No description available.

No description available.

No description available.

High Temperature Superconductors (HTS) materials are ideal for many electrical applications. These applications include high speed interconnects, microwave structures and transmission lines, as well as electronic devices that utilize the unique electrical and magnetic properties of these materials. To date, the use of high temperature superconductors has been limited to a narrow range of substrate materials, due to the reactive nature of these superconductors. Chemical reactions between the substrate and the superconductor cause decomposition of the superconductor into an insulator. The researcher has developed a thick film system that allows the production of high quality HTS films on reactive substrates, such as alumina (Al203). This system utilizes a thick film buffer layer of pure silver in combination with thick film superconductors composed of Y1Ba2~CU30X. The silver buffer layer is designed to prevent contact between the substrate and the superconductor, thereby eliminating chemical reactions between the two materials. The development as well as the comprehensive characterization of these films is described in this work. / Master of Science

The problem with which we shall concern ourselves in this paper is the self-scattering and self-absorption of beta particles by the source.

Since the development of thick film hybrid microelectronic processing, there has been a need for methods to adjust for tighter tolerances for electrical components through a trimming process. Components/elements, as produced, show a tolerance of the order of ±10% due to the variability of the screen printing process associated with film curing conditions. The methods that have arisen from this need encompass a variety of technologies and techniques. The usefulness of each method is based on its operation, flexibility, repeatability, and post-trim effects on the resistor's reliability. The work in this thesis concerns the laser trimming of resistor components to a tight tolerance. It is the objective of this thesis to address the performance of an Nd:YAG laser operation and interface with a computer. The first task involves a computer hardware system to be interfaced to the laser control system, this task includes both design and implementation. The second task consists of a software operating environment to be flowcharted, written, and tested. The third task involves the computer interface driving the laser in the process of trimming resistor components using different types of cuts. The trimmed resistor performance is evaluated as part of the study. / Master of Science

This work presents introductory research to provide the relationship between electrical measurements and residual stresses caused by hybrid processing. X-ray diffraction is used to measure residual stresses in the ceramic substrate as well as metallization of wideband coplanar thick film probes. The probes are also tested for electrical performance using Time Domain Reflectometry (TDR) technique. This thesis presents results that indicate that significant tensile residual stresses were generated on the back of the substrate, particularly during the laser scribing phase of the finished device. Significant tensile stresses were also observed in the Silver-Palladium (Ag-Pd) metallization. TDR measurements indicated significant response variations which were attributed to these induced stresses. Attempts were also made to reduce these stresses by an annealing process in order to improve the TDR response uniformity. / Master of Science

This work deals with the problem of the thick-film pastes and their printing. In the main chapter of this work, the realization of a workplace for thick-film pastes' printing is described. The construction of the realized plotter and the controlling electronics of the plotter is depicted in detail.In the following chapter, the console, through which the plotter is controlled via PC, and the CAD program, which serves for projecting of the motives printed, are described.In the final chapter of this work, the measured profiles of the paste printed for various settings of printing parameters and the photographs of the motives printed are stated.

Eine der drei Säulen der Krebsbehandlung ist die Strahlentherapie. Einer der neuesten Ansätze hierbei ist die Bestrahlung mit Ionen, zurzeit insbesondere Protonen und Kohlenstoffionen. Diese Hochpräzisionstherapie erfordert ein hohes Maß an Kontrolle, da die applizierte Dosisverteilung sehr empfindlich von Dichteveränderungen im durchstrahlten Gewebe abhängt. Das bisher einzige klinisch eingesetzte Verfahren zur in vivo Überwachung der Dosisapplikation bei Ionenbestrahlungen ist die Positronen-Emissions-Tomographie (PET). Sie ermöglicht eine Verifikation der Teilchenreichweite sowie der Lage des Bestrahlungsfeldes. Die mit der PET-Methode gemessene Aktivitätsverteilung lässt sich jedoch nicht direkt mit der geplanten Dosisverteilung vergleichen. Daher ist eine Vorherberechnung der erwarteten Aktivitätsverteilung auf der Grundlage des Bestrahlungsplanes notwendig, welche dann mit der Messung verglichen wird und eine qualitative Beurteilung der Bestrahlung ermöglicht. Die Vorherberechnung der erwarteten Aktivitätsverteilung erfordert bislang die Kenntnis einer Vielzahl von Wirkungsquerschnitten. Nur für wenige dieser Wirkungsquerschnitte liegen jedoch Messdaten im benötigten Energiebereich und mit ausreichender Genauigkeit vor. Daher verwenden viele Monte-Carlo-Simulationen intrinsische Kernmodelle oder semi-empirische Modellierungen, die häufig eine unzureichende Genauigkeit aufweisen. In Fachkreisen ist bisher noch nicht geklärt, welches die optimale Ionensorte für die Tumortherapie ist. Insbesondere Lithiumionen weisen aufgrund ihrer physikalischen und radiobiologischen Eigenschaften ein großes Potenzial auf. Auch für Bestrahlungen mit diesen Ionen ist ein PET-Monitoring der Therapie erstrebenswert. In der vorliegenden Arbeit wird zunächst die Anwendbarkeit der Reichweite-Verifikation mittels PET bei Bestrahlung mit Lithiumionen gezeigt. Des Weiteren wird ein Konzept zur Modellierung der Positronenemitter-Verteilung ohne Kenntnis der Wirkungsquerschnitte entwickelt. Diese Vorhersage beruht auf in Referenzmaterialien (Wasser, Graphit und Polyethylen) gemessenen tiefenabhängigen Positronenemitter-Yields, mit welchen durch geeignete Linearkombination die Verteilung der Positronenemitter in beliebigen Materialien bekannter Stöchiometrie vorausberechnet werden kann. Die Anwendbarkeit des Yield-Konzeptes wird gezeigt für Lithium- und Kohlenstoffbestrahlungen homogener Polymethylmethacrylat (PMMA) Targets sowie verschiedener inhomogener Targets.

This work deals with the problem of the thick-film pastes and their printing. In the main chapter of this work, the realization of a workplace for thick-film pastes' printing is described. The construction of the realized plotter and the controlling electronics of the plotter is depicted in detail.In the following chapter, the console, through which the plotter is controlled via PC, and the CAD program, which serves for projecting of the motives printed, are described.In the final chapter of this work, the measured profiles of the paste printed for various settings of printing parameters and the photographs of the motives printed are stated.