Physics Commons^™

A Contextual Analysis Of The Early Work Of Andrzej Trautman And Ivor Robinson On Equations Of Motion And Gravitational Radiation, Donald Salisbury, Daniel Kennefick

Physics Faculty Publications and Presentations

In the mid-1950s, Andrzej Trautman published a series of papers connected with his dissertation work written under Leopold Infeld. In these, he drew upon the slow motion approximation developed by Infeld, the general covariance-based strong conservation laws enunciated by Bergmann and Goldberg, the Riemann tensor attributes explored by Goldberg and related geodesic deviation exploited by Pirani, the permissible metric discontinuities identified by Lichnerowicz, O'Brien and Synge, and finally Petrov's classification of vacuum spacetimes. With several significant additions he produced a comprehensive overview of the state of research in equations of motion and gravitational waves that was presented in a widely …

The Nanograv 15 Yr Data Set: Search For Gravitational-Wave Memory, Gabriella Agazie, Akash Anumarlapudi, Anne M. Archibald, Zaven Arzoumanian, Jeremy G. Baier, Paul T. Baker, Bence Bécsy, Laura Blecha, Adam Brazier, Paul R. Brook, Sarah Burke-Spolaor, Rand Burnette, J. Andrew Casey-Clyde, Maria Charisi, Shami Chatterjee, Tyler Cohen, James M. Cordes, Neil J. Cornish, Fronefield Crawford, H. Thankful Cromartie, Kathryn Crowter

Pacific Faculty Work

We present the results of a search for nonlinear gravitational-wave (GW) memory in the NANOGrav 15 yr data set. We find no significant evidence for memory signals in the data set, with a maximum Bayes factor of 3.1 in favor of a model including memory. We therefore place upper limits on the strain of potential GW memory events as a function of sky location and observing epoch. We find upper limits that are not always more constraining than previous NANOGrav results. We show that it is likely due to the increase in common red noise between the 12.5 and 15 …

Yb:Ylf Optical Cryocoolers: Saturation Effects, Pump Management, Robust Thermometry, And Novel Architectures, Jackson Kock

Optical Science and Engineering ETDs

Solid-state optical refrigeration using anti-Stokes fluorescence offers a compact, vibration-free route to cryogenic cooling. This dissertation advances ytterbium-doped yttrium lithium fluoride (Yb:YLF) refrigerators, achieving a world record payload cooling temperature of 124 K by addressing key limitations due to absorption saturation. An expanded theoretical model incorporating saturation effects enables accurate predictions of cooling performance under high pump intensities. To improve pump control, a modeling framework for astigmatic Herriott cells was developed, revealing how beam clipping and intensity impact coupling efficiency. A novel fluorescence-based thermometry method was also established, providing accurate, orientation-independent temperature sensing by overcoming reabsorption and crystal orientation. Finally, …

Generation Of Non-Maxwell-Boltzmann Energy Distributions During Thermalization Of Interacting Baths, Roberto Onofrio, Bala Sundaram

Data and Datasets

data associated with all the figures in the publication.

Development Of A Near Terahertz Backward Wave Oscillator Using Standard Waveguide, Alexander Glick

Electrical and Computer Engineering ETDs

There is a demand for terahertz (THz) frequency radiation sources. Applications include, but are not limited to, imaging for medical and security purposes, biochemical and organic spectroscopy, and velocimetry. Historically, there was a limited supply of THz devices due to technological limitations. In recent years much progress has been made to reduce this “gap” in supply and demand for THz sources. This work proposes a vacuum electronic device that produces high power, extremely high frequency radiation in the G-band, by utilizing a backward wave oscillator (BWO) based on WR3 standard waveguide. This device is compact, fundamentally simple, and has great …

Uncovering Multiscale Structure-Property Correlations Via Active Learning In Scanning Tunneling Microscopy, Ganesh Narasimha, Deja Kong, Paras Regmi, Rongying Jin, Zheng Gai, Rama Vasudevan, Maxim Ziatdinov

Faculty Publications

Atomic arrangements and local sub-structures fundamentally influence emergent material functionalities. These structures are conventionally probed using spatially resolved studies and the property correlations are deciphered by a researcher based on sequential explorations, thereby limiting the efficiency and scope. Here we demonstrate a multi-scale Bayesian deep-learning based framework that automatically correlates material structure with its electronic properties using scanning tunneling microscopy (STM) measurements in real-time. Its predictions are used to autonomously direct exploration toward regions of the sample that optimize a given material property. This method is deployed on a low-temperature ultra-high vacuum STM to understand the structure-property relationship in a …

2d Cuo/Rgo Nanocomposite: A Novel Architecture For Enhanced Cr(Vi) Photo-Reduction, Islam Gomaa, Nasser M. Hosny, Medhat A. Ibrahim

Nanotechnology Research Centre

he urgent need for efficient detoxification of carcinogenic hexavalent chromium (Cr(VI)) in aquatic environments has driven the development of advanced photocatalytic materials. This study presents the synthesis of 2D CuO/reduced graphene oxide (rGO) nanocomposite via probe sonication, designed to synergistically enhance the photocatalytic reduction of Cr(VI) to less toxic Cr(III). The nanocomposite was meticulously characterized using XRD, HRTEM, FESEM, XPS, and UV-Vis diffuse reflectance spectroscopy. Structural analysis confirmed the formation of CuO nanosheets (average size: 396 nm, thickness: 6 nm) integrated with rGO, where the rGO acted as an electron acceptor, mitigating charge recombination. XPS revealed Cu²⁺ in CuO and …

Exploring The Very Early Cosmological History With Dark Matter And Primordial Black Holes, Phuc Duc Loc Ngo

Physics & Astronomy ETDs

We explore the possibilities of nonstandard early cosmological histories and their potential roles to explain DM. We study how particle DM is produced with scenarios of early matter domination (EMD), how primordial black holes (PBHs), which could also be a DM candidate in certain mass ranges, are formed with enhanced curvature perturbation or FOPT and the corresponding gravitational wave (GW) signals, how PBHs could increase their mass by accretion during EMD and the corresponding GW signals.

The Thermodynamic Fate Of Isolated Quantum Systems, John Keim, Isabel Martinez-Robles, Nicolaus A. Chlanda, Sage M. Thomas, Maja Teofilovska, Sarah E. Spielman, Jordyn Strunk, Tina Zhao, Juniper J. Bauroth-Sherman, Hannah Conley, Philip Conte, Aidan Kirk, Thomas J. Carroll, Michael W. Noel

Physics and Astronomy Summer Fellows

Isolated quantum systems are typically observed to come to thermal equilibrium. The weak Eigenstate Thermalization Hypothesis (wETH) states that the vast majority of eigenvectors are thermal. This implies that most initial states should thermalize. Studying the rare cases in which they fail to thermalize could reveal insight into quantum dynamics. In our experiment, we excite Rydberg atoms and allow them to exchange energy via dipole-dipole interactions. We find that they do not thermalize. We present numerical and theoretical results that show that our experimental initial state is not typical.

Investigation Of Isobaric Mixing As A Mechanism For Boundary-Layer Cloud Formation, Jaemin Yeom, Nithin Allwayin, Virendra P. Ghate, Katia Lamer, Fan Mei, Raymond A. Shaw

Michigan Tech Publications

This study investigates the potential role of isobaric mixing in the formation of marine boundary layer clouds. Cloud formation theory emphasizes uplift and adiabatic cooling, but recent observations support the existence of small clouds forming at various altitudes, even below the lifting condensation level. Isobaric mixing of air with different thermodynamic properties can generate localized supersaturation. A Gaussian mixing model is employed to simulate this process, considering the correlation between temperature and water vapor. Cloud droplet size distributions from aircraft measurements show a persistent and prominent mode of small droplets at 9 (Formula presented.) m, and the size of this …

Deep Neural Networks For Particle Identification In Simulated Proton-Proton Collisions At Lhc And Rhic, Omar Mazhar Khalaf

Theses and Dissertations

Particle identification is an essential part of experimental high-energy physics, which allows the study of the most fundamental constituents of matter. This thesis explores the use of deep neural networks for identifying particles in simulated proton-proton collisions at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC). The deep neural networks were trained on LHC datasets which have various momentum ranges including regions of high transverse momentum above 3 GeV/c. The key findings of thesis include achieving an accuracy of 99.99%, 98.3%, and 90.14% for 3-5 pt, 5-7 pt and above 7 pt regions respectively for the …

Hydrogen Storage In Multilayer Ti3c2tx Mxene, Yi Zhi Chu, Kah Chun Lau

Michigan Tech Publications

In this work, we systematically investigated the hydrogen storage properties of multilayer Ti3C2Tx MXene using density functional theory (DFT) coupled with the quantum-thermodynamic model to include the thermodynamic effect on hydrogen adsorption and storage behavior over a wide range of applied pressure and temperature. In addition to the surface-adsorbed hydrogen, we show that the interlayer spacing is a plausible storage route that could contribute to an additional hydrogen storage capacity. Due to hydrogen-bond bounded multilayer Ti3C2Tx, the insertion, diffusion, and adsorption of hydrogen molecules into the interlayer spacing of the multilayer structure require sufficient external pressure to overcome the energy …

Basic Theory And Implementations Of Quantum Error Correction, Derek Rodriguez

Undergraduate Theses, Capstones, and Recitals

The introduction of quantum computing has presented algorithmic solutions to computationally difficult challenges that are far more efficient than those of classical computers. These algorithms leverage the properties of quantum mechanics to manipulate the quantum properties of subatomic particles, requiring immense precision and stability. Current quantum hardware, however, is too noisy and introduces too many errors for these algorithms to be useful in practice, necessitating the use of error correction algorithms. This field survey seeks to introduce various principles of quantum mechanics relevant to quantum computing and quantum error correction (QEC), detail the implementation and motivations of a basic QEC …

The Spectral Response Of Time-Resolved Piv In A Turbulent Boundary Layer, Peter Manovski, Wagih Abu Rowin, Henry Ng, Paul Gulotta, Matteo Giacobello, Charitha De Silva, Nicholas Hutchins, Ivan Marusic

Student Publications

This study presents the application of time-resolved particle image velocimetry (TR-PIV) to measure the mean and fluctuating velocity components in a turbulent boundary layer (TBL) over an axisymmetric body of revolution. A narrow wall-normal strip of the flow was captured using a synchronised high-speed laser and camera at a recording frequency of up to 80 kHz. The resulting streamwise and wall-normal velocity TR-PIV data were validated against hot-wire anemometry measurements and direct numerical simulations (DNS) of a flat plate under matched flow conditions. The mean flow results showed good agreement between all methods, while the expected attenuation due to the …

Theoretical Investigation On The Magnetic And Spintronic Behaviour Of 2d Mxenes, Abhinav Prashant Gotmare

University Departments

No abstract provided.

Composite Magnetic Monopoles, Moreshwar Pathak

University Departments

No abstract provided.

Zeeman Effect Observations Of Water Masers In The Star Forming Region Ngc 7129 Firs2, Marina Bethann Beltran

College of Science and Health Theses and Dissertations

Magnetic fields likely play an important role in star formation, yet their influence remains poorly understood due to the observational challenges in measuring them. The only direct method for measuring magnetic fields is through the Zeeman effect, the splitting of spectral lines in the presence of a magnetic field. Water masers, which trace high-density shocked regions, are known to occur throughout some of the earliest stages of the star formation process. They provide an excellent opportunity to observe the Zeeman effect. However, Zeeman detections in H2O masers have so far been limited primarily to isolated, high-intensity maser lines with simple …

Shrinkage Study In Photopolymerisable Hybrid Sol-Gel Through Holographic Patterning, Jamshed Aftab, Izabela Naydenova, Tatsiana Mikulchyk

Articles

Photopolymerisation induced shrinkage of holographic materials is one of the main factors which needs to be considered for designing holographic optical elements (HOEs) with high accuracy in light redirection with maximum efficiency. This work studies the shrinkage in photopolymerisable hybrid sol-gel (PHSG) by examining the properties of volume transmission gratings recorded in PHSG layers. It explores both the dependence of shrinkage on the holographic grating parameters (thickness, spatial frequency, slant angle) and the effect of material aging. By using the fringe-plane rotation model, shrinkage is found to have the maximum value of 1.37 % at 765 lines/mm (19.36° slant angle) …

The Rise Of Faint, Red Active Galactic Nuclei At Z > 4: A Sample Of Little Red Dots In The Jwst Extragalactic Legacy Fields, Dale D. Kocevski, Steven L. Finkelstein, Guillermo Barro, Anthony J. Taylor, Antonello Calabrò, Brivael Laloux, Johannes Buchner, Jonathan R. Trump, Gene C.K. Leung, Guang Yang, Mark Dickinson, Pablo G. Pérez-González, Fabio Pacucci, Kohei Inayoshi, Rachel S. Somerville, Elizabeth J. Mcgrath, Hollis B. Akins, Micaela B. Bagley, Rebecca A.A. Bowler, Laura Bisigello, Adam Carnall

Pacific Faculty Work

We present a sample of 341 “little red dots” (LRDs) spanning the redshift range z ∼ 2-11 using data from the CEERS, PRIMER, JADES, UNCOVER, and NGDEEP surveys. Unlike past use of color indices to identify LRDs, we employ continuum slope fitting using shifting bandpasses to sample the same rest-frame emission blueward and redward of the Balmer break. This enables the detection of LRDs over a wider redshift range and with less contamination from galaxies with strong breaks that otherwise lack a rising red continuum. The redshift distribution of our sample increases at z < 8 and then undergoes a rapid decline at z ∼ 4.5, which may tie the emergence of these sources to the inside-out growth that galaxies experience during this epoch. We find that LRDs are ∼1 dex more numerous than X-ray- and UV-selected active galactic nuclei (AGN) at z ∼ 5-7. Within our sample, we have identified the first two X-ray-detected LRDs. An X-ray spectral analysis confirms that these AGN are moderately obscured with log ( N H / cm 2 ) of 23 . 3 − 1.3 + 0.4 and 22.7 2 − 0.16 + 0.13 . Our analysis reveals that reddened AGN emission dominates their rest-optical light, while the rest-UV originates from their host galaxies. We also present NIRSpec observations from the RUBIES survey of 17 LRDs that show broad emission lines consistent with AGN activity. The confirmed AGN fraction of our sample is 71% for sources with F444W < 26.5. In addition, we find three LRDs with blueshifted Balmer absorption features in their spectra, suggesting an outflow of high-density, low-ionization gas from near the central engine of these faint, red AGN.

Higher-Order Exceptional Points In A Non-Reciprocal Waveguide Beam Splitter, Hamed Ghaemidizicheh, Shahram Dehdashti, Andreas Hanke, Ahmed Touhami, Janis Nötzel

Physics & Astronomy Faculty Publications

Non-Hermitian systems have attracted significant interest because of their intriguing properties, including exceptional points (EPs), where eigenvalues and the corresponding eigenstates coalesce. In particular, quantum systems with EPs exhibit an enhanced sensitivity to external perturbations, which increases with the order of the EP. Therefore, higher-order EPs hold significant potential for advanced sensing applications, but they are challenging to achieve due to stringent symmetry requirements. In this work, we study the dynamics of a generalized lossy waveguide beam splitter with asymmetric coupling by introducing non-reciprocity as a tunable parameter to achieve higher-order EPs even without dissipation. Moreover, we analyze the evolution …

A Veblenian Approach To Chaos Theory, Isaiah Henry

Hatfield Graduate Journal of Public Affairs

This paper provides a comparative analysis of Veblen's belief in disequilibrium, the field of chaos theory, and how these two frameworks connect. We explore the similarities and differences between Veblen's theories and the principles of chaos theory, including their shared emphasis on complexity and unpredictability. By analyzing the connections between Veblen's economic theories and chaos theory, we can gain a deeper understanding of the nature of disequilibrium and the complex forces that shape our world.

Effects Of Elevated Temperatures On Tooth Structure During Polymerization Of Composite Resin With A Variety Of Light Sources, Enas G. Yonis

Al-Bahir

This study investigated the impact of high temperatures on dental tissues during the polymerization of optical fillings using a diode laser and two types of pulsed and continuous LED devices. Three distinct light source units were employed: a laser diode, an LEDition, and a LED.B. Temperature increases were measured at a distance of 1 mm from the thermocouple to the tip of the device. To create an experimental model, we fixed the operational voltage of the polymerization device and maintained a 1 mm gap between the terminal and the thermocouple wire. Temperature readings and thermal background (TO) measurements were taken …

Revised Unsteady Drag Force And Its Impact On Particle Dynamics At High Reynolds Numbers, Ahmad Talaei, Timothy J. Garrett

Physics Student Research

The accurate modeling of particle motion in viscous fluids at high Reynolds numbers remains a fundamental challenge, particularly under unsteady flow conditions where nonlinear effects dominate. This study introduces a revised unsteady drag formulation, extending its applicability beyond previous studies. By integrating classical solutions of the Navier–Stokes equations, the new formulation overcomes the limitations of the Maxey–Riley–Gatignol (MRG) equation, addressing non-physical memory effects associated with Basset drag and extending its applicability to higher Reynolds numbers.

Through experimental comparisons and direct numerical simulations (DNS), the revised equation of motion is compared to the MRG equation, both during steady-state conditions and non-equilibrium …

Preliminary Evidence For Lensing-Induced Alignments Of High-Redshift Galaxies In Jwst-Ceers, Viraj Pandya, Abraham Loeb, Elizabeth J. Mcgrath, Guillermo Barro, Steven L. Finkelstein, Henry C. Ferguson, Norman A. Grogin, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Casey Papovich, Nor Pirzkal, L.Y. Aaron Yung

Pacific Faculty Work

The majority of low-mass ( log 10 M * / M ⊙ = 9 - 10 ) galaxies at high redshift (z > 1) appear elongated in projection. We use JWST-CEERS observations to explore the role of gravitational lensing in this puzzle. The typical galaxy-galaxy lensing shear γ ∼ 1% is too low to explain the predominance of elongated early galaxies with an ellipticity e ≈ 0.6. However, nonparametric quantile regression with Bayesian Additive Regression Trees (or BART) reveals hints of an excess of tangentially aligned source-lens pairs with γ > 10%. On larger scales, we also find evidence for weak-lensing shear. …

Teaching Diffuse, Specular, And Total Internal Reflection Via A Halo Effect, Paul R. Destefano, Ralf Widenhorn

Physics Faculty Publications and Presentations

Interesting and pedagogically useful physics can be found in the halo produced by a laser pointer directed into a shallow body of water. We describe a simple model for this phenomenon using geometric optics and support this model with empirical evidence. We also discuss and verify extensions to this model that explain variations in the visual pattern. These variants include a double halo pattern and a disk of dim light that can be produced with minor modifications of the single halo configuration. Although the level of complexity differs, all of these models rely on the same ray optics, specifically refraction …

Electrochemically-Assisted Low Power Density Laser Writing On Stainless Steel Via Enrichment Of Chromium Oxides, Zechariah J. Pfaffenberger, Lianlian Liu, Tae Kyong John Kim, Vignesh Venkataramani, Lydia Kisley

Faculty Scholarship

Laser color marking produces nearly permanent, environmentally friendly, vibrant colors on surfaces. However, previous work has used high-power-density pulsed lasers to induce the physicochemical reactions for marking. Here, laser color marking on stainless steel 304 (SS304) is performed with a less expensive continuous wave (CW) laser and a power density five orders of magnitude below that previously reported by combining an electrochemical cell with a fluorescence microscope. Using a combination of optical microscopy, x-ray photoelectron spectroscopy, and bulk electrochemistry, it is demonstrated that the laser-induced luminescence and colors are due to enrichment (32 ± 9% increase) of Cr₂O₃ in the …

Measurements Lab Quiz – Exported As Brightspace Package, Vasiliy Znamenskiy

Open Educational Resources

This Brightspace-ready quiz assesses foundational measurement skills in physics laboratory settings. It includes 16 questions covering key concepts such as random and systematic errors, least counts of measurement tools (micrometer, Vernier caliper, meter stick, graduated cylinder, and triple-beam balance), and data interpretation from physical instruments. The quiz features multiple-choice and numerical answer formats, including visual instrument reading exercises via linked images. Designed for use in college-level introductory physics courses, this package supports automated grading and student feedback within the Brightspace LMS environment.

Exploitation Of Plasma Treatment-Assisted Monocarboxylic Cobalt Phthalocyanine Nanorod Growth For High-Efficiency Photodetection Applications, Ahmed Ramzy, Ahmed M. El-Mahalawy, M A. Abd El Ghaffar, Wael A. Abbas

Nanotechnology Research Centre

Here, the effect of cobalt phthalocyanine (CoPC) functionalization by a monocarboxylic group in the form of thermally evaporated thin films followed by plasma treatment for variable time intervals is introduced. The effect of plasma treatment on crystalline structure, molecular structure, and morphology was examined using the XRD, FT-IR, and FE-EEM techniques. Significant modifications were observed in the crystal structure and morphology with increasing plasma treatment time intervals. The plasma treatment for 5 min enhanced the formation of the nanorods along the deposited surface with improved crystallinity. Tracking the optical properties variation of the deposited MCCoPc thin films under plasma treatment …

Atomistic Characterization Of Hydration-Dependent Fuel Cell Ionomer Nanostructure: Validation By Vibrational Spectroscopy, Dan J. Donnelly, Moon Young Yang, Nicholas Dimakis, Seung Soon Jang, William A. Goddard Iii, Eugene S. Smotkin

Physics & Astronomy Faculty Publications

The development of Nafion alternatives for fuel cells and electrolyzers requires a fundamental understanding of hydration-dependent ion-exchange site acid/base chemistry. We present here reactive force field (ReaxFF) molecular dynamics (MD) simulations of Nafion at varying molar water/ion-exchange-site ratios (λ), which we correlate to our experimental and density functional theory-based vibrational spectra. ReaxFF describes the formation and breaking of covalent bonds, enabling simulations of proton exchange between sulfonic acid/sulfonate groups and water/hydronium. Our MD simulations determine the λ-dependent equilibrium proportions of protonated and deprotonated sites. We find that protonated sites persist across all λ from 0 to 20, challenging the widely …

Measurement And Improvement Of Photon Identification Efficiencies Using Machine Learning Techniques In The Atlas Detector At The Lhc, Abdulla Esam Mahboub

Thesis/ Dissertation Defenses

Photons play a crucial role in numerous analyses at the Large Hadron Collider (LHC), particularly in studies like the Higgs boson decay to two photons. Precise photon identification is essential for enhancing the sensitivity and accuracy of such measurements. This thesis focuses on the development of a machine learning (ML)-based photon identification algorithm to improve the photon identification efficiency within the ATLAS detector, using a Deep Neural Network (DNN) approach. The primary goal is to boost photon identification efficiency by using advanced neural network techniques. Traditional photon identification relies on cuts applied to shower shape variables, which can limit the …