ISSN:0049-8246    

DOI:10.1002/xrs.1300170102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractVarious compilations of mass absorption coefficients are currently used in fundamental parameter computer programs for correction of inter‐element effects in quantitative x‐ray fluorescence analysis. Statistically significant differences in results of analysis were observed for certain sample types when three commonly used compilations were compared, especially when only pure element standards were used for calibration. When type standards combined with a second degree polynomial fit to the standards are used for calibration. When type standards combined with a second degree polynomial fit to the standards are used for calibration, differences between compilations become negligible as determined from the analysis resu

ISSN:0049-8246    

DOI:10.1002/xrs.1300170103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe production yields for characteristic x‐rays from the bombardment of thick targets by protons are calculated by integrating the x‐ray production cross‐section for each element for the whole range of the protons, taking into account the self‐absorption of x‐rays. A simple approximation which can be applied with a pocket calculator is also presented, using simplified relationships for the energy dependence of the proton stopping power and the x‐ray production cross‐sections. The approximation allows very fast calculations, has an accuracy of better than 5% for low‐energy protons and is also very useful for the first steps in a computer program for PIXE analysis of thick targets, using the method of iterations. The calculated yields are compared with experimental results obtained on thick specimens of pure elements, compound

ISSN:0049-8246    

DOI:10.1002/xrs.1300170104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe preparation of a pre‐fused flux for use in X‐ray fluorescence analysis is described. The flux is fused in graphite, quenched in water and then reduced to a fine powder in a polyurethane‐lined ball mill using tungsten carbide

ISSN:0049-8246    

DOI:10.1002/xrs.1300170105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractA method of measuring the dead time of nuclear detectors using a pulsed beam is described. The application of the method to detectors used in an electron microprobe device is reported and results obtained in this way are presented. The method seems to be suitable for measuring the dead time of any nuclear x‐ray counting system which can be operated with a pulsed bea

ISSN:0049-8246    

DOI:10.1002/xrs.1300170106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractRelative experimental detector yields and yield ratios measured on mono‐ and bi‐element standard samples from 1984 to 1987 are presented. Above 3 keV photon energy the yields show good long‐term reproducibility. For example, the spread of 38 single yield measurements on the Au Lα x‐ray line is 1.5%. No temporary changes are observed. In contrast, the measured yields in the photon energy range from 3 keV down to 0.9 keV show distinct temporary changes. At the beginning and end of the measurement period the detector was routinely warmed and re‐pumped in order to ensure a good vacuum in the detector housing. At these times the yields show jumps, which increase with decreasing photon energy up to 20% for Na K x‐rays with 1.041 keV photon energy. Between the detector regenerations the yields show a decreasing tendency with time. This behaviour is attributed to the photon absorption in a varying ice layer on the liquid nitrogen‐cooled Si(Li) detector crystal. After the first regeneration the ice layer thickness was reduced by 0.7 μm. Between the regenerations the ice layer growth rate is estimated to be 0.004 μm per month corresponding to a 0.15 μm ice layer after 35 months. The second regeneration reduced the ice layer by

ISSN:0049-8246    

DOI:10.1002/xrs.1300170107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe K‐shell fluorescence yields of nine elements with atomic numbers 33, 55, 59, 63, 66, 69, 71, 73 and 80 were measured from a knowledge of nuclear decay parameters. The results are in good agreement with earlier measurements and the fitted values of Bambyneket al.The merits and demerits of the method are discusse

ISSN:0049-8246    

DOI:10.1002/xrs.1300170108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractAn energy‐dispersive x‐ray spectrometer was used to make a quantitative estimate of potassium in whole blood samples from diabetic subjects and controls. A single standard method employing a fundamental parameter approach was followed for the quantification of potassium x‐ray intensities. The results show that the potassium levels in diabetics are about double those in con

ISSN:0049-8246    

DOI:10.1002/xrs.1300170109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300170110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

ISSN:0049-8246    

DOI:10.1002/xrs.1300170112

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY