scholarly journals The finer things in X-ray diffraction data collection

1999 ◽  
Vol 55 (10) ◽  
pp. 1718-1725 ◽  
Author(s):  
J. W. Pflugrath
Keyword(s):  
Data Collection ◽  
Diffraction Data ◽  
Rotation Angle ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Software Suite ◽  
X Ray ◽  
Position Sensitive ◽  
X Ray Background ◽  
Position Sensitive Detectors

X-ray diffraction images from two-dimensional position-sensitive detectors can be characterized as thick or thin, depending on whether the rotation-angle increment per image is greater than or less than the crystal mosaicity, respectively. The expectations and consequences of the processing of thick and thin images in terms of spatial overlap, saturated pixels, X-ray background andI/σ(I) are discussed. Thed*TREKsoftware suite for processing diffraction images is briefly introduced, and results fromd*TREKare compared with those from another popular package.

Design of a Real-Time Two-Dimensional Residual Stress Analyzer

1986 ◽  
Vol 30 ◽  
pp. 523-526
Author(s):  
G. M. Borgonovi
Keyword(s):  
Residual Stress ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Detector Plane ◽  
Flat Detector ◽  
One Dimensional ◽  
X Ray ◽  
State Of Stress ◽  
Position Sensitive ◽  
Position Sensitive Detectors

Measurements of residual stress by X-ray diffraction are usually carried out with diffractometers or with one-dimensional position sensitive detectors. The stress is determined from the displacement of the peak that results from intersecting a diffraction cone at high angle with the line scanned by the detector. If a two-dimensional flat detector is used, the intersection of the diffraction cone with the detector plane is a ring, or section of a ring, which is also slightly displaced by the stress. The suggestion has been made use a two-dimensional detector to determine the surface state of stress.

A stochastic algorithm for reconstruction of grain maps of moderately deformed specimens based on X-ray diffraction

2007 ◽  
Vol 40 (2) ◽  
pp. 313-321 ◽  
Author(s):  
L. Rodek ◽  
H. F. Poulsen ◽  
E. Knudsen ◽  
G. T. Herman
Keyword(s):  
Data Collection ◽  
Diffraction Data ◽  
Stochastic Algorithm ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Discrete Tomography ◽  
Prior Model ◽  
X Ray ◽  
Model Based ◽  
Dimensional Section

In a recent paper [Alpers, Poulsen, Knudsen & Herman (2006).J. Appl. Cryst.39, 582–588] a stochastic algorithm was presented for reconstruction of grain maps of undeformed polycrystals based on X-ray diffraction data. Here the formalism is extended to moderately deformed specimens. Each two-dimensional section of the specimen is reconstructed independently. Using a dual assignment of a grain label and an orientation to each pixel in a section and a prior model based on methods of discrete tomography, our stochastic algorithm converges in a few minutes for a 64\times64 map. Simulations with higher than typical levels of noise in the data collection for three typical moderately deformed microstructures resulted in grain maps with the fraction of erroneously assigned pixels being 1.7% or much less.

X-ray position-sensitive detectors

1986 ◽  
Vol 19 (3) ◽  
pp. 145-163 ◽  
Author(s):  
U. W. Arndt
Keyword(s):  
X Rays ◽  
Two Dimensional ◽  
Physical Processes ◽  
X Ray ◽  
General Terms ◽  
Position Sensitive ◽  
Position Sensitive Detectors

The physical processes are examined which can be used for the detection of X-rays in the range between about 3 and about 20 keV and for the positional localization of the incident photons. The criteria for choosing a detector for particular purposes are discussed in general terms. Specific examples of one- and two-dimensional detectors are then considered with particular emphasis on devices which are still in a state of development, and an attempt is made to summarize the nature, performance and suitability for different experiments of available detectors.

scholarly journals Automated harvesting and processing of protein crystals through laser photoablation

2016 ◽  
Vol 72 (4) ◽  
pp. 454-466 ◽  
Author(s):  
Ulrich Zander ◽  
Guillaume Hoffmann ◽  
Irina Cornaciu ◽  
Jean-Pierre Marquette ◽  
Gergely Papp ◽  
...  
Keyword(s):  
Data Collection ◽  
Macromolecular Crystallography ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Methods ◽  
Repeated Sample ◽  
Sample Recovery ◽  
Through Diffusion ◽  
X Ray Background ◽  
Low X

Currently, macromolecular crystallography projects often require the use of highly automated facilities for crystallization and X-ray data collection. However, crystal harvesting and processing largely depend on manual operations. Here, a series of new methods are presented based on the use of a low X-ray-background film as a crystallization support and a photoablation laser that enable the automation of major operations required for the preparation of crystals for X-ray diffraction experiments. In this approach, the controlled removal of the mother liquor before crystal mounting simplifies the cryocooling process, in many cases eliminating the use of cryoprotectant agents, while crystal-soaking experiments are performed through diffusion, precluding the need for repeated sample-recovery and transfer operations. Moreover, the high-precision laser enables new mounting strategies that are not accessible through other methods. This approach bridges an important gap in automation and can contribute to expanding the capabilities of modern macromolecular crystallography facilities.

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.

Masquerade: removing non-sample scattering from integrated reflection intensities

2012 ◽  
Vol 45 (2) ◽  
pp. 292-298 ◽  
Author(s):  
J. A. Coome ◽  
A. E. Goeta ◽  
J. A. K. Howard ◽  
M. R. Probert
Keyword(s):  
Data Collection ◽  
Diffraction Data ◽  
Low Temperatures ◽  
Test Case ◽  
X Rays ◽  
Atmospheric Conditions ◽  
X Ray Diffraction ◽  
New Approach ◽  
X Ray ◽  
Internal Agreement

X-ray diffraction experiments at very low temperatures require samples to be isolated from atmospheric conditions and held under vacuum. These conditions are usually maintainedviathe use of beryllium chambers, which also scatter X-rays, causing unwanted contamination of the sample's diffraction pattern. The removal of this contamination requires novel data-collection and processing procedures to be employed. Herein a new approach is described, which utilizes the differences in origin of scattering vectors from the sample and the beryllium to eliminate non-sample scattering. The programMasqueradehas been written to remove contaminated regions of the diffraction data from the processing programs. Coupled with experiments at different detector distances, it allows for the acquisition of decontaminated data. Studies of several single crystals have shown that this approach increases data quality, highlighted by the improvement in internal agreement factor with the test case of cytidine presented herein.

Instrumental aspects in X-ray diffraction on polycrystalline materials

2005 ◽  
Vol 20 (4) ◽  
pp. 294-305 ◽  
Author(s):  
R. Guinebretière ◽  
A. Boulle ◽  
O. Masson ◽  
A. Dauger
Keyword(s):  
Polycrystalline Materials ◽  
Acquisition Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Experimental Parameters ◽  
Recent Developments ◽  
Instrumental Resolution ◽  
Position Sensitive ◽  
Two Parameters ◽  
Position Sensitive Detectors

The purpose of this paper is to give a rapid overview of the recent developments in the field of X-ray diffraction on polycrystalline materials from the viewpoint of the instruments. After a brief historical report, the main types of laboratory diffractometers are presented. At the end of the twentieth century the apparition of position sensitive detectors and artificial crystal monochromators have induced the conception of new diffractometer often based on old geometrical arrangements. Those modern diffractometers are described with respect to the more conventional ones. Among the experimental parameters which can characterize a given diffractometer, the instrumental resolution function and the acquisition time of the pattern are of primary importance. The different apparatus are compared with respect to those two parameters.

Two-dimensional position-sensitive gaseous detectors for high-resolution neutron and X-ray diffraction

2002 ◽  
Vol 74 (0) ◽  
pp. s252-s254 ◽  
Author(s):  
M. Marmotti ◽  
M. Haese-Seiller ◽  
R. Kampmann
Keyword(s):  
High Resolution ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Position Sensitive
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