Incident 0.5 to 2.5 MeV charged particle beams were used to ionize the inner-shells of selected targets and study their subsequent emission of characteristic x-rays. ⁹Be⁺ ions were used to examine K-shell x-ray production from thin F, Na, Al, Si, P, Cl, and K targets, L-shell x-ray production from thin Cu, An, Ge, Br, Zr and Ag targets, and M-shell x-ray production from thin Pr, Nd, Eu, Dy, Ho, Hf, W, Au, Pb and Bi targets. L-shell x-ray production cross sections were also measured for ²⁷Al⁺ ions incident upon Ni, Cu, Zn, As, Zr, and Pd targets. M-shell x-ray production cross sections were measure for ²⁷Al⁺ and ⁴⁰Ar⁺ ions incident upon Pr, Nd, Gd, Dy, Lu, Hf, Au, Pb, Bi, and U targets. These measurements were performed using the 2.5 MV Van de Graaff accelerator at North Texas State University. The x-rays were detected with a Si(Li) detector whose efficiency was determined by fitting a theoretical photon absorption curve to experimentally measure values. The x-ray yields were normalized to the simultaneously measured Rutherford backscattered (RBS) yields which resulted in an x-ray production cross section per incident ion. The RBS spectrum was obtained using a standard surface barrier detector calibrated for to account for the "pulse height defect." The experimental results are compared to the predictions of both the first Born and ECPSSR theories; each of which is composed of two parts, the direct ionization (DI) of the target electron to the continuum and the capture (EC) of the target electron to the projectile. The first Born describes DI by the Plane-Wave-Born-Approximation (PWBA) and EC by the Oppenheimer-Brinkman-Kramers treatment of Nikolaev (OBKN). ECPSSR expands upon the first Born by using perturbed (PSS) and relativistic (R) target electron wave functions in addition to considering the energy loss (E) of the projectile in the target and its deviation from straight line trajectory (Coulomb deflection (C)). The measurements presented show that the first Born theories overestimate the measured results rather significantly for all experiments using the ⁹Be beams to examine the inner shell x-rays, while the ECPSSR predictions fir the measured data much better. For incident ²⁷Al and ⁴⁰Ar ions, the measured results are not predicted by the theories. The first Born generally over-predicts the data for low target atomic numbers while under-predicting at high atomic numbers. The ECPSSR theory greatly under-predicts the results (factors of 10³ to 10²⁰). Reasons for this behavior are discussed as well as suggestions for future experiments.

The problem with which this investigation is concerned is that of making experimental measurements of proton-induced K-shell x-ray production cross sections and to study the dependence of these cross sections upon the energy of the incident proton. The measurements were made by detection of the characteristic x-rays emitted as a consequence of the ionization of the K-shell of the atom. The method for relating this characteristic x-ray emission to the x-ray production cross section is discussed in this work.

X-ray diffraction topography, using both conventional and synchrotron sources, has been employd t reveal, to a resoltuoon of 1um, internal structural imperfections in diamonds from Brazil. Many of these diamonds were found to be twinned; and X-ray studies have been made of twinned diamonds from Brazil and elsewhere, in order to elucidate the mechanisms of twinning in diamond. Numerous X-ray topographs have been taken of contact twins (mcles), interpenetrant cubes and mulitple twins. The well collimated beam of synchrotron radiation at the SERV Daresbury Laboratory has proved most useful in revealing, in the forward reflexion Laue photographers, small twinned regions of diamons: the presence of which would have been mised by conventioanl methods.

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No description available.

Since the discovery of X-rays over a century ago the techniques applied to the engineering of X-ray sources have remained relatively unchanged. From the inception of thermionic electron sources, which, due to simplicity of fabrication, remain central to almost all X-ray applications at this time, there have been few fundamental technological advances. The emergence of new materials and manufacturing techniques has created an opportunity to replace the traditional thermionic devices with those that incorporate Field Emission electron sources. One of the most important attributes of Field Emission X-ray sources is their controllability, and in particular the fast response time, which opens the door to applying techniques which have formerly been the preserve of optical systems. The work in this thesis attempts to bridge the gap between the fabrication and optimisation of the vacuum electronic devices and image processing aspects of a new approach to high speed radiographic imaging, particularly with a view to addressing practical real-world problems. Off the back of a specific targeted application, the project has involved the design of a viable field emission X-ray source, together with the development of an understanding of the failure modes in such devices, both by analysis and by simulation. This thesis reviews the capabilities and the requirements of X-ray sources, the methods by which nano-materials may be applied to the design of those devices and the improvements and attributes that can be foreseen. I study the image processing methods that can exploit these attributes, and investigate the performance of X-ray sources based upon electron emitters using carbon nanotubes. Modelling of the field emission and electron trajectories of the cathode assemblies has led me to the design of equipment to evaluate and optimise the parameters of an X-ray tube, which I have used to understand the performance that is achievable. Finally, I draw conclusions from this work and outline the next steps to provide the basis for a commercial solution.

The Computer Tomography (CT) scanned images are very important for the Treatment Planning System (TPS) to provide the electron density of the different types of tissues that the radiation penetrates in the path to the tumor to be treated. This electron density is converted to an attenuation coefficient, which varies with tissue for each structure and even varies by the tissue volume. The purpose of this research is to evaluate the CT numbers, and convert them into relative electron densities. Twenty-five patients’ data and CT numbers were evaluated in the CT scanner and in Eclipse and were converted into relative electron density and compared with each other. The differences between the relative electron density in the Eclipse was found to be from 0 up to 6% between tissue equivalent materials, the final result for all equivalent tissue materials was about 2%. For the patients’ data, the percentage difference of CT number versus electron density was found to be high for high relative electron density organs, namely the final average result for the spine was 8%, less for pelvis, and less for rib while for the other organs it was even less. The very lowest was 0.3% compared with 1% which is acceptable for clinical standards. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection

Soft X-ray spectroscopy is a useful observational tool, offering information about high-temperature (10⁶ -- 10⁷ K) astrophysical plasmas and providing useful characterizations of a number of energetic systems, including accreting young stars, cosmic filaments between galaxies, and supermassive black holes. In order to yield high resolution spectra with good signal-to-noise, however, soft X-ray spectrometers must realize improvements in resolving power and effective area through the development of high performance gratings. Off-plane reflection gratings offer the capability to work at high dispersions with excellent throughput, and are a viable candidate technology for future X-ray spectroscopy missions. The off-plane geometry requires a customizable grating meeting distinct fabrication requirements, and a process for producing gratings meeting these requirements has been developed. These fabricated gratings have been evaluated for performance in terms of resolution and diffraction efficiency. Furthermore, these gratings have been conceptually implemented in a soft X-ray spectrometer, the Off-Plane Grating Rocket Experiment (OGRE), whose optical design provides a template for future missions to achieve high performance within a small payload envelope.

High Mass X-Ray Binary Stars (HMXBs) are stars that contain one early-type main sequence or giant star and one of a black hole, neutron star or white dwarf. HMXBs in the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC) are instructive to study because both galaxies are metal poor in compari- son to the Milky Way and they are fairly transparent to both optical and X-ray radiation. This allows a more complete study of the whole population, without the biasing effects of gas and dust that occur in our own Galaxy. The objective of this study was to find the periods of HMXBs in the LMC and SMC with known optical counterparts in the dataset acquired by the Robotic Optical Transient Search Ex- periment telescope. Two possible orbital periods were found for the objects XTE J0055-724 and RX J0101.3-7211 of 1724 days and 478 days, respectively. Continued observations are recommended to conrm the two periods.

The objective of this research project was to establish a better understanding of the mechanism(s) and route(s) by which selenium (Se) may enter an aquatic ecosystem that has been receiving treated metal mine effluent from an upstream uranium milling operation. Synchrotron based X-ray absorption spectroscopy (XAS) and X-ray fluorescence (XRF) imaging, which require little sample pre-treatment, were employed to study the speciation and distribution of Se in complex sediment and benthic invertebrates samples collected from the field. Laboratory based inductively coupled plasma mass spectrometry (ICP-MS) provided quantitative Se concentrations. Samples were taken from Fox Lake and Unknown Lakes, downstream of the mill, and Yeoung Lake as a control. The variation in Se speciation as a function of depth in intact sediment cores may provide insight into the species of Se available to the sediment dwelling benthic invertebrate communities. Therefore, a custom sample holder was designed to facilitate analysis of intact sediment cores at cryogenic temperatures. Additionally, laboratory reared chironomids were water-exposed to various Se species, to compare their Se speciation and localization to chironomids collected in the field. The successful demonstration of the custom sample holder and viable use of synchrotron XAS and XRF in studying sediment and chironomid samples have revealed that biologically relevant Se forms were present in sediment at depths accessible by the benthic invertebrate community. These Se forms included selenomethionine-like and selenite species, and to a lesser degree elemental Se; an increased proportion of reduced Se species was observed as depth increased. Other elements measured concurrently with Se included As, Zn, Cu, Ni, Fe, and Mn, providing an estimation of the redox boundary found both in Fox and Unknown Lake, as well as suggesting the presence of iron species that could aid in the reduction of Se. Field and laboratory reared chironomids showed similar Se species, and XRF imaging revealed the localization of Se in 4 distinct regions: head capsule, brain, salivary glands, and gut lining. Overall, the project has provided important insights into the interactions of Se with this aquatic ecosystem, which may have future applications in cold water systems with elevated Se concentrations.