bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Plasma Controlled X-Ray Tube
Authors: McGee James F. , Saha Timo 
Published: March 2019

AbstractMany x-ray tubes, used by crystallographers and others, operate with the aid of a tungsten filament in the region of 2500°K, The high operating temperature results in evaporation of the filament material with two serious consequences. The first is a finite but relatively short lifetime. The second is contamination of the target and windows with tungsten. In addition, if the tube is of the demountable type, connected to an oil-diffusion pump and a mechanical fore-pump, carbonaceous deposits can be a problem. In a typical tube, the filament is mounted within a centimeter or two of the target. The resulting radiant heating of the target presents additional cooling problems especially with low melting-point targets. Many if not all of the above objectional features are circumvented by a plasma controlled x-ray tube using a low pressure atmosphere of helium and a cage-like cathode fabricated from nickel wire-mesh. An experimental model has been operated for several hours at 15 kv and 10 ma on an aluminum target. Scaling up of the apparatus will permit power dissipations in the kilowatt range limited mainly by the available power source or vaporization of the target material.
X-Ray Emission from High-Temperature Laboratory, Plasmas
Authors: Nagel D. J. 
Published: March 2019

AbstractThe radiation from plasmas hotter than 106K falls in the x-ray region. Such plasmas are required for fusion power generation. They can also be used as x-ray sources. Measurements of x-ray emission from high temperature plasma yields (a) diagnostic information on the plasma conditions and (b) the characteristics of plasma x-ray sources which determine their applications. Hence, measurements of x-rays from plasmas are finding widespread use.
Determination of Actinide Elements in Nuclear Fuels by X-Ray Analysis
Authors: von Baeckmann A.H.E. , Ertel D. , Neuber J. 
Published: March 2019

AbstractX-ray fluorescence analysis has been used for some years at two Institutes of the Karlsruhe Nuclear Research Center to determine routinely thorium, uranium, and plutonium in unirradiated and irradiated nuclear fuels. It has "been used in addition to assay neptunium, americium and curium contained in irradiated samples. The method excels because it is versatile, rapid, tamperproof, and efficient. As a rule, fission products, pollutions, and foreign activities do not interfere with the determination which can be made in a direct way without chemical separation. In practice, the nuclear fuels are dissolved prior to the analysis and a given amount of an appropriate element as an “internal standard” is added. The accuracies attainable (1 σ RSD better than 1 %) are comparable with the mass spectrometric isotope dilution analysis so that in the input analysis of reprocessing plants X-ray fluorescence analysis constitutes a true alternative to the mass spectrometric isotope dilution analysis.Within the efforts to automate the method the prototype of the fully automated system is presently tested with non-active material. A first, not yet fully automated, development stage is being installed in the Karlsruhe Reprocessing Plant. It is anticipated that it will be tested soon under operating conditions. Complete automation of the system is scheduled to be completed at a later date.
X-Ray Fluorescence Experiments with Polarized X-Rays*
Authors: Howell R. H. , Pickles W. L. , Cate J. L. 
Published: March 2019

AbstractTwo methods of obtaining polarized x-rays for fluorescence experiments are discussed. Compton scattering from a low-Z scatterer is the usual method used in such experiments. The polarization of x-rays undergoing anomalous Borrmann transmission in a dislocation-free crystal is also described and preliminary results are presented. Approximate expressions, useful for comparing scatter-polarizing systems, are derived for the dependence of scatter rejection and fluorescent efficiency on two scattering-system parameters: the thickness of the scattering polarizer and the geometric limit to solid angles and angular divergences in the system.
Proton Induced X-Ray Fluorescence Analysis Using a Cockcroft-Walton Accelerator
Authors: Bales D. I. , Landolt R. R. , Toll W. E. 
Published: March 2019

AbstractThe production of characteristic x rays by 100-keV protons has been studied to determine the feasibility of using a Cockcroft- Walton accelerator as an excitation source for x ray fluorescence analysis. Because of the low cross sections at this proton energy, it was necessary to concentrate on characteristic x rays below 6 keV and to use beam currents of 10 to 100 μA. The x rays were measured by a high resolution Si(Li) detector.The preparation of various types of samples and the problems that arise when working at low proton energies and high beam currents are discussed.It was found that the technique is useful for low atomic number elements down to less than 1 ppm in a water sample when there are no other significant impurities. When other elements are present, however, proton absorption becomes an important factor and quantitative determinations become very difficult. Proton absorption and its effect upon the usefulness of the technique are discussed.The precision for the technique was determined and found to be better than 20% for most measurements. This includes errors in sample preparation which was considered to be a significant portion of the uncertainty.
Quality Control Through Determination of Interelement Effects in Iron-Gadolinium-Yttrium Solutions Using X-Ray Secondary Emission
Authors: Magathan E. M. , Short D. W. , Yocom R. L. 
Published: March 2019

AbstractAn analytical quality control procedure using x-ray Secondary Emission Spectrometry has been developed to monitor iron, yttrium, and gadolinium metal ion ratios in feed stock solutions. Binary and ternary laboratory standard solutions were analyzed to determine absorption and enhancement effects using approaches suggested by Rasberry-Heinrich, Beattie-Brissey, and Claisse-Quintin. A computation scheme combining these methods is presented which enables the user to improve his ability to predict composition. This approach has yielded relative errors of less than 1.0% for each of the three metals studied.
Charged Particle Induced X-Ray Analysis of Malaria Infected Blood
Authors: Barnes B. K. , Coleman R. M. , Kegel G. H. R. , Quinn P. W. , Rencricca N. J. 
Published: March 2019

AbstractBlood samples from normal and Plasmodium berghei infected mice are being analyzed for trace elements by charged particle induced x-rays. Approximately 0.25 ml of the sample (whole blood, washed red cells, or plasma) is dry ashed. The ashes are mounted on a 0.003 inch Kapton foil. The analysis is performed by bombardment of the samples by a beam of 2.0 MeV protons and detection of the characteristic x-rays by a 175-eV-resolution lithium-drifted silicon detector. The data are analyzed by an on-line PDP-9 computer-based data acquisition system. Results indicate an increase in the K, Ca, Cu, and Zn per unit volume of the red cells of the malaria infected mice relative to the amounts measured for uninfected blood, and a decrease in the K, Ca, and Fe and an increase in the Cu per unit volume in the plasma of the infected mice.
A Multiple Regression Procedure for Elemental Analysis at Low Concentrations
Authors: Mencik Z. , Berneburg P. L. , Short M. A. 
Published: March 2019

AbstractUsing a multiple regression procedure, X-ray fluorescence analysis has been applied to a 15-element system associated with ceramic supported automobile emissions catalysts. An equation taking inter-element effects into account was used to relate the concentrations and X-ray intensities of the active elements and contaminants deposited on the ceramic substrate. The major elements present in the substrate were intentionally excluded from the regression. The regression coefficients were determined from a set of 240 calibration standards using a multiple linear least-square regression. Elemental concentrations in the standards ranged from 0.05 to ten weight percent. The ceramic matrix was the same in both the standards and the unknowns to be analyzed and constituted at least 85 percent of the total weight of each sample. The regression coefficients were then used to solve for the contents of the elements in unknown samples. Limits of accuracy were determined by using the set of available standards. The performance of the regression was improved in certain cases by imposing constraints on the regression.
A High Intensity, Monochromatic, Spatially Coherent X-Ray Source
Authors: Burns S. J. 
Published: March 2019

AbstractAn x-ray source is described that can have high brilliance, monochromaticity and spatial coherence. This source filters, by successive diffraction, spontaneous x-ray radiation produced by electron impact in a Bonse-Hart monolithic crystal monochromater. A germanium single crystal was grooved to form a monolithic monochromater and subsequently was fitted with a filament. Field emitted electrons from the filament impact on the crystal side walls. Thus, the passive Bonse-Hart monochromater is converted into an active x-ray source. The detailed diffraction geometry within the cavity, in the limit of kinematic diffraction theory, is described and compared to the experimentally observed radiation pattern. Since this radiation source achieves its monochromaticity and spatial coherence by filtering it is highly inefficient. However, the diffraction process is highly efficient when the radiation is in the proper geometric direction to satisfy Bragg's law. Thus, the stationary radiation source can have a high brilliance although the input of electrical energy could be well in excess of a rotating anode x-ray tube.
Crystallite Orientation Analysis from Incomplete Pole Figures
Authors: Morris Peter R. 
Published: March 2019

AbstractThe use of incomplete pole figures results in the loss of orthogonality relations among the associated Legendre functions, and necessitates explicitly evaluating integrals of products of these functions. The required indefinite integrals of associated Legendre functions and their products have been evaluated for cubic crystallographic symmetry and orthotropic physical symmetry through sixteenth order.The solution has been particularized for {200}, {222}, and {110} back-reflection pole figures, where data are confined to the region not exceeding 60 degrees from the sheet normal direction.Data obtained from a sample of low—manganese steel sheet are used to illustrate the method, and results are compared to those obtained using complete pole figures obtained with a composite sample of the same material.The method described makes it possible to study crystallite orientation distribution as a function of distance from the sheet surface, by a series of pole figure measurements on the surface after successive material removals by polishing and etching.
Bone Mineral (Apatite) Assay by Photon Scattering - A Survey of Sources and Experimental Evaluation
Authors: Preuss Luther E. , Piper Dennis G. , Bugenis Claudius 
Published: March 2019

AbstractCurrent methods of measuring bone mineral content In vitro are either inaccurate or measure density in non-intuitive units. A recently developed system overcomes these difficulties by utilizing the Compton scattering of photons from bone. Two sources of monoenergetic photons with related properties are required. The range includes energetic x-rays and low energy gamma rays. This study analyzes a number of the possible nuclide source combinations, and reports experimental results accomplished with a 153Gd-170-Tm combination. In vitro measurement of the density of ox bones by this method agreed with Archimedean measurements within three percent.
Microprobe Analysis of Soil Erosion Aerosols
Authors: Gitlin Sonia N. 
Published: March 2019

AbstractPure standards of molybdenum disulfide, silver, and calcium silicide particles 0.5 μm in diameter and larger, were used to obtain calibration curves for size effect on x-ray intensities. The decrease in intensity with size follows a straight line down to about 3 μm. For the smaller sizes the intensities decrease exponentially. Good agreement has been found between curves calculated using simplified models of diffusion volumes intercepted by the particles and curves of measured x-ray intensities.The intensity versus size was plotted as a percentage of the intensity of a flat, infinite standard. Therefore, the number of counts measured for a sample of known size can be converted to the intensity it would have if it were an infinite surface. These values can then be plugged into existing computer programs for quantitative analysis. Samples of atmospheric aerosols were analyzed by using these calibration curves.
Crystallinity, Crystallite Size and Lattice Perfection in Fibrous Polymers
Authors: Johnson D. J. 
Published: March 2019

The X-ray diffraction patterns from fibrous polymers are generally characterized by a small number of relatively broad overlapping peaks often overlaid with a diffuse halo. Single fibres give the same pattern as a parallel bundle of fibres, so that the pattern is equivalent to the rotation pattern of a single crystal. Despite the inherent difficulty of insufficient well-defined reflections, all commercially useful fibres have been indexed, starting with cellulose, through nylon 66 and polyester, to the more recent fibres, such as Nomex and Kevlar. Only the structural complexities of the natural fibres of keratin (wool and hair) remain to be fully determined.Many sophisticated computations have been carried out to refine unit-cell constants; unfortunately, much of this work is of doubtful value to those interested in fibre characterisation. Fibres are semicrystalline materials and their molecules are insufficiently well ordered for precision calculations of atomic positions. Indeed, there can be significant error involved in evaluating unit-cell constants from overlapping peaks, unless precise profile resolution is carried out.
Reproducibility and Precision of Measurements of Guinier Powder Patterns Using Powdered Silicon Calibrant
Authors: Brown A. , Edmonds J. W. , Foris C. M. 
Published: March 2019

AbstractCalibrated powder patterns of a number of high symmetry crystalline materials were recorded in three different Guinier-type focusing cameras. The films were then measured by three different techniques, one visual and two instrumental. Cell parameters were calculated by three different data reduction procedures. The aim of the work was to establish the level of reproducibility for cell parameters obtained in routine work with these instruments.
Time-Resolved X-Ray Powder Diffractometry Using Lihear Position-Sensitive Proportional Counters
Authors: Göbel Herbert E. 
Published: March 2019

AbstractSeveral examples of time-resolved X-ray powder diffraction studies with linear position-sensitive proportional counters (PSPC) are described. The changing patterns are recorded by spectrum multiplexing in a multichannel counter device. The time resolution for single processes is limited to seconds or tenths of seconds mainly because of the counting statistics of the observed peaks. Repetitive processes, however, where the interesting peaks can be accumulated over a large number of periods, permit much higher time resolution. It is finally determined by the timing of a detected X-ray quantum. Using a continuous beam source like a conventional X-ray tube the incidence of a photon into the PSPC can be timed with an accuracy of 20 ns (fwhm). A pulsed synchrotron radiation source, like a storage ring, will be able to define this resolution to its pulse duration, which is less than 200 ps.Before approaching those limits this paper presents the high temperature phase transformations in iron for different steel specimens as an example of single processes. It also discusses domain-wall effects and electrostriction in ferroelectric perovskites as a function of polarization at frequencies of up to 10 Hz, and elastic lattice distortions of a steel sheet vibrating at about 200 Hz. The timing limit of 20 ns for the PSPC detection system was measured at the storage ring DORIS at DESY, Hamburg.
The Application of an Automated Single Crystal Orienter for Large Specimens
Authors: Karg A. V. , Walsh J. M. , LaGrotta J. M. 
Published: March 2019

AbstractA special purpose, automated, four circle goniometer arrangement has been developed for the rapid orientation of large specimens of single crystal turbine hardware. This system rapidly establishes the complete orientation of these large components and generates a fully documented stereographic projection. The system is also capable of generating detailed information on crystal quality including rocking curves in several dimensions. X, Y translational capability of the specimen makes it possible to characterize crystallographic defects such as sub-grain boundaries.
X-Ray Fluorescence Analysis of High Z Materials with Mercuric Iodide Room Temperature Detectors
Authors: Nissenbaum J. , Holzer A. , Roth M. , Schieber M. 
Published: March 2019

AbstractMercuric iodide HgI2 room temperature solid state radiation spectrometers having 4% energy resolution at 100 KeV detected the x-ray fluorescence (XRF) of the K shell of intermediate and high Z elements. The excitation of the K shells which emit XRF more energetic than 60 KeV was achieved with 7mCi collimated 57Co and for XRF less energetic than 60 KeV the excitation was done with a 10mCi 241Am source. The K shell XRF spectra of a 1:1 mixture of U and Th, and also of the single elements of Au, Tb, Ba, Ag, Mo, and Rb are shown. The results prove the feasibility of developing mercuric iodide portable XRF spectrometers which operate at room temperature and which have a wide range of geochemical and industrial applications.
Multiple Scattering and the Polarization of X-Rays
Authors: Zahrt John D. , Ryon Richard 
Published: March 2019

In order to improve the overall performance of energy dispersive x-ray secondary emission spectrometry one can make use of polarized x-rays. We have used polarized x-rays produced by 90° scattering to reduce the background intensity due to the primary x-ray source.An effort has been made to optimize the polarizing scatterer for the elements being analyzed. A discrepancy appears in the theory of such optimization between a simple one point formula and a more elaborate integral formula. Possible reasons for such disparities might lie in 1) collimator geometric effects, 2) multiple scattering and 3) actual primary intensity. The first problem has been dealt with in an unpublished manuscript. This report concerns itself with point 2, multiple scatter, and in particular with double scatter including polarization effects.
Advances in Low-Energy Electron-Induced X-Ray Spectroscopy (LEEIXS)
Authors: Bador René , Romand Maurice , Charbonnier Marlène , Roche Alain 
Published: March 2019

AbstractUsing low-energy electron induced X-ray spectroscopy (LEEIXS) with a cold cathode tube as excitation source and appropriate calibrations, quantitative surface composition informations are obtained. The results concern anodic film thicknesses and carbon impurities, In addition, qualitative informations on the chemical state of the film components are deduced from the fine structure of X-ray emission bands. The results concern oxygen K emission spectra from CuO and Cu2O, SnO, SnO2 and anodized Sn. It is also shown the capabilities of LEEIXS for gaining element-depth profiles, One example pertaining to phosphorus impurities in Al2O3 anodic films is given. Finally advantages and disadvantages of LEEIXS over ion-induced X-ray spectroscopy are discussed.
Leveling Device for Forming X-Ray Specimen
Authors: Won Vann Y. 
Published: March 2019

A device was made for preparing accurate definition of surface, depth and volume of liquid x-ray fluorescence specimens.The apparatus used in conjunction with a specimen holder and plastic film window material accurately and consistently forms a flat bobble-free analysis window on the open face of the specimen holder. The specimen holder in the form of a shallow cylinderical cup is slightly over filled and covered by the plastic film. Placement of the mating leveling apparatus over the film squeezes out trapped air bubbles, levels the exposed face of the specimen, draws the plastic film tightly over the exposed face of the specimen and allows easy installation of a film retaining O-ring to maintain the specimen material in a level state within the holder.
Monte Carlo Determinations of Optimal Photon Energies for XRF Analysis of Iodine In Vivo
Authors: Grönberg T. , Mattsson S. 
Published: March 2019

After the pioneering work of HOFFER et al. on fluorescent scanning of natural iodine in the thyroid, several authors have suggested the use of X-ray fluorescence analysis to follow in vivo the distribution and elimination of stable tracers injected prior to the investigation. The normal method of performing such studies is to inject iodine containing contrast media and then follow the variation in iodine concentration by in vivo measurements over the organ or tissue of interest.A theoretical treatment of the application of X-ray fluorescence in in vivo studies has been made by TINNEY by means of analytical calculations.
Analysis of Refractory Metals and WC-Based Hard Metals by Energy Dispersive X-Ray Fluorescence
Authors: Wegscheider Wolfhard , Müller Kurt , Ortner Hugo M. 
Published: March 2019

AbstractThe potential of energy-dispersive X-ray fluorescence spectrometry for analysis of refractory metals and WC-based hard metals is investigated. Both, photon excitation by filtered tube radiation and by the characteristic, lines of a secondary target are employed. Both excitation systems give good results. If the counting times are adjusted to account for the lower sensitivity of energy dispersive as opposed to wavelength dispersive X-ray spectrometry the detection limit and precision data are comparable. The multielement analyses of interest in these applications that comprise an energy range of 5 keV or more are better handled by direct excitation with filtered tube radiations than either by secondary target excitation or by wavelength dispersive X-ray spectrometry.
A Rapid and Precise Computer Method for Qualitative X-Ray Fluorescence Analysis
Authors: Huang T. C. , Parrish W. , Ayers G. L. 
Published: March 2019

AbstractThis paper describes a computer method for wavelength dispersive (WD) qualitative X-ray fluorescence (XRF) analysis. It determines the elements, spectral lines, wavelengths, reflection angles and peak intensities of the first and second order reflections in less than half a minute of time using an IBM Series/1 minicomputer. The resolution and precision are significantly better than the energy dispersive (ED) method and when combined with high speed computer recording the speed is comparable.
Monte Carlo Studies on the Design of Radioisotope Source Holders and Shields for EDXRF Analyzers
Authors: Doster J. M. , Gardner R. P. 
Published: March 2019

AbstractInherent in the use of radioisotope sources with secondary fluorescers is the background produced by scattering of the source photons from the exciter system. A Monte Carlo program has been developed that is capable of simulating the backscattered photon spectrum as a function of the system geometry, including shielding and collimation variations. This computer program generates the scattered photon spectrum incident on both the sample and detector. The program is applied to a commercially available exciter system to study the effect of specific geometric design changes on the scattered spectrum.