Understanding the formation and evolution of disk galaxies remains one of the most intriguing and unsolved problems in cosmology. Despite the steady improvement in the number and quality of observations over the last decade, a clear consensus about the evolution of disks has not been reached. Using wide field data from the Canada-France-Hawaii Telescope Legacy Survey, we examine the size and surface brightness evolution of approximately 20,000 disk galaxies from z = 0.2 to z = 1. This is the largest. sample size of high-redshift disk measurements to date. We perform two dimensional bulge+disk decompositions on all objects in the fields and select only those that are highly disk dominated. The size function of these disks shows that the distribution of sizes is unchanged over this redshift interval. Examination of various models of pure luminosity evolution show that there has been 0.5 +0.1 magnitudes of evolution over the redshift range 0.4 < z < 1.0 and 1.5 ± 0.3 magnitudes of evolution over 0.2 < z < 1.0. This is mostly consistent with passive evolution and suggests that disks were assembled prior to z = 1.

In preparation for the ATLAS experiment at the LHC at CERN. the high pseudorapidity region (|n| > 2.5) of the ATLAS end-cap liquid argon calorimeters underwent particle beam testing in 2004. One of the main goals of these tests is to study energy reconstruction in the complex interface region between the electromagnetic. hadronic, and forward calorimeters at. 1 - 3.2. These detectors were exposed to beams of electrons and pions with energies ranging from 6 GeV to 200 GeV. Three methods of calibration in the electromagnetic end-cap calorimeter (EMEC) are studied and compared to the results of a previous beam test. of the EMEC. The electromagnetic scale factor (aEM) is computed and compared to the previous beam test value. Studies of the energy response and resolution of the high pseudorapidity region of the three end-cap calorimeters to the particle beam position scans are given.

Structures within general relativity are examined. The differences between man-made structures and those predicted by the Einstein differential equations are very subtle. Exotic structures such as the Godel Universe and the Gott cosmic string are examined with emphasis on closed time-like curves. Newtonian models are seen to also have an exotic aspect in that a vast halo consisting of unknown matter dominates the galaxy. We introduce a model for galaxies based on a general relativity framework with the goal of excluding such artifacts from the system while describing the flat-rotation curves. Structures within this model were speculated to be exotic but after close scrutiny, their nature is shown to be benign. Numerical approaches are applied to model four galaxies: The Milky Way, NGC 3031, NGC 3198 and NGC 7331. Density and mass are deduced from these models and compared to the Newtonian models. Within the visible/HI region, there is 30% reduction in total mass. Extending the model to 10 times beyond the HI region using various fall-off scenerios, it is shown that there is only modest increase of the accumulated mass. In comparison to the Newtonian approach to galactic dynamics, the massive halos are not required to account for the flat velocity profiles.

The Kuiper belt is a population of planetesimals outside the orbit of Neptune. The high inclinations and eccentricities exhibited by many belt members, and its very low mass (M 0.1M) present an enigma to planetesimal accretion scenarios: the high relative encounter velocities (vrei 1 km s-1), and infrequent collisions of the largest members make the growth of Pluto-sized bodies impossible over the age of the Solar system. Accretion in the early stages of planet-building must have been in a more dense environment allowing large objects to grow before growth was halted. The current Kuiper belt population is the left-over relic of accretion, which has undergone collisional re-shaping since the epoch of accretion. The shape of the size distribution can provide constraint on the accretion timescale, the primordial Kuiper belt mass, and the collisional processing the belt has undergone. Thus, a measure of the size distribution provides one of the primary constraint on models which attempt to explain the formation of the Kuiper belt. We have performed a large-scale ecliptic Kuiper belt survey, with an aerial cov¬erage of 3.3 square degrees to a limiting magnitude m(R) 27. From these ob¬servations, we have discovered more than 100 new Kuiper belt objects. Using this survey we have provided the best measurement of the Kuiper belt luminosity function to-date, from which we have inferred the size distribution. We have found that the size distribution is well described by a power-law for large objects with a steep slope q1 = 4.8, that breaks, or rolls over to a shallower power-law with slope q2 = 2 at ob¬ject diameter ~ 60 km. The steep large object slope is indicative of a short accretion phase, lasting no more than a few 100 Myr. The large break diameter demonstrates that the Kuiper belt has undergone substantial collisional processing. We have developed a collisional evolution model which we have used to study the effects of planetesimal bombardment and disruption on the size distribution. We have found that, in the current Kuiper belt, little to no evolution is occurring, or has occurred for the observable Kuiper belt. We conclude that the large break diameter cannot be produced in the current environment over the age of the Solar system. A period of intense collisional evolution in a much more dense, and hence, more massive belt is required. These findings are consistent with accretion models; the typical finding is that growth of the largest Kuiper belt objects over the age of the Solar system requires a much more massive belt than currently observed. These results point to a history in which an initially much more massive Kuiper belt underwent a short period of quiescent accretion producing Pluto size bodies. Some event then occurred, which dynamically excited the planetesimals, producing an erosive environment which effectively halted planet growth and rapidly depleted the majority of the primordial mass. The remnant of this depletion is the Kuiper belt we observe today.

Clusters of galaxies are the largest and most massive gravitationally bound objects in the universe. They contain several hundreds to thousands of galaxies orbiting in the gravitational potential well of the cluster. The space between galaxies is filled with a hot plasma that loses its thermal energy via X-ray emission. In the absence of heating sources in the ICM, the radiative cooling of the gas leads to a significant accumulation of cold gas in the cluster core which then should ultimately condense into stars or cold gas clouds (e.g.. Fabian 1994). However, high-resolution X-ray spectroscopy of the hot intracluster gas has revealed that there is little or no signature of significant cool gas in the cluster core. This strongly suggests that there must be other forms of heating mechanisms that offset radiative losses in the intracluster medium (ICM). In this dissertation, we focus on one of the potential heating sources in the ICM, and that involves the kinetic energy in the orbital motions of cluster galaxies. We examine in detail the effects of the heating due to dynamical friction of galaxies on the evolution of the ICM. We find that galaxy heating is immaterial in systems that are in cool core configurations with no other heating mechanisms operating in the ICM. Accordingly. dynamical friction-mediated heating can not be the only heating mechanism in galaxy clusters. The situation is, however, completely different if the systems have experienced sufficient amounts of energy input to warm or hot cores. We show that the role of dynamical friction heating in moderating radiative cooling cannot be neglected in these systems. We also address the results of the last generation of non-radiative cosmological simulations of galaxy clusters (Voit et al. 2005). According to these studies, the radial entropy distribution of the simulated clusters tends to follow a power law at large radii, with cores present in the entropy configurations of these systems at small radii. The origin of the entropy cores is presently unclear. We argue that the generation of entropy cores in non-radiative simulated clusters is the result of galaxy stirring.

A prototype rapid, high precision fan beam optical computed tomography (OptCT) scanner for three-dimensional polymer gel dosimetry of complex radiotherapy protocols has been developed. This study documents the design. construction and characterization of the system, as well as preliminary reconstructed optical attenuation images and dosimetric verification experiments. The principal goal in scanner design and implementation was to satisfy the Radiotherapy Accuracy and Precision (RTAP) criteria consisting of a spatial resolution of 1 x 1 x 1 mm3, an imaging time of 60 minutes, a dose accuracy within 3% and a precision within 1%. The scanner, which employs a sixty degree fan beam of 543 nm laser light to scan irradiated polymer gel samples up to 19 cm in cross-sectional diameter. has several defining attributes. Data acquisition for a single slice through a dosimeter is achieved in two minutes, using one signal acquisition per CT projection angle over a total of 360 projections. The effects of scatter and refraction of visible light are minimized by using the unique radial design of the matching medium tank, the concentric arrangement of a prototype, computer numerical control (CNC)-machined collimator and five Hamamatsu photodiode detector arrays for light detection. The novel tertiary collimation eliminates scattered light by 13% and improves reconstructed image contrast-to-noise ratio. Other characteristics of the scanner include: a laser power output variation of only 0.7%:, signal-to-noise ratio (SNR.) for calibration projections of up to 294:1, SNR for transmission projections through an irradiated polymer gel dosimeter of up to 161:1, a large absorbance dynamic range extending from 0.1 to 1.7 absorbance units and a spatial resolution of 0.25 mm2 in the axial plane of the scan¬ning geometry and 0.8 mm along the longitudinal z-axis of the scan plane. Images of optical attenuation coefficients and concomitant dose maps extracted from irradi¬ated, normoxic N--isopropylacylamide (NIPAM) polymer gels were used to investigate the potential of the system for dosimetric verification. Three different NIPAM gel irradiation experiments were performed and the resultant OptCT dose distributions were compared to the Eclipse® (Varian Medical Systems. Palo Alto. CA.) treatment planning system model. While the fan beam OptCT scanner provides promising ini¬tial images of reconstructed optical attenuation coefficients, its dosimetric accuracy compared to Eclipse - nominally 7% in low dose gradient regions and 5% on the field edges - constitutes the most significant area for future refinement.

In this dissertation I present a detailed survey of molecular line emission (including NH3, C2S, HC5N, N2H+, N2D+ and H2D+) towards clustered star forming Cores in the nearby Ophiuchus molecular cloud, with the aim of characterizing the distribution and kinematics of the dense gas within a clustered star forming environment and compare these results with those found in more isolated star forming regions. I show that the dense Oph Cores present characteristics of both isolated and clustered star forming regions in several key parameters, including Core kinematics, temperatures and chemistry. At the higher gas densities where the N2H+ emission is excited, I show that the presence of an embedded protostar is correlated with increased gas motions. I additionally present evidence of N2H+ depletion from the gas phase, suggesting that in higher density, clustered environments N2H+ may not accurately trace the physical conditions of the densest core gas. I present the distribution of H2D+ and N2D+ across the Oph B Core, and show the distribution is not simple or easily explained by chemical models of evolving, isolated cores. Finally, I summarize the results of this dissertation, the questions it raises concerning the exploration of how stars form in clusters, and discuss how these questions may be answered through upcoming observational surveys and by new telescope facilities.

Supernovae of Type Ia, SNe Ia, are currently the most powerful tool of modern cosmology, but their progenitor scenario is not yet well constrained. Recent studies of SN Ia rates in radio-loud early-type galaxies, and members of rich clusters, suggest a possible influence on SN Ia explosions outside of the established correlation with the age of the parent galaxy's stellar population (via the current specific star formation rate, sSFR). These rates were used to show that the characteristics of SN Ia progenitor systems may be inconsistent with theoretical expectations of the most popular scenarios. The astrophysical question of this thesis is: do parent galaxy and environment influence the rates and properties of Type Ia supernovae, and, if so, how? Towards this end, we combine the database of Type Ia supernovae from the Canada-France-Hawaii Telescope's Supernova Legacy Survey with publicly available catalogs including: galaxy photometric and spectroscopic redshifts, radio and infrared sources, and members of galaxy groups and clusters. This is the most comprehensive set of multi-wavelength host properties and environment parameters for intermediate redshift Type Ia supernovae yet compiled. We present the SNLS SN Ia rate per unit mass in a variety of parent galaxy and environment samples. We also statistically assess the probability of discrepancies between our rates, those of previous works at low redshift, rates in the general population of galaxies, and predictions of established empirical SN Ia rate models. In general, we do not find statistically significant evidence for SN Ia rate enhancements over the general population in galaxies which are radio-loud, infrared-bright, or associated with galaxy groups and clusters. In cases where we do find a suggestive rate enhancement, it is always with less than 2-sigma confidence. These rates agree with established empirical rate models, which in turn are consistent with theoretical expectations of the most plausible progenitor scenarios. Furthermore, we find the properties of SNLS SNe Ia in these types of hosts and environments are consistent with the predictions of these scenarios. We conclude that, aside from the established correlation with host sSFR, no conclusive evidence is observed with SNLS data for strictly environmental effects on SN Ia rates. This supports their continued status as cosmological standard candles.

Designs for future nuclear fusion power reactors rely on the ability to create a stable plasma (hot ionized gas of hydrogen isotopes) as a medium with which to sustain nuclear fusion reactions. My dissertation work involves designing, constructing, testing, installing, operating, and validating a new diagnostic for spherical tokamaks, a type of reactor test facility. Through detecting charged particles emitted from the plasma, this instrument can be used to study fusion reaction rates within the plasma and how they are affected by plasma perturbations. Quantitatively assessing nuclear fusion reaction rates at specific locations inside the plasma and as a function of time can provide valuable data that can be used to evaluate theory-based simulations related to energy transport and plasma stability. The Proton Detector (PD), installed in the Mega Amp Spherical Tokamak (MAST) at the Culham Centre for Fusion Energy (CCFE) in Abingdon, England, was the first instru- ment to experimentally detect 3 MeV Protons and 1 MeV Tritons created from deuterium- deuterium (hydrogen isotopes) nuclear fusion reactions inside a spherical tokamak’s plasma. The PD consists of an array of particle detectors with a protective housing and the neces- sary signal conditioning electronics and readout. After several years of designing (which included simulations for detector orientations), fabricating, and testing the PD, it was installed in MAST and data were collected over a period of two months in the summer of 2013. Proton and triton rates as high as 200 kHz were measured and an initial radial profile of these fusion reaction rates inside the plasma was extracted. These results will be compared to a complementary instrument at MAST as well as theory-based simulations and form the knowledge basis for developing a larger future in- strument. The design and performance of all instrument components (electrical, computa- tional, mechanical), and subsequent data analysis methods and results are described in this dissertation.

The Scheffler reflector is a new solar concentrator design which maintains a fixed focus while only having a single axis tracking mechanism. This design makes the construction and operation of high temperature solar concentrators accessible to developing nations. In this project, I wrote computer simulation codes to better understand the dynamics and the effect of deformation or deviations from ideal conditions in order to define necessary manufacturing and operational tolerances. These tools and knowledge drove the prototyping of new reflector concepts by myself and other students on my team. A fiberglass prototype was able to drive the cost of a reflector to sub-$50 and a wood reflector was manufactured with accessible materials and techniques used in boat building.