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A theoretical model with experimental verification is presented to enhance the quantum efficiency of a superconducting single-photon detector without increasing the length or thickness of the active element. The basic enhancement framework is based on: (1) Utilizing the plasmonic nature of a superconducting layer to increase the surface absorption of the input optical signal. (2) Enhancing the critical current of the nanowires by reducing the current crowding at the bend areas through optimally rounded-bend implementation. The experimental system quantum efficiency and fluctuation rates per second are assessed and compared to the proposed theoretical model. The model originated from an accurate description of the different liberation mechanisms of the nano-patterned superconducting films (vortex hopping and vortex-antivortex pairing). It is built complimentary to the existing, well-established models by considering the effects of quantum confinement on the singularities' energy states. The proposed model explains the dynamics of singularities for a wide range of temperatures and widths and describe an accurate count rate behavior for the structure. Furthermore, it explains the abnormal behaviors of the measured fluctuation rates occurring in wide nano-patterned superconducting structures below the critical temperature. In accordance to this model, it has been shown that for a typical strip width, not only is the vortex-antivortex liberation higher than the predicted rate, but also quantum tunneling is significant in certain conditions, and cannot be neglected as it has been in previous models. Also it is concluded that to satisfy both optical guiding and photon detection considerations of the design, the width and the thickness of the superconducting wires should be carefully determined in order to maintain the device sensitivity while crossing over from the current crowding to vortex-based detection mechanisms.

This thesis presents the findings of the investigation into the Monte Carlo simulation of superficial cancer treatments of the head and neck region. The EGSnrc system of codes for the Monte Carlo simulation of the transport of electrons and photons through a phantom representative of either a water phantom or treatment site in a patient is utilised. Two clinical treatment units are simulated using the BEAMnrc system of codes: the Varian Medical Systems Clinac® 2100C accelerator for 6MeV electron fields and the Pantak Therapax SXT 150 X-ray unit for 80kV and 100kV photon fields. Depth dose, profile and isodose curves are compared against those measured from a PTW MP3 water phantom with good agreement being achieved. Quantitative dose distributions are determined for both MeV electron and kV photon fields with treatment sites containing high atomic number materials, rapidly sloping surfaces and different density interfaces. This highlights the relatively high level of dose deposition of dose in tissue-bone and tissue-cartilage interfaces in the kV photon fields. From these dose distributions DVH and dose comparators are used to assess the simulated treatment fields.

München, Techn. University, Diss., 2007.

Thesis (M.S..)--Cornell University, May, 2008. / Vita. Includes bibliographical references (leaves 77-92).

Zugl.: Berlin, Humboldt-Univ., Diss., 2009

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 170-178).

Thesis (Ph. D.)--University of Oregon, 2004. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 102 -106). Also available for download via the World Wide Web; free to University of Oregon users.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 107-114). Available also in a digital version from Dissertation Abstracts.