Optical potential and escape depth for electron scattering at very low energies

A review on the positron scattering from atoms and molecules is presented in this article. The focus on positron scattering studies is on the rise due to their presence in various fields and application of cross section data in such environments. Positron scattering is usually investigated using theoretical approaches that are similar to those for electron scattering, being its anti-particle. However, most experimental or theoretical studies are limited to the investigation of electron and positron scattering from inert gases, single electron systems and simple or symmetric molecules. Optical potential and polarized orbital approaches are the widely used methods for investigating positron scattering from atoms. Close coupling approach has also been used for scattering from atoms, but for lighter targets with low energy projectiles. The theoretical approaches have been quite successful in predicting cross sections and agree reasonably well with experimental measurements. The comparison is generally good for electrons for both elastic and inelastic scatterings cross sections, while spin polarization has been critical due to its sensitive perturbing interaction. Positron scattering cross sections show relatively less features than that of electron scattering. The features of positron impact elastic scattering have been consistent with experiment, while total cross section requires significant improvement. For scattering from molecules, utilization of both spherical complex optical potential and R-matrix methods have proved to be efficient in predicting cross sections in their respective energy ranges. The results obtained shows reasonable comparison with most of the existing data, wherever available. In the present article we illustrate these findings with a list of comprehensive references to data sources, albeit not exhaustive.

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SURFACE SENSITIVITY OF VERY LOW ENERGY ELECTRONS

Surface Review and Letters ◽

10.1142/s0218625x99000603 ◽

1999 ◽

Vol 06 (05) ◽

pp. 631-633 ◽

Cited By ~ 4

Author(s):

I. BARTOŠ ◽

W. SCHATTKE

Keyword(s):

Density Functional ◽

Local Density ◽

Quantitative Description ◽

Low Energy ◽

Imaginary Component ◽

Functional Formalism ◽

Self Energy ◽

Surface Sensitivity ◽

Escape Depth ◽

Low Energies

The surface sensitivity of electron diffraction and of electron spectroscopies is determined by the imaginary component of the electron self-energy. In crystals, the energy and direction dependence of the electron attenuation and of the escape depth should be taken into account at very low energies. Strong anisotropy of the electron attenuation has been obtained around 20 eV from peak shapes in VLEED intensity profiles from (111) transition metal surfaces. Extension of the local density approximation in the density functional formalism provides quantitative description of the electron self-energy. The one-step model of angular resolved photoemission incorporating the self-energy predicts a strong energy and angle dependence of the escape depth of low energy photoelectrons emitted from GaAs(110).

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Nuclear Rms charge radii from relative electron scattering measurements at low energies

The European Physical Journal A ◽

10.1007/bf01391614 ◽

1973 ◽

Vol 265 (4) ◽

pp. 401-403 ◽

Cited By ~ 55

Author(s):

G. Fey ◽

H. Frank ◽

W. Sch�tz ◽

H. Theissen

Keyword(s):

Electron Scattering ◽

Charge Radii ◽

Scattering Measurements ◽

Low Energies ◽

Nuclear Rms Charge Radii ◽

Relative Electron

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Search for anomalous behavior in the real n-208Pb optical potential at low energies

Journal of Physics G Nuclear and Particle Physics ◽

10.1088/0954-3899/15/9/001 ◽

1989 ◽

Vol 15 (9) ◽

pp. L179-L184 ◽

Cited By ~ 4

Author(s):

J Barnes ◽

R E Shamu

Keyword(s):

Optical Potential ◽

Anomalous Behavior ◽

The Real ◽

Low Energies

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Light WIMP Searches Involving Electron Scattering

Advances in High Energy Physics ◽

10.1155/2018/6257198 ◽

2018 ◽

Vol 2018 ◽

pp. 1-14 ◽

Cited By ~ 5

Author(s):

J. D. Vergados ◽

Ch. C. Moustakidis ◽

Yeuk-Kwan E. Cheung ◽

H. Ejiri ◽

Yeongduk Kim ◽

...

Keyword(s):

Dark Matter ◽

Cross Section ◽

Electron Scattering ◽

Mass Range ◽

Bound State ◽

Particle Model ◽

Electron Mass ◽

Bound State Wave Function ◽

Low Energies ◽

The Cross

In the present work we examine the possibility of detecting electrons in light dark matter searches. These detectors are considered to be the most appropriate for detecting dark matter particles with a mass in the MeV region. We analyze theoretically some key issues involved in such detection. More specifically we consider a particle model involving WIMPs interacting with fermions via Z-exchange. We find that for WIMPs with mass in the electron mass range the cross section for WIMP-atomic electron scattering is affected by the electron binding. For WIMPs more than 20 times heavier than the electron, the binding affects the kinematics very little. As a result, many electrons can be ejected with energy which increases linearly with the WIMP mass, but the cross section is somewhat reduced depending on the bound state wave function employed. On the other hand for lighter WIMPs, the effect of binding is dramatic. More specifically at most 10 electrons, namely, those with binding energy below 10 eV, become available even in the case of WIMPs with a mass as large as 20 times the electron mass. Even fewer electrons contribute if the WIMPs are lighter. The cross section is, however, substantially enhanced by the Fermi function corrections, which become more important at low energies of the outgoing electrons. Thus events of 0.5–2.5 per kg-y become possible.

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