scholarly journals Perturbation perspective of partial coherence discussion on imperfect x-ray optical elements

Author(s):  
Lingfei Hu ◽  
John Sutter ◽  
Hongchang Wang ◽  
Kawal Sawhney
Author(s):  
E.G Churin ◽  
V.P Koronkevich ◽  
G.N Kulipanov ◽  
O.A Makarov ◽  
L.A Mezentseva ◽  
...  
Keyword(s):  

2009 ◽  
Author(s):  
D. Margarone ◽  
M. Kozlova ◽  
J. Nejdl ◽  
B. Rus ◽  
T. Mocek ◽  
...  

2017 ◽  
Vol 50 (2) ◽  
pp. 475-480 ◽  
Author(s):  
Peter Zaumseil

Four different SiGe/Si layer structures, pseudomorphically grown and (partially) relaxed, are used as examples to demonstrate that reflections in symmetric skew geometry can successfully be used to realize a complex analysis of these systems. Taking the intensity exactly along the truncation rod of a reciprocal lattice point, it is possible to simulate this diffraction curve and determine the layer parameter in the projection according to the netplane tilt relative to the surface. The main precondition for this technique and for performing reciprocal space mapping with sufficiently high resolution is a low angular divergence of the incident and detected beams perpendicular to the diffraction plane, which can also be achieved by suitable optical elements on laboratory-based diffractometers.


1998 ◽  
Vol 5 (5) ◽  
pp. 1243-1249 ◽  
Author(s):  
José I. Espeso ◽  
Peter Cloetens ◽  
José Baruchel ◽  
Jürgen Härtwig ◽  
Trevor Mairs ◽  
...  

The lateral coherence length is of the order of 100 µm at the `long' (145 m) ID19 beamline of the ESRF, which is mainly devoted to imaging. Most of the optical elements located along the X-ray path can thus act as `phase objects', and lead to spurious contrast and/or to coherence degradation, which shows up as an enhanced effective angular size of the source. Both the spurious contrast and the coherence degradation are detrimental for the images (diffraction topographs, tomographs, phase-contrast images) produced at this beamline. The problems identified and the way they were solved during the commissioning of ID19 are reported. More particularly, the role of the protection foils located in the front end, the beryllium windows, the filters and the monochromator defects (scratches, dust, small vibrations) is discussed.


2012 ◽  
Author(s):  
Takashi Imazono ◽  
Naoji Moriya ◽  
Yoshihisa Harada ◽  
Kazuo Sano ◽  
Masato Koike

2017 ◽  
Vol 24 (6) ◽  
pp. 1195-1208 ◽  
Author(s):  
Álvaro Martín Ortega ◽  
Ana Lacoste ◽  
Stéphane Béchu ◽  
Alexandre Bès ◽  
Nader Sadeghi

X-ray gas attenuators are used in high-energy synchrotron beamlines as high-pass filters to reduce the incident power on downstream optical elements. The absorption of the X-ray beam ionizes and heats up the gas, creating plasma around the beam path and hence temperature and density gradients between the center and the walls of the attenuator vessel. The objective of this work is to demonstrate experimentally the generation of plasma by the X-ray beam and to investigate its spatial distribution by measuring some of its parameters, simultaneously with the X-ray power absorption. The gases used in this study were argon and krypton between 13 and 530 mbar. The distribution of the 2pexcited states of both gases was measured using optical emission spectroscopy, and the density of argon metastable atoms in the 1s5state was deduced using tunable laser absorption spectroscopy. The amount of power absorbed was measured using calorimetry and X-ray transmission. The results showed a plasma confined around the X-ray beam path, its size determined mainly by the spatial dimensions of the X-ray beam and not by the absorbed power or the gas pressure. In addition, the X-ray absorption showed a hot central region at a temperature varying between 400 and 1100 K, depending on the incident beam power and on the gas used. The results show that the plasma generated by the X-ray beam plays an essential role in the X-ray absorption. Therefore, plasma processes must be taken into account in the design and modeling of gas attenuators.


2014 ◽  
Vol 70 (a1) ◽  
pp. C1737-C1737
Author(s):  
Pawel Grochulski ◽  
Miroslaw Cygler ◽  
Michel Fodje ◽  
Shaunivan Labiuk ◽  
James Gorin ◽  
...  

The Canadian Macromolecular Crystallography Facility (CMCF) at the Canadian Light Source (CLS) is a suite of fully automated beamlines, 08ID-1 and 08B1-1 [1]. It serves over 60 Canadian groups plus academic and commercial users in the US. Besides remote data collection, we offer Mail-In service where data are collected by CMCF staff. Beamline 08B1-1 has been in operation since 2011 and beamline 08ID-1 since 2006. When beamline 08ID-1 was designed, over 10 years ago, small crystals were defined as having sizes of 50-100 μm. Today, the most challenging experiments require more intense X-ray beams that can be focused to accommodate much smaller crystal sizes of less than 5 μm with flux on the order of 10^11 photons/s. To reach these stringent parameters, a new more powerful source of X-rays will be required, which will be provided by a longer small-gap in-vacuum undulator (SGU). To accommodate the higher power levels and to focus X-rays to a smaller focal spot with a high degree of spatial and temporal stability, the existing X-ray optical elements need to be upgraded. The remaining components of the project include a 5-axis alignment table for improving alignment of small samples with the microbeam, a high-efficiency robotic sample-changer and a single-photon X-ray detector. Several options for the new design will be discussed. These developments are consistent with the current direction of structural biology research at the CLS [2]. Since 2006 over 225 (240) papers and 400 (444) PDB deposits reported data collected at beamline 08ID-1. Parentheses indicate the total number for the CMCF. Many of these have been published in very high impact journals such as N. Engl. J. Med., Nature, Cell, Science, PNAS, among others (http://cmcf.lightsource.ca/publications/).


1998 ◽  
Vol 5 (3) ◽  
pp. 239-245 ◽  
Author(s):  
A. Erko ◽  
M. Veldkamp ◽  
W. Gudat ◽  
N. V. Abrosimov ◽  
S. N. Rossolenko ◽  
...  

Using X-ray diffractometry and spectral measurements, the structure and properties of graded X-ray optical elements have been examined. Experimental and theoretical data on X-ray supermirrors, which were prepared by the magnetron sputtering technique using precise thickness control, are reported. Measurements on graded aperiodic Si1−x Ge x single crystals, which were grown by the Czochralski technique, are also presented. The lattice parameter of such a crystal changes almost linearly with increasing Ge concentration. The measurements indicate that Si1−x Ge x crystals with concentrations up to 7 at.% Ge can be grown with a quality comparable to that of pure Si crystals.


1999 ◽  
Vol 32 (10A) ◽  
pp. A184-A192 ◽  
Author(s):  
A Souvorov ◽  
M Drakopoulos ◽  
I Snigireva ◽  
A Snigirev
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