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Full-Text Articles in Physics
Fabrication, Measurements, And Modeling Of Semiconductor Radiation Detectors For Imaging And Detector Response Functions, Corey David Ahl
Fabrication, Measurements, And Modeling Of Semiconductor Radiation Detectors For Imaging And Detector Response Functions, Corey David Ahl
Doctoral Dissertations
In the first part of this dissertation, we cover the development of a diamond semiconductor alpha-tagging sensor for associated particle imaging to solve challenges with currently employed scintillators. The alpha-tagging sensor is a double-sided strip detector made from polycrystalline CVD diamond. The performance goals of the alpha-tagging sensor are 700-picosecond timing resolution and 0.5 mm spatial resolution. A literature review summarizes the methodology, goals, and challenges in associated particle imaging. The history and current state of alpha-tagging sensors, followed by the properties of diamond semiconductors are discussed to close the literature review. The materials and methods used to calibrate the …
Total Absorption Spectroscopy Of Mo-106 And Tc-106, Michael Cooper
Total Absorption Spectroscopy Of Mo-106 And Tc-106, Michael Cooper
Doctoral Dissertations
Total absorption spectroscopy is a method of gamma-ray spectroscopy that has gained prominence in the past several decades, as nuclear data revisions are performed on older nuclear data, which is often incomplete. A strong understanding of underlying nuclear data, particularly fission and beta decay data, is essential for nuclear reactors and nuclear fuel decay heat. This PhD work involves the analysis of fission fragments 106Mo [Mo-106] and 106Tc [Tc-106]. These neutron rich isotopes contribute upwards of 6% of the cumulative fission yield of 241Pu [Pu-241] fission, and 4% of 239Pu [Pu-239] fission. Prior data for these two fission fragments only …
Near-Ir Spectroscopic Analysis Of The Primary Volatile Composition Of Long And Short-Period Comets, Younas Khan
Near-Ir Spectroscopic Analysis Of The Primary Volatile Composition Of Long And Short-Period Comets, Younas Khan
Doctoral Dissertations
"Comets are among the most well-preserved objects that formed in the protosolar nebula ∼4.5 Gyr ago. Hence, they are important for understanding various aspects of the formation, evolution, and habitability of the solar system. Multiple primary volatiles (molecules directly sublimating into the coma from the nucleus) emit via rovibrational transitions in the near-IR, providing opportunities to calculate their abundances. To date, only ∼50 comets have been characterized for their primary volatiles, with the short-period Jupiter-family comets (JFCs) being significantly underrepresented. In contrast, hundreds of comets have been sampled at optical/UV wavelengths, primarily for the composition of daughter species, leading to …
Spectroscopic Properties Of Ferroic Superlattices, Shiyu Fan
Spectroscopic Properties Of Ferroic Superlattices, Shiyu Fan
Doctoral Dissertations
The interplay between charge, structure, magnetism, and orbitals leads to rich physics and exotic cross-coupling in multifunctional materials. Superlattices provide a superb platform to study the complex interactions between different degrees of freedom. In this dissertation, I present a spectroscopic investigation of natural and engineered superlattices including FexTaS2 and (LuFeO3)m/(LuFe2O4)1 under external stimuli of temperature and magnetic field as well as chemical substitution. Studying the phase transitions, symmetry-breaking, and complex interface interactions from a microscopic viewpoint enhances fundamental understanding of coupling mechanism between different order parameters and the …
Pulsed Inductive Plasma Studies By Spectroscopy And Internal Probe Methods, Warner C. Meeks
Pulsed Inductive Plasma Studies By Spectroscopy And Internal Probe Methods, Warner C. Meeks
Doctoral Dissertations
The broad effort of the Missouri Plasmoid Experiment is to elucidate the energy conversion processes in a pulsed inductive discharge due to the presence of plasma. The test article is a 440 to 490 kHz theta-pinch (or solenoidal) geometry coil with a stored energy of around 80 joules. In this work experimental hydrogen, helium, argon and xenon data at back-fill pressures of 10 to 100 mTorr (1.3 to 133.3 Pa) are obtained and interpreted. Spectral and internal probe studies were performed on MPX Mk.I and Mk.II devices, respectively. IR spectra were acquired in the Mk.I device for argon and xenon. …
The Characterization Of Volatiles Associated With Young Stellar Objects, Kari Anne Wojtkowski
The Characterization Of Volatiles Associated With Young Stellar Objects, Kari Anne Wojtkowski
Doctoral Dissertations
In the first portion of this work, we searched for differences in volatiles within a single star forming region, Rho Ophiuchi. We determined the amount, temperature, and composition of two ice features, the bending modes of CO₂ and H₂O at 15 µm and 6 µm, respectively, toward 28 Young Stellar Objects (YSOs). We found that more than 50% of the YSOs studied contained a portion of crystalline CO₂ ice. We also found that some sources with Flat or borderline Class II Spectral Energy Distributions (SEDs) have a larger abundance of CO₂ ice with respect to H₂O ice. In addition to …