Other Physics Commons^™

Evaluation Of Neutron Skyshine Contributions During Injection At An Electron Synchrotron Facility Using Fluka, Andrew D. Hastings

LSU Master's Theses

The Center for Advanced Microstructures and Devices (CAMD) is a 1.5 giga-electron volt (GeV) electron synchrotron research facility under the jurisdiction of Louisiana State University (LSU). When originally constructed in 1992, CAMD was surrounded by pasture and woodland. Over the past several years, urban development of the area has found CAMD bracketed by a shopping center, apartment complex, and business offices. These developments raised concerns amongst the CAMD radiation safety personnel regarding an increased potential for public exposure to radiation. To ensure compliance with the annual public effective dose equivalent limit of 1 milli-sievert (mSv), the radiation monitoring program was …

Characterization Of Magma Storage And Dynamics At Akutan, Semisopochnoi, And Okmok Volcanoes From Analytical And Numerical Models Of Geodetic, Seismic, And Petrologic Data, Kimberly Degrandpre

Earth Sciences Theses and Dissertations

Volcanic eruptions can cause significant socioeconomic loss, but a better understanding of the processes and dynamics influencing the evolution of volcanic plumbing systems will advance the development of eruption forecasting models that will ultimately mitigate hazards and risks associated with eruptive events. Geologic and geophysical data must be integrated in 3D, finite- element, multiphysical, numerical models to define the coupled evolution of magmatic and crustal stress regimes in volcanic environments, but in data limited regions this is not always an option. The remote nature of the Aleutian Island Arc restricts ground-based monitoring and sampling efforts, and due to sparse temporal …

Comprehensive Investigation Of Radiation Techniques For Whole Breast And Post-Mastectomy Irradiations, Yibo Xie

LSU Doctoral Dissertations

Purpose: The purpose of this dissertation is to compare treatment outcomes and cost-effectiveness of various radiotherapy techniques for post-mastectomy radiotherapy (PMRT) and whole breast radiotherapy (WBRT) patients.

Methods: Treatment planning comparison of standard volumetric modulated arc therapy (STD-VMAT), multiple arc VMAT (MA-VMAT), non-coplanar VMAT (NC-VMAT), intensity modulated radiotherapy (IMRT), helical tomotherapy (HT), mixed beam therapy and proton therapy was performed for 9 PMRT patients, and cost-effectiveness of those PMRT techniques compared to standard of care (SOC) were evaluated using a Markov model. Treatment planning comparison of SOC, field-in-field (FIF), hybrid IMRT, full IMRT, STD-VMAT, MA-VMAT and NC-VMAT was performed …

Efficiency And Performance Improvement Via Using Optical Reflectors Of On-Grid Cigs Pv Solar System, Alaa N. Abed, Hazim H. Hussain, Naseer K. Kasim

Karbala International Journal of Modern Science

CIGS PV solar module is a thin film technology (second generation) that is fabricated from Copper-Indium Gallium Selenide. CIGS an abbreviation of Copper-Indium Gallium Selenide. The system, with which reflectors are incorporated, is 5kWp On-Grid CIGS PV Solar system is located at Al Mansour company, Iraq-Baghdad (latitude 33.3°N, longitude 44.4°E and 41m above the sea level). This study improves performance ratio, array efficiency, electrical power and current. All these improvements are done via increasing solar irradiance by using optical reflectors (fabricates from aluminum metal). The maximum values ( at 12:00PM) of the improved and reference …

The Emergence Of The Local Moment Molecular Spin Transistor, Guanhua Hao, Ruihua Cheng, Peter Dowben

Peter Dowben Publications

Local moment molecular systems have now been used as the conduction channel in gated spintronics devices, and some of these three terminal devices might even be considered molecular spin transistors. In these systems, the gate voltage can be used to tune the molecular level alignment, while applied magnetic fields have an influence on the spin state, altering the magnetic properties, and providing insights to the magnetic anisotropy. More recently, the use of molecular spin crossover complexes, as the conduction channel, has led to devices that are both nonvolatile and have functionality at higher temperatures. Indeed, some devices have now been …

Probing Ferroelectricity By X-Ray Absorption Spectroscopy In Molecular Crystals, Fujie Tang, Xuanyuan Jiang, Hsin Yu Ko, Jianhang Xu, Mehmet Topsakal, Guanhua Hao, Alpha T. N'Diaye, Peter Dowben, Deyu Lu, Xiaoshan Xu, Xifan Wu

Peter Dowben Publications

We carry out X-ray absorption spectroscopy experiment at the oxygen K edge in croconic acid (C₅H₂O₅) crystal as a prototype of ferroelectric organic molecular solid, whose electric polarization is generated by proton transfer. The experimental spectrum is well reproduced by the electron-hole excitation theory simulations from configuration generated by ab initio molecular dynamics simulation. When inversion symmetry is broken in the ferroelectric state, the hydrogen bonding environment on the two bonded molecules become inequivalent. Such a difference is sensitively probed by the bound excitation in the pre-edge, which is strongly localized on the excited …

Optimizing Llrf Parameters In The Electron-Ion Collider, William M. Bjorndahl

Physics

To improve particle interaction in the future Electron-Ion Collider (EIC), we investigated different feedback implementations to control the accelerating voltage and examined the power and beam phase for each instance. Using MATLAB, we studied three feedback mechanisms: Direct, One Turn, and Feedforward. Enacting feedforward yielded the best performance. To minimize the klystron power consumption, we analyzed different Low-Level Radio Frequency (LLRF) parameters such as detuning. Combining theory and simulated results, we found the optimal detuning value that minimizes klystron power consumption.

Designing Writing Intensive Upper Division Laboratories In Physics, Sara Callori

Q2S Enhancing Pedagogy

California State University San Bernardino is currently transitioning from quarters to semesters, starting in Fall 2020. As part of this transition, the Department of Physics has transformed its curriculum to better suit the needs of its students. One major facet of this redesign has been the creation of two writing intensive, upper division laboratory courses. From a practical standpoint, under the revamped general education program, we are able to incorporate upper division writing into the major. More importantly, there are many benefits where having a writing-intensive major course aligns with program goals and professional organization recommendations. This includes designing activities …

Homestead National Monument Of America, Acoustic Monitoring Report, 2017, Emma Brown

United States National Park Service: Publications

Executive Summary

This report presents acoustical data gathered by Student Conservation Association interns and the Natural Resource Specialist at Homestead National Monument of America in 2017. Data were collected at one site to provide park managers with information about the acoustical environment, sources of noise, and the existing ambient sound levels within the monument. This deployment also captured acoustic conditions during the total solar eclipse on 8/21/2017. (Results of the eclipse monitoring effort are provided in Appendix B.)

In this deployment, sound pressure level (SPL) was measured continuously every second by a calibrated sound level meter. Other equipment included an …

Homestead National Monument Of America, Acoustic Monitoring, 2011-2012

United States National Park Service: Publications

Executive Summary

This report presents acoustical data gathered by Student Conservation Association interns and the Natural Resource Specialist at Homestead National Monument of America in 2011 and 2012. Data were collected at four sites to provide park managers with information on the acoustical environment, sources of noise, and the existing ambient sound levels within the monument. The data will also inform the park managers with information regarding the potential impact of traffic on Highway 4.

Monitoring occurred at each site during two different seasons (except HOME002) in order to document seasonal variations. In each deployment, sound pressure level (SPL) was …

Density Functional Theory Study Of Two-Dimensional Boron Nitride Films, Pradip R. Niraula

Dissertations, Theses, and Capstone Projects

Since graphene was isolated in 2004, the number of two-dimensional (2D) materials and their scientific relevance have grown exponentially. Besides graphene, one of the most important and technolocially promizing 2D materials that has emerged in recent years is hexagonal boron nitride, in its monolayer or multilayer form. In my thesis work, I used density functional theory (DFT) calculations to investigate the properties of boron nitride films. In particular, I first studied the properties (i.e. formation energy, defect states, and structure) of point charged defects in monolayer and bilayer hexagonal boron nitride, and subsequently, I focused on the linear and nonlinear …

Overview Of Trends In Indian Optics Research (2008 – 2018), Mallikarjun Kappi, Biradar B S

Library Philosophy and Practice (e-journal)

The present study deals with the assessment of Indian optics research output as reflected in Web of Science (WOS) database for the period 2008 to 2018 for identifying the research output in the field of optics literature. It also provides a comparative evaluation and performance of different types of scientometric indicators, such as number of publications, number of citations and collaboration from India. The Indian optics research has increased exponentially over the last decade.

Itinerant Ferromagnetism And Intrinsic Anomalous Hall Effect In Amorphous Iron-Germanium, D. S. Bouma, Z. Chen, B. Zhang, F. Bruni, M. E. Flatté, A. Ceballos, R. Streubel, L. W. Wang, R. Q. Wu, F. Hellman

Robert Streubel Papers

The amorphous iron-germanium system (a-Fe_xGe_1-x) lacks long-range structural order and hence lacks a meaningful Brillouin zone. The magnetization of a-Fe_xGe_1-x is well explained by the Stoner model for Fe concentrations x above the onset of magnetic order around x=0.4, indicating that the local order of the amorphous structure preserves the spin-split density of states of the Fe-3d states sufficiently to polarize the electronic structure despite k being a bad quantum number. Measurements reveal an enhanced anomalous Hall resistivity ρ_xy^AH relative to crystalline FeGe; this ρ_xy^AH is compared to density-functional …

Dual-Axis Solar Tracker, Bryan Kennedy

All Undergraduate Projects

Renewable energies, and fuels that are not fossil fuel-based, are one of the prolific topics of debate in modern society. With climate change now becoming a primary focus for scientists and innovators of today, one of the areas for the largest amount of potential and growth is that of the capturing and utilization of Solar Energy. This method involves using a mechanical system to track the progression of the sun as it traverses the sky throughout the day. A dual-axis solar tracker such as the one designed and built for this project, can follow the sun both azimuthally and in …

Performing Near Field Acoustic Holography Scans For The Purpose Of Finding The Acoustic Impedance Of A Violin, Zamara Tomko

Student Research, Papers, and Creative Works

This project aimed to measure the acoustic impedance of the violin so that the violin can be better understood from an acoustic standpoint. Near field acoustic holography scans are to be conducted at the open A string resonance of the violin (440 Hz). Pressure microphones along the back plate of the violin allow pressure and particle velocity to be measured, and with that, the acoustic impedance to be calculated and mapped in 1 cm x 1cm increments. This work presents a guide for this procedure. The set-up method and materials used are detailed and the analysis and computations of values …

Diffusion Doping Of Cobalt In Rod-Shape Anatase Tio2 Nanocrystals Leads To Antiferromagnetism†, Shahzahan Mia, Shelton J.P. Varapragasam, Aravind Baride, Choumini Balasanthiran, Balamurugan Balasubramanian, Robert M. Rioux, James D. Hoefelmeyer

Nebraska Center for Materials and Nanoscience: Faculty Publications

Cobalt(II) ions were adsorbed to the surface of rod-shape anatase TiO2 nanocrystals and subsequently heated to promote ion diffusion into the nanocrystal. After removal of any remaining surface bound cobalt, a sample consisting of strictly cobalt-doped TiO2 was obtained and characterized with powder Xray diffraction, transmission electron microscopy, UV-visible spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectroscopy, SQUID magnetometry, and inductively-coupled plasma atomic emission spectroscopy. The nanocrystal morphology was unchanged in the process and no new crystal phases were detected. The concentration of cobalt in the doped samples linearly correlates with the initial loading of cobalt(II) ions on the nanocrystal surface. Thin …

Detection Of Decoupled Surface And Bulk States In Epitaxial Orthorhombic Sriro3 Thin Films, Prescott E. Evans, Takashi Komesu, Le Zhang, Ding-Fu Shao, Andrew J. Yost, Shiv Kumar, Eike F. Schwier, Kenya Shimada, Evgeny Y. Tsymbal, Xia Hong, P. A. Dowben

Peter Dowben Publications

We report the experimental evidence of evolving lattice distortion in high quality epitaxial orthorhombic SrIrO3(001) thin films fully strained on (001) SrTiO3 substrates. Angle-resolved X-ray photoemission spectroscopy studies show that the surface layer of 5 nm SrIrO3 films is Sr–O terminated, and subsequent layers recover the semimetallic state, with the band structure consistent with an orthorhombic SrIrO3(001) having the lattice constant of the substrate. While there is no band folding in the experimental band structure, additional super-periodicity is evident in low energy electron diffraction measurements, suggesting the emergence of a transition layer with crystal symmetry evolving from the SrTiO3 substrate …

Manipulation Of The Molecular Spin Crossover Transition Of Fe(H2b(Pz)2)2(Bipy) By Addition Of Polar Molecules, Paulo S. Costa, Guanhua Hao, Alpha T. N'Diaye, Lucie Routaboul, Pierre Braunstein, Xin Zhang, Jian Zhang, Thilini K. Ekanayaka, Qin Yin Shi, V. L. Schlegel, Bernard Doudin, Axel Enders, Peter Dowben

Peter Dowben Publications

The addition of various dipolar molecules is shown to affect the temperature dependence of the spin state occupancy of the much studied spin crossover Fe(II) complex, [Fe{H2B(pz)2}2(bipy)] (pz = pyrazol-1-yl, bipy = 2,2′-bipyridine). Specifically, the addition of benzimidazole results in a re-entrant spin crossover transition, i.e. the spin state starts in the mostly low spin state, then high spin state occupancy increases, and finally the high spin state occupancy decreases with increasing temperature. This behavior contrasts with that observed when the highly polar p -benzoquinonemonoimine zwitterion C6H2(..NH2)2(..O)2 was mixed with [Fe{H2B(pz)2}2(bipy)], which resulted in locking [Fe{H2B(pz)2}2(bipy)] largely into a low …

Launching A New Dimension With 3d Magnetic Nanostructures, Peter Fischer, Dédalo Sanz-Hernández, Robert Streubel, Amalio Fernández-Pacheco

Robert Streubel Papers

The scientific and technological exploration of three-dimensional magnetic nanostructures is an emerging research field that opens the path to exciting novel physical phenomena, originating from the increased complexity in spin textures, topology, and frustration in three dimensions. One can also anticipate a tremendous potential for novel applications with those systems in a magnetic sensor and information processing technologies in terms of improved energy efficiency, processing speed, functionalities, and miniaturization of future spintronic devices. These three-dimensional structures are distinct from traditional bulk systems as they harness the scientific achievements of nanomagnetism, which aimed at lowering the dimensions down to the atomic …

Gas Adsorption In Carbon Nanohorns: Equilibrium And Kinetics, Justin Matthew Petucci

Electronic Theses and Dissertations

A study of gas adsorption has been carried out with the focus of better understanding the relationships between the individual properties of the adsorbent/adsorbate (e.g. material structure, interactions, gas size and shape, etc.) and the overall adsorptive properties of the combined system (e.g. capacity, binding strength, equilibration time, etc.) as a function of thermodynamical variables. This is useful from the perspective of a comprehensive and fundamental understanding as well as for practical applications. The equilibrium regime of adsorption on carbon nanostructure materials (nanohorns, nanotubes, and graphite) is investigated using molecular statics (MS) and grand canonical monte carlo (GCMC) methods for …