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

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.

Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Electrical and Computer Engineering." Includes bibliographical references (p. 188-191).

The quantum properties of electromagnetic radiation at single photon level promise to offer what are classically inaccessible. Single photon sources and detectors are therefore on demand for exploiting these properties in practical applications, including but not limited to quantum information processing and communication. In this thesis, I advance Superconducting Nanowire Single Photon Detectors (SNSPD) both in terms of models describing their operation, and their performance. I report on characterization, semi-empirical modeling, quantum-optical modeling and detector tomography. The results provide more accurate methods and formulations to characterize and mathematically describe the detectors, valuable findings from both application and device points of views. I also introduce the concept of Gated SNSPDs, show how to implement and how to characterize them. Through series of theoretical and experimental investigations, I show performance advantages of Gated SNSPDs in terms of dead time and dark count rate, important figures for many applications like quantum key distribution. The ultimate limitations of gated operation are also explored by physical modeling and simulation steps.

The quantum properties of electromagnetic radiation at single photon level promise to offer what are classically inaccessible. Single photon sources and detectors are therefore on demand for exploiting these properties in practical applications, including but not limited to quantum information processing and communication. In this thesis, I advance Superconducting Nanowire Single Photon Detectors (SNSPD) both in terms of models describing their operation, and their performance. I report on characterization, semi-empirical modeling, quantum-optical modeling and detector tomography. The results provide more accurate methods and formulations to characterize and mathematically describe the detectors, valuable findings from both application and device points of views. I also introduce the concept of Gated SNSPDs, show how to implement and how to characterize them. Through series of theoretical and experimental investigations, I show performance advantages of Gated SNSPDs in terms of dead time and dark count rate, important figures for many applications like quantum key distribution. The ultimate limitations of gated operation are also explored by physical modeling and simulation steps.

This thesis presents the development of kinetic inductance detectors (KIDs) for cosmic microwave background (CMB) polarimetry. Increasingly precise measurements of the CMB have led to much of our understanding of the observable universe; future measurements of the CMB will require the development of new detectors as progressively fainter signals are targeted. In particular, a measurement of the primordial B-mode polarization signal, which would offer strong evidence of inflation, will require at least a 50 times increase in detector count. KIDs are an attractive detector option for next-generation CMB experiments due to their low-noise and high-multiplexing factor. In this thesis, I present KIDs optimized for ground-based CMB observations, which are sensitive to a 150 GHz spectral band where the CMB spectrum peaks. This research demonstrates the first systematic studies of lumped-element KIDs (LEKIDs) optimized for CMB surveys and shows the readiness of the detectors for on-sky observations. First, I present the design and performance of horn-coupled LEKIDs, which are sensitive to a single polarization. I show that KIDs can meet the stringent noise and sensitivity requirements necessary for a competitive CMB detector. Second, I present a novel method for reducing crosstalk between LEKIDs, which is important for controlling instrument systematics. Third, I present the design and performance of dual-polarization LEKIDs, which are sensitive to orthogonal polarizations within a single spectral band and double the number of detectors per array, increasing the sensitivity. Finally, I present the initial analysis of millimeter-wave observations of a nearby galaxy cluster, Abell 2443, taken with the LEKID-based NIKA2 instrument on the IRAM 30 m telescope. This is part of ongoing research to make high-resolution measurements of the Sunyaev–Zel'dovich effect, seen as a distortion in the CMB spectrum.

The characterization and measurement of the spatial, temporal and energy emission of air-scattered photons, electrons and neutrons generated near 10 MV or greater accelerator-based bremsstrahlung photon sources is becoming important in many applications. The national and homeland security research community is interested in developing technologies which can detect illicit materials at substantial standoff distances in outdoor environments. These systems are referred to as "active" interrogation systems and are defined as inspection systems that take advantage of an externally applied "source" to perform traditional imaging of, or to stimulate characteristic emissions from, an inspected object. A key concern in the development of these systems is the ability to effectively predict the dose equivalents at long standoff distances from these sources in order to ascertain the operational radiation safety of said systems. Current computational radiation transport simulation tools have the ability to effectively model these systems; however, a paucity of experimental data exists in comparing the results of these simulations. A methodology to assess the radiation dose surrounding a high-energy bremsstrahlung-based accelerator system for national defense applications was developed. Fluence-to-dose conversion coefficients for the International Commission on Radiation Units and Measurements operational quantity ambient dose equivalent were calculated for photons and electrons up to 25 MeV utilizing the Los Alamos National Laboratory Monte Carlo N-Particle code, MCNP5 Version 1.51. Special consideration was given to the treatment of secondary charged particle equilibrium in all simulations. An extensive set of system simulations was performed to model a prototype high-energy bremsstrahlung-based accelerator system to obtain photon, electron and neutron fluence spectra. These fluence data were folded with the calculated ambient dose equivalent conversion coefficients as well as previously published effective dose conversion coefficients. A set of integral air-scatter measurements for accelerator-generated primary and secondary radiations (photon and neutron) were performed around the prototype system in order to provide a comparative data set from which to determine the total dose equivalent both in the beam (on-axis) and outside of the beam (off-axis).

No description available.

Thesis (Ph.D)--University of Western Australia, 2007.