High Precision Studies on the Level Scheme ofSe80by the Resonant-Scattering Method

1973 ◽  
Vol 8 (4) ◽  
pp. 1429-1432 ◽  
Author(s):  
H. Szichman
2021 ◽  
Vol 7 (1) ◽  
pp. 2
Author(s):  
Kenichi Kato ◽  
Kazuya Shigeta

The total scattering method, which is based on measurements of both Bragg and diffuse scattering on an equal basis, has been still challenging even by means of synchrotron X-rays. This is because such measurements require a wide coverage in scattering vector Q, high Q resolution, and a wide dynamic range for X-ray detectors. There is a trade-off relationship between the coverage and resolution in Q, whereas the dynamic range is defined by differences in X-ray response between detector channels (X-ray response non-uniformity: XRNU). XRNU is one of the systematic errors for individual channels, while it appears to be a random error for different channels. In the present study, taking advantage of the randomness, the true sensitivity for each channel has been statistically estimated. Results indicate that the dynamic range of microstrip modules (MYTHEN, Dectris, Baden-Daettwil, Switzerland), which have been assembled for a total scattering measurement system (OHGI), has been successfully restored from 104 to 106. Furthermore, the correction algorithm has been optimized to increase time efficiencies. As a result, the correcting time has been reduced from half a day to half an hour, which enables on-demand correction for XRNU according to experimental settings. High-precision X-ray total scattering measurements, which has been achieved by a high-accuracy detector system, have demonstrated valence density studies from powder and PDF studies for atomic displacement parameters.


2017 ◽  
Author(s):  
Juan Pablo Fernandez-Garcia ◽  
A. Di Pietro ◽  
M. Fisichella ◽  
M. Alcorta ◽  
M. J. G. Borge ◽  
...  

Author(s):  
Honggang Zhao ◽  
Yongmin Yang ◽  
Yue Li ◽  
Xisen Wen

Practical design of composite materials suggests a need for an improved quantitative understanding of the interaction between acoustic waves and microspheres. In this work, we first investigate the Mie resonance of a single spherical microsphere embedded in polymer by referring to the elements of the scattering matrices. It shows that a hollow glass microsphere presents a similar monopole resonance as an air microsphere, but the resonance of a hollow glass microsphere occurs at a higher frequency with a wider bandwidth than that of an air microsphere. Then, using the multiple scattering method, we show that the low-frequency gap of a periodic array of microspheres in polymer is mainly induced by the monopole resonance of the single microsphere, and find a wide band gap under very low concentrations of the microspheres. The viscosity of the components induces the energy dissipation under the resonant scattering, and the attenuation of ultrasonic longitudinal waves in the polymer slab is dominated by energy absorption.


1970 ◽  
Vol 141 (3) ◽  
pp. 561-576 ◽  
Author(s):  
R. Cesareo ◽  
M. Giannini ◽  
P.R. Oliva ◽  
D. Prosperi ◽  
M.C. Ramorino

1961 ◽  
Vol 13 (2) ◽  
pp. 284-306 ◽  
Author(s):  
Bernard Hamermesh ◽  
J.E Monahan ◽  
Robert K Smither

Author(s):  
J. C. Russ ◽  
T. Taguchi ◽  
P. M. Peters ◽  
E. Chatfield ◽  
J. C. Russ ◽  
...  

Conventional SAD patterns as obtained in the TEM present difficulties for identification of materials such as asbestiform minerals, although diffraction data is considered to be an important method for making this purpose. The preferred orientation of the fibers and the spotty patterns that are obtained do not readily lend themselves to measurement of the integrated intensity values for each d-spacing, and even the d-spacings may be hard to determine precisely because the true center location for the broken rings requires estimation. We have implemented an automatic method for diffraction pattern measurement to overcome these problems. It automatically locates the center of patterns with high precision, measures the radius of each ring of spots in the pattern, and integrates the density of spots in that ring. The resulting spectrum of intensity vs. radius is then used just as a conventional X-ray diffractometer scan would be, to locate peaks and produce a list of d,I values suitable for search/match comparison to known or expected phases.


Author(s):  
K. Z. Botros ◽  
S. S. Sheinin

The main features of weak beam images of dislocations were first described by Cockayne et al. using calculations of intensity profiles based on the kinematical and two beam dynamical theories. The feature of weak beam images which is of particular interest in this investigation is that intensity profiles exhibit a sharp peak located at a position very close to the position of the dislocation in the crystal. This property of weak beam images of dislocations has an important application in the determination of stacking fault energy of crystals. This can easily be done since the separation of the partial dislocations bounding a stacking fault ribbon can be measured with high precision, assuming of course that the weak beam relationship between the positions of the image and the dislocation is valid. In order to carry out measurements such as these in practice the specimen must be tilted to "good" weak beam diffraction conditions, which implies utilizing high values of the deviation parameter Sg.


Author(s):  
Klaus-Ruediger Peters

Differential hysteresis processing is a new image processing technology that provides a tool for the display of image data information at any level of differential contrast resolution. This includes the maximum contrast resolution of the acquisition system which may be 1,000-times higher than that of the visual system (16 bit versus 6 bit). All microscopes acquire high precision contrasts at a level of <0.01-25% of the acquisition range in 16-bit - 8-bit data, but these contrasts are mostly invisible or only partially visible even in conventionally enhanced images. The processing principle of the differential hysteresis tool is based on hysteresis properties of intensity variations within an image.Differential hysteresis image processing moves a cursor of selected intensity range (hysteresis range) along lines through the image data reading each successive pixel intensity. The midpoint of the cursor provides the output data. If the intensity value of the following pixel falls outside of the actual cursor endpoint values, then the cursor follows the data either with its top or with its bottom, but if the pixels' intensity value falls within the cursor range, then the cursor maintains its intensity value.


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