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Entropy-Driven Structural Transition From Tetragonal To Cubic Phase: High Thermoelectric Performance Of Cucdinse3 Compound, Tingting Luo, Yihao Hu, Shi Liu, Fanjie Xia, Junhao Qiu, Haoyang Peng, Keke Liu, Quansheng Guo, Xingzhong Li, Dongwang Yang, Xianli Su, Jinsong Wu, Xinfeng Tang

Nebraska Center for Materials and Nanoscience: Faculty Publications

Cu based chalcopyrite is an important class of thermoelectric materials with excellent electronic properties, however, the thermal conductivity is relatively high due to the simple tetragonal structure with highly ordered configuration on cation sites, limiting the thermoelectric performance. Herein, we realize that the modulation of entropy via alloying CdSe achieves the structural transition from tetragonal structure with ordered configuration on cations sites in CuInSe₂ compound to cubic CuCdInSe₃. CuCdInSe₃ crystallizes in a zinc blende (ZnS) structure where Cu, Cd and In cations randomly occupy the Zn site with the occupancy fraction 1/3. This entropy driven order-disorder …

Higher-Order Cumulants And Correlation Functions Of Proton Multiplicity Distributions In √Snn = 3 Gev Au+Au Collisions At The Rhic Star Experiment, The Star Collaboration

Physics and Astronomy Faculty Publications

We report a measurement of cumulants and correlation functions of event-by-event proton multiplicity distributions from fixed-target Au+Au collisions at √sNN = 3 GeV measured by the STAR experiment. Protons are identified within the rapidity (y) and transverse momentum (pT ) region −0.9 < y < 0 and 0.4 < pT < 2.0 GeV/c in the center-of-mass frame. A systematic analysis of the proton cumulants and correlation functions up to sixth order as well as the corresponding ratios as a function of the collision centrality, pT , and y are presented. The effect of pileup and initial volume fluctuations on these observables and the respective corrections are discussed in detail. The results are compared to calculations from the hadronic transport UrQMD model as well as a hydrodynamic model. In the most central 5% collisions, the value of proton cumulant ratio C4/C2 is negative, drastically different from the values observed in Au+Au collisions at higher energies. Compared to model calculations including lattice QCD, a hadronic transport model, and a hydrodynamic model, the strong suppression in the ratio of C4/C2 at 3 GeV Au+Au collisions indicates an energy regime dominated by hadronic interactions.

Dna Capture And Translocation Through Nanopore, Swarnadeep Seth

Graduate Thesis and Dissertation 2023-2024

This thesis investigates DNA dynamics and translocation through nanopores using Brownian dynamics (BD) simulations, offering insights into sequencing technologies, DNA marker detection, and accurate barcoding utilizing solid-state nanopore platforms. First, we in silico study the intricate process of capture and translocation in a single nanopore. Our simulation reveals a high probability of hairpin loop formation during the capture process. However, attaching a charged tag to one end of DNA improves multi-scan rates and enhances unidirectional translocations. We use modulating voltage biases to multi-scan a lambda-phage dsDNA with oligonucleotide flap markers (tags) through a single and double nanopore system. Our study …

Optical Characterization Of Liquids: Refractive Index And Raman Gain Coefficient Measurements, Cesar A. Lopez-Zelaya

Graduate Thesis and Dissertation 2023-2024

Novel technologies capable of generating wavelengths not accessible with typical laser gain media have been among the primary drivers of the field of nonlinear optics. Here, we are interested in the linear and nonlinear properties of liquids beyond the visible spectrum, motivated in part by their use as core materials in optical fibers. Given their dispersion, nonlinearities, transparency, and ability to be mixed, liquids show potential for exploiting in-fiber nonlinear phenomena for developing the new generation of low cost, size, weight, and power wavelength-agile fiber-laser sources. For the design, modeling, and experimental realization of these liquid-core fiber laser sources, proper …

Optical Design Study Of A High-Resolution Spectrograph Utilizing Photonic Lanterns For A Large Fiber Array Telescope, Richard D'Alo

Graduate Thesis and Dissertation 2023-2024

Large area fiber array telescopes are a relatively modern development in the long history of telescope design and effectively create a single large equivalent aperture by combining many smaller unit telescopes at a fraction of the cost. In this study a spectrograph optical design is demonstrated that utilizes photonic lanterns in the input fiber feed for the Large Fiber Array Spectroscopic Telescope (LFAST) design concept, where photonic lanterns provide a simplified approach to the fiber feed originally proposed for LFAST. Conservation of etendue is applied to derive the relationship between slit size and photonic lantern ratio, and classical echelle spectrograph …

A Theoretical Study Of Elementary Processes In Interstellar Plasma, Joshua Forer

Graduate Thesis and Dissertation 2023-2024

Interstellar plasma — interstellar clouds in particular — play an important role in determining the structure and evolution of galaxies. Understanding the time evolution of such plasmas requires knowledge of the chemical processes that drive their dynamics. Two processes are studied in this dissertation: radiative electron attachment (REA) via dipole-bound states (DBSs) and dissociative recombination (DR). Of the several hundred molecules detected in the interstellar medium, only eight anions have been detected: CN-, C3N-, C5N-, C7N-, C4H-, C6H-, C8H-, and C10H-. Their production mechanism is not well known; REA was suggested as a possible formation pathway, but previous theoretical studies …

Piv Measurements Of Open-Channel Turbulent Flow Under Unconstrained Conditions, James K. Arthur

Faculty Journal Articles

Many open-channel turbulent flow studies have been focused on highly constrained conditions. Thus, it is rather conventional to note such flows as being fully developed, fully turbulent, and unaffected by sidewalls and free surface disturbances. However, many real-life flow phenomena in natural water bodies and artificially installed drain channels are not as ideal. This work is aimed at studying some of these unconstrained conditions. This is achieved by using particle image velocimetry measurements of a developing turbulent open-channel flow over a smooth wall. The tested flow effects are low values of the Reynolds number based on the momentum thickness Re …

Growth And Characterization Of Sm3hfbi5, Patrick Lambdin

Graduate Theses/Dissertations

First found experimentally in 2015, topological Weyl materials are desirable compounds that have garnered much interest due to their ability to conduct electricity via their surface states even though the bulk material is a semimetal. Such a candidate, Sm3HfBi5, was discovered with a flux crystal growth method, following an extensive amount of reaction syntheses. This thesis reports on the discovery, growth, structural characterization via x-ray diffraction, and magnetization measurements on Sm3HfBi5.

Investigating The Structural Properties Of Licoo2 Through Annealing In A Reducing Atmosphere And Characterization Using Raman Spectroscopy And X-Ray Diffraction, Mathew A. Boeser

Graduate Theses/Dissertations

The electrochemical performance of lithium cobalt oxide (LiCoO₂) cathode materials in lithium-ion batteries is strongly influenced by their structural and chemical characteristics. Annealing in a reducing atmosphere is able to modify the crystal structure of LiCoO₂ by inducing oxygen vacancies, ideally enhancing its electrochemical performance. This master's thesis presents an investigation into the effects of low to mid-range annealing temperatures in a reducing atmosphere on bulk LiCoO₂ powder, utilizing Raman spectroscopy and X-ray Diffraction (XRD).

Development Of Advanced Germanium Detectors For Rare Event Physics, Sanjay Bhattarai

Dissertations and Theses

High Purity Germanium (HPGe) detectors are widely used in rare-event physics searches for dark matter, neutrinoless double-beta decay, and solar neutrinos. This dissertation fo- cuses on improving crystal quality by controlling the impurity concentration, dislocation density, and growth environment as well as developing advanced Ge detectors for various physics applications. The dissertation presents experimental investigations of electrical conduction mechanisms in p-type amorphous germanium (a-Ge), which is used as an elec- trical contact material in HPGe detectors. By measuring the surface leakage current from three high-purity planar Ge detectors, we determine the localization length and hopping parameters in a-Ge. The dissertation …

Development Of Novel Hpge Detector For Rare Event Physics, Mathbar Singh Raut

Dissertations and Theses

This dissertation focuses on the enhancement of crystal quality in High Purity Germanium (HPGe) detectors, which play a crucial role in rare-event physics investigations such as dark matter detection, neutrinoless double-beta decay, geo-neutrinos, and solar neutrinos. The primary objective of this research is to improve crystal quality by controlling impurity concentration, dislocation density, and growth environment. Additionally, the development of advanced Ge detectors for various physics applications is explored. One significant aspect examined in this dissertation is the investigation of systematic errors associated with the Hall effect system. The goal is to identify a reliable technique that minimizes the systematic …

Background Discrimination Of A Neutrino Detector With Dense Neural Networks, Perry Siehien

Dissertations and Theses

Neutrinos are subatomic particles that weakly interact with matter due to their neutral charge and small cross section. Detectors that search for neutrinos require sensitive instrumentation, which makes them susceptible to various background sources such as gamma rays. Additionally, coherent elastic neutrino-nucleus scattering events, or CEvNS, are the weakest neutrino interactions at 1-25 keV, making them exceptionally difficult to observe. To understand the physics of CEvNS events within the detector material, the recoil signatures of relevant interactions must be determined. Traditional analysis methods are effective, but cannot be applied to energies below 50 keV, due to the overlap of discrimination …

Fabrication And Characterisation Of Large Area, Uniform And Controllable Surface Relief Patterns In Photopolymer Material, Owen Kearney, Izabela Naydenova

Conference Papers

As the risk of antibiotic resistant pathogens increases, development of convenient point of care devices is essential. Such devices would help avoid infection – ensure cleanliness of environments and assist in bacteria analysis. The ultimate aim of the research presented here is to develop a compact, cost effective, easy to use optical device which is capable of detecting and quantifying bacteria in an aqueous sample. The surface relief patterns have a dual role, they provide a diffracted light signal, and control the adhesion of the bacteria to the surface. The strength of the diffracted signal is expected to provide a …

Jwst/Nirspec Balmer-Line Measurements Of Star Formation And Dust Attenuation At Z ∼ 3–6, Alice E. Shapley, Ryan L. Sanders, Naveen Reddy, Michael W. Topping, Gabriel B. Brammer

Physics and Astronomy Faculty Publications

We present an analysis of the star formation rates (SFRs) and dust attenuation properties of star-forming galaxies at 2.7 ≤ z < 6.5 drawn from the Cosmic Evolution Early Release Science Survey. Our analysis is based on JWST/NIRSpec Micro-Shutter Assembly R ∼ 1000 spectroscopic observations covering approximately 1-5 μm. Our primary rest-frame optical spectroscopic measurements are Hα/Hβ Balmer decrements, which we use as an indicator of nebular dust attenuation. In turn, we use Balmer decrements to obtain dust-corrected Hα-based SFRs (i.e., SFR(Hα)). We construct the relationship between SFR(Hα) and stellar mass (M _*) in three bins of redshift (2.7 ≤ z < 4.0, 4.0 ≤ z < 5.0, and 5.0 ≤ z < 6.5), which represents the first time the star-forming main sequence has been traced at these redshifts using direct spectroscopic measurements of Balmer emission as a proxy for SFR. In tracing the relationship between SFR(Hα) and M _* back to such early times (z > 3), it is essential to use a conversion factor between Hα and SFR that accounts for the subsolar metallicity prevalent among distant galaxies. We also use measured Balmer decrements to investigate the relationship between dust attenuation and stellar mass out to z ∼ 6. The lack of significant redshift evolution in attenuation at fixed stellar mass, previously confirmed using Balmer decrements out …

Beam Energy Dependence Of Fifth- And Sixth-Order Net-Proton Number Fluctuations In Au + Au Collisions At Rhic, Star Collaboration

Physics and Astronomy Faculty Publications

We report the beam energy and collision centrality dependence of fifth and sixth order cumulants (C5, C6) and factorial cumulants (κ5, κ6) of net-proton and proton number distributions, from center-of-mass energy (sNN) 3 GeV to 200 GeV Au+Au collisions at RHIC. Cumulant ratios of net-proton (taken as proxy for net-baryon) distributions generally follow the hierarchy expected from QCD thermodynamics, except for the case of collisions at 3 GeV. The measured values of C6/C2 for 0%-40% centrality collisions show progressively negative trend with decreasing energy, while it is positive for the lowest energy studied. These observed negative signs are consistent with …

Measurement Of Sequential ϒ Suppression In Au + Au Collisions At √Snn = 200 Gev With The Star Experiment, Star Collaboration

Physics and Astronomy Faculty Publications

We report on measurements of sequential ϒ suppression in Au+Au collisions at sNN=200 GeV with the STAR detector at the Relativistic Heavy Ion Collider (RHIC) through both the dielectron and dimuon decay channels. In the 0%-60% centrality class, the nuclear modification factors (RAA), which quantify the level of yield suppression in heavy-ion collisions compared to p+p collisions, for ϒ(1S) and ϒ(2S) are 0.40±0.03(stat)±0.03(sys)±0.09(norm) and 0.26±0.08(stat)±0.02(sys)±0.06(norm), respectively, while the upper limit of the ϒ(3S) RAA is 0.17 at a 95% confidence level. This provides experimental evidence that the ϒ(3S) is significantly more suppressed than the ϒ(1S) at RHIC. The level of …

Measurementus Magnetic Moment To 0.20 Ppm Of The Positive Muon Anomalo, The Muon G − 2 Collaboration

Physics and Astronomy Faculty Publications

We present a new measurement of the positive muon magnetic anomaly, aμ(gμ-2)/2, from the Fermilab Muon g-2 Experiment using data collected in 2019 and 2020. We have analyzed more than 4 times the number of positrons from muon decay than in our previous result from 2018 data. The systematic error is reduced by more than a factor of 2 due to better running conditions, a more stable beam, and improved knowledge of the magnetic field weighted by the muon distribution, p′, and of the anomalous precession frequency corrected for beam dynamics effects, ωa. From the ratio ωa/p′, together with precisely …

Quantum Computing And Its Applications In Healthcare, Vu Giang

OUR Journal: ODU Undergraduate Research Journal

This paper serves as a review of the state of quantum computing and its application in healthcare. The various avenues for how quantum computing can be applied to healthcare is discussed here along with the conversation about the limitations of the technology. With more and more efforts put into the development of these computers, its future is promising with the endeavors of furthering healthcare and various other industries.

Direct Parameter Fitting Of Action Potentials In Skeletal Muscle Cells Which Include Longitudinal Segments, Tyme Suda

Browse all Theses and Dissertations

Excitation of skeletal muscle cells triggers a large voltage spike known as an action potential (AP), leading to muscle contraction. Modeling of an AP is typically done using the method developed by scientists Hodgkin and Huxley (HH). In the HH method, voltage and time gated Na+ and K+ ionic currents are simulated, along with a positive “Leak” ionic current and capacitive current. Due to the complexity and the computational time required for simulation, direct fitting of HH parameters to experimental APs has rarely been attempted. A previous thesis at Wright State performed direct fitting for the case of a single …

A First Study Of The Effect Of Surface Roughness In Additive-Manufactured Copper At Thz Frequencies, Tomas Di Fulvio, Elliott R. Brown, Andrew J. Huebner, Michael A. Saville, Paul Sotirelis

Physics Faculty Publications

The surface roughness of additive-manufactured copper is characterized by profilometry, and its effect on the THz reflectance is measured at 600 GHz. A strong specular component is measured, as well as a non-specular component displaying fluctuations in the wings of the angular reflectance plot.

Simulation Of Coherent Remission In Planar Disordered Medium, Pablo Jara-Palacios, Ho Chun Lin, Chia Wei Hsu, Hui Cao, Alexey Yamilov

Physics Faculty Research & Creative Works

Waves remitted from a scattering medium carry information that can be used for non-invasive imaging and sensing. Such techniques are usually limited by a low photon budget. Recent progress in optical wavefront shaping has enabled coherent control with an order-of-magnitude enhancement of remission [1]. This experimental study necessitated increasingly demanding numerical simulations. Extending this line of research requires more sophisticated computational techniques capable of simulating multiple instances of even larger systems. Here, we demonstrate that remission geometry can be efficiently simulated using a novel open-source software package [2] Maxwell's Equations Solver with Thousands of Inputs (MESTI). To verify its numerical …

New Features In Landyne 5 - A Software Suite For Materials Characterization And Crystallography By Transmission Electron Microscopy, Xing-Zhong Li

Nebraska Center for Materials and Nanoscience: Faculty Publications

Landyne software suite (version 5) includes fifteen standalone computer programs for materials characterization and crystallography by transmission electron microscopy [1]. A launcher interface is provided for users to access all components conveniently. The purpose of this software suite is twofold: i) as research tools to analyze experimental results, ii) as teaching tools to explore the varieties of electron diffraction methods and crystallographic image processing principles.

The Landyne suite previously included: PTable, an interactive periodic table of elements; SVAT, a structural visual and analytical tool; SAED and PCED, simulation and analysis of electron diffraction (spot and ring) patterns; QSAED and QPCED, …

Reflective Planar Optics With Cholesteric Liquid Crystal For Near-Eye Displays, Yannanqi Li

Electronic Theses and Dissertations, 2020-2023

Display market has undergone dramatic changes as the near eye displays (NED) are gaining increasing attention because they offer a deeper level of human-computer interaction with the advancement of electronic devices and computer sciences. The NEDs can be presented in two ways: virtual reality (VR) and augmented reality (AR). The former is completely immersive while the latter combines the digital information with the surrounding scenes. Although several VR headsets have been commercialized for consumers and AR products for prosumers because of their high cost, but there is still a long way to go to satisfy the strict requirements of human …

Efficient Text Bounding Box Identification Using Mask R-Cnn: Case Of Thai Documents, Phanthakan Kiatphaisansophon

Chulalongkorn University Theses and Dissertations (Chula ETD)

Text detection is a fundamental task in computer vision, particularly for Optical Character Recognition (OCR) application. This research focuses on text detection part of the OCR. Our previous text detection model, CRAFT (Character-Region Awareness For Text detection) has shown promising outcomes in bounding box identification. Nevertheless, it encounters issues associated with post-processing and multiline text. The post-processing related to the necessity to reconfigure the model when new documents are introduced, resulting in inefficiencies and complexities. Also the CRAFT model tends to blend bounding boxes from consecutive lines, introducing errors and impacting the accuracy in the text recognition part of the …

Computational Modeling, Simulation, And Potential Applications Of Optical Stochastic Cooling, Austin J. Dick

Graduate Research Theses & Dissertations

With the rising demand for intense particles beams, much research is being conducted in the area of particle beam cooling. One of these methods, called Stochastic Cooling (SC) (developed at CERN in the 1970's), delivered a feedback method to improve the quality and lifetime of circulating proton beams by reducing their 6D phase-space and has been widely implemented in a number of hadron machines. However, traditional stochastic cooling schemes are limited by the bandwidth of microwave frequency systems. Optical Stochastic Cooling (OSC) is a promising extension of the stochastic cooling beam cooling technique. OSC instead uses optical wavelengths which allows …

The Mceliece Cryptosystem As A Solution To The Post-Quantum Cryptographic Problem, Isaac Hanna

Senior Honors Theses

The ability to communicate securely across the internet is owing to the security of the RSA cryptosystem, among others. This cryptosystem relies on the difficulty of integer factorization to provide secure communication. Peter Shor’s quantum integer factorization algorithm threatens to upend this. A special case of the hidden subgroup problem, the algorithm provides an exponential speedup in the integer factorization problem, destroying RSA’s security. Robert McEliece’s cryptosystem has been proposed as an alternative. Based upon binary Goppa codes instead of integer factorization, his cryptosystem uses code scrambling and error introduction to hinder decrypting a message without the private key. This …

Can The Xy+Z Heisenberg Model Be Compressed Using The Yang-Baxter Equation? An Exploration Of The Compression Of Quantum Time Dynamic Circuits Describing Heisenberg Spin Chains, Miriam Caron, Bo Peng Dr., Scott Gould Dr., Kevin Setter Dr., Niranjan Govind Dr.

Pitzer Senior Theses

Quantum computing is currently deployed on noisy intermediate-scale quantum (NISQ) devices, which are only able to simulate circuits reliably on shallow depth quantum circuits. A promising problem on near-term quantum computers is quantum time dynamics (QTD). However, QTD circuits grow with increasing time simulations making them difficult to simulate on NISQ devices. This thesis project explores QTD simulations in variations of 1D Heisenberg spin chains with nearest-neighbor and transverse external field interactions with an eye towards studying the dynamics in broader classes of spin models. I first study the quantum Yang-Baxter equation (YBE) and how it has been shown to …

Beam Dynamics Simulations And Systematic Studies For The Muon G-2 Experiment At Fermilab, Abel M. Lorente Campos

Theses and Dissertations--Physics and Astronomy

The first results of the positive muon anomalous magnetic moment from the Muon g-2 Experiment at Fermilab differs from the Standard Model prediction by 3.3 standard deviations, with an experimental uncertainty of 0.46 ppm. Combining this result with the previous measurement from the Brookhaven National Laboratory, it sets the difference between experiment and theory at 4.2 standard deviations. The goal of the Muon g-2 Experiment at Fermilab is to increase this discrepancy to 5 standard deviations, which would require unprecedented precision in the measurements of 0.14 ppm. Of significant importance to achieving this precision, beam and spin dynamics simulations are …

Nonequilibrium Dynamics Of Correlated Disordered Systems Under Interaction Quenches, Eric A. Dohner

Legacy Theses & Dissertations (2009 - 2024)

Correlated, disordered lattice fermion systems out of equilibrium have been understudied, at least in part for lack of tools to study them. The development of a new method, the NE-DMFT+CPA, is explicated, for investigating the properties of these systems. This method combines DMFT and the CPA using the Kadanoff-Baym-Keldysh contour-time formalism to study the dynamics of interacting disordered systems out of equilibrium. The method is detailed, then applied to the case of the Anderson-Hubbard model: first to replicate well-known equilibrium results, then to study the case of the model under the effect of an interaction quench. Here the effect of …

Surface Reconstruction In Iron Garnets, Sushree Dash

Dissertations, Master's Theses and Master's Reports

This dissertation presents the results of a study investigating the physical mechanisms underlying an unexpectedly large increase in magneto-optic efficiency observed in iron garnet. Such materials are technologically important for telecommunications due to their nonreciprocal optical action. In the past, our group had found evidence of an enhanced Faraday rotation in bismuth-substituted iron garnet films less than 50 nm thick. Subsequent investigation revealed that this enhancement could be traced to surface effects. This is significant because understanding these phenomena could be used to formulate engineering solutions for device miniaturization. In this dissertation, we present the result of a research project …