Call number: LD2668 .T4 1966 R923 / Master of Science

Solar flare soft x-ray emission from 0.5 Å to 8.5 Å was observed during 1967-68 by U.S. Naval Research Laboratory Bragg crystal (LiF and EDDT) spectrometers aboard the OS0-4 satellite and also by NRL broad band ionization detectors aboard the OG0-4 satellite. In this work, instrumental parameters for the LiF crystal spectrometer based on experimental values have been determined and used in the data analysis. The source continuum spectra between 1 Å and 3.8 Å have been obtained for selected flares from OS0-4 spectrometer scans. As these spectra are each affected by time variations over 14 minutes, they are compared with the thermal continuum (free-free and free-bound) spectra predicted in the following manner. The instantaneous electron kinetic temperature and emission measure (equal to the product of the square of the electron number density and the total volume) of the flare plasma are determined from the available OG0-4 broad band data. The expected continuum flux is calculated by using these parameters. The comparison shows that there is good agreement between 2 Å and 3.8 Å. Thus it has been concluded that reliable values of the average electron temperature can be determined from the OG0-4 flare data. The earlier wavelength assigrunent and line identification list published by Meekins et al (1970, Solar Physics 13, 198) has been substantially improved in this work by separately summing a large number of OS0-4 spectrometer scans of the flaring and active sun. All identified wavelengths are found to agree with the more accurate theoretical valuesto within + 0.01 Å. Identifications of several weak lines as due to hydrogen-like and helium-like ions of chlorine and phosphorus have also been suggested. The temporal behaviour of selected ion line intensities (due to Fe, Ca, Si, S, Al, and Mg) indicates that they follow the expected temperature variations during the flare. The total continuum emission in the 0.5 to 3 Å and the 1 to 8 Å broad band segments has been determined from OG0-4 data for 21 flares. In doing this, a simple and approximate method of converting the total emission based on the gray body approximation (in which the OG0-4 data are reported) to one based on the thermal continuum spectrum has been developed. This study shows that the total energy lost in the 0.5 to 8 Å soft x-ray channel is of the order of 10²⁸ to 10³⁰ ergs depending on the Hα importance of the flare (from sub- to class 2); it is also shown that this energy is comparable with that emitted in higher wave length segments estimated by other authors. / Graduate

The techniques of x-ray diffraction of liquids are employed to study the salt TlCo(CO)4 in two solvents, tetrahydrofuran and dimethylsulfoxide. Radial distribution functions calculated from scattering data are analyzed in terms of the structure of these solutions, and the results are compared to those of other studies of the same and similar solutions investigated by infrared techniques. In tetrahydrofuran, a solvent of low dielectric constant, the evidence indicates close association of anion and cation, and contact ion pair and covalent models are presented and discussed. In dimethylsulfoxide, a solvent of high dielectric constant, the evidence indicates relatively loose association or no association of anion and cation, and solvent-separated ion pair and free ion models are presented and discussed.

There is mounting evidence that supermassive black holes (SMBHs) form and grow in bulgeless galaxies. However, a robust determination of the fraction of active galactic nuclei (AGNs) in bulgeless galaxies, an important constraint to models of SMBH seed formation and merger-free models of AGN fueling, is unknown, since optical studies have been shown to be incomplete for AGNs in low-mass galaxies. In a recent study using the Wide-field Infrared Survey Explorer, we discovered hundreds of bulgeless galaxies that display mid-infrared signatures of extremely hot dust suggestive of powerful accreting massive black holes, despite having no signatures of black hole activity at optical wavelengths. Here we report X-ray follow-up observations of J122434.66+555522.3, a nearby (z = 0.052) isolated bulgeless galaxy that contains an unresolved X-ray source detected at the 3 sigma level by XMM-Newton with an observed luminosity uncorrected for intrinsic absorption of L2-10 (keV) = (1.1 +/- 0.4) x 10(40) erg s(-1). Ground-based near-infrared spectroscopy with the Large Binocular Telescope and multiwavelength observations from ultraviolet to millimeter wavelengths together suggest that J1224+5555 harbors a highly absorbed AGN with an intrinsic absorption of N-H > 10(24) cm(-2). The hard X-ray luminosity of the putative AGN corrected for absorption is L2-10 keV similar to 3 x 10(42) erg s(-1), which, depending on the bolometric correction factor, corresponds to a bolometric luminosity of the AGN of L-bol 6 x 10(43)-3 x 10(44) erg s(-1). and a lower mass limit for the black hole of M-BH similar or equal to 2 x 10(6) M-circle dot, based on the Eddington limit. While enhanced X-ray emission and hot dust can be produced by star formation in extremely low metallicity environments typical in dwarf galaxies, J1224+5555 has a stellar mass of similar to 2.0 x 10(10) M-circle dot and an above solar metallicity (12 + logO/H = 9.11), typical of our WISE-selected bulgeless galaxy. sample. While collectively. these observations suggest the presence of an AGN, we caution that identifying obscured AGNs in the low-luminosity regime is challenging. and often requires multiwavelength observations. These observations suggest that low-luminosity AGNs can be heavily obscured and reside in optically quiescent galaxies, adding to the growing body of evidence that the fraction of bulgeless galaxies with accreting black holes may be significantly underestimated based on optical studies.

Laser copper plasma sources are a compact, economical means of producing high intensity x-rays at the correct wavelengths for x-ray lithography. Copper debris in the form of vapor, ions, dust, and high-speed particles is an unwanted byproduct of the laser copper plasma technique. Improved methods for debris mitigation are essential for production x-ray lithography using laser copper plasma sources. The objective of this project was to develop and implement a tool for the study of the size, amount, and velocity spectrum of high speed particulate debris. The measurements used a source-laser-pulse-synchronized high speed spinning disc. An optical scanning boom microscope analyzed debris collected on a target. Debris target imagery was analyzed using an image processing and pattern recognition program. This provided an unbiased assessment of debris accumulation. The position of debris particles was used to determine their velocity using kinematic triangulation. Velocities of copper debris particles were found to be in the hundreds of meters per second, roughly one order of magnitude slower than previously believed. The accuracy of these results was compromised by multi-pulse aliasing. The new understanding of debris velocities suggests reconsideration of a host of countermeasures previously thought to be too slow to effectively stop high speed debris particles. This study also suggests that x-rays emitted at high laser pulse rates could be blocked by the low speed debris generated during the previous laser pulse. The target location and laser spot size and focal point are critical elements in the plasma generation process and were found to have a low tolerance for variation. This finding identified the mechanics of plasma generation and parameter control as areas requiring further refinement and study.

Narrow Line Type-1 Seyfert active galaxies can exhibit a high degree of variability in the X-ray regime. This thesis examines that variability in the context of reverberation models, in which a flare in activity has an extended, energy dependent, response. A novel method is developed for estimating the response function in different energy bands. This method is then applied to three AGN: Ark 564, 1H 0707{495, and NGC 4051. The striking evidence for reverberation revealed in Ark 564 leads to a more thorough examination of that object, combining spectral and temporal approaches to develop a plausible physical model for its behaviour. The preferred model is one in which the reverberation is due to scattering from hot Comptonizing material approximately 1500 light-seconds from the central source. This conclusion is reinforced by a simulation of the angular dependence of reflection by Comptonizing gas.

by Cheung Man Kit. / Errata slip inserted / Bibliography: leaves 83-84 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1985

Thesis (M.Phil.)--Chinese University of Hong Kong. / Bibliography: leaves 88-90.

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1940. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed March 10, 2010) Includes bibliographical references (p. 26-27).

Thesis (Sc. D.)--University of Michigan, 1932. / "Reprinted from the Journal of Morphology, vol. 55, no. 1, September, 1933." "Literature cited": p. 178.