Inelastic scattering of slow positrons by helium, neon, and argon atoms

1982 ◽  
Vol 60 (4) ◽  
pp. 584-590 ◽  
Author(s):  
P. G. Coleman ◽  
J. T. Hutton ◽  
D. R. Cook ◽  
C. A. Chandler
Keyword(s):  
Energy Loss ◽  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Time Of Flight ◽  
Angular Distributions ◽  
Atomic Excitation ◽  
Helium Neon

Measurements of the excitation and ionization of helium, neon, and argon by positrons of energies between threshold and 50 eV, utilising time-of-flight energy loss spectrometry, are reported. Scattering into forward angles up to 60° is observed and the measurements suggest that sharp forward lobes exist in the angular distributions of positrons scattered following atomic excitation. Multiple scattering corrections to the measurements are described. Comparison is made with the inelastic scattering of electrons by the same atoms, and connections drawn between the present results and those of the recent complementary studies of Griffith et al. and Charlton et al.

scholarly journals Influence of nuclear multiple scattering on axially channeled protons in a bent crystal

2018 ◽  
Vol 33 (2) ◽  
pp. 195-200
Author(s):  
Nace Stojanov ◽  
Srdjan Petrovic ◽  
Dragan Jakimovski
Keyword(s):  
Energy Loss ◽  
Multiple Scattering ◽  
Transverse Energy ◽  
Equations Of Motion ◽  
Simulation Method ◽  
Transverse Plane ◽  
Angular Distributions ◽  
Crystal Thickness ◽  
Bent Crystal ◽  
Axial Channeling

The influence of nuclear multiple scattering on axially channeled protons with an energy of 7 TeV through a bent <100> Si crystal, is presented in this paper. The aims of the investigation are the processes correlated to the axial channeling, such as dechanneling, angular distributions and energy loss distribution. The data for these processes are generated via the numerical solution of the proton equations of motion in the transverse plane and the computer simulation method. In the simulations, the crystal thickness is varied from 1 to 5 mm while the bending angle is varied from 0 to 20 mrad. The increasing of the transverse energy of axially channeled protons is due to its multiple scattering by atomic strings and the bending dechanneling mechanism. The analysis of the generated data shows that in the cases we are considering, the dechanneling function, the energy loss spectra, and the angular distributions do not undergo to any significant changes when the effect of nuclear multiple scattering is included in the ion-atom interactions.

scholarly journals The large angle scattering of electrons in gases.—II

1932 ◽  
Vol 138 (835) ◽  
pp. 469-478 ◽  
Keyword(s):  
Elastic Scattering ◽  
Energy Loss ◽  
Inelastic Scattering ◽  
Large Angle ◽  
Angular Distributions ◽  
Mercury Vapour ◽  
Discrete Energy ◽  
Elastic And Inelastic Scattering ◽  
Angle Scattering ◽  
Large Angle Scattering

The results of the investigation of the angular distributions of electrons scattered elastically and inelastically in helium, argon, and mercury vapour have been described in a previous paper. It was found that the inelastic angular distributions in mercury vapour and argon exhibited diffraction maxima and minima similar to those which appeared in the elastic angular distributions. Recently Tate and Palmer have investigated the elastic scattering in mercury vapour for angles of scattering between 5° and 125°, and the inelastic scattering (corresponding to a discrete energy loss) between 5° and 55°. Hughes and McMillen have measured the angular distributions of the elastic and inelastic scattering in hydrogen between 40° and 165°, and the elastic scattering in helium between 15° and 150°. These papers are also concerned with the large angle scattering of those electrons which make ionising collisions.

Practical Aspects of Neutron Scattering

2020 ◽  
pp. 343-404
Author(s):  
Andrew T. Boothroyd
Keyword(s):  
Inelastic Scattering ◽  
Neutron Scattering ◽  
Multiple Scattering ◽  
Time Of Flight ◽  
Scattering Data ◽  
Data Normalization ◽  
Polarization Analysis ◽  
Ewald Sphere ◽  
Anisotropic Displacement Parameters ◽  
Counting Statistics

In this chapter, aspects of the planning and optimization of a neutron scattering experiment are covered, including attenuation, multiple scattering, data normalization, counting statistics, resolution, corrections for polarization analysis, and spurions. Practical aspects of diffraction experiments are described, including instrumentation, Rietveld refinement, anisotropic displacement parameters, the Ewald sphere construction, Lorentz factors, extinction and multiple scattering. Practical aspects of spectroscopy are also described, including triple-axis, time-of-flight and backscattering spectrometers, direct and indirect geometry, and some specific points arising in time-of flight inelastic scattering.

Energy-loss effects in multiple-scattering angular distributions of ions in matter

1994 ◽  
Vol 49 (4) ◽  
pp. 2690-2695 ◽  
Author(s):  
Jorge E. Valdés ◽  
Néstor R. Arista
Keyword(s):  
Energy Loss ◽  
Multiple Scattering ◽  
Angular Distributions

Analysis of STEM micrographs of thick objects

1978 ◽  
Vol 36 (2) ◽  
pp. 106-107
Author(s):  
S. Golladay
Keyword(s):  
Inelastic Scattering ◽  
Multiple Scattering ◽  
Mass Distribution ◽  
Cross Sections ◽  
Phase Contrast ◽  
Image Point ◽  
Contrast Effects ◽  
Total Cross Sections ◽  
Elastic And Inelastic Scattering

The theory of multiple scattering has been worked out by Groves and comparisons have been made between predicted and observed signals for thick specimens observed in a STEM under conditions where phase contrast effects are unimportant. Independent measurements of the collection efficiencies of the two STEM detectors, calculations of the ratio σe/σi = R, where σe, σi are the total cross sections for elastic and inelastic scattering respectively, and a model of the unknown mass distribution are needed for these comparisons. In this paper an extension of this work will be described which allows the determination of the required efficiencies, R, and the unknown mass distribution from the data without additional measurements or models. Essential to the analysis is the fact that in a STEM two or more signal measurements can be made simultaneously at each image point.

Background Fitting in the Low-Loss Region of Electron Energy Loss Spectra

1990 ◽  
Vol 48 (2) ◽  
pp. 56-57
Author(s):  
C P Scott ◽  
A J Craven ◽  
C J Gilmore ◽  
A W Bowen
Keyword(s):  
Energy Loss ◽  
Multiple Scattering ◽  
Simple Form ◽  
Single Scattering ◽  
Low Loss ◽  
Characteristic Energy ◽  
Normal Method ◽  
Fitting In ◽  
Electron Energy Loss ◽  
Electron Energy Loss Spectra

The normal method of background subtraction in quantitative EELS analysis involves fitting an expression of the form I=AE-r to an energy window preceding the edge of interest; E is energy loss, A and r are fitting parameters. The calculated fit is then extrapolated under the edge, allowing the required signal to be extracted. In the case where the characteristic energy loss is small (E < 100eV), the background does not approximate to this simple form. One cause of this is multiple scattering. Even if the effects of multiple scattering are removed by deconvolution, it is not clear that the background from the recovered single scattering distribution follows this simple form, and, in any case, deconvolution can introduce artefacts.The above difficulties are particularly severe in the case of Al-Li alloys, where the Li K edge at ~52eV overlaps the Al L2,3 edge at ~72eV, and sharp plasmon peaks occur at intervals of ~15eV in the low loss region. An alternative background fitting technique, based on the work of Zanchi et al, has been tested on spectra taken from pure Al films, with a view to extending the analysis to Al-Li alloys.

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