GEOMETRICAL ABERRATIONS IN THE VON HAMOS AND THE PLANE BRAGG CRYSTAL SPECTROMETERS

1997 ◽  
Vol 07 (03n04) ◽  
pp. 117-133 ◽  
Author(s):  
T. Tadic ◽  
Y. Mokuno ◽  
Y. Horino ◽  
M. Jaksic
Keyword(s):  
Numerical Model ◽  
Ray Tracing ◽  
Numerical Calculations ◽  
X Ray Diffraction ◽  
Pixe Analysis ◽  
X Ray ◽  
Analytical Studies ◽  
Position Sensitive ◽  
Produce Line

Numerical calculations of the effect of the finite dimensions and orientations of source and crystal are presented for plane and von Hamos Bragg crystal spectrometers for PIXE analysis, combined with a position sensitive (X-ray) detector. Analytical studies of all effects are provided. It is shown that some parameters can produce line shifts and asymmetries. A numerical model for an X-ray diffraction ray-tracing procedure for a crystal Bragg spectrometer is described.

Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

2020 ◽  
Vol 86 (6) ◽  
pp. 29-35
Author(s):  
V. P. Sirotinkin ◽  
O. V. Baranov ◽  
A. Yu. Fedotov ◽  
S. M. Barinov
Keyword(s):  
Phase Composition ◽  
Calcium Phosphates ◽  
Position Sensitive Detector ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impurity Phases ◽  
Position Sensitive ◽  
Diffraction Peaks ◽  
Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

Micro Diffraction Imaging of Bulk Polycrystalline Materials

2006 ◽  
Vol 524-525 ◽  
pp. 273-278
Author(s):  
Thomas Wroblewski ◽  
A. Bjeoumikhov ◽  
Bernd Hasse
Keyword(s):  
High Spatial Resolution ◽  
Polycrystalline Materials ◽  
X Rays ◽  
X Ray Diffraction ◽  
Short Sample ◽  
X Ray ◽  
Detector Distance ◽  
Transmission Geometry ◽  
Diffraction Imaging ◽  
Position Sensitive

X-ray diffraction imaging applies an array of parallel capillaries in front of a position sensitive detector. Conventional micro channel plates of a few millimetre thickness have successfully been used as collimator arrays but require short sample to detector distances to achieve high spatial resolution. Furthermore, their limited absorption restricts their applications to low energy X-rays of around 10 keV. Progress in the fabrication of long polycapillaries allows an increase in the sample to detector distance without decreasing resolution and the use of high X-ray energies enables bulk investigations in transmission geometry.

Correction of X-ray Diffraction Profiles Measured by PSPC System

1989 ◽  
Vol 33 ◽  
pp. 397-402 ◽  
Author(s):  
Shin'ichi Ohya ◽  
Yasuo Yoshioka
Keyword(s):  
Profile Analysis ◽  
X Rays ◽  
X Ray Diffraction ◽  
Diffraction Profile ◽  
X Ray ◽  
Geometrical Problem ◽  
Straight Line ◽  
Background Line ◽  
Diffraction Angle ◽  
Position Sensitive

When an x-ray diffraction profile Is measured for stress analysis or profile analysis by the use of a linear (straight line) position sensitive proportional counter (PSPC) , a convex-type background line is obtained because of the geometrical problem and the absorption of x-rays. Such phenomenon is remarkable when a wide angular range is set on a linear PSPC and it is, in particular, necessary to correct with a straight background for accurate measurement of diffraction angle or half-value breadth of the broadened diffraction profile.

The Use of 2-D Detector Utilizing Laser-Stimulated Luminescence for X-ray Diffraction Studies on Mechanical Behaviour of Materials

1989 ◽  
Vol 33 ◽  
pp. 389-396 ◽  
Author(s):  
Y. Yoshioka ◽  
T. Shinkai ◽  
S. Ohya
Keyword(s):  
Fracture Analysis ◽  
X Rays ◽  
Large Reduction ◽  
X Ray Diffraction ◽  
Crystalline Materials ◽  
X Ray ◽  
Material Evaluation ◽  
Position Sensitive ◽  
Diffraction Patterns ◽  
Position Sensitive Detectors

The development of linear position-sensitive detectors (PSD) has resulted in a large reduction of data acquisition times in the field of x-ray stress analysis. However, we also require two-dimensional (2-D) diffraction patterns for material evaluation. Especially, the microbeam x-ray diffraction technique gives valuable information on the structure of crystalline materials and this technique has been applied to fracture analysis by x-rays. Many kinds of 2-D PSD have been developed that have insufficient spatial resolution. So x-ray film has still been used as a 2-D detector, but it requires relatively long exposure times and then the process after exposure is very troublesome.

A High-Speed Signal Processor Using a Digital Divider for Position Sensitive Proportional Counters

1980 ◽  
Vol 24 ◽  
pp. 173-176
Author(s):  
S. Kobashi ◽  
K. Mochiki ◽  
K. Hasegawa ◽  
A. Sekiguchi ◽  
H. Hashizume ◽  
...  
Keyword(s):  
High Speed ◽  
Dead Time ◽  
Present System ◽  
X Ray Diffraction ◽  
Analog To Digital ◽  
X Ray ◽  
System A ◽  
Proportional Counters ◽  
Position Sensitive ◽  
A Charge

Most position sensitive proportional counters (PSPCs) currently used in X-ray diffraction experiments have a dead time longer than 5 μs. Though such PSPCs are useful in measuring weak diffraction diagrams, a faster counter is needed to detect strong X-ray diagrams produced with synchrotron radiation sources. The long dead time of PSPCs using a charge division position read-out is due to the slow analog division circuit plus analog-to-digital converter employed in the present system. A fast processor can be built utilising two high-speed ADCs to digitize voltage signals from the detector, followed by a digital divider to compute position of detected photons. The present paper describes the design of such a processor and some preliminary testings of its performances.

A Phi-Psi-Diffract (Meter for Residual Stress Measurements

1982 ◽  
Vol 26 ◽  
pp. 275-282 ◽  
Author(s):  
C.N.J. Wagner ◽  
M.S. Boldrick ◽  
V. Perez-Mendez
Keyword(s):  
Strain Tensor ◽  
Sample Surface ◽  
X Ray Diffraction ◽  
Diffraction Vector ◽  
Diffraction Plane ◽  
X Ray ◽  
Integral Methods ◽  
Isotropic Elasticity ◽  
Measured Strain ◽  
Position Sensitive

AbstractA ϕ-ψ diffractometer has been designed and constructed to evaluate residual stresses in polycrystalline samples by x-ray diffraction. It permits rotations of the x-ray diffraction apparatus, consisting of an x-ray tube and a position-sensitive proportional counter, about two axes ϕ and ψ. The ϕ-rotation from 0° to 360° is carried out about the normal to the surface of the stationary sample, whereas the ψ-motion consists of a rotation from -45° to +45° about an axis lying in the sample surface and the diffraction plane, but perpendicular to the diffraction vector. This ϕ-ψ diffractometer permits the application of the ϕ- and ψ-differential and integral methods for the evaluation of the strain tensor and its gradient averaged over the depth of x-ray penetration into the sample. Assuming that isotropic elasticity theory is applicable, the stress tensor can then be evaluated from the measured strain tensor.

Second Order Stresses Distribution in Textured Copper

2006 ◽  
Vol 524-525 ◽  
pp. 859-864
Author(s):  
Neila Hfaiedh ◽  
Manuel François ◽  
Khemais Saanouni
Keyword(s):  
Peak Position ◽  
Second Order ◽  
Polycrystalline Materials ◽  
Internal Stresses ◽  
Plastic Strains ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Position Sensitive ◽  
Specific Correction

Internal stresses are an important factor in understanding the work hardening behaviour of polycrystalline materials. The goal of the present paper is to study the development of second order stresses in textured copper sheets at large plastic strains, up to fracture by X-ray diffraction. Second order stresses manifest themselves as peak displacements and width changes as azimuth and tilt angles are varied. As the acquisition is performed with a position sensitive detector, a specific correction of intensities is required in order to take into account texture influence on peak shape and consequently on peak position and width.

scholarly journals Scanning X-Ray Diffraction: A Technique With High Compositional Resolution for Studying Phase Formation in Co-Deposited Thin Films

1994 ◽  
Vol 343 ◽  
Author(s):  
T.I. Selinder ◽  
D.J. Miller ◽  
K.E. Gray ◽  
M.A. Beno ◽  
G.S. Knapp
Keyword(s):  
Thin Films ◽  
Phase Formation ◽  
Structural Information ◽  
Metastable Phase ◽  
Ternary Systems ◽  
Composition Gradient ◽  
X Ray Diffraction ◽  
X Ray ◽  
Analysis Technique ◽  
Position Sensitive

ABSTRACTInvestigation of the formation of new metastable phases in alloy thin films requires ways of quickly determining the crystalline structure of samples with different compositions. We report a novel technique for acquiring structural information from films intentionally grown with a composition gradient. For example, binary metal alloy films were deposited using a phase-spread sputtering method. In this way essentially the entire composition range could be grown in a single deposition. By using a narrow incident x-ray beam and a translating sample stage combined with a position sensitive x-ray detector technique, detailed information of the metastable phase diagram can be obtained rapidly. Compositional resolution of the order of ±0.2% can be achieved, and is limited by the brightness of the x-ray source. Initial results from studies of phase formation in Zr-Ta alloys will be presented. Extensions of the analysis technique to ternary systems will be discussed.

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