X-ray Detectors: Pulse Height Shifts, Escape Peaks and Counting Losses

1990 ◽  
Vol 34 ◽  
pp. 319-324
Author(s):  
Michael A. Short
Keyword(s):  
Data Processing ◽  
Pulse Height ◽  
Fluorescence Analysis ◽  
Operating Characteristics ◽  
X Ray ◽  
Computer Based ◽  
Computer Controlled ◽  
Computerized Data Processing

With the ever increasing emphasis on computer-controlled hardware, computerized data processing and computer-based display of results, there is a tendency to forget the operating characteristics of some of the older, more mundane, components of X-ray diffractometers and X-ray fluorescence analysis units. We place our trust in the specifications of the components supplied by the equipment manufacturers and, while usually complete, it nevertheless behooves us to be well aware of the operation of the various hardware components of diffractometers and spectrometers.

scholarly journals Determination of Calcium in Wolframite Concentrates by Fluorescent X-Ray Spectrography

1958 ◽  
Vol 2 ◽  
pp. 313-332 ◽  
Author(s):  
William J. Campbell ◽  
John W. Thatcher
Keyword(s):  
Gas Flow ◽  
Position Effect ◽  
Pulse Height ◽  
Calcium Content ◽  
Accurate Method ◽  
Counting Efficiency ◽  
Matrix Composition ◽  
Operating Characteristics ◽  
X Ray ◽  
Small Depth

AbstractThe purpose of this investigation was to develop a rapid, accurate method of analysis for small amounts of calcium in wolframite concentrates. This analysis is necessary to determine if wolframite concentrates meet the U. S. National Stockpile Specification P-57R2, which limits the calcium content to 0.2 per cent.Because of the small depth of sample analyzed in fluorescent x-ray spectrography the calcium Kα line intensity was found to be a function of the chemical composition of the calcium-bearing particle as well as the matrix composition. This particle-conn position effect was particularly important in this analysis because the calcium may be present as a carbonate, tungstate, phosphate, etc. Three methods of sample preparation were found to eliminate the variation of calcium Kα intensity with mineralogical occurrences: (1) Reduction in particle size by extensive grinding, (2) chemical fusion wtli sodium carbonate, and (3) solution of the calcium by an add.Determinations by all three procedures are believed to be accurate to within ± 5 per cent for more than 0.30 per cent calcium and ± 10 per cent at the 0.1-per cent level. The lower limit of detectability is in the order of 0.005-0.01 per cent.The operating characteristics of a gas-flow proportional counter used in conjunction with a pulse-height analyzer were studied in detail. This detector was found to have a high counting efficiency for calcium Ka radiation, to have a low counting efficiency for overlapping higher order radiation and to have counting stability equivalent to Geiger tubes.

Pulse-Height Selection in X-Ray Fluorescence

1960 ◽  
Vol 4 ◽  
pp. 370-381
Author(s):  
Kurt F.J. Heinrich
Keyword(s):  
Energy Levels ◽  
Pulse Height ◽  
Fluorescence Analysis ◽  
Higher Order ◽  
Pulse Height Analyzer ◽  
X Ray ◽  
Qualitative And Quantitative ◽  
Systematic Application ◽  
Pulse Height Analysis ◽  
Qualitative Work

AbstractPulse-height analysis is a valuable tool in X-ray fluorescence analysis, both for qualitative and quantitative purposes. The elimination of higher order interferences permits determinations that would otherwise be very difficult or impossible, The systematic application of pulse-height analysis in qualitative work greatly simplifies the interpretation of complex spectra. In certain cases one can apply nondispersive analysis, relying on the pulse-height analyzer alone for separating energy levels of X-ray photons. Technique and limitations of pulse-height analysis will be discussed.

A Non-Dispersive X-ray Fluorescence Unit for the Analysis of Biological Tissue Sections

1957 ◽  
Vol 1 ◽  
pp. 297-313
Author(s):  
Theodore Hall
Keyword(s):  
Proportional Counter ◽  
Biological Tissue ◽  
Matrix Effects ◽  
Pulse Height ◽  
Fluorescence Analysis ◽  
Mineral Elements ◽  
X Ray ◽  
Tissue Sections ◽  
Characteristic Lines ◽  
Secondary Radiator

AbstractAn X-ray fluorescence analysis unit has been designed and built especially for the measurement of certain mineral elements in individual biological tissue sections. Such a section may contain in the neighborhood of 10-10 grams of an element of interest, in a concentration in the range of 1-100 p.p.m.The unit consists of a special high-power X-ray tube with a builtin interchangeable secondary radiator, which irradiates the speciman with the characteristic lines of the radiator element) and a proportional counter and pulse-height analyzer system, which provides analysis of the X-ray spectrum emitted by the specimen. Because the emitted spectrum is greatly simplified by the use of an appropriate radiator element, a diffracting crystal can be omitted, permitting a great increase in absolute sensitivity.The system is feasible only because of two peculiarities of our biological specimens: they are so thin that matrix effects are negligible, and they consist essentially of a few mineral elements in a light matrix.Design considerations, calibration procedures, procedures for the analysis of the observed proportional counter pulse-height spectra and results to date will be discussed.

Computerized data processing from an X-ray texture-goniometer

1969 ◽  
Vol 37 (287) ◽  
pp. 428-430 ◽  
Author(s):  
P. B. Attewell ◽  
J. W. Aucott ◽  
A. S. Burgess
Keyword(s):  
Data Processing ◽  
X Ray ◽  
Computerized Data Processing

Use of a New Versatile Interactive Regression Analysis Program for X-Ray Fluorescence Analysis

1978 ◽  
Vol 22 ◽  
pp. 375-384 ◽  
Author(s):  
W. N. Schreiner ◽  
R. Jenkins
Keyword(s):  
Regression Analysis ◽  
Fluorescence Analysis ◽  
Mass Storage ◽  
Analysis Program ◽  
Correction Model ◽  
X Ray ◽  
Line Intensities ◽  
The Past ◽  
Computer Controlled ◽  
Measured Line

XRF can be a powerful tool for quantitative elemental analysis-it can also be a big headache. The problem is, of course, that to perform a proper quantitative analysis one needs to first develop a good matrix correction model to convert the measured line intensities to concentrations. For empirical models, aside from the inherent difficulties in optimizing a set of interelement correction coefficients, the commercially available computer controlled spectrometers have in the past either provided rather poor regression analysis programs with their software or none at all. The reason for this has been the rather limited core size of the online computer and the lack of fast efficient mass storage facilities such as floppy disks.

Sodium and Magnesium Fluorescence Analysis—Part I: Method

1962 ◽  
Vol 6 ◽  
pp. 361-376 ◽  
Author(s):  
Burton L. Henke
Keyword(s):  
Atomic Number ◽  
Proportional Counter ◽  
High Intensity ◽  
Pulse Height ◽  
Fluorescence Analysis ◽  
Aluminum Foil ◽  
Incident Radiation ◽  
Line Radiation ◽  
X Ray ◽  
Beam Collimation

AbstractAs is well known, the fluorescent yield decreases very rapidly with the atomic number with the result, for example, that sensitive sodium and magnesium analysis is extremely difficult if not impossible with conventional X-ray spectrographs. It is demonstrated, however, that analysis for sodium and magnesium can be accomplished with sensitivity comparable to that conventionally obtained for elements such as aluminum, silicon, and phosphorous, providing that the conditions for excitation and measurement of the associated soft X-radiations are optimized, A high-intensity demountable tube using an aluminum anode has been developed which can be used interchangeably with the conventional spectrographic X-ray source. This provides a large amount of incident radiation, aluminum foil filtered, optimally close in wavelength to that of the line radiation being excited. A gypsum analyzing crystal is used along with greatly reduced beam collimation. The standard flow proportional counter and pulse height discrimination is employed. An appropriate filter, such as aluminum foil, is used as a window for the counter1 to provide further discrimination and enhanced signal-to-background ratio.

X-Ray Fluorescence Analysis of Stainless Steels and Low Alloy Steels Using Secondary Targets and the Exact Program

1978 ◽  
Vol 22 ◽  
pp. 325-335 ◽  
Author(s):  
J. C. Harmon ◽  
G.E.A. Wyld ◽  
T. C. Yao ◽  
J. W. Otvos
Keyword(s):  
Stainless Steels ◽  
Fluorescence Analysis ◽  
Low Alloy Steels ◽  
X Rays ◽  
X Ray ◽  
Fundamental Parameters ◽  
Alloy Steels ◽  
Computer Based ◽  
Low X ◽  
Selection Of

Exact is a mini-computer based fundamental parameters program which is utilized for matrix corrections in energy-dispersive X-ray analyses. We have previously shown this technique to work well with radioactive sources. However, due to the limited selection of isotopic sources available and their inherent low X-ray flux, we have investigated the use of Fe, Sn, and Dy secondary-targets as sources of monochromatic X-rays. Results to date indicate that the secondary-targets provide X-ray radiation which has sufficient monochromaticity for our technique to remain valid.

Fluorescence Analysis of Trace Amounts of Hafnium in Zirconium Using a Silicon Crystal

1960 ◽  
Vol 4 ◽  
pp. 488-494
Author(s):  
J.C. Parks ◽  
D.G. Plackmann ◽  
G. H. Beyer
Keyword(s):  
Silicon Crystal ◽  
Pulse Height ◽  
Fluorescence Analysis ◽  
Second Order ◽  
Proper Choice ◽  
Pulse Height Analyzer ◽  
X Ray

AbstractThe proper choice of an analyzing crystal sometimes makes It possible to suppress second-order reflections which interfere with X-ray fluorescence analysis. Some of the problems associated with the analysis of small amounts of hafnium in zirconium, using a silicon crystal and a pulse-height analyzer, are discussed.

Identification of origins of lesser snow geese by X-ray spectrometry

1977 ◽  
Vol 55 (4) ◽  
pp. 718-732 ◽  
Author(s):  
John P. Kelsall ◽  
Roland Burton
Keyword(s):  
Chemical Elements ◽  
Pulse Height ◽  
Silicon Detector ◽  
Discriminant Functions ◽  
Emission Energy ◽  
X Ray ◽  
Snow Geese ◽  
Lesser Snow Geese ◽  
Computer Controlled ◽  
The Times

An attempt to apply computer-controlled. X-ray spectrometric methods for the identification of origins of waterfowl, through the analysis of chemical elements in their primary flight feathers, is described. Materials were gathered from three geographically distinct populations of wild lesser snow geese (Chen caerulescens). They were laundered, dried, and irradiated by 25 mCi (1 Ci = 37 GBq) Americium 241. Chemical spectra were developed using a lithium-drifted silicon detector, and a computer-controlled pulse-height analyzer that provided results in 512 channels of emission energy between about 2.3 and 40 keV. Computer programs were written or adapted to process our data. Multivariate discriminant functions were used (among other techniques) to examine potential significant differences between populations, and between different year classes within one population. Attempts were made to classify unknown feathers through use of discriminant functions. Best results were obtained by measuring the areas under K alpha peaks of emission energy for recognizable chemical elements in the spectra and using those, and the times for analysis, as significant variables. Two other methods of using the data are compared with that method. Efforts to discriminate geographically different populations, and to classify unknowns are encouraging. However, there are residual problems to be dealt with.

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