Peaks in the 20–40 keV region of Si(Li) X-ray spectra exhibit pronounced low-energy tailing due to Compton scattering of X-rays en route to the detector. An analytic description of this tailing is proposed and tested...
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Peaks in the 20–40 keV region of Si(Li) X-ray spectra exhibit pronounced low-energy tailing due to Compton scattering of X-rays en route to the detector. An analytic description of this tailing is proposed and tested using proton-induced X-rays from thick targets. In the PIXE context this provides more accurate extraction of peak intensity and a better description of the matrix background.
Various semi-empirical schemes for generating x-ray attenuation coefficients, μ/ρ, devised primarily for use in electron probe microanalysis, are considered for application in the PIXE analysis of thick specimens wh...
Various semi-empirical schemes for generating x-ray attenuation coefficients, μ/ρ, devised primarily for use in electron probe microanalysis, are considered for application in the PIXE analysis of thick specimens where the relevant x-ray energy region is 1–40 keV. Using selected high-accuracy experimental data, it is shown that current theoretical values of μ/ρ agree better with the data than do the various schemes. The errors transmitted into PIXE analysis by use of the theoretical values are estimated, and a new parameterization of these values suitable for microcomputer use is justified and tested.
An exact but computationally economical treatment of secondary fluorescence in PIXE is presented. A major difference from previous treatments is the use of Subshell photoelectric absorption cross sections as opposed t...
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An exact but computationally economical treatment of secondary fluorescence in PIXE is presented. A major difference from previous treatments is the use of Subshell photoelectric absorption cross sections as opposed to total cross sections and absorption edge jump ratios. Numerical comparisons show significant predictive differences relative to previous work and some simple experimental tests are described. The first calculations to date of tertiary fluorescence enhancement are presented and this effect is shown to be small.
A differential method for measuring the thickness of aluminum foils used as X-ray absorbers in thick-target PIXE analysis is described. It involves the change in K β K α X-ray intensity resulting from transmission t...
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A differential method for measuring the thickness of aluminum foils used as X-ray absorbers in thick-target PIXE analysis is described. It involves the change in K β K α X-ray intensity resulting from transmission through the foil and provides better acc than direct X-ray attenuation measurements.
The first full account of the Guelph software for fitting PIXE spectra and deriving elemental concentrations is presented. The entire data base has been updated since the program was first reported. Some of the less s...
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The first full account of the Guelph software for fitting PIXE spectra and deriving elemental concentrations is presented. The entire data base has been updated since the program was first reported. Some of the less standard procedures used are discussed in detail; these include the approach to error estimation, the ability to define an element in a thick specimen as a bulk or surface constituent, the ability to redefine the principal line of an element's X-ray spectrum and safeguards against premature elimination from the fit of elements having low concentration. In addition to peak areas, element concentrations and corresponding errors, the program provides limits of detection and a measure of the depth analysed for each element.
Published theoretical L x-ray emission rates based upon a fixed atomic potential cover the atomic number range Z = 4 to 94. However, the presumably more accurate calculations employing different initial- and final-sta...
Published theoretical L x-ray emission rates based upon a fixed atomic potential cover the atomic number range Z = 4 to 94. However, the presumably more accurate calculations employing different initial- and final-state potentials have been done for only 21 values of Z . The ratio of these two rates for each electric dipole transition as a function of Z is fitted using polynomials in piece-wise fashion. The fixed-potential emission rates are then renormalized by these interpolated ratios to provide equivalent two-potential rates. The errors incurred are generally under 0.2%.
Vacuum-ultraviolet continuous emission spectra have been acquired from dense, cold helium gas in the pressure of solid hydrogen during excitation by a 6.5-MeV proton beam. The emission has been identified as the D2Σ+...
Vacuum-ultraviolet continuous emission spectra have been acquired from dense, cold helium gas in the pressure of solid hydrogen during excitation by a 6.5-MeV proton beam. The emission has been identified as the D2Σ+→X Σ+2 radiative dissociation of HeH, based on theoretical potential curves and the qualitative similarities of the continuum to discrete bands previously observed with this experimental technique.
There is yet to be a complete quantum mechanical version of the Fokker-Feynman model for many-particle systems with interactions of electromagnetic origin, because the corresponding Lagrangian is of infinite order. It...
A solution is presented for the outstanding problem of formulating a classical relativistic dynamics for many-particle systems via a Lagrangian. The Fokker-Wheeler-Feynman approach is both modified and generalized to ...
We study the possibility of making precision measurements of W-boson properties with an e-γ collider. We find that the measurements are comparable in sensitivity to W-pair production measurements to be made at the LE...
We study the possibility of making precision measurements of W-boson properties with an e-γ collider. We find that the measurements are comparable in sensitivity to W-pair production measurements to be made at the LEPII e + e − collider. In addition this process will be able to measure the W-photon anomalous magnetic moment, κ γ , independently of the W-Z 0 anomalous magnetic moment, κ Z 0 . This process is potentially a goldmine of W-boson physics and we strongly encourage that serious thought be given to the possibility of building such a collider.
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