Influence of Tilt Angle on Hole Count and Secondary Fluorescence in x-ray Microanalysis

1990 ◽  
Vol 48 (2) ◽  
pp. 462-463
Author(s):  
E. A. Kenik ◽  
J. Bentley
Keyword(s):  
Tilt Angle ◽  
High Energy ◽  
Primary Electron ◽  
Objective Lens ◽  
X Rays ◽  
Bremsstrahlung Radiation ◽  
X Ray ◽  
Backscattered Electrons ◽  
The Magnetic Field ◽  
Secondary Fluorescence

The spatial resolution and accuracy of X-ray microanalysis in an analytical electron microscope (AEM) are limited by a variety of factors, two of which are the hole count and secondary fluorescence. The hole count arises from uncollimated radiation, either electrons or X rays, which excites areas of the specimen other than that excited by the primary electron beam. This can result in X-ray generation even when the probe does not hit the specimen; hence the name hole count. Secondary fluorescence deals with X-ray generation resulting from radiation produced by the interaction of the incident probe with the specimen. This radiation may be either backscattered electrons spiraling in the magnetic field of the objective lens or high energy X rays, particularly forward-peaked bremsstrahlung radiation. As the interaction of both the uncollimated radiation and the secondary radiation with the specimen can be influenced by the tilt angle of the specimen, the variation of the hole count and secondary fluorescence with specimen tilt was investigated.

scholarly journals Progress in HAXPES performance combining full-field k-imaging with time-of-flight recording

2019 ◽  
Vol 26 (6) ◽  
pp. 1996-2012 ◽  
Author(s):  
K. Medjanik ◽  
S. V. Babenkov ◽  
S. Chernov ◽  
D. Vasilyev ◽  
B. Schönhense ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Time Of Flight ◽  
High Energy ◽  
Objective Lens ◽  
X Rays ◽  
Full Field ◽  
X Ray ◽  
Alternative Approach ◽  
Field Imaging ◽  
Phase Differences

An alternative approach to hard-X-ray photoelectron spectroscopy (HAXPES) has been established. The instrumental key feature is an increase of the dimensionality of the recording scheme from 2D to 3D. A high-energy momentum microscope detects electrons with initial kinetic energies up to 8 keV with a k-resolution of 0.025 Å−1, equivalent to an angular resolution of 0.034°. A special objective lens with k-space acceptance up to 25 Å−1 allows for simultaneous full-field imaging of many Brillouin zones. Combined with time-of-flight (ToF) parallel energy recording this yields maximum parallelization. Thanks to the high brilliance (1013 hν s−1 in a spot of <20 µm diameter) of beamline P22 at PETRA III (Hamburg, Germany), the microscope set a benchmark in HAXPES recording speed, i.e. several million counts per second for core-level signals and one million for d-bands of transition metals. The concept of tomographic k-space mapping established using soft X-rays works equally well in the hard X-ray range. Sharp valence band k-patterns of Re, collected at an excitation energy of 6 keV, correspond to direct transitions to the 28th repeated Brillouin zone. Measured total energy resolutions (photon bandwidth plus ToF-resolution) are 62 meV and 180 meV FWHM at 5.977 keV for monochromator crystals Si(333) and Si(311) and 450 meV at 4.0 keV for Si(111). Hard X-ray photoelectron diffraction (hXPD) patterns with rich fine structure are recorded within minutes. The short photoelectron wavelength (10% of the interatomic distance) `amplifies' phase differences, making full-field hXPD a sensitive structural tool.

Application of Tapered Monocapillary in a Laboratory Mxrf Set-Up

1995 ◽  
Vol 39 ◽  
pp. 81-86
Author(s):  
N. Gao ◽  
I. Ponomarev ◽  
Q. F. Xiao ◽  
W. M. Gibson ◽  
D. A. Carpenter
Keyword(s):  
Experimental Work ◽  
High Energy ◽  
X Rays ◽  
Output Beam ◽  
Bremsstrahlung Radiation ◽  
X Ray ◽  
Set Up

Simulation and experimental work that compare the performance of straight and tapered monocapillaries when used with laboratory x-ray sources are reported. Detailed simulations for various taper profiles give several important conclusions for optimizing the design of a tapered monocapillary. Several tapered monocapillaries were prepared. With a 16W x-ray source, beam intensities of 4×105 photon/sec/μm2 and 3×105photon/sec/μm2 of Cu Kα x rays were obtained from the tapered monocapillaries for output diameters of 8μm and 3.5μm, respectively. These intensities are 1.4 and 1.5 times that obtained from straight capillaries with the same output beam sizes at the experimental set-up optimized for a straight capillary. In addition to the gain in x-ray flux, the tapered monocapillaries produce output beams with significantly reduced high energy bremsstrahlung radiation and increased flux stability with respect to shifts of the x-ray source spot.

scholarly journals OPTIMIZATION OF A COMPTON DIRECT-CHARGE DETECTOR FOR MONITORING HIGH-ENERGY BREMSSTRAHLUNG RADIATION

2019 ◽  
pp. 158-162
Author(s):  
V.I. Nikiforov ◽  
I.N. Shlyakhov ◽  
V.A. Shevchenko ◽  
A.Eh. Tenishev ◽  
V.L. Uvarov
Keyword(s):  
Computer Simulation ◽  
Atomic Number ◽  
Electron Accelerator ◽  
High Energy ◽  
X Rays ◽  
Bremsstrahlung Radiation ◽  
Charge Generation ◽  
Point Energy ◽  
X Ray ◽  
Different Thickness

The conditions of application of a Compton direct-charge detector (DCD) for monitoring of intensity of the highenergy bremsstrahlung (X-ray) radiation are studied. A method is described for calculation of characteristics of the secondary е,Х-radiation at exit of an electron accelerator, and also for providing the conditions of the electronic equilibrium. By means of computer simulation, the processes of charge generation in a DCD monitor comprising two plates of different thickness from various metals are analyzed. On the basis of the obtained results, the requirements imposed on DCD composition for providing the maximum of its sensitivity are formulated. It is shown, that within the suggested DCD geometry, the monitor sensitivity reveals a weak dependence on the atomic number of its material at Z>29, and also on the end-point energy of X-rays in the span of 20…100 MeV.

scholarly journals Vertical intensity modulation for improved radiographic penetration and reduced exclusion zone

2016 ◽  
Vol 44 ◽  
pp. 1660213 ◽  
Author(s):  
J. Bendahan ◽  
W.G.J. Langeveld ◽  
V. Bharadwaj ◽  
J. Amann ◽  
C. Limborg ◽  
...  
Keyword(s):  
Electron Beam ◽  
High Energy ◽  
Dual Energy ◽  
X Rays ◽  
Exclusion Zone ◽  
Bremsstrahlung Radiation ◽  
Radiographic Images ◽  
Power Sources ◽  
X Ray ◽  
Energy Beam

In the present work, a method to direct the X-ray beam in real time to the desired locations in the cargo to increase penetration and reduce exclusion zone is presented. Cargo scanners employ high energy X-rays to produce radiographic images of the cargo. Most new scanners employ dual-energy to produce, in addition to attenuation maps, atomic number information in order to facilitate the detection of contraband. The electron beam producing the bremsstrahlung X-ray beam is usually directed approximately to the center of the container, concentrating the highest X-ray intensity to that area. Other parts of the container are exposed to lower radiation levels due to the large drop-off of the bremsstrahlung radiation intensity as a function of angle, especially for high energies (>6 MV). This results in lower penetration in these areas, requiring higher power sources that increase the dose and exclusion zone. The capability to modulate the X-ray source intensity on a pulse-by-pulse basis to deliver only as much radiation as required to the cargo has been reported previously. This method is, however, controlled by the most attenuating part of the inspected slice, resulting in excessive radiation to other areas of the cargo. A method to direct a dual-energy beam has been developed to provide a more precisely controlled level of required radiation to highly attenuating areas. The present method is based on steering the dual-energy electron beam using magnetic components on a pulse-to-pulse basis to a fixed location on the X-ray production target, but incident at different angles so as to direct the maximum intensity of the produced bremsstrahlung to the desired locations. The details of the technique and subsystem and simulation results are presented.

scholarly journals FORMATION AND MONITORING OF SECONDARY X-RAY RADIATION UNDER PRODUCT PROCESSING WITH ELECTRON BEAM

2021 ◽  
pp. 201-205
Author(s):  
R.I. Pomatsalyuk ◽  
V.A. Shevchenko ◽  
D.V. Titov ◽  
A.Eh. Tenishev ◽  
V.L. Uvarov ◽  
...  
Keyword(s):  
Electron Beam ◽  
Primary Electron ◽  
X Rays ◽  
Bremsstrahlung Radiation ◽  
X Ray ◽  
Free Air ◽  
Industrial Radiation ◽  
Radiation Processes ◽  
Cultural Heritage Objects ◽  
Electron And Photon

When conducting an industrial radiation processes at an electron accelerator, a part of the beam energy is trans-formed into bremsstrahlung radiation. In such a way, the mixed e,X-radiation is formed in the area behind an irra-diated object. The intensity of the electron and photon components in the radiation is determined by the energy and power of the primary electron beam, as well as by the parameters of the object and devices located behind it. In paper, the characteristics of the e,X-radiation accompanying the product processing by a scanning electron beam with energy 8…12 MeV at a LU-10 Linac of NSC KIPT are studied. The conditions for obtaining a source of sec-ondary X-rays in the state of electronic equilibrium, as well as its monitoring using an extended free-air ionization chamber are explored. Such an extra-source of radiation can be used for carrying out various non-commercial pro-grams like radiation tests, sanitization of archival materials and cultural heritage objects, etc.

The Basic Physical Principles of Ion, Electron, and X-Ray Detectors and Their Application to Microanalysis

1985 ◽  
Vol 43 ◽  
pp. 154-157
Author(s):  
A.J. Tousimis
Keyword(s):  
Ion Beam ◽  
Depth Resolution ◽  
Sample Surface ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Electrons And Ions ◽  
Spatial Depth ◽  
Minimum Surface Area ◽  
Physical Principles

An integral and of prime importance of any microtopography and microanalysis instrument system is its electron, x-ray and ion detector(s). The resolution and sensitivity of the electron microscope (TEM, SEM, STEM) and microanalyzers (SIMS and electron probe x-ray microanalyzers) are closely related to those of the sensing and recording devices incorporated with them.Table I lists characteristic sensitivities, minimum surface area and depth analyzed by various methods. Smaller ion, electron and x-ray beam diameters than those listed, are possible with currently available electromagnetic or electrostatic columns. Therefore, improvements in sensitivity and spatial/depth resolution of microanalysis will follow that of the detectors. In most of these methods, the sample surface is subjected to a stationary, line or raster scanning photon, electron or ion beam. The resultant radiation: photons (low energy) or high energy (x-rays), electrons and ions are detected and analyzed.

Comparison of high-angle take-off and low-angle take-off EDX detector geometry of the HF-2000 FE-TEM

1993 ◽  
Vol 51 ◽  
pp. 252-253
Author(s):  
Y. Sato ◽  
T. Hashimoto ◽  
M. Ichihashi ◽  
Y. Ueki ◽  
K. Hirose ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Field Emission ◽  
Solid Angle ◽  
Energy Dispersive ◽  
Objective Lens ◽  
X Rays ◽  
High Angle ◽  
X Ray ◽  
Detector Geometry

Analytical TEMs have two variations in x-ray detector geometry, high and low angle take off. The high take off angle is advantageous for accuracy of quantitative analysis, because the x rays are less absorbed when they go through the sample. The low take off angle geometry enables better sensitivity because of larger detector solid angle.Hitachi HF-2000 cold field emission TEM has two versions; high angle take off and low angle take off. The former allows an energy dispersive x-ray detector above the objective lens. The latter allows the detector beside the objective lens. The x-ray take off angle is 68° for the high take off angle with the specimen held at right angles to the beam, and 22° for the low angle take off. The solid angle is 0.037 sr for the high angle take off, and 0.12 sr for the low angle take off, using a 30 mm2 detector.

scholarly journals High-energy x-ray nanotomography introducing an apodization Fresnel zone plate objective lens

2021 ◽  
Vol 92 (2) ◽  
pp. 023701 ◽  
Author(s):  
Akihisa Takeuchi ◽  
Kentaro Uesugi ◽  
Masayuki Uesugi ◽  
Hiroyuki Toda ◽  
Kyosuke Hirayama ◽  
...  
Keyword(s):  
Fresnel Zone ◽  
High Energy ◽  
Zone Plate ◽  
Objective Lens ◽  
Fresnel Zone Plate ◽  
X Ray

A multi-length-scale USAXS/SAXS facility: 10–50 keV small-angle X-ray scattering instrument

2013 ◽  
Vol 46 (5) ◽  
pp. 1508-1512 ◽  
Author(s):  
Byron Freelon ◽  
Kamlesh Suthar ◽  
Jan Ilavsky
Keyword(s):  
Small Angle ◽  
Soft Matter ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
X Ray Scattering ◽  
Wide Range ◽  
And Performance ◽  
New Facility ◽  
Ray Scattering

Coupling small-angle X-ray scattering (SAXS) and ultra-small-angle X-ray scattering (USAXS) provides a powerful system of techniques for determining the structural organization of nanostructured materials that exhibit a wide range of characteristic length scales. A new facility that combines high-energy (HE) SAXS and USAXS has been developed at the Advanced Photon Source (APS). The application of X-rays across a range of energies, from 10 to 50 keV, offers opportunities to probe structural behavior at the nano- and microscale. An X-ray setup that can characterize both soft matter or hard matter and high-Zsamples in the solid or solution forms is described. Recent upgrades to the Sector 15ID beamline allow an extension of the X-ray energy range and improved beam intensity. The function and performance of the dedicated USAXS/HE-SAXS ChemMatCARS-APS facility is described.

A high-energy triple-axis X-ray diffractometer for the study of the structure of bulk crystals

2004 ◽  
Vol 37 (6) ◽  
pp. 901-910 ◽  
Author(s):  
C. Seitz ◽  
M. Weisser ◽  
M. Gomm ◽  
R. Hock ◽  
A. Magerl
Keyword(s):  
High Energy ◽  
X Rays ◽  
Bulk Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Intensity ◽  
High Penetration ◽  
Massive Sample ◽  
Laue Geometry ◽  
The Ideal

A triple-axis diffractometer for high-energy X-ray diffraction is described. A 450 kV/4.5 kW stationary tungsten X-ray tube serves as the X-ray source. Normally, 220 reflections of thermally annealed Czochralski Si are employed for the monochromator and analyser. Their integrated reflectivity is about ten times higher than the ideal crystal value. With the same material as the sample, and working with the WKα line at 60 keV in symmetric Laue geometry for all axes, the full width at half-maximum (FWHM) values for the longitudinal and transversal resolution are 2.5 × 10−3and 1.1 × 10−4for ΔQ/Q, respectively, and the peak intensity for a non-dispersive setting is 3000 counts s−1. In particular, for a double-axis mode, an energy well above 100 keV from theBremsstrahlungspectrum can be used readily. High-energy X-rays are distinguished by a high penetration power and materials of several centimetre thickness can be analysed. The feasibility of performing experiments with massive sample environments is demonstrated.

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