Digital Commons Network^™

Ultralight Vector Dark Matter Search Using Data From The Kagra O3gk Run, A. Abac, R. Abbott, H. Abe, Teviet Creighton, Mario C. Diaz, Francisco Llamas, Soma Mukherjee, Gaukhar Nurbek, Volker Quetschke, Wenhui Wang

Physics & Astronomy Faculty Publications

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the …

Hot Wire Chemical Vapor Deposition Of Tungsten Oxides For Photocatalytic Hydrogen Production From Water, Marvin Bonney

Theses and Dissertations

Anthropogenic climate change has generated an ever-increasing global ecological, economic, and political disaster for the world. In order to contain the damage and bring atmospheric carbon under control, human use of non-renewable hydrocarbons as the primary source of fuels for transportation and electrical generation needs to be phased out at the earliest possible date. Renewable, clean energy generation is currently technologically feasible and could provide the means for decarbonization of the global energy economy, but has to overcome challenges related to the intermittency of production. Hydrogen gas is a clean burning, renewable, and highly flexible method of storing such energy …

Development Of A Balloon Mission To Test Flight A Novel Mini-Dilution Refrigerator And A Tes Gamma-Ray Detector Array, And New Measurement Of The Spin Of The Black Hole Cygnus X-1, Md. Arman Hossen

Arts & Sciences Graduate Student Theses and Dissertations

Transition-edge sensor (TES) detectors have become increasingly common in X-ray and gamma-ray astrophysics due to their high resolving power and feasibility of fabricating thousands of pixels within a compact area. In the framework of my thesis, I have tested a 32-pixel microwave multiplexed TES detector array, a smaller version of the SLEDGEHAMMER (Spectrometer to Leverage Extensive Development of Gamma-ray TESs for Huge Arrays using Microwave Multiplexed Enabled Readout) gamma-ray detector developed by NIST to perform X-ray and gamma-ray observation on a balloon mission known as DR-TES. DR-TES is scheduled to be launched from Fort Sumner, New Mexico, in the fall …

Experimental Determination Of The Unusual Ch Stretch Frequency Of Protonated Fullerenes, Laura Finazzi, Vincent J. Esposito, Julianna Palotás, Jonathan Martens, Els Peeters, Jan Cami, Giel Berden, Jos Oomens

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

We report experimental values for the CH stretch frequencies of the protonated fullerenes C₆₀H⁺ and C₇₀H⁺. Anharmonic frequency calculations at the B3LYP/6-31G level of theory, which are independent of empirical scaling factors, reproduce the experimental values to within approximately 5 cm⁻¹. Scaling theoretical harmonic frequencies by applying factors derived for polycyclic aromatic hydrocarbons deviate significantly from the experimentally measured frequency. We attribute this deviation to the unusual hydrocarbon structure that affects the degree of anharmonicity of the CH stretch. This result allows us to propose an original, specific scaling factor of …

Unraveling The Structure And Star Formation History Of Polar Ring Galaxies, Kyle Lackey

Theses and Dissertations

Polar ring galaxies (PRGs) are a fascinating subgroup of early-type galaxies (ETGs) consisting of a central host galaxy - typically E/S0 - surrounded by a ring of gas, dust and stars orbitting perpedicular to the major axis of that host. In order to estimate physical properties and origins of five such objects taken from Whitmore's 1990 PRC catalog, we conduct a photometric study in optical and infrared wavebands. Data are taken from SDSS, GMOS-S, HST-WFPC2, and SST-IRAC. Each object was decomposed into a host galaxy bulge, host galaxy disk, and polar ring, and each component was fit with a Sersic …

Unveiling The Magnetic And Structural Properties Of Hydrohematite : A Potential Water-Bearing Mineral On The Surface Of Mars, Abdullah Al Maruf

Dartmouth College Master’s Theses

Hematite (α-Fe₂O₃) is one of the most prevalent iron oxides in sedimentary rocks and on the surface of Mars. Recent studies suggest that natural "hydrohematite" exists, wherein hematite accommodates cations through compensation at the Fe³⁺–site, forming –OH bonds (i.e., structural water), with important implications for water in arid planetary environments. We present a detailed magnetic characterization to elucidate the magnetic response of H–doping on these samples, corroborating the results with first-principles calculations. First-order reversal curves show a sharp diagonal wing due to triaxial basal plane anisotropy. Low-temperature cooling experiments show the complete suppression of …

Scheduling Meetings: Are The Odds In Your Favor?, Harsh Mathur

Faculty Scholarship

Abstract: Polling all the participants to find a time when everyone is available is the ubiquitous method of scheduling meetings nowadays. We examine the probability of a poll with m participants and ℓ possible meeting times succeeding, where each participant rejects r of the ℓ options. For large ℓ and fixed r/ℓ, we can carry out a saddle-point expansion and obtain analytical results for the probability of success. Despite the thermodynamic limit of large ℓ, the ‘microcanonical’ version of the problem where each participant rejects exactly r possible meeting times, and the ‘canonical’ version where each participant has a probability …

Questioning Reality: The Progressive Development Of Modern Physics, Joshua Lancman

STEM Month

Humanity has a tendency to divide time. The past is distinct from the present which is entirely separate from the future. In supposedly 20-20 vision history is neatly divided into different sections, distinct eras with sharp lines between them. What is present and in the future is always modern. What is past is something else with another name.

Yet time is not divided so neatly. We know this living through it: years and decades blend into one another in a non-uniform progression. To divide human history into separate eras is a necessary simplification, as it helps to ascribe order onto …

A Review Of Stable, Traversable Wormholes In F(R) Gravity Theories, Ramesh Radhakrishnan, Patrick Brown, Jacob Matulevich, Eric Davis, Delaram Mirfendereski, Gerald Cleaver

Physics & Astronomy Faculty Publications

It has been proven that in standard Einstein gravity, exotic matter (i.e., matter violating the pointwise and averaged Weak and Null Energy Conditions) is required to stabilize traversable wormholes. Quantum field theory permits these violations due to the quantum coherent effects found in any quantum field. Even reasonable classical scalar fields violate the energy conditions. In the case of the Casimir effect and squeezed vacuum states, these violations have been experimentally proven. It is advantageous to investigate methods to minimize the use of exotic matter. One such area of interest is extended theories of Einstein gravity. It has been claimed …

Maximizing Legged Accelerations: A Matter Of Force, Time, And Gravity, Lance Brooks

Applied Physiology and Wellness Theses and Dissertations

Sprint running accelerations require runners to apply surface forces that: support body weight by pushing downward, accelerate the body horizontally by pushing backward, and align the direction of the push with the body’s mass center to maintain balance and posture, which imposes an upper limit on the average forward acceleration force equal to the average gravitational force (1.0 G) acting on the runner. This expectation arises from the mechanical constraints imposed by the need to generate sufficient vertical force to support body weight against gravity while simultaneously producing horizontal force to accelerate forward and aligning the push through the center …

Madelung Mechanics And Superoscillations, Mordecai Waegell

Mathematics, Physics, and Computer Science Faculty Articles and Research

In single-particle Madelung mechanics, the single-particle quantum state Ψ(⃗x, t) = R(⃗x, t)eiS(⃗x,t)/h is interpreted as comprising an entire conserved fluid of classical point particles, with local density R(⃗x, t)2 and local momentum ⃗∇S(⃗x, t) (where R and S are real). The Schrödinger equation gives rise to the continuity equation for the fluid, and the Hamilton–Jacobi equation for particles of the fluid, which includes an additional density-dependent quantum potential energy term Q(⃗x, t) = − ¯h2 2m ⃗∇R(⃗x,t) R(⃗x,t) , which is all that makes the fluid behavior nonclassical. In particular, the quantum potential can become negative and create a …

On Weak Solutions And The Navier-Stokes Equations, Aryan Prabhudesai

Mathematical Sciences Undergraduate Honors Theses

In this paper, I will discuss a partial differential equation that has solutions that are discontinuous. This example motivates the need for distribution theory, which will provide an interpretation of what it means for a discontinuous function to be a “solution” to a PDE. Then I will give a detailed foundation of distributions, including the definition of the derivative of a distribution. Then I will introduce and give background on the Navier-Stokes equations. Following that, I will explain the Millennium Problem concerning global regularity for the Navier-Stokes equations and share mathematical results regarding weak solutions. Finally, I will go over …

Tuning Electronic Transport And Magnetic Properties Of Layered Magnetic Materials, Md Rafique Un Nabi

Graduate Theses and Dissertations

Two-dimensional magnetic materials (2DMMs) have gained significant interest due to their potential for novel physical phenomena and device applications. Mn_2-xZn_xSb, with its tunable magnetic properties and stable tetragonal layered structure, offers a rich platform for exploring these phenomena. The introduction of Zn into the Mn₂Sb lattice efficiently tunes magnetic and electronic properties, making it a compelling candidate for high-performance spintronic devices.

With this motivation, we synthesized Mn_2-xZn_xSb (0 ≤ x ≤ 1) single crystals using a flux method. Mn2Sb exhibits ferrimagnetic order below 550 K with antiparallel spins aligned along …

Methods For Improving Low Frequency Selection And Electrode Firing Order In Cochlear Implants, James H. Keen Jr.

LSU New Orleans Theses and Dissertations

The Advanced Bionics cochlear implant devices allocate static frequency bins to electrode channels based on the natural tonotopic organization of the cochlea. These frequency bins are wide and limited, especially in the lower range. Considering that the fundamental tones of the human voice and the primary melodic tones in music are in this lower range, it is important to have accurate representation of this frequency content. Here, adjustments to the frequency bin allocation algorithm used in the crowdsourced CI Hackathon code are made to allow a more accurate representation of the original signal. First, the frequency bins allocated to each …

Implementing Radformation At Personalized Radiation Oncology: Enhancing Efficiency And Precision, Devin J. Peart

UNLV Theses, Dissertations, Professional Papers, and Capstones

RadMachine is a data quality management application implemented at Personalized Radiation Oncology (PRO) to streamline quality assurance (QA) tests. It offers various functions assisting medical physicists in a radiation oncology clinic, including inputting, analyzing, managing, exporting, and monitoring QA data. Physicists create test lists following the recommendations provided by the American Association of Medical Physics (AAPM). These lists track results for units such as the Varian Edge, Varian BRAVOS, and Siemens SOMATOM go.Open Pro CT scanner. Ancillary equipment used for testing also has assigned test lists to store calibration factors and receive calibration expiration reminders. The primary goal of utilizing …

Rabi Oscillations And Entanglement Between Two Rydberg Atoms In An Optical Cavity Studied By The Jaynes-Cummings Model And Quantum Circuits On Qiskit, Francisco D. Santillan

Theses and Dissertations

Rydberg atoms are highly excited atoms in which one electron has a large principal quantum number. Due to their unusual atomic properties, Rydberg atoms are promising building blocks of two-qubit gates and light-atom quantum interfaces in quantum information processing. For two atoms at close distance (< 10 mm) the Rydberg blockade prevents the two atoms to be simultaneously in the excited state whereas this blockade is absent for atoms far apart. Recently, this effect was used to engineer a quantum processor based on two-dimensional arrays of neutral atoms which are trapped and transported by optical tweezers. Motivated by these experiments, we study the light-atom interaction and entanglement of two Rydberg atoms interacting by the Rydberg blockade in an optical cavity using the Jaynes-Cummings model. We find a rich variety of Rabi oscillations and entanglement as a function of initial conditions and interaction time, which may be used to generate two-qubit gates. Furthermore, we develop and simulate a quantum circuit of this system using Qiskit, an open-source software development kit designed to emulate the operation of a real Quantum Computer.

Density Functional Theory Calculations On Electronic And Optical Properties Of Mos2/Metal Heterojunction, Mos2/Graphene/Metal Vertical Heterostructure Interfaces And Sulfur Vacancies On Mos2/Au, Shishir Timilsena

Theses and Dissertations

In this study, we conducted a comprehensive investigation on computational simulations and analyses of heterostructures formed by two-dimensional (2D) molybdenum disulfide (MoS2) and graphene (Gr) on various metal coated substrates, including gold (Au), copper (Cu), nickel (Ni), and platinum (Pt). The frequency-dependent dielectric function (ɛ(ω)), refractive index (n), and reflectivity (R) are determined using light polarization parallel and perpendicular to the c axis of the 2D layers. Our findings reveal that MoS2/Au, MoS2/Cu, and MoS2/Pt heterostructures exhibit a direct bandgap at the K-point of the Brillouin zone, whereas their corresponding MoS2/MoS2/Metal structures present an indirect bandgap. The reduced interlayer spacing …

Thermodynamic Feasibility Of Potential Nano-Energetic Systems Based On Metal Oxynitrides, Manoj Chhetri

Theses and Dissertations

A computational study was undertaken with the objective of identifying the nano-energetic systems containing aluminum as fuel and metal oxynitrides as oxidizer, aiming to achieve an exothermic reaction characterized by the maximum values of gas generation, adiabatic combustion temperature, and energy release. For the thermodynamic calculation, nine systems based on metal oxynitrides were taken using the THERMO software that works based on the Gibbs free energy minimization, together with HSC Chemistry 7 to calculate the thermodynamic equilibrium concentrations of reactants and products corresponding gas generation, temperature and energy release by varying the fuel to oxidizer ratio. Among all the chosen …

Consistency Of Advanced Radiation Therapy Qa Methods And Global Auditing Systems, Fre'etta Brooks

Dissertations and Theses (Open Access)

Consistency of Advanced Radiation Therapy QA Methods and Global Auditing Systems

Fre’Etta M.D. Brooks, B.S.

Advisory Professor: Stephen F. Kry, Ph.D.

Abstract

Auditing systems provide a means to verify the implementation and operation of all equipment and radiation parameters used by an institution providing radiation therapy treatments. The systems are important tools that are used to determine if an institution can accurately deliver radiation therapy that requires complex planning in the form of IMRT or VMAT and credential radiotherapy treatment institutions for specific clinical trial protocols; to assure the quality of treatment to all patients. Auditing techniques vary by region …

Influential Factors And Predicting Dose Delivery Accuracy For Imaging And Radiation Oncology Core’S Phantom Program Using Machine Learning, Hunter Mehrens

Dissertations and Theses (Open Access)

IROC’s mission is to help ensure consistent and comparable, high-quality radiotherapy across clinics that participate in national clinical trials. To obtain this mission, IROC’s phantom program provides a third-party end-to-end check of the clinical workflow of a patient receiving radiotherapy. The goal of the phantom audit is to compare the dose delivered to the dose planned by the treatment system ensuring dose delivery accuracy. While IROC’s phantoms are better equipped to catch dose delivery errors compared to a clinic’s QA process, the end-to-end process and reporting of results is time-consuming creating a bottleneck for clinical trial participation. Furthermore, IROC’s passing …

Quantum Circuit Optimization Leveraging Multi-Qubit Exchange Interactions In Spin Qubits, Miguel Gonzalo Rodriguez

Open Access Theses & Dissertations

This thesis looks into how multi-qubit exchange interactions can be used to improve quantumcircuits in semiconductor quantum devices. Pairwise interactions between qubits are a common tenet of traditional quantum computing paradigms, although they can impose complexity and depth constraints on circuits. In order to improve the efficiency and scalability of quantum circuits, this research explores the theoretical underpinnings and practical uses of multi-qubit interactions. A thorough theoretical framework is formulated, outlining the mathematical equivalence of a unitary matrix representing interactions between multiple qubits. We obtain the timeevolution operator by analyzing the Hamiltonian of three spin-1/2 particles. A number of quantum …

Understanding And Control Of Frustration And Topological Defects In Ferroic Matter, Suyash Rijal

Graduate Theses and Dissertations

Ferroic matter are of great importance as they provide a platform to extend the understanding of many-body physics and also for their amazing functional properties relevant for technological advancements. The work in this dissertation is dedicated to two of such ferroic materials.

First is CrGeTe₃ (CGT), a two dimensional (2D) magnet discovered in 2017. The discovery of two-dimensional magnetism has invigorated the research community as their low dimensionality offers a unique avenue to understand and investigate the origin of magnetism in these atomically thin systems and harvest diverse application such as information processing, storage and transfer using their magnetic …

Temperature-Dependent Optical Constants Of Vanadium Dioxide Thin Films Deposited On Polar Dielectrics, Imtiaz Ahmad, Satya R. Kachiraju, Sundar Kunwar, Zachary M. Brown, Pinku Roy, Matthew Gaddy, Vladimir Kuryatkov, Yejin Kwon, Ayrton A. Bernussi, Myoung-Hwan Kim

Physics & Astronomy Faculty Publications

Coating polar dielectrics with thin film vanadium dioxide (VO2) enables one to exploit the temperature-dependent phase transition within VO2 to actively tune and modulate surface phonon polaritons at mid-infrared. However, controlling the behavior of such systems requires intimate knowledge of the temperature-dependent optical constants of VO2, which depend greatly on the growth conditions and substrate material. Here, we accurately determine the complex optical constants of VO2 on polar dielectrics across the insulator-to-metal phase transition (IMT) using only normal incident reflectance spectra by analyzing the reflectance with Kramers–Kronig relations and thin film Fresnel equations. This non-ellipsometry technique offers an …

Smart Automatic Modal Hammer Predictor–Corrector Approach For Accurate Excitation Of Dynamical Systems, Mohammad Nasr

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

This research introduces an innovative solution that revolutionizes the study of linear and nonlinear dynamical systems—a smart automatic modal hammer. With its affordability and intelligent capabilities, this automatic modal hammer becomes an invaluable tool for research and industry, enabling repeatable strikes with precise force control. This system's significance becomes particularly evident when studying nonlinear systems, which heavily rely on the excitation level for their dynamics. By offering a cost-effective design this proposed system proves to be robust in accelerating research on nonlinear dynamics, providing researchers with an efficient and accessible means to delve deeper into these complex systems. The proposed …

Search For Physics Beyond The Standard Model In Top Quark Production With Additional Leptons In The Context Of Effective Field Theory, Furong Yan

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

The dissertation presents a search for new physics impacting top quark productions within the framework of effective field theory (EFT). Potential new physics effects are parameterized in terms of 26 dimension-six EFT operators into the event yields of six distinct top production processes in the detector level. The analysis targets multilepton final states consisting of two leptons of the same charge, three leptons and four leptons. The events are further categorized and binned in terms of kinematic distributions in order to gain sensitivity to the new physics effects. A likelihood function is formulated based on the predicted distribution in each …

Studying The Chemistry-Property Relationship In Magnetic And Optical Materials: Spin S = 3/2 Systems Of Neodymium, Manganese, And Cobalt Oxyanions, Xudong Huai

All Dissertations

This dissertation describes the design and tunability of new magnetic and optical materials, emphasizing the intricate relationship between their crystal structures and their optical, electronic, and magnetic properties.

Two new frustrated magnets, ANd(SO₄)₂ (A = Rb, Cs), were designed and synthesized to examine the influence of the the counter cation A site in Nd lanthanide materials featuring a distorted triangular magnetic lattice with S = 3/2. This work demonstrates how the tunability of magnetic and photoluminescent properties can be achieved through the A sites, with findings validated through density functional theory calculations.

AMnTeO₆ (A = Ca, …

Novel Emergent Phases In A Two-Dimensional Superconductor, Simrandeep Kaur, Hemanta Kumar Kundu, Sumit Kumar, Anjana Dogra, Rajesh Narayanan, Thomas Vojta, Aveek Bid

Physics Faculty Research & Creative Works

In this letter, we report our observation of an extraordinarily rich phase diagram of a LaScO₃/SrTiO₃ heterostructure. Close to the superconducting transition temperature, the system hosts a superconducting critical point of the Infinite-randomness type characterized by an effective dynamical exponent ν z that diverges logarithmically. At lower temperatures, we find the emergence of a magnetic field-tuned metallic phase that co-exists with a quantum Griffiths phase (QGP). Our study reveals a previously unobserved phenomenon in 2D superconductors—an unanticipated suppression of the QGP below a crossover temperature in this system. This concealment is accompanied by the destruction of the …

Microwave Spectroscopy And Large Amplitude Motion Of Chlorosulfonic Acid (Clso2oh), Aaron J. Reynolds, Diego E. Rodriguez, Wei Lin, Kenneth R. Leopold

Physics & Astronomy Faculty Publications

The high-resolution rotational spectrum of chlorosulfonic acid (ClSO2OH) has been studied using both broadband and cavity-based Fourier transform microwave spectrometers over the frequency range of 5–18 GHz. a-, b-, and c-type transitions have been recorded for both the 35Cl and 37Cl isotopologues. The observation of c-type lines establishes that the molecule lacks a plane of symmetry and suggests that the OH group can undergo large amplitude motion between equivalent structures. Interconversion between these structures can be achieved via internal rotation through two inequivalent barriers occurring at Cl-S-O-H torsional angles of 0 or 180 degrees. As in …

Instantons In Φ4 Theories: Transseries, Virial Theorems, And Numerical Aspects, Ludovico T. Giorgini, Ulrich D. Jentschura, Enrico M. Malatesta, Tommaso Rizzo, Jean Zinn-Justin

Physics Faculty Research & Creative Works

We discuss numerical aspects of instantons in two- and three-dimensional φ4 theories with an internal O(N) symmetry group, the so-called N-vector model. By combining asymptotic transseries expansions for large arguments with convergence acceleration techniques, we obtain high-precision values for certain integrals of the instanton that naturally occur in loop corrections around instanton configurations. Knowledge of these numerical properties is necessary in order to evaluate corrections to the large-order factorial growth of perturbation theory in φ4 theories. The results contribute to the understanding of the mathematical structures underlying the instanton configurations.

Qcd Bounds On Leading-Order Hadronic Vacuum Polarization Contributions To The Muon Anomalous Magnetic Moment, Siyuan Li, T. G. Steele, Jason N.E. Ho, R. Raza, K. Williams, R. T. Kleiv

Faculty Work Comprehensive List

QCD bounds on the leading-order (LO) hadronic vacuum polarization (HVP) contribution to the anomalous magnetic moment of the muon [𝑎HVP,LO𝜇, 𝑎𝜇 =(𝑔−2)𝜇/2] are determined by imposing Hölder inequalities and related inequality constraints on systems of finite-energy QCD sum rules. This novel methodology is complementary to lattice QCD and data-driven approaches to determining 𝑎HVP,LO𝜇. For the light-quark (𝑢, 𝑑, 𝑠) contributions up to five-loop order in perturbation theory in the chiral limit, LO in light-quark mass corrections, next-to-leading order in dimension-four QCD condensates, and to LO in dimension-six QCD condensates, we findthat (657.0±34.8) ×10−10 ≤𝑎HVP,LO𝜇 ≤(788.4±41.8) ×10−10, bridging the range between …