Calculation of photoabsorption cross sections in the low-energy region

AbstractQuantitative analysis by x-ray fluorescence and photoelectron and Auger electron analysis can be effectively extended through a precise knowledge of the total aad subshell photoionization cross sections. Light element and intermediate element analysis, as based upon K and L series fluorescence respectively, involve x-ray interactions in the low energy region, Optimized analysis for essentially all the elements by x-ray induced photoelectron and Auger electron spectroscopy involves both x-ray and electron interactions in the low energy region. Unfortunately, theory and measurement for interaction cross sections in this 100-1500 eV region are difficult, particularly for the heavier elements. Nevertheless, recent advances in experimental and computerized-theoretical techniques for the determination of low energy interaction coefficients do permit establishing appreciatly more complete tabulations of cross sections than are currently available in this energy region.In this paper, the types of interaction cross section data that are needed for quantitative x-ray and electron analysis are defined. Such data that are available from experiment and from theory are reviewed and compared. Some newer techniques for the measurement of cross sections are discussed. And finally, new “state of the art” tables are presented for the mass absorption coefficients of all of the elements and of some special laboratory materials. These are tabulated specifically for twenty-six of the most commonly applied characteristic wavelengths in the 8-110 A region and are based upon the best currently available theoretical and experimental data.

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Evaluated Integral Cross Sections of the 3H(t,2n)4He Reaction in the Low-Energy Region Obtained with Regard to Electron Screening

Bulletin of the Russian Academy of Sciences Physics ◽

10.3103/s106287381806031x ◽

2018 ◽

Vol 82 (6) ◽

pp. 626-631 ◽

Cited By ~ 1

Author(s):

S. M. Taova ◽

L. N. Generalov ◽

V. A. Zherebtsov

Keyword(s):

Cross Sections ◽

Energy Region ◽

Low Energy ◽

Electron Screening

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Information, Localization, and Damage in the Stim

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092475 ◽

1976 ◽

Vol 34 ◽

pp. 502-503

Author(s):

Wm. H. Escovitz ◽

T. R. Fox ◽

R. Levi-Setti

Keyword(s):

High Resolution ◽

Radiation Damage ◽

Cross Sections ◽

Energy Region ◽

Figure Of Merit ◽

Low Energy ◽

Empirical Estimate ◽

Scanning Transmission ◽

The Relationship

We present an estimation and evaluation of cross sections relevant to the performance of the scanning transmission ion microscope (STIM). Figure 1 shows the relationship between the total elastic and inelastic cress sections (σe, σi) for protons and electrons at energies important to microscopy. Assuming equal collection efficiencies, the ratio σe/σi is a figure-of-merit for evaluating high resolution information obtainable for a given amount of radiation damage for different microscopes. The ratio σe/σjis calculated for carbon. Since there is no reliable calculation of σifor protons in the low energy region, we obtained an empirical estimate of σiby the following procedure. First, it was assumed that the ratio Ri of dE/dx for protons (experimental2) and dE/dx for electrons (theoretical3) is the same as the ratio of the respective σi:

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Photon induced KΛ production on the proton in the low energy region

International Journal of Modern Physics E ◽

10.1142/s0218301320500512 ◽

2020 ◽

Vol 29 (07) ◽

pp. 2050051

Author(s):

A. Fatima ◽

Z. Ahmad Dar ◽

M. Sajjad Athar ◽

S. K. Singh

Keyword(s):

Cross Sections ◽

Energy Region ◽

Sigma Model ◽

Branching Ratio ◽

Theoretical Models ◽

Current Data ◽

Low Energy ◽

Nonlinear Sigma Model ◽

Nucleon Resonances ◽

Coupling Strengths

The associated photoproduction of [Formula: see text] from the proton in the low energy region is studied using an isobar model in which the nonresonant contributions are obtained from the nonlinear sigma model with chiral SU(3) symmetry which predicts, in a natural way, the contact term with its coupling strength along with the coupling strengths of the various Born terms predicted by the nonlinear sigma model. The present model is an extension of the nonlinear sigma model with chiral SU(2) symmetry, used earlier to study the photo, electro, and neutrino productions of pions. In the resonance sector, the contributions from the well established nucleon resonances ([Formula: see text]) in the [Formula: see text] channel, the hyperon resonances ([Formula: see text]) in the [Formula: see text] channel, and the kaon resonances ([Formula: see text] and [Formula: see text]) in the [Formula: see text] channel having spin [Formula: see text] and mass [Formula: see text][Formula: see text]GeV with a significant branching ratio in [Formula: see text] decay mode, have been considered. The strong and electromagnetic couplings of the [Formula: see text] channel nucleon resonances are taken from experiments while the couplings for the resonances in the [Formula: see text] and [Formula: see text] channels are fitted to reproduce the current data on the associated photoproduction of [Formula: see text] in this energy region. The numerical results are presented for the total and differential cross-sections and are compared with the available experimental data from CLAS and SAPHIR as well as with some of the recent theoretical models.

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