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An application of the coupled-channels optical method is given for the energy-dependent phenomena of positron-hydrogen resonances below the n=2 excitation threshold. The equivalent local optical potential is used to account for the target polarization and positronium formation. The calculation includes 9 explicitly physical coupled channels. The lowest S-wave resonance energy position and new resonances are found. Angular dependence of the cross section in the resonance region are investigated. 相似文献
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Positron scattering with atomic lithium is investigated by using a coupled-channel optical method.The ionization continuum and positronium formation channels are taken into account via a complex equivalent-local optical potential.The positronium formation cross sections and the ionization cross sections,as well as the total scattering cross sections,are reported at energies above 3 eV and compared with available experimental and theoretical data. 相似文献
4.
A new calculation for the total cross section of positron-sodium scattering is performed in an energy range down to a few tenths of one electron volt using the coupled-channel optical method.The ionization continuum and the positronium formation channels are included via an equivalent-local complex potential.The role played by the break-up and rearrangement processes in the low energy positron-sodium scattering is also investigated.The total scattering cross section is reported and compared with the available theoretical and experimental data. 相似文献
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Coupled-channels optical calculations for total and resonance excitation integral cross sections for electron scattering on the metastable level 2^1,3S of helium are presented. The results are in agreement with other theoretical and experimental data. 相似文献
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A new calculation for the total cross section of positron-sodium scattering is performed in an energy range down to a few tenths of one electron volt using the coupled-channel optical method. The ionization continuum and the positronium formation channels are included via an equivalent-local complex potential. The role played by the break-up and rearrangement processes in the low energy positron-sodium scattering is also investigated. The total scattering cross section is reported and compared with the available theoretical and experimental data. 相似文献
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Investigations of resonances and threshold behaviors in positron-helium scattering have been made using the momentum-space coupled-channels optical method.The positronium formation channels are considered via an equivalent-local complex potential.The s-wave resonances and the Wigner cusp feature at the positronium(n = 1) formation threshold are compared with the previous reports.The p-and the d-wave resonances and a Wigner cusp feature at the positronium(n = 2) formation threshold are reported for the first time. 相似文献
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Elastic and inelastic positron--helium scatterings have
been investigated with the coupled-channel optical method (CCO).
Ionization continuum and positronium formation channels are included
via a complex equivalent-local optical potential. Calculations are
reported of cross sections of elastic scattering, total excitation
and n=2, 3, and 4 excitations of ground-state helium for
incident energies from 30~eV to 400~eV. The present calculation
shows that the ionization and Ps-formation channels significantly
affect the cross sections of elastic and inelastic
positron--helium scatterings. 相似文献
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The electron-impact ionization of lithium-like ions C3+,N4+,O5+,Ne7+,and Fe23+is studied using a combination of two-potential distorted-wave and R-matrix methods with a relativistic correction.Total cross sections are computed for incident energies from 1 to 10 times of ionization energy and better agreements with the experimental results are obtained in comparison with the theoretical data available.It is found that the indirect ionization processes become significant for the incident energy larger than about four times of the ionization energy.Contributions from the exchange effects along the isoelectronic sequence are also discussed and found to be important.The present method can be used to obtain systematic ionization cross sections for highly charged ions across a wide incident energy range. 相似文献
10.
An approximation formula is developed to determine the tune-out wavelengths for the ground states of the alkalinemetal atoms lithium,sodium and cesium from the existing relativistic reduced matrix elements and experimental energies.The first longest tune-out wavelengths for Li,Na,and Cs are 670.971 nm,589.557 nm,and 880.237 nm,respectively.This is in good agreement with the previous high precise results of 670.971626 nm,589.5565 nm,and 880.25 nm from the relativistic all-order many-body perturbation theory(RMBPT) calculation[Phys.Rev.A 84 043401(2011)]. 相似文献