Discrepancy Between Theory and Experiments in Muonic X Rays—A Critical Discussion

1974 ◽  
Vol 52 (20) ◽  
pp. 2037-2059 ◽  
Author(s):  
P. J. S. Watson ◽  
M. K. Sundaresan
Keyword(s):  
Standard Deviation ◽  
Vacuum Polarization ◽  
Finite Size ◽  
Critical Discussion ◽  
Electron Screening ◽  
X Rays ◽  
X Ray ◽  
Muonic Atoms ◽  
Theory And Experiments

The discrepancy between theoretical and experimental X-ray energies in muonic atoms is reviewed. We give brief descriptions of all the known corrections, such as finite size, vacuum polarization and electron screening, and attempt to estimate the theoretical errors. The discrepancy is found to remain at the two standard deviation level in eight transitions, and we offer some speculations on the resolution of the problem.

Test of electron screening and vacuum polarization in heavy muonic atoms

1976 ◽  
Vol 278 (2) ◽  
pp. 109-116 ◽  
Author(s):  
J. L. Vuilleumier ◽  
W. Dey ◽  
R. Engfer ◽  
H. Schneuwly ◽  
H. K. Walter ◽  
...  
Keyword(s):  
Vacuum Polarization ◽  
Electron Screening ◽  
Muonic Atoms

Stepped Diffractor for Point Focusing of Monochromatic X RAYS

1990 ◽  
Vol 48 (2) ◽  
pp. 114-115
Author(s):  
David B. Wittry ◽  
Songquan Sun
Keyword(s):  
Single Crystal ◽  
Finite Size ◽  
Physical Basis ◽  
Design Parameters ◽  
Bulk Single Crystal ◽  
X Rays ◽  
Rocking Curve ◽  
X Ray ◽  
Monomolecular Films ◽  
Stepped Surface

Point focusing x-ray diffractors can be obtained by a geometry that corresponds to rotating the Johansson geometry about a line joining the source and image points. Methods by which such a diffractor can be made from bulk single crystal materials have been previously described. In the present paper, we consider the design of a diffractor with a stepped surface that could utilize layered diffracting materials such as multiple monomolecular films or layered synthetic microstructure (LSM). First we consider the effect of the diffractor material's rocking curve on the performance in focusing diffractors. Then we consider limitations on the focusing that arise from the width of the rocking curve and the finite size of the steps, and we give an example of the design parameters of a point focusing diffractor with stepped surface.Effect of The Rocking Curve. Width For diffractors used in focusing applications, it is important to know the physical basis for the rocking curve in order to determine whether the width of the rocking curve will affect the angle of diffraction.

Critical discussion of the vacuum polarization measurements in muonic atoms

1974 ◽  
Vol 88 (2) ◽  
pp. 419-453 ◽  
Author(s):  
Johann Rafelski ◽  
Berndt Müller ◽  
Gerhard Soff ◽  
Walter Greiner
Keyword(s):  
Vacuum Polarization ◽  
Critical Discussion ◽  
Polarization Measurements ◽  
Muonic Atoms

Notizen:Values for the Electron Screening in Muonic Atoms for all Z

1975 ◽  
Vol 30 (10) ◽  
pp. 1328-1329 ◽  
Author(s):  
B. Fricke ◽  
V. L. Telegdi
Keyword(s):  
Electron Screening ◽  
X Ray ◽  
Muonic Atoms ◽  
Hartree Fock

Abstract The electron screening correction in the X-ray transitions in muonic atoms is calculated within a relativistic SCF Hartree-Fock procedure for many transitions and all Z.

White-Light Coronal Structures: Streamers and CMEs

1994 ◽  
Vol 144 ◽  
pp. 82
Author(s):  
E. Hildner
Keyword(s):  
Emission Line ◽  
Electron Density ◽  
White Light ◽  
Coronal Mass Ejections ◽  
X Rays ◽  
Solar Cycles ◽  
Temperature Function ◽  
X Ray ◽  
Eclipse Observations ◽  
Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

Chemical Species Identification in an SEM by Changes in Emitted X-Ray Energies

1974 ◽  
Vol 32 ◽  
pp. 570-571
Author(s):  
R. H. Duff
Keyword(s):  
Species Identification ◽  
Valence Electron ◽  
Chemical Species ◽  
X Rays ◽  
Chemical Bonds ◽  
Small Shift ◽  
X Ray ◽  
Electron Transitions ◽  
Peak Energy ◽  
Chemical Combination

A material irradiated with electrons emits x-rays having energies characteristic of the elements present. Chemical combination between elements results in a small shift of the peak energies of these characteristic x-rays because chemical bonds between different elements have different energies. The energy differences of the characteristic x-rays resulting from valence electron transitions can be used to identify the chemical species present and to obtain information about the chemical bond itself. Although these peak-energy shifts have been well known for a number of years, their use for chemical-species identification in small volumes of material was not realized until the development of the electron microprobe.

Influence of X-Ray Induced Fluorescence on Energy Dispersive X-Ray Analysis of Thin Foils

1977 ◽  
Vol 35 ◽  
pp. 328-329
Author(s):  
E. A. Kenik ◽  
J. Bentley
Keyword(s):  
Thin Foil ◽  
Electron Excitation ◽  
Simple Approach ◽  
Foil Thickness ◽  
X Rays ◽  
X Ray ◽  
Hole Spectrum ◽  
Illumination System ◽  
Thin Foils ◽  
Intensity Ratios

Cliff and Lorimer (1) have proposed a simple approach to thin foil x-ray analy sis based on the ratio of x-ray peak intensities. However, there are several experimental pitfalls which must be recognized in obtaining the desired x-ray intensities. Undesirable x-ray induced fluorescence of the specimen can result from various mechanisms and leads to x-ray intensities not characteristic of electron excitation and further results in incorrect intensity ratios.In measuring the x-ray intensity ratio for NiAl as a function of foil thickness, Zaluzec and Fraser (2) found the ratio was not constant for thicknesses where absorption could be neglected. They demonstrated that this effect originated from x-ray induced fluorescence by blocking the beam with lead foil. The primary x-rays arise in the illumination system and result in varying intensity ratios and a finite x-ray spectrum even when the specimen is not intercepting the electron beam, an ‘in-hole’ spectrum. We have developed a second technique for detecting x-ray induced fluorescence based on the magnitude of the ‘in-hole’ spectrum with different filament emission currents and condenser apertures.

X-ray micro tomography in the scanning electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 106-107 ◽  
Author(s):  
W. Brünger
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Target Surface ◽  
The Body ◽  
X Rays ◽  
Cross Sectional ◽  
X Ray ◽  
Micro Tomography ◽  
Scanning Electron

Reconstructive tomography is a new technique in diagnostic radiology for imaging cross-sectional planes of the human body /1/. A collimated beam of X-rays is scanned through a thin slice of the body and the transmitted intensity is recorded by a detector giving a linear shadow graph or projection (see fig. 1). Many of these projections at different angles are used to reconstruct the body-layer, usually with the aid of a computer. The picture element size of present tomographic scanners is approximately 1.1 mm2.Micro tomography can be realized using the very fine X-ray source generated by the focused electron beam of a scanning electron microscope (see fig. 2). The translation of the X-ray source is done by a line scan of the electron beam on a polished target surface /2/. Projections at different angles are produced by rotating the object.During the registration of a single scan the electron beam is deflected in one direction only, while both deflections are operating in the display tube.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

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