X-Ray Polarization: Bragg Diffraction and X-Ray Flurorescence

1982 ◽  
Vol 26 ◽  
pp. 331-336
Author(s):  
John D. Zahrt
Keyword(s):  
State Of The Art ◽  
Detection Limits ◽  
Bragg Diffraction ◽  
X Rays ◽  
X Ray ◽  
Signal Noise ◽  
Noise Ratio ◽  
Minimum Detection Limits

Recent, state of the art, x-ray spectrometers have made use of polarizing the source x-rays by scattering through 90° (1) . One then observes the analyte fluorescence in a direction perpendicular to the scattering plane in which the polarized x-rays are generated. The signal/noise ratio at the detector is much improved. Unfortunately there is a concomitant loss of intensity and analysis times increase. This adversely affects the minimum detection limits.

Multilayer Scatterers for Use in Polarized X-Ray Flourescence

1985 ◽  
Vol 29 ◽  
pp. 435-441
Author(s):  
John D. Zahrt ◽  
Richard W. Ryon
Keyword(s):  
Trace Elements ◽  
Narrow Range ◽  
Broad Band ◽  
Detection Limits ◽  
Single Element ◽  
X Rays ◽  
Minor And Trace Elements ◽  
X Ray ◽  
Edxrf Analysis ◽  
Minimum Detection Limits

In the EDXRF analysis of minor and trace elements in a variety of matrices, the use of a polarized x-ray source incident on a sample will provide minimum detection limits three to five times lower than the use of non-polarized sources (1,2). There are various methods of producing monochromatic polarized x-rays for specimen excitation (3,4,5,6 ). Such x-ray sources may produce the lowest detection limits for a single element or a narrow range of elements. However, if one is interested in simultaneously analyzing a broad range of elements, a polychromatic source is desired (7,8,9). We present here a new method for producing broad-band polarized x-rays.

Signal/Noise Ratio and Elemental Detectivity by Eels

1982 ◽  
Vol 40 ◽  
pp. 488-489
Author(s):  
R. F. Egerton
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Elemental Analysis ◽  
Electron Energy Loss Spectroscopy ◽  
Emission Spectroscopy ◽  
X Ray ◽  
Signal Noise ◽  
Characteristic Signal ◽  
Noise Ratio ◽  
Electron Energy Loss

An important parameter governing the sensitivity and accuracy of elemental analysis by electron energy-loss spectroscopy (EELS) or by X-ray emission spectroscopy is the signal/noise ratio of the characteristic signal.

scholarly journals Development of X-ray streak camera electronics at AWRE

1986 ◽  
Vol 4 (1) ◽  
pp. 145-156 ◽  
Author(s):  
M. C. Jackson ◽  
R. D. Long ◽  
D. Lee ◽  
N. J. Freeman
Keyword(s):  
Streak Camera ◽  
Sweep Rate ◽  
Bragg Diffraction ◽  
X Rays ◽  
Crystal Spectrometer ◽  
One Dimensional ◽  
X Ray ◽  
Ramp Generator ◽  
Laser Facility ◽  
User Facility

The paper reviews a number of X-ray streak cameras developed at AWRE. These cameras are used to provide temporal and one-dimensional spatial or spectral information on X-rays emitted from laser produced plasmas. Two of these cameras have been designed to be combined with other diagnostic instrumentation; one with a Wolter X-ray microscope (×22 magnification) and the other with a Bragg diffraction crystal spectrometer. This latter instrument provides a few eV spectral resolution and ∼15 ps temporal resolution; a typical experimental application at the AWRE HELEN laser facility will be described. The paper describes the circuitry of the bipolar avalanche transistor ramp generator used to drive the streak plates of the cameras. Improvements to this include: (a) increasing the fastest streak rate to ∼10 ps mm−1 by a distributed capacitance network across each of the bipolar stacks of transistors, and (b) reducing the trigger jitter to approximately ±10 ps by the use of a new mix of transistors in the stack and a Raytheon RS 3500 avalanche transistor. Additional improvements have now been added. These include a ‘half-scan’ user facility to aid initial camera timing and direct switching to select the sweep rate of the camera.

Bragg and Fresnel Diffraction Imaging Using Highly Coherent X-Rays

1998 ◽  
Vol 4 (S2) ◽  
pp. 376-377
Author(s):  
P. Cloetens ◽  
J. Baruchel ◽  
J.P. Guigay ◽  
W. Ludwig ◽  
L. Mancini ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Optical Path Length ◽  
Fresnel Diffraction ◽  
Crystal Defects ◽  
Bragg Diffraction ◽  
X Rays ◽  
Transmitted Beam ◽  
X Ray ◽  
Diffraction Imaging ◽  
Phase Variations

X-ray imaging started over a century ago. For several decades its only form was absorption radiography, in which contrast is due to local variations in beam attenuation. About forty years ago, a new form of X-ray imagery, Bragg-diffraction imaging or X-ray topography, developed into practical use. It directly reveals crystal defects in the bulk of large single crystals, and paved the way to microelectronics by leading to the growth of large, practically perfect, crystals. The advent of third-generation synchrotron radiation sources of X-rays such as ESRF and APS is now making possible, through the coherence of the X-ray beams, a novel form of radiography, in which contrast arises from phase variations across the transmitted beam, associated with optical path length differences, through Fresnel diffraction. Phase radiography and its three-dimensional companion, X-ray phase tomography, are providing new information on the mechanics of composites as well as on biological materials.

Overview of polycapillary X-ray optics

2002 ◽  
Vol 17 (2) ◽  
pp. 70-80 ◽  
Author(s):  
Paul J. Schields ◽  
David M. Gibson ◽  
Walter M. Gibson ◽  
Ning Gao ◽  
Huapeng Huang ◽  
...  
Keyword(s):  
Focal Spot ◽  
State Of The Art ◽  
Substantial Reduction ◽  
Spot Size ◽  
Source Size ◽  
Total External Reflection ◽  
X Rays ◽  
Focal Spot Size ◽  
Polycapillary Optics ◽  
X Ray

Polycapillary optics are utilized in a wide variety of applications and are integral components in many state of the art instruments. Polycapillary optics operate by collecting X-rays and efficiently propagating them by total external reflection to form focused and parallel beams. We discuss the general parameters for designing these optics and provide specific examples on balancing the interrelations of beam flux, source size, focal spot-size, and beam divergence. The development of compact X-ray sources with characteristics tailored to match the requirements of polycapillary optics allows substantial reduction in size, weight, and power of complete X-ray systems. These compact systems have enabled the development of portable, remote, and in-line sensors for applications in industry, science and medicine. We present examples of the utility and potential of these optics for enhancing a wide variety of X-ray analyses.

Kα2 elimination algorithm for Cu, Co and Cr radiations

1983 ◽  
Vol 16 (1) ◽  
pp. 24-27 ◽  
Author(s):  
G. Platbrood
Keyword(s):  
Calculation Method ◽  
Target Material ◽  
X Ray Diffraction ◽  
Acta Cryst ◽  
X Ray ◽  
Signal Noise ◽  
Elimination Algorithm ◽  
Suitable Target ◽  
Noise Ratio

It is well known that the extraneous Kα 2 line complicates the interpretation of X-ray diffraction spectra. Experience has shown that the arms and weights calculated by Ladell's method [Laddell, Parrish & Taylor (1959). Acta Cryst. 12, 561–567] have to be determined for each user's X-ray diffractometer, rather than using the published coefficients, for an accurate Kα 2 elimination. When different materials are analyzed, the signal/noise ratio can be optimized by choosing a suitable target material. Kα 2 correction coefficients have been calculated for Cu, Co and Cr radiations using a fast Fourier calculation method.

scholarly journals Pixel detectors for diffraction-limited storage rings

2014 ◽  
Vol 21 (5) ◽  
pp. 1006-1010 ◽  
Author(s):  
Peter Denes ◽  
Bernd Schmitt
Keyword(s):  
Synchrotron Radiation ◽  
Storage Ring ◽  
Dynamic Range ◽  
State Of The Art ◽  
Storage Rings ◽  
X Rays ◽  
X Ray ◽  
Current State ◽  
Pixel Detectors ◽  
Radiation Sources

Dramatic advances in synchrotron radiation sources produce ever-brighter beams of X-rays, but those advances can only be used if there is a corresponding improvement in X-ray detectors. With the advent of storage ring sources capable of being diffraction-limited (down to a certain wavelength), advances in detector speed, dynamic range and functionality is required. While many of these improvements in detector capabilities are being pursued now, the orders-of-magnitude increases in brightness of diffraction-limited storage ring sources will require challenging non-incremental advances in detectors. This article summarizes the current state of the art, developments underway worldwide, and challenges that diffraction-limited storage ring sources present for detectors.

Energy-Dispersive X-ray Spectrometry Performance on Multiple Transmission Electron Microscope Platforms

2010 ◽  
Author(s):  
James Demarest ◽  
Chris Deeb ◽  
Thomas Murray ◽  
Hong-Ying Zhai
Keyword(s):  
State Of The Art ◽  
Analytical Tool ◽  
The Other ◽  
Energy Dispersive ◽  
X Rays ◽  
X Ray ◽  
Root Cause ◽  
Analytical Tem ◽  
Transmission Electron ◽  
Multiple Transmission

Abstract Energy-dispersive X-ray spectrometry (EDS) is a key analytical tool aiding root cause determination in the failure analysis (FA) process. This paper looks at a number of analytical TEM microscopes currently in use in various facilities: microscope A, a STEM operated at 200kV; microscope B, a 300kV TEM; and microscopes C and D, both 200kV TEMs. EDS counts per unit time from multiple microscope platforms were examined. Microscope D demonstrated two orders of magnitude higher counts per unit time than the other three microscopes. Microscope D represents the state-of-the-art EDS analytical TEM configuration and has achieved this through a novel windowless EDS configuration which significantly increases the detector area (by about a factor of three) that receives X-rays generated from the sample.

Effect of X-ray Tube Window Thickness on Detection Limits for Light Elements in XRF Analysis

1994 ◽  
Vol 38 ◽  
pp. 299-305
Author(s):  
Daniel J. Whalen ◽  
D. Clark Turner
Keyword(s):  
Light Element ◽  
Detection Limits ◽  
X Rays ◽  
Light Elements ◽  
Absorption Data ◽  
Element Analysis ◽  
X Ray ◽  
Data Compilation ◽  
Beryllium Window ◽  
X Ray Background

Abstract Widespread interest in light element analysis using XRF has stimulated the development of thin x-ray tube windows. Thinner windows enhance the soft x-ray output of the tube, which more efficiently excite the light elements in the sample. A computer program that calculates the effect of window thickness on light element sample fluorescence has been developed. The code uses an NIST algorithm to calculate the x-ray tube spectrum given various tube parameters such as beryllium window thickness, operating voyage, anode composition, and take-off angle. The interaction of the tube radiation with the sample matrix is modelled to provide the primary and secondary fluorescence from the sample. For x-rays in the energy region 30 - 1000 eV the mass attenuation coefficients were interpolated from the photo absorption data compilation of Henke, et al. The code also calculates the x-ray background due to coherent and incoherent scatter from the sample, as well as the contribution of such scatter to the sample fluorescence. Given the sample fluorescence and background the effect of tube window thickness on detection limits for light elements can be predicted.

Observations from the Hinotori mission

1991 ◽  
Vol 336 (1643) ◽  
pp. 339-347 ◽  
Keyword(s):  
Solar Flares ◽  
Bragg Diffraction ◽  
High Dispersion ◽  
X Rays ◽  
Crystal Spectrometer ◽  
Quartz Crystals ◽  
X Ray ◽  
X Ray Imaging ◽  
Imaging Telescope ◽  
First Time

The satellite Hinotori was launched in 1981 by the Institute of Space and Astronautical Science of Japan. Two major experiments on board the Hinotori satellite were a hard X-ray imaging telescope with modulation collimators, and a high dispersion soft X-ray crystal spectrometer utilizing the Bragg diffraction of X-rays on quartz crystals. These two instruments have revealed for the first time that solar flares show varying characteristics depending on the environment of flaring regions, and that flares produce plasmas as hot as 3-4 x 10 7 K.

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