scholarly journals X-Ray Detectors: Present and Future

1996 ◽  
Vol 4 (3) ◽  
pp. 8-9
Author(s):  
Don Chernoff
Keyword(s):  
Trace Elements ◽  
Detection Limit ◽  
Background Radiation ◽  
Signal To Noise Ratio ◽  
Energy Dispersive Spectrometer ◽  
Data Gathering ◽  
X Rays ◽  
Signal To Noise ◽  
X Ray ◽  
Wavelength Dispersive Spectrometer

If you want to collect X-rays on your SEM or TEM you have the choice of using an energy dispersive spectrometer (EDS) or a wavelength dispersive spectrometer (WDS). Which is better? That depends on what you want to do with it.WDS is much more sensitive and has much higher resolution than EDS. Sensitivity means that WDS has a much lower minimum detection limit for trace elements. WDS can be up to several orders of magnitude more sensitive. This does not mean it is more accurate. Accuracy of analysis can be just as good for EDS as with WDS if the analyst takes the same care in sample prep, data gathering, and standardizing. Sensitivity simply means that WDS can detect much smaller amounts of a particular element than EDS. Why? Because the superior resolution provides much better signal to noise ratio than with EDS. Noise, in this case, is mostly contributed by background radiation from the sample. Because of its superior resolution, WDS can also resolve peak overlaps.

Intensity and Distribution of Background X-Rays in a Wavelength-Dispersive Spectrometer. II. Applications

1988 ◽  
Vol 32 ◽  
pp. 83-87
Author(s):  
K. Omote ◽  
T. Arai
Keyword(s):  
Trace Elements ◽  
Spectroscopic Analysis ◽  
Background Intensity ◽  
X Rays ◽  
Correction Procedure ◽  
Minor And Trace Elements ◽  
X Ray ◽  
Powder Samples ◽  
Analytical Accuracy ◽  
Wavelength Dispersive Spectrometer

In the spectroscopic analysis of minor and trace elements by fluorescent X-rays, many improvements in the analytical performance of trace element measurements have been made. For the analysis of trace elements, the background intensity governs the analytical accuracy and the lowest detection limit in a sample. A comparison is made between experimental and theoretically calculated background X-ray intensities in a previous paper. It is based on the formula for scattered X-ray intensity, from the estimation of Thomson and Compton scattered X-rays. Also, the asymmetrical peak profiles at the base of the giant intensity peak are discussed and are clearly shown in the skirt part of K beta X-rays, e.g. , Ni-K beta or Fe-K beta X-rays. The purpose of this report is to investigate the intensity of background X-rays, using glass beads and powder samples of iron oxide and quartz, based on the previous fundamental studies and the overlapping correction procedure for cobalt determination in low-alloy and stainless steel.

Efficient implementation of X-ray ghost imaging based on a modified compressive sensing algorithm

2022 ◽  
Author(s):  
Haipeng Zhang ◽  
Ke Li ◽  
Changzhe Zhao ◽  
Jie Tang ◽  
Tiqiao Xiao
Keyword(s):  
Image Reconstruction ◽  
Compressive Sensing ◽  
Signal To Noise Ratio ◽  
Efficient Implementation ◽  
X Rays ◽  
Ghost Imaging ◽  
Signal To Noise ◽  
X Ray ◽  
Efficient Data ◽  
Reconstruction Time

Abstract Towards efficient implementation of X-ray ghost imaging (XGI), efficient data acquisition and fast image reconstruction together with high image quality are preferred. In view of radiation dose resulted from the incident X-rays, fewer measurements with sufficient signal-to-noise ratio (SNR) are always anticipated. Available methods based on linear and compressive sensing algorithms cannot meet all the requirements simultaneously. In this paper, a method based a modified compressive sensing algorithm called CGDGI, is developed to solve the problem encountered in available XGI methods. Simulation and experiments demonstrated the practicability of CGDGI-based method for the efficient implementation of XGI. The image reconstruction time of sub-second implicates that the proposed method has the potential for real time XGI.

Quantitative measurement of crystalline impurity in a pharmaceutical tablet by X-ray powder diffraction and method validation

2013 ◽  
Vol 28 (3) ◽  
pp. 222-230
Author(s):  
R. Casella ◽  
S. Boudreau ◽  
James A. Wesley ◽  
Robert D'Aloise
Keyword(s):  
Detection Limit ◽  
Relative Humidity ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
X Ray ◽  
Pharmaceutical Tablet ◽  
Quantitation Limit ◽  
Sample Stability ◽  
Noise Ratio ◽  
Sample Packing

A powder X-ray diffraction method was developed and validated to measure the crystalline impurity 4-(5-cyclopentyloxy-carbonylamino-1-methyl-indol-3-ylmethyl)-3-methoxy-N-o-tolylsulfonylbenzamide hydrate in a pharmaceutical tablet ranging from 0.6 to 3% (w/w). The calibration plot was found to be linear with a correlation coefficient (r2) of 0.996, and was reproducible among operators. The detection limit was determined to be 0.6% with a signal-to-noise ratio of 3:1. The quantitation limit was determined to be 1% with a signal-to-noise ratio of 5:1. Instrument precision at the quantitation limit was 5.8%. Method precision was 6.1% at the quantitation limit and 7.4% at the detection limit. Intermediate precision at the quantitation limit was 7.3% during a 6-month study. Accuracy measurements using crystalline impurity standards prepared in an excipient mixture ranged from 89.3 to 105.5%. Accuracy measurements using tablets containing spiked quantities of crystalline impurity ranged from 72.0 to 92.7%. Accuracy measurements using spiked tablets were complicated because the crystalline impurity was lost during the manufacturing process and a correction factor was used. Ruggedness was assessed by evaluating repetitive assay, repetitive packing, sample packing, and sample stability. Repetitive assays show the exposure of standards to a relative humidity in excess of 57% caused displacement error because of an increase in sample volume and a peak-position shift. Repetitive-packing studies show the analyte was extracted from the sample at a low relative humidity because of a static-charge induction. Sample-packing studies show that two subjective packing techniques were equivalent, and that under- and over-packing samples cause changes in sample density which would not affect results within ±16%. Sample-stability studies show that the quantitation-limit standard was stable as long as the sample was exposed to a relative humidity below 57%.

scholarly journals High Spatial Resolution in X-Ray Fluorescence

1986 ◽  
Vol 30 ◽  
pp. 77-83
Author(s):  
John D. Zahrt
Keyword(s):  
Spatial Resolution ◽  
Amorphous Materials ◽  
High Spatial Resolution ◽  
Signal To Noise Ratio ◽  
Bragg Angle ◽  
X Rays ◽  
Bremsstrahlung Radiation ◽  
Signal To Noise ◽  
X Ray ◽  
The Past

During the past eight years or so there has been growing interest in using a polarized x-ray source in energy dispersive x-ray fluorescence spectrometers (1,2,3,4). The effect is to annihilate the source x rays before they scatter into the detector, thus significantly increasing the signal to noise ratio.Both characteristic or Bremsstrahlung radiation can be polarized by 90° scattering from crystals (Bragg angle = 45°) or from amorphous materials respectively. This 90° polarizing scatter event greatly reduces the incident source radiation on a sample. In an effort to regain some intensity use is made of concave surfaces to utilize a manifold of beams (5,6,7).

IMPROVEMENT OF THE DETECTION EFFICIENCY OF THE IN-AIR SUBMILLI-PIXE CAMERA FOR BIOLOGICAL APPLICATIONS

2012 ◽  
Vol 22 (01n02) ◽  
pp. 37-43
Author(s):  
H. SUGAI ◽  
K. FUJIKI ◽  
K. ISHII ◽  
S. MATSUYAMA ◽  
A. TERAKAWA ◽  
...  
Keyword(s):  
Detection Limit ◽  
Detection Efficiency ◽  
Detection System ◽  
Heavy Elements ◽  
X Rays ◽  
Biological Applications ◽  
Geometrical Configuration ◽  
Signal To Noise ◽  
X Ray

The detection efficiency of the submilli-PIXE camera was improved by installing a new X-ray detector with a smaller distance from specimens. The distortion of elemental images caused by position dependent detection efficiency was corrected by estimating the detection efficiency based on the geometrical configuration of the detection system. The detection efficiency of characteristic X-rays from heavy elements such as iron and bromine became from 11 to 23 times higher than the previous system. The signal to noise ratios was improved from 1.8 to 2.5 times higher and detection limit was also decreased from 1/8 to 1/6 compared to the previous system. The in-air submilli-PIXE camera with improved detection system can be useful to biological applications.

Polarization of X-Rays by Scattering from the Interior of a Cylinder

1983 ◽  
Vol 27 ◽  
pp. 505-511
Author(s):  
John D. Zahrt ◽  
Richard Ryon
Keyword(s):  
Trace Elements ◽  
Field Vector ◽  
X Rays ◽  
Electric Field Vector ◽  
Concomitant Increase ◽  
Signal To Noise ◽  
X Ray ◽  
Experimental Problem ◽  
Reduced Intensity ◽  
Secondary Fluorescence

It is of interest today to use polarized X-rays in X-ray secondary fluorescence as a means of improving signal to noise ratios in the analysis of trace elements. Current experimental design makes use of two mutually perpendicular scatterings from plane parallel materials. Radiation with the electric field vector in the scattering plane (scattering angle = 90°) will be annihilated. Hence, after the mutually orthogonal, 90° scatterings no source X-rays should reach the detector. In practice source X-rays will only be greatly reduced at the detector due to such things as multiple scatter and collimator divergence. An experimental problem associated with this design however is the reduced intensity of the signal because of the scatterings with concomitant increase in analysis time.

Miniature diamond anvils for X-ray Raman scattering spectroscopy experiments at high pressure

2017 ◽  
Vol 24 (1) ◽  
pp. 276-282 ◽  
Author(s):  
Sylvain Petitgirard ◽  
Georg Spiekermann ◽  
Christopher Weis ◽  
Christoph Sahle ◽  
Christian Sternemann ◽  
...  
Keyword(s):  
High Pressure ◽  
Raman Scattering ◽  
Signal To Noise Ratio ◽  
High Energy ◽  
X Rays ◽  
Signal To Noise ◽  
X Ray ◽  
Custom Made ◽  
Diamond Anvils ◽  
Noise Ratio

X-ray Raman scattering (XRS) spectroscopy is an inelastic scattering method that uses hard X-rays of the order of 10 keV to measure energy-loss spectra at absorption edges of light elements (Si, Mg, Oetc.), with an energy resolution below 1 eV. The high-energy X-rays employed with this technique can penetrate thick or dense sample containers such as the diamond anvils employed in high-pressure cells. Here, we describe the use of custom-made conical miniature diamond anvils of less than 500 µm thickness which allow pressure generation of up to 70 GPa. This set-up overcomes the limitations of the XRS technique in very high-pressure measurements (>10 GPa) by drastically improving the signal-to-noise ratio. The conical shape of the base of the diamonds gives a 70° opening angle, enabling measurements in both low- and high-angle scattering geometry. This reduction of the diamond thickness to one-third of the classical diamond anvils considerably lowers the attenuation of the incoming and the scattered beams and thus enhances the signal-to-noise ratio significantly. A further improvement of the signal-to-background ratio is obtained by a recess of ∼20 µm that is milled in the culet of the miniature anvils. This recess increases the sample scattering volume by a factor of three at a pressure of 60 GPa. Examples of X-ray Raman spectra collected at the OK-edge and SiL-edge in SiO2glass at high pressures up to 47 GPa demonstrate the significant improvement and potential for spectroscopic studies of low-Zelements at high pressure.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

High spatial resolution x-ray microanalysis of interfaces

1995 ◽  
Vol 53 ◽  
pp. 284-285
Author(s):  
J. R. Michael
Keyword(s):  
Spatial Resolution ◽  
Electron Probe ◽  
Solid Angle ◽  
Collection Efficiency ◽  
Spatial Scales ◽  
Energy Dispersive Spectrometer ◽  
X Rays ◽  
X Ray ◽  
Probe Size ◽  
Brightness Field

X-ray microanalysis in the analytical electron microscope (AEM) refers to a technique by which chemical composition can be determined on spatial scales of less than 10 nm. There are many factors that influence the quality of x-ray microanalysis. The minimum probe size with sufficient current for microanalysis that can be generated determines the ultimate spatial resolution of each individual microanalysis. However, it is also necessary to collect efficiently the x-rays generated. Modern high brightness field emission gun equipped AEMs can now generate probes that are less than 1 nm in diameter with high probe currents. Improving the x-ray collection solid angle of the solid state energy dispersive spectrometer (EDS) results in more efficient collection of x-ray generated by the interaction of the electron probe with the specimen, thus reducing the minimum detectability limit. The combination of decreased interaction volume due to smaller electron probe size and the increased collection efficiency due to larger solid angle of x-ray collection should enhance our ability to study interfacial segregation.

XRMF applications of a monolithic, polycapillary, focusing x-ray optic

1996 ◽  
Vol 54 ◽  
pp. 240-241
Author(s):  
D. A. Carpenter ◽  
Ning Gao ◽  
G. J. Havrilla
Keyword(s):  
Trace Elements ◽  
Point Source ◽  
Focal Spot ◽  
Fluorescence Analysis ◽  
X Rays ◽  
Focal Distance ◽  
Spot Diameter ◽  
X Ray ◽  
Focal Spot Diameter

A monolithic, polycapillary, x-ray optic was adapted to a laboratory-based x-ray microprobe to evaluate the potential of the optic for x-ray micro fluorescence analysis. The polycapillary was capable of collecting x-rays over a 6 degree angle from a point source and focusing them to a spot approximately 40 µm diameter. The high intensities expected from this capillary should be useful for determining and mapping minor to trace elements in materials. Fig. 1 shows a sketch of the capillary with important dimensions.The microprobe had previously been used with straight and with tapered monocapillaries. Alignment of the monocapillaries with the focal spot was accomplished by electromagnetically scanning the focal spot over the beveled anode. With the polycapillary it was also necessary to manually adjust the distance between the focal spot and the polycapillary.The focal distance and focal spot diameter of the polycapillary were determined from a series of edge scans.

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