Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 68 for “"Hard x-ray"”.
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A Statistical Study of Hard X-Ray Solar Flares
The results of a statistical study of hard x-ray solar flares are presented in this dissertation. Two methods of analysis were used, the Diffusion Entropy (DE) method coupled with an analysis of the data distributions and the Rescaled Range (R/S) Method, sometimes referred to as "Hurst's method". …
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Hard X-ray and radio studies of solar flares
Combined X-ray and radio observations of the Sun provide powerful diagnostics of particle acceleration and transport effects during solar flares. In this thesis we present observations of two solar flares. In the first event we report what we believe to be the first observation of hard X-ray …
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HEFT measurement of the hard X-ray size of the Crab Nebula and the hard X-ray optics of the Nuclear Spectroscopic Telescope Array (NuSTAR)
… (HEFT) and the Nuclear Spectroscopic Telescope Array (NuSTAR). HEFT is the first experiment done with imaging telescopes in the hard X-ray energy band (~20-70 keV). I briefly describe the instrument and the balloon campaign. The inflight calibration of the Point Spread Function (PSF) is done with …
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Influence of photospheric back-scatter on flare hard x-ray diagnostics.
… influence of solar photospheric back–scatter on Hard X–Ray (HXR) flare diagnostics. Specifically the thesis presented is concerned with the effect of back–scatter photons upon the morphology of the Hard X–Ray photon spectrum and its effect on the inferred parent electron spectrum. I present a …
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Fabrication and characterization of multilayers for focusing hard x-ray optics
… thicknesses and their performance as x- ray mirrors for the next generation of focusing telescopes. Different material combinations were studied for the first time employing a consistent methodology for the DC magnetron sputtering growth of the multilayers and their characterization by …
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Machine learning from hard x-ray surveys: applications to magnetic cataclysmic variable studies
… the production of unbiased future soft gamma-ray source catalogues. The feature extraction process on an initial candidate list is described together with feature merging. Three trainng and testing sets are created in order to deal with the diverse time-scales encountered when dealing with the …
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Characterization and prototyping of the rotating modulator hard x-ray/gamma-ray telescope
A hard x-ray/gamma-ray telescope with high sensitivity and wide field of view would be capable of performing an all-sky census of black holes over a wide range of obscuration and accretion rates. As an example, NASA's Black Hole Finder Probe mission was designed to provide a 5-sigma flux …
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Charge density wave incommensuration in tise2 systems measured with hard x-ray scattering
… phase in sulfur substituted samples. Our hard x-ray diffraction experiments determined that the charge order phase does not terminate inside the superconductive phase of these systems, as was formerly believed. The phase diagrams established in this work suggest that incommensurations of …
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Hard X-ray diagnostics of particle acceleration and energy release in solar flares and coronal jets
… of which are driven by magnetic reconnection. Hard X-ray (HXR) emissions, produced via bremsstrahlung, provide direct diagnostics of thermal plasma and energetic electron populations, offering critical insights into the energy release and particle acceleration processes in these events. One …
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Experimental studies in laser interaction with wavelength scale matter via second harmonic production and hard x-ray production
… measured and characterized an increase in x-ray yield of a target coated with wavelength scale spheres. We conducted the experiment with a range of sphere sizes and we noted a peak in the x-ray yield at a sphere diameter of 0.26 micrometers corresponding to a size parameter of 2.04.
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Diagnostics of solar flare energetic particles: neglected hard X-ray processes and neutron astronomy in the inner heliosphere
… processes in solar flares. On our work on hard X-ray (HXR) emission from flares, we have shown that non-thermal recombination emission can compare with the bremsstrahlung HXR flux for certain flare conditions. In this thesis, we show spectral features characteristic of non-thermal …
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The analysis and the three-dimensional, forward-fit modeling of the hard x-ray and the microwave emissions of major solar flares
… the flare impulsive phase, observed in the hard X-ray (HXR) and microwave (MW). The two emissions are considered to be produced by a “common population” of the electrons, but some studies have also reported temporal, spatial, and energy discrepancies between them, challenging the widely-used …
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A space focused ion time of flight mass spectrometer, and spectroscopy of hydrogen chloride, deuterium chloride, and hydrogen sulfide at "hard" x-ray energies
A space-focused ion time-of-flight mass spectrometer was used to study the relaxation dynamics of HCl, DCl, and H{dollar}\sb2{dollar}S following the excitation of a K-shell electron using synchrotron radiation. On resonance, fragmentation of the molecule involving neutral dissociation of hydrogen …
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Magnetic X-ray Reflectivity
… and multilayer systems via magnetic soft and hard x-ray reflectivity. The focus here is on 3d transition metals, which are used mainly for development of numerous noval magnetic devices, that are both technologically and scientifically interesting. Complementary to Neutron diffraction, which …
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Electron acceleration in a flare plasma via coronal circuits
… flares are sources of energetic particles. Hard X-ray observations (e.g., by NASA's RHESSI spacecraft) reveal that a large fraction of the energy released during a flare is transferred into the kinetic energy of electrons. However the mechanism that accelerates a large number of electrons to …
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Improved temporal coherence and short pulse generation in free electron lasers
… fully transformlimited FEL pulses in the hard X-ray at 0.15 nm. In the second part of the thesis it is shown how the magnetic chicanes may be used to synthesise the effect of an optical cavity with an axial mode structure, and how these axial modes may be phase locked, using concepts from …
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MODELING X-RAY DATA OF BLACK HOLE BINARIES
… disc models using multiwavelength (optical/UV/X-ray) data from the 2005 hard state outburst of the black hole SWIFT J1753.5-0127. This system is both fairly bright and has fairly low interstellar absorption, so gives one of the best datasets to study the weak, cool disc emission in this state. We …
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