Study of structure and interface morphology of magnetic thin films is crucial in obtaining a better understanding of the coupling mechanisms in such systems. In this thesis various x-ray scattering techniques are applied to a series of Co/Cr trilayers, Cu/Co multilayers and spin valve structures. It is demonstrated that modifications to the distorted wave Born approximation allow the modelling of grazing incidence diffuse scatter originating from graded systems such as Co/Cr. Grazing incidence scattering techniques are also employed to investigate the out of plane correlations of lateral roughness in Cu/Co multilayers, as well as in miscible trilayer structures. The use of soft x-rays in the investigation of 3d transition metal multilayers is also presented. Such experiments are sensitive to the component of magnetisation aligned with the direction of the incident beam. In a series of magnetisation experiments, the dependence of the x-ray scatter sensitive to this component of magnetisation are analysed. For the first time evidenced is found for correlated magnetic roughness, which has lateral correlation lengths far greater than the structural roughness length scales. This magnetic roughness is measured in detail, and the correlation length is found to vary with applied field direction. Grazing incidence x-ray fluorescence is applied to two spin valve structures. These experiments provide a direct measure of buried layer thicknesses which is not possible by other x-ray scattering techniques. This novel method for the determination of the copper layer thickness in spin valves shows the versatility of non-destructive x-ray methods for the characterisation of magnetic metallic multilayers.

No description available.

This thesis presents a lithic attribute and geochemical analysis of the lithic material recovered from coastal site of Fatumafuti, on Tutuila Island, in the Samoan archipelago during 1050-520 BP. The goal of this thesis is to clarify the nature of stone tool production and to add to our current understanding of the cultural transformations from Lapita to a Polynesian identity. To complete this goal four research questions are addressed. What is the stage of reduction (cha ne operatoire) at Fatumafuti? Does the assemblage vary over space and time? Where did the source material come from? And, what was the organization of lithic craft production? Specifically, is there evidence for specialization? The lithics at Fatumafuti contain multiple segments in the technical sequence of tool manufacture (cha ne operatoire). The two major segments are middle stage and late stage reduction, and two minor segments are early stage reduction and tool rejuvenation. Expedient tools found on site indicate that prehistoric groups did not rely on a completely curated technology. Tool manufacture was geared toward producing a variety of tools, as opposed to a specific product. Production was most intense towards the coastal portion of the site during the earlier cultural component and then shifted towards the talus base during the later cultural component. Using non-destructive Energy Dispersive X-Ray Fluorescence (EDXRF), elemental concentrations were analyzed and compared to those of Tataga-matau, Lau?agae, Asiapa and Alega. One, possibly two, sources were utilized at this site; however, they are not chemically similar to Tatagamatau, Lau'agae, Asiapa and Alega. I conclude that people of Fatumafuti practiced independent household production at the end of the Aceramic and beginning of the Recent period. Either the intensification of lithic craft production that is seen during the height of complex chiefdoms is not seen at Fatumafuti, or these social transformations had not yet taken hold. With more cases that date to this time, we may find that Samoan chiefdoms had not attained full complexity at this point.

The application and use of non-destructive portable x-ray fluorescence (XRF) analysis is a critical tool in the preservation and interpretation of cultural material. Portable XRF instrumentation produce elemental compositional data that is used to reconstruct current artifact composition, which can be related to materials and methods of manufacture, technological practice, as well as object condition and presence of corrosion surfaces. Portable XRF analysis is used to assess a variety of material classes utilized in artifact manufacture. The dissertation research is based on a series of three case studies that represent typical groups of material culture commonly encountered in conservation and conservation science research.Conservators and conservation scientists frequently undertake analysis and interpretation of disparate groups of materials. Often, these objects are tied together by research questions or themes directed by outside influences including preservation issues requiring action; curatorial research interests; museum exhibition programs; as well as many other cultural heritage stakeholders. To this end, both non-destructive and destructive tools that provide measurements of interest play critical roles in analysis. The case studies have been designed to answer common compositional questions relating to (a) bulk analysis of Chinese coins, (b) characterization of Southwestern ceramic colorants, and, (c) chemical examination of post-depositional manganese dioxide accretions occurring on archaeological ceramic materials. They evaluate the value of data produced using effectiveness of non-destructive portable XRF analysis for the interpretation of archaeological materials. The case studies provide a template for the development of conservation science research, predicated on object preservation, which produce meaningful data for the interpretation and conservation of the analyzed archaeological artifacts. Portable XRF provides useful data that is used to successfully interpret archaeological materials through (a) classification of metal alloys that can be related to published coin data, (b) identification of ceramic colorants and production technologies, and, (c) characterization of post-depositional product composition when used with established visual typologies.

No description available.

The practice of using X-Ray fluorescence analysis as a method in ar-chaeological, forensic and osteological studies have resulted in a vast amount of data. It is time and cost efficient, and the method of µXRF element analysis has been of great use to archaeologists, forensic an-thropologists and osteologists to understand dietary customs, techno-logical trade patterns, understanding of diagenesis, elemental accumu-lation in bone and more. Moreover, the method has been crucial due to its non-destructive nature since bones and ancient artifacts are fragile and thus a nonde-structive method is preferable. This essay will give the reader an intro-duction to the basics of micro X-Ray fluorescence analysis and will explore the possibilities of trace elements in right (dexter) and left (sinister) thighbones (femur) on a medieval population in Visby Got-land, namely Sankt Hans. The reader will also come to know the fun-damental principles, applications, strengths and weaknesses of mi-croX-Ray fluorescence, as well as its limitations. Keywords: µXRF, non-destructive, data, method, left, right, thigh-bone, elements, analysis.

The quantification of plutonium (Pu) in spent nuclear fuel is an increasingly important safeguards issue. There exists an estimated worldwide 980 metric tons of Pu in the nuclear fuel cycle and the majority is in spent nuclear fuel waiting for long term storage or fuel reprocessing. This study investigates utilizing the measurement of x-ray fluorescence (XRF) from the spent fuel for the quantification of its uranium (U) to Pu ratio. Pu quantification measurements at the front end of the reprocessing plant, the fuel cycle area of interest, would improve input accountability and shipper/receiver differences. XRF measurements were made on individual PWR fuel rods with varying fuel ages and final burn-ups at Oak Ridge National Laboratory (ORNL) in July 2008 and January 2009. These measurements successfully showed that it is possible to measure the Pu x-ray peak at 103.7 keV in PWR spent fuel (~1 percent Pu) using a planar HPGe detector. Prior to these measurement campaigns, the Pu peak has only been measured for fast breeder reactor fuel (~40 percent Pu). To understand the physics of the measurements, several modern physics simulations were conducted to determine the fuel isotopics, the sources of XRF in the spent fuel, and the sources of Compton continuum. Fuel transformation and decay simulations demonstrated the Pu/U measured peak ratio is directly proportional to the Pu/U content and increases linearly as burn-up increases. Spent fuel source simulations showed for 4 to 13 year old PWR fuel with burn-up ranges from 50 to 67 GWd/MTU, initial photon sources and resulting Compton and XRF interactions adequately model the spent fuel measured spectrum and background. The detector simulations also showed the contributions to the Compton continuum from strongest to weakest are as follows: the fuel, the shipping tube, the cladding, the detector can, the detector crystal and the collimator end. The detector simulations showed the relationship between the Pu/U peak ratio and fuel burn-up over predict the measured Pu/U peak but the trend is the same. In conclusion, the spent fuel simulations using modern radiation transport physics codes can model the actual spent fuel measurements but need to be benchmarked.

The study was conducted to develop a technique that measures the amount of gadolinium based contrast agent accumulated in a head tumour by x-ray fluorescence, while a patient is exposed to neutrons or during external beam radiotherapy planning. In this research, measurements of the gadolinium concentration in a vessel simulating a brain tumour located inside a head phantom, by the x-ray fluorescence method were taken, where the Magnevist contrast medium which has gadolinium atom, in the tumour vessel, was excited by a 36 GBq (0.97 Ci) 241Am source that emits gamma rays of 59.54 keV, in 35.7 % of it’s decays, resulting the emission of characteristic fluorescence of gadolinium at 42.98 keV that appeared in the X-ray fluorescence spectrum. A Cadmium Telluride (CdTe) detector was used to evaluate and make an analysis of the gadolinium concentration. Determinations of the gadolinium content were obtained directly from the detector measurements of XRF from gadolinium in the exposed tumour vessel. The intensity measured by the detector was proportional to the gadolinium concentration in the tumour vessel. These concentrations of gadolinium were evaluated for dose assessment. The positioning of the head phantom was selected to be in the lateral and vertex positions for different sizes of tumour vessels. Spherical tumour vessels of 1.0, 2.0, 3.0 cm and an oval tumour vessel of 2.0 cm diameter and 4.0 cm length, containing the gadolinium agent, contained concentration between 5.62 to 78.63 mg/ml. They were placed at different depths inside a head phantom at different positions in front of the detector and the source for the measurements. These depths ranged from 0.5 cm to 5.5 cm between the center of the tumour and interior wall of the head phantom surface. The total number of measurements in all four sizes of the tumour vessel was 478; 78 examinations of a 1.0 cm spherical tumour vessel, 110 examinations of a 2.0 cm spherical tumour vessel, 150 examinations of a 3.0 cm spherical tumour vessel and 140 examinations of a 2.0 x 4.0 cm ellipsoid tumour vessel. To measure the size and the shape of the tumour by the alternative radiographic method, a general x-ray machine with radiograph film was used. Based on that, the appropriate shape of concentration could be selected for therapy. The differences of optical density in the x-ray films showed that the noise was increased with low concentration of the Gd. Because radiographic film may be subjected to different chemical processes where the darkness will be affected, these measurements would be very hard to be quantitative. Accordingly it is difficult to use the film for Gd concentrations. The obtained data show that the method works very well for such measurements.

The study was conducted to develop a technique that measures the amount of gadolinium based contrast agent accumulated in a head tumour by x-ray fluorescence, while a patient is exposed to neutrons or during external beam radiotherapy planning. In this research, measurements of the gadolinium concentration in a vessel simulating a brain tumour located inside a head phantom, by the x-ray fluorescence method were taken, where the Magnevist contrast medium which has gadolinium atom, in the tumour vessel, was excited by a 36 GBq (0.97 Ci) 241Am source that emits gamma rays of 59.54 keV, in 35.7 % of it’s decays, resulting the emission of characteristic fluorescence of gadolinium at 42.98 keV that appeared in the X-ray fluorescence spectrum. A Cadmium Telluride (CdTe) detector was used to evaluate and make an analysis of the gadolinium concentration. Determinations of the gadolinium content were obtained directly from the detector measurements of XRF from gadolinium in the exposed tumour vessel. The intensity measured by the detector was proportional to the gadolinium concentration in the tumour vessel. These concentrations of gadolinium were evaluated for dose assessment. The positioning of the head phantom was selected to be in the lateral and vertex positions for different sizes of tumour vessels. Spherical tumour vessels of 1.0, 2.0, 3.0 cm and an oval tumour vessel of 2.0 cm diameter and 4.0 cm length, containing the gadolinium agent, contained concentration between 5.62 to 78.63 mg/ml. They were placed at different depths inside a head phantom at different positions in front of the detector and the source for the measurements. These depths ranged from 0.5 cm to 5.5 cm between the center of the tumour and interior wall of the head phantom surface. The total number of measurements in all four sizes of the tumour vessel was 478; 78 examinations of a 1.0 cm spherical tumour vessel, 110 examinations of a 2.0 cm spherical tumour vessel, 150 examinations of a 3.0 cm spherical tumour vessel and 140 examinations of a 2.0 x 4.0 cm ellipsoid tumour vessel. To measure the size and the shape of the tumour by the alternative radiographic method, a general x-ray machine with radiograph film was used. Based on that, the appropriate shape of concentration could be selected for therapy. The differences of optical density in the x-ray films showed that the noise was increased with low concentration of the Gd. Because radiographic film may be subjected to different chemical processes where the darkness will be affected, these measurements would be very hard to be quantitative. Accordingly it is difficult to use the film for Gd concentrations. The obtained data show that the method works very well for such measurements.

David Richard Walker’s Metrology of the Roman Silver Coinage analyzed the silver content of over 5000 Roman denarii, antoniniani, and drachmae using x-ray fluorescence (XRF) spectrometry. His results have been widely cited and used by scholars in the fields of Roman economic theory and numismatics. This thesis seeks to prove that Walker’s XRF results were not only inaccurate, but inconsistently so. Corrosion and surface enrichment on silver-copper coins have caused surface-level elemental examinations, like XRF, to produce incorrect results. The results from Walker’s XRF analysis have been compared against results from four individual wet chemical studies. The comparisons display striking, and significant, differences. I am forced to conclude that Walker’s data does not in any way align with the true silver content of the coins he analyzed. As a result, this thesis will re-examine several theories and hypotheses posed by scholars who used Walker’s data and propose new, more appropriate, uses for Walker and XRF analysis outside of the examination of corroded silver-copper coins.