The ultimate objective of this project was to develop a small, transportable X-ray microscope which would be able to view a wide range of biological specimens without the need for any type of sample preparation at a resolution greater than that obtainable by conventional light microscopy (ie. about 250nm). Of the various possible implementations of X-ray microscopy currently being investigated, contact microscopy was chosen as being the most suitable for the development of such a small-scale instrument, while at the same time minimizing the effects on image quality of radiation damage to the biological specimen. The requirement for a high brightness pulsed X-ray source of less than 50ns duration for illumination of the specimen was met by the production of laser generated plasmas. These were formed by focusing a 2.2J KrF laser beam, of wavelength 248nm and duration 20ns, onto the surface of one of a number of different target materials. In order to obtain the large intensities required for the production of a sufficiently high temperature plasma, a doubly pre-ionized, discharge-pumped amplifier KrF laser was developed. This was seeded by a smaller oscillator laser by means of a coupled unstable resonator configuration. A number of different cavity arrangements were investigated and an output beam divergence of 2.5 times the diffraction limit was achieved. The plasmas generated by focusing the laser beam to an intensity of 10¹⁴W/cm² onto carbon, titanium, molybdenum and tungsten targets were characterized as fully as was necessary for their use in the X-ray microscope. Preliminary investigations on the use of a grazing incidence ellipsoidal mirror to focus the emitted X-rays onto the specimen of the microscope were made and such an optical component was manufactured and tested. Finally, numerous images of a number of different biological specimens were made and resolutions of better than 100nm were achieved. Images were read out using a Park Scientific Instruments atomic force microscope, which enabled the entire microscopy process to be carried out in a single working day. The system is now in routine use and can produce more than ten images per session.

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I present a detailed study of the behaviour of the exotic X-ray binary Cygnus X-3 at radio, (sub)mm, infrared, red-optical and X-ray wavelengths. Further unusual properties of the system are unearthed and previously expounded models are refined by new observations. In order to address the broader picture, a multiwavelength comparison of Cygnus X-3 with other ‘radio-jet’ X-ray binaries is also undertaken. Infrared observations of Cyg X-3 at high time resolution reveal many rapid flare events superimposed upon the 4.8 hr (presumed) orbital motion. Photometry simultaneously in the H & K-bands allows strong constraints to be placed upon T & N_ε for the flaring component. Dereddening of RI- J-H-K-L-L’ photometry places limits on the likely extinction to Cyg X-3 of 4.5 ≤ A_J ≤ 7.5 mag. Further infrared study, simultaneous with radio monitoring and observations with OSSE/GRO and the INT shed greater light on the source, including possible orbital colour changes and a longterm correlation between radio and infrared flux levels. Deep imaging of the field reveals many previously undiscovered infrared sources within a few arcsec of Cyg X-3. Simultaneous millimetre and radio observations of Cyg X-3 reveal anomalously strong mm fluxes. Interpreting this in terms of significant absorption of the cm fluxes during the passage outwards of the radio-emitting plasmons, strengthens the case for a dense stellar wind in the Cyg X-3 system. Further radio and sub(mm) observations of Cyg X-3 during outburst confirm previously observed phenomena such as quenched radio emission prior to outburst, and establish the importance of radiation loss mechanisms in the decay of radio plasmons ejected from the source. A model describing the qualitative behaviour of the source during outburst is presented.

Asphalt composites are used to construct 90% of roads in the United States. These composites consist of asphalt binder, which is a product of the refinery process of oil, aggregates, and air voids. Fatigue cracking is one of the most important distresses that causes damage in asphalt pavements. However, there is still a gap in the understanding of the fatigue process of asphalt composites, such as the influence of material properties on this phenomenon and how the material microstructure changes as a result of fatigue damage. This study focuses on the results of two experiments that were performed on asphalt composites to better understand phenomena related to fatigue cracking: nano-mechanical characterization of the properties of the asphalt composite material and X-ray Computed Tomography nondestructive imaging of damage in the microstructure. These experimental measurements were performed on specimens that are first damaged in the Dynamic Mechanical Analyzer (DMA). The DMA is a tool commonly used for the characterization of fatigue cracking. This test method applies cyclic loads on asphalt composites, damaging them, and in the process determines the viscoelastic properties of the composite throughout the test. The nano-mechanical characterization experiment gives valuable results of the elastic modulus and hardness of the aggregate, binder, and the aggregate-binder interface that can be used to characterize different binder and aggregate combinations. The nanoindentation experiment successfully measured interface properties in the mix. The interface has elastic modulus and hardness values greater than the binder but smaller than the aggregate. This demonstrates that an interaction between these two phases creates a dissimilar phase between the two. The second experiment using X-ray CT gives measurements that are indicative of the influences of fatigue damage on micro-level changes in the material microstructure. The results of this experiment revealed important changes regarding the nature of fatigue damage and its relationship to changes in the geometry of air voids and cracks in asphalt composites. The X-ray CT experiment measured size and shape parameters of air voids at 20 microns/pixel resolution at different damage levels. These results illustrated that reduction in bonding strength in the binder is involved in failure in the mix and thus fatigue cracking is not solely responsible for failure. This conclusion is made based on the results not showing a statistically significant change in air void shape and size parameters with increased damage. This is illustrated by viewing changes in the air void structure within the mix, there is no evidence of crack propagation, or drastic changes in the shape, size, or volume of air voids within the mix.

X-ray imaging has become one of the most pervasive and effective means of diagnosis in medical clinics today. As more imaging systems transition to digital modes of capture and storage, new applications of x-ray imaging, such as tomosynthesis, become feasible. These new imaging modalities have the potential to expose patients to large amounts of radiation so the necessity to use sensitive imagers that reduce dose and increase contrast is essential. An experimental design that utilizes laterally oriented detectors and amorphous semiconductors on crystalline silicon substrates has been undertaken in this study. Emphasis on fabricating a device suitable for medical x-ray imaging is the key principle throughout the design process. This study investigates the feasibility and efficiency of a new type of x-ray imager that combines the high speed, low noise, and potential complexity of CMOS circuit design with the high responsivity, large area uniformity, and flexibility of amorphous semiconductors. Results show that the design tradeoffs made in order to create a low cost, high fill factor, and high speed imager are realistic. The device exhibits good responsively to optical light, possesses a sufficient capacitive well, and maintains CMOS characteristics. This study demonstrates that with sufficient optimization it may be possible to design and deploy real time x-ray system on chip imagers similar to those used in optical imaging.

X-ray absorption spectroscopy (XAS) is a powerful probe of electronic and spatial structure that has been at the heart of many advances in physics, biology, chemistry, engineering and the earth sciences. Unfortunately, the existing experimental techniques are subject to fundamental limitations that complicate the interpretation of x-ray absorption spectra in many important cases. These limitations have motivated an effort to develop an alternative measure of the absorption cross-section that is not subject to the same set of limitations. In this thesis, a technique known as inverse partial fluorescence yield (IPFY) is described which addresses this problem. IPFY differs from existing approaches in a significant way — by using an energy-discriminating photon detector, one gains access to fluorescence information from both resonant and non-resonant x-ray emission processes. We will show that the non-resonant emission is fundamentally related to the total absorption cross-section of a material through an inverse relation. This will be proven by extension of the general theory of fluorescence yield for the case of a thick, homogeneous specimen. We will also demonstrate the utility of IPFY with measurements of NiO, NdGaO₃, LNSCO, and stainless steel 304 at soft and intermediate x-ray energies. These experiments will highlight some essential features of IPFY spectroscopy and demonstrate how it can be an invaluable tool when the other experimental techniques fail to provide reliable spectra. We will also demonstrate how one can exploit the geometry dependence of IPFY to quantitatively determine the composition of a sample and the total x-ray absorption coefficient. Additionally, we will consider the special cases of multilayers and powder specimens, where the theory of fluorescence yield requires approximations and is not as well-behaved as in thick, homogenous specimens. Ultimately, these experiments and theoretical developments will be used to support the claim that IPFY is a bulk sensitive measure of the total x-ray absorption coefficient. Moreover, we will show that IPFY is not affected by saturation effects, is insensitive to surface contamination layers and provides reliable spectra even for strongly insulating materials. These properties make IPFY a suitable spectroscopic technique for studying XAS in a wide range of materials.

There are many causes of structural failure. One of the most important factors leading to material failure is residual stress. This stress represents effects left in structures after processing or removal of external loads including changes in shape and crystallite size. In aggregate, residual stress changes the mechanical behaviour of materials. Various measurement techniques encompassing destructive, semi destructive, and non-destructive testing can be used to measure residual stresses. Thin plates are common in engineering applications. This thesis analyzes residual stresses on circular AISI 1020 steel alloy plates after removal of external loads using two-dimensional X-ray diffraction. Two identical thin circular plates are used in this experiment; one of which is statically loaded. The other plate is used as a control specimen. Residual stresses in the plates are measured using two-dimensional X-ray diffraction and the measurements are compared to those obtained using finite element analysis. It was found that experimentally measured residual stress occurred due to manufacture processing. Also, modules A and B showed the external effect of applying not enough to reach the plastic region to deform specimen 2 and obtain residual stress results distribution.

The Canadian Penning Trap (CPT) mass spectrometer at the Argonne National Laboratory makes precise mass measurements of both stable and unstable nuclides. To date, more than 60 radioactive isotopes having half-lives as short as one second have been measured with the CPT with a mass precision approaching 10 ppb. This thesis will present measurements made of nuclides along the rp-process path, which describes a process resulting from a series of rapid proton-capture reactions in an astrophysical environment. One possible site for the rp-process mechanism is an x-ray burst which results from the rapid accretion of hydrogen and helium from one star onto the surface of its neutron star binary companion. Mass measurements are required as key inputs to network calculations used to describe the rp-process in terms of the abundances of the nuclides produced, the light-curve profile of the x-ray bursts, and the energy produced. This thesis will describe the CPT apparatus, explain the method used to make precise mass measurements, and present the masses of the "waiting-point" nuclides ⁶⁸Se and ⁶⁴Ge. The mass measurement results, when used in x-ray burst models, confirm both ⁶⁸Se and ⁶⁴Ge as waiting-point nuclides which delay the rp-process by approximately 30 s and 7 s respectively.