University Changchun Institute of Applied Chemistry Chinese Academy of Science

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.

关键词： DM formula ionization cross sections electron-impact

Positron scattering and ionization of neon atoms—theoretical investigations

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第10期19卷 245-250页

作者： Harshit N. Kothari K. N. Joshipura Department of Physics Sardar Patel University Vallabh Vidyanagar-388120 India

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.

关键词： ionization cross sections positron scattering complex potential total cross sections

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

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2016年第3期25卷 169-173页

作者：郭义盼杨治虎杜树斌常宏伟夏清良徐秋梅 Institute of Modern Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Department of Nuclear Physics China Institute of Atomic Energy

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.

关键词： vacancy sharing ionization cross sections Binary-Encounter approximation model