| 41. |
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| 42. |
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| 43. |
- Johansson, Thomas B, et al.
(author)
-
Analytical Use of Proton-Induced X-Ray Emission
- 1976
-
In: Journal of Radioanalytical and Nuclear Chemistry. - 0236-5731. ; 32:1, s. 207-217
-
Journal article (peer-reviewed)abstract
- Proton-induced X-ray emission, PIXE, is capable of simultaneous quantitative determination of 10-15 elements. An introduction to the physical properties of the method is given and detection limits are shown for a routine analysis of a thin aerosol sample. Examples of applications to both thick and thin samples are presented. Human tooth dentine is analysed for lead, with simple sample preparation, indicating lead values of a few ppm for Swedish children. Quantitative analyses of several other elements are obtained simultaneously. Cascade impactors axe used for sampling aerosols in work environment during welding operations giving information of size distribution and concentrations of the elements present. The aerosol is dominated by particle sizes between 0.5 and 2 um as measured by the impactor, but the size distributions are different for different elements and welding techniques and depend on the distance from the welding source. The relative abundance of the elements found in the aerosol indicates the presence of fractionation mechanisms.
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| 44. |
- Johansson, Thomas B, et al.
(author)
-
Analytical Use of Proton-Induced X-Ray Emission
- 1975
-
In: Trans Am Nucl Sci; Proceedings: Summary on a lecture at the International Nuclear and Atomic Activation Conference and the 19th Annual Meeting on Analytical Chemistry in Nuclear Technology. ; 21, s. 31-31
-
Conference paper (peer-reviewed)
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| 45. |
- Kaufmann, Henry C, et al.
(author)
-
Non-Linear Least Squares Analysis of Proton-Induced X-Ray Emission Data
- 1975
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In: Advances in X-Ray Analysis. - Boston, MA : Springer US. ; 18, s. 353-361
-
Journal article (peer-reviewed)abstract
- A Fortran program for analysis of spectra obtained in proton induced x-ray emission spectroscopy is under development. The first version is working and some results are shown. The program uses a model which describes the physics involved in the analysis. The continuum is described by an exponentially decreasing function representing secondary electron induced bremsstrahlung and a constant approximating different Compton scattering processes. Absorption effects are also included. All parameters in the model are fitted simultaneously. About 100 test runs have been made with good results. The continuum was accurately fitted for each spectrum. Other advantages are reliability, speed, and the fact that the program is easily adaptable to a small computer with 16K memory.
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| 46. |
- Kaufmann, Henry C, et al.
(author)
-
REX: A Computer Program for PIXE Spectrum Resolution of Aerosols
- 1976
-
In: Advances in X-Ray Analysis. ; 19, s. 355-366
-
Journal article (peer-reviewed)abstract
- REX is a Fortran program for analysis of spectra obtained in PIXE analysis. The underlying model is still under development; however, one year of experience has demonstrated REX’s capability to be a fast reliable tool. The modeling of the different components and effects of the physical model is briefly discussed. Evidence is shown that secondary effects mostly due to Compton-scattering in and around the detector are important factors. In order to assure that heavy elements are recorded with sufficient sensitivity during short bombardment times, low energy X-rays are suppressed but not completely absorbed by use of a Mylar absorber with a hole. Such an absorber sometimes introduces severe problems for other techniques of spectrum analysis. However, to REX there is only the job to find the transmission curve of the absorber.
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| 47. |
- Kaufmann, Henry C., et al.
(author)
-
REX - A Computer Programme for PIXE Analysis
- 1977
-
In: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 142:1-2, s. 251-257
-
Journal article (peer-reviewed)abstract
- The implementation of a physics-based model for non-linear least-squares analysis of proton-induced X-ray emission spectra via a Fortran programme REX is discussed. The modelling of distinct spectral components and of the physical effects involved is briefly discussed. Results are presented in graphical and tabular form. The limitations of the present model are discussed and future refinements indicated.
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| 48. |
- Lannefors, Hans, et al.
(author)
-
Aerosolsammansättning i ett renluftsområde
- 1979
-
Reports (other academic/artistic)abstract
- Aerosolsammansättningen i ett renluftsområde i Mellansverige (Velen) har studerats under en årscykel. Aerosolpartiklarna har uppdelats efter aerodynamisk storlek i 7 fraktioner. Varje fraktion från 113 provtagningstillfällen har analyserats m a p svavel och tungmetaller m h a partikelinducerad röntgenstrålning s k PIXE-analys. Resultaten påvisar variationer i ämneskoncentrationer mellan enskilda mättillfällen omspännande två storleks ordningar. Årsmedelkoncentrationerna ligger på samma nivå som i rural miljö i Bolivia, Canada, Norge och Schweiz. Jämfört med motsvarande koncentrationer i urban miljö (Köpenhamn m fl storstäder) är tungmetallkoncentrationerna en till två storleksordningar (svavelkoncentrationen endast en faktor tre) lägre i Velen. Inga påtagliga säsongsvariationer kunder spåras varken för antropogent eller naturligt bildade ämnen. Klassificering av mättillfällena efter luftmassans historia kunde förklara mycket av de stora koncentrationsvariationerna. Grundämneskoncentrationerna var mellan en faktor 2 och 10 högre i luftmassor som kom från den europeiska kontinenten eller Storbritannien jämfört med de som kom norrifrån. Lägst var koncentrationerna i luftmassor som kom från Nordatlanten eller Norska Havet. Svavelkoncentrationerna visade störst beroende av luftmassans historia.
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| 49. |
- Lannefors, Hans, et al.
(author)
-
Ambient Air Contamination by Micron and Submicron Particles from Welding Operations
- 1977
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In: Bulletin of Environmental Contamination and Toxicology. - 0007-4861. ; 17:5, s. 521-527
-
Journal article (peer-reviewed)abstract
- Impactor sampling and PIXE analysis constitute a good combination in detecting the influence of fugitive emission and ventilation air on ambient air quality. In total filter samples heavier natural particles mask the increase in mass due to the smaller industrial particles. Multielemental analysis of many samples is important in finding unknown sources and in evaluating the effect of all the sources. PIXE is well suited for this kind of analysis. The health effects of low-concentration air-pollution exposure on large population groups including such sensitive groups as children, elderly and sick people are not well understood, which is encouraging for sampling more basic information for epidemiological studies. The increases of the concentration of iron, potassium and manganese are evident. Although the reported values are below air-quality limit values, there are some reasons for being careful. Firstly, the increases are most significant in submicron particles. Secondly, with different weather conditions and from other industrial areas, indoor contribution could be orders of magnitude larger. Thirdly, in PIXE analysis only elemental constituents heavier than about sulphur are detected and there may be other lighter constituents. It is, e.g., known that water-soluble fluorine is abundant in fumes from electrodes with basic coatings. Thus considerable attention should be given to the ambient air when planning means of improving work environment and when allocating new industrial areas.
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| 50. |
- Lannefors, Hans, et al.
(author)
-
Grundämnessammansättning i olika partikelstorleksfraktioner av den atmosfäriska aerosolen
- 1978
-
Reports (other academic/artistic)abstract
- Beskrivning ges av analysteknik (protoninducerad röntgenstrålning), provtagningsteknik (kaskadimpaktor av Battelle-typ) och provberedningsteknik. Utfört arbete i form av provbehandlingsförbättringar, konstruktion och förbättring av provtagare, bestämning av lämpliga analysparametrar samt uppbyggnad av ett dataprogramsystem presenteras. Sammanställning av resultat i form av beräknade medelvärden i klasser efter luftmassans historia redovisas.
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