# Physics Commons™

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## Full-Text Articles in Physics

Electromagnetic Fields From Quantum Sources In Heavy Ion Collisions, Balthazar Peroutka Jan 2019

#### Electromagnetic Fields From Quantum Sources In Heavy Ion Collisions, Balthazar Peroutka

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We compute electromagnetic fields created by a relativistic charged spin-half particle in empty space at distances comparable to the particle Compton wavelength. The particle is described as a wave packet evolving according to the Dirac equation. It produces the electromagnetic field that is essentially different from the Coulomb field due to the quantum diffusion effect.

Jan 2019

#### Feasibility Study For The Measurement Of J/Ψ Particles In Sphenix, Deborah Israel

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No abstract provided.

Jan 2019

#### Grain Growth In Cadmium Selenide Thin Films For The Optimization Of Cdse Based Solar Cells, Saba Sharikadze

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No abstract provided.

#### Nucleation, Packing And Beyond Geometrical Packing Of Hard Spheres: Study Using Lennard-Jones Models, Shang Ren

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In first part, we study crystal nucleation by using the recently introduced Persistent Embryo Method (PEM). The method provides detailed characterization of pre-critical, critical and post-critical nuclei, as well as nucleation rates that compare favorably with those obtained using other methods (umbrella sampling, forward flux sampling or seeding). We further map our results to a hard sphere model allowing to compare with other existing predictions. Implications for experiments are also discussed.

In second part, we investigate stable structures for the mixture of hard spheres. Our results show that different types of stable structures will appear by tunneling the sizes of ...

Symmetry Reduction In K − P Problems, Benjamin Sheller Jan 2019

#### Symmetry Reduction In K − P Problems, Benjamin Sheller

$K-P$ problems are a class of geometric optimal control problems on finite-dimensional real semisimple Lie groups which arise, for example, in the control of quantum systems when the Lie group is $SU(n)$. In these problems, the sub-Riemannian distribution corresponds to the $\p$-part of a Cartan decomposition (also known as the $-1$ eigenspace of a Cartan involution), and these systems are totally controllable. However, finding a particular optimal trajectory can be in general a computationally difficult problem, and from an analytic perspective, the Lie groups are sufficiently complicated to make finding such objects as the cut locus difficult. $K-P ... Jan 2019 #### Tuning Of Layered Materials: Studies Of Craute4, Pdsn4 And Wte2, Na Hyun Jo ##### Graduate Theses and Dissertations Layered materials are of great and growing interest for material scientists and condensed matter physicists, not only because of their possible applications but also because of the diverse and controllable ground states. In addition, tuning of layered materials through external fields, doping, or strain can lead to the emergence of novel phenomena. In this dissertation, the importance of the study of layered materials is emphasized in Chapter 1. Before getting into experimental results, the theoretical background and experimental methods, including growth of single crystals of selected layered materials, are introduced in Chapter 2 and Chapter 3. Chapters 4, 5 and ... #### Multiphysics Analysis Of Electrochemical And Electromagnetic System Addressing Lithium-Ion Battery And Permanent Magnet Motor, Abhishek Sarkar ##### Graduate Theses and Dissertations Lithium-ion batteries are the leading energy storage technology in the electronic-driven society. With the need for portable, long-life electronics the demand for lithium batteries has escalated over the decade. Lithium-ion batteries show remarkable electrochemical characteristics, including but not limited to, long cycle-life, high cut-off voltages and high energy-density. However, lithium-ion cells are problematic to design due to their inherent thermal and/or mechanical instability. The objective of the current research framework is to establish the criteria causing thermo-mechanical failure of the battery systems, material properties effecting the performance, and model cycle-life degradation due to electrolyte loss by solid electrolyte interface ... #### Study Of The Energy Gap Structure In Iron-Based Superconductors Using London Penetration Depth And Controlled Artificial Disorder, Serafim Teknowijoyo ##### Graduate Theses and Dissertations A combination of London penetration depth and artificial disorder was used to probe the energy gap structure and symmetry of a few members of the iron-based superconductor systems. Information regarding the gap structure and symmetry is an important clue which helps uncover the mechanism behind the unconventional, non-BCS-type superconductors. We used the tunnel-diode resonator method to do London penetration depth measurements with high precision down to 50~mK base temperature. The disorder is introduced by electron irradiation, which was performed at the SIRIUS facility in Ecole Polytechnique (Palaiseau France) to produce point-like disorder in the materials of study. Non-magnetic defects ... Search For Novel Electronic Properties In Topological Materials, Benjamin Schrunk Jan 2018 #### Search For Novel Electronic Properties In Topological Materials, Benjamin Schrunk ##### Creative Components ØAFM MFM project •Sample preparation •AFM/MFM overview •Results • ØARPES project •Dirac and Weyl Materials •ARPES overview •Results Oleds On Flexible Substrates, Chamika M. Hippola Jan 2018 #### Oleds On Flexible Substrates, Chamika M. Hippola ##### Creative Components In some applications flexible plastic substrates are advantageous over glass substrates for organic light emitting diode (OLED) fabrication due to properties such as higher refractive index, ease ofnano-patterning for enhanced extraction of light generated in the OLED, and promise in wearable electronics and biochemical sensing. Defects, impurities, and in particular sharp edges that may be formed in patterned plastic substrates such as polycarbonate (PC) can lead to catastrophic shorts when biased due to very high local electric fields. This work evaluated various PC substrates and their treatment with the goal of identifying the best substrates for patterning for enhancing OLED ... Pressure Effects On Magnetism And Superconductivity, Udhara Sampath Kaluarachchi Jan 2018 #### Pressure Effects On Magnetism And Superconductivity, Udhara Sampath Kaluarachchi ##### Graduate Theses and Dissertations This thesis summarizes experimental work using high pressure as a tuning parameter in the study of selected correlated electron systems at low temperatures. This thesis contains 8 chapters and 2 appendices. After giving the introduction in Chapter 1, experimental techniques are discussed in Chapter 2. Chapters 3 and 5 are devoted to pressure studies of ferromagnetic materials. In ferromagnetic systems, the appearance of quantum criticality is avoided either by a change of the second order transition to one of the first-order at a tricritical point or by the appearance of modulated, antiferromagnetic, phase. Chapter 3 summarizes the pressure study of ... #### Search For New Long-Lived Hadronically-Decaying Particles Produced In Association With A Z Boson With The Atlas Detector At The Lhc, Michael Werner ##### Graduate Theses and Dissertations The standard model fails to fully explain several observations about the universe, one of the prominent ones is the existence of dark matter. Many different models have been proposed for dark matter candidates, but it is possible that the dark matter itself will remain elusive. Dark sector models contain both dark matter and a new force which acts upon it. The force-carrying boson of this dark sector may be more easily detected than dark matter itself. These models contain a number of free parameters, some combinations of which result in the dark sector particle being long-lived but unstable, resulting in ... #### Studies Of Spin Dynamics In 122 Transition Metal Arsenides Using Inelastic Neutron Scattering Technique, Aashish Sapkota ##### Graduate Theses and Dissertations The diverse physical properties and interrelationship between various ground states offer a rich physics to explore in 122$A$TM$_2$As$_2$($A = $Ca, Sr, Ba and TM = 3d transition metals). This thesis discusses three examples of the 122$A$TM$_2$As$_2$compounds, TM = Fe, Co and Mn, where the focus is to understand their diverse magnetic properties and interplay between the magnetism and electronic properties including superconductivity. Therefore, the spin dynamics (spin fluctuations) of these compounds were studied using inelastic neutron scattering technique. CaFe$_2$As$_2$and the derived compounds are the first system discussed ... Jan 2018 #### Nuclear Magnetic Resonance Studies Of Magnetic Fluctuations And Nematic Order In Iron-Based Superconductors, Paul Waymouth Wiecki ##### Graduate Theses and Dissertations This thesis illustrates the use of the nuclear magnetic resonance (NMR) technique as a local probe for the study of static and dynamic magnetism in the iron-based superconductors. First, a Korringa ratio analysis of 59Co and 75As NMR data reveals the existence of ferromagnetic (FM) spin fluctuations in SrCo2As2 and the hole- and electron-doped BaFe2As2 families of iron-pnictide superconductors. The analysis further shows that the FM fluctuations compete with AFM fluctuations to suppress superconductivity in these materials. The FM fluctuations are thus a crucial ingredient to understanding the variability of the superconducting transition temperature (Tc) and the shape of the ... Constraints On Neutrino Oscillation Parameters With The Nova Experiment, Erika Cantano-Mur Jan 2018 #### Constraints On Neutrino Oscillation Parameters With The Nova Experiment, Erika Cantano-Mur ##### Graduate Theses and Dissertations NOvA is a long-baseline neutrino oscillation experiment, which consists of two finely-segmented liquid-scintillator detectors operating 14 mrad off-axis from the NuMI muon neutrino beam. With an 810 km baseline, the combined measurements of muon neutrino disappearance and electron neutrino appearance allow the determination of neutrino oscillation unknowns, namely the mass hierarchy, the octant of the largest neutrino mixing angle, and the CP violating phase. In this dissertation, I present the joint analysis of$\nu_\mu\to\nu_\mu$and$\nu_mu\to\nu_e$oscillation data with an exposure of$8.85\times10^{20}$protons on target on the 14 kton detector ... Structural And Magnetic Studies On Srco2as2 And Ca(Co1−Xfex)Yas2 Compounds Using X-Ray And Neutron Scattering, Wageesha Tharuki Jayasekara Jan 2018 #### Structural And Magnetic Studies On Srco2as2 And Ca(Co1−Xfex)Yas2 Compounds Using X-Ray And Neutron Scattering, Wageesha Tharuki Jayasekara ##### Graduate Theses and Dissertations The AM2X2 (A = alkaline, alkaline earth or rare earth element M = transition metals, and X = pnictogen), 122 type ternary compounds acquire overwhelming attention due to their richness of the correlations and competition between the lattice, electronic, and magnetic degrees of freedom. Properly controlling those correlations can lead to a variety of novel ground states including different crystallographic structures, magnetically ordered states, or high-temperature superconductors. This thesis summarizes experimental work using high pressure and element substitution as tuning parameters in the study of selected 122 systems to understand their diverse structural and magnetic properties and interplay between the magnetism and electronic ... Jan 2018 #### Jet Longitudinal Double Spin Asymmetry In Phenix$P+P \Sqrt{S} = 510 Gev$, Milap Patel ##### Graduate Theses and Dissertations The longitudinal double-spin asymmetry (A\textsubscript{LL}) in spin-polarized \emph{p+p} collisions provides insight into the gluon contribution to the proton's spin by accessing the gluon helicity distribution$\Delta$g. Prior PHENIX$\pi$\textsuperscript{0} and STAR jet A\textsubscript{LL} measurements show a non-zero asymmetries and hence indicate a nonzero$\Delta$g in an NLO analysis. The STAR measurements of jet A\_LL in$\surd$s = 200 and 510 GeV polarized p+p collisions provide the strongest constraints on$\Delta$g at intermediate to high \textit{x}. A measurement of the jet A\textsubscript{LL} at$\surd ...

Growth, Properties And Magnetism Of Cakfe4as4, William Richard Meier Jan 2018

#### Growth, Properties And Magnetism Of Cakfe4as4, William Richard Meier

CaKFe4As4 is a new stoichiometric member of the iron-based superconductors (FeSCs) which is a superconductor below 35 K. In this thesis I outline how single crystals of this material are grown for the first time and their basic properties. I discuss how substituting Ni or Co for Fe stabilizes antiferromagnetism at the expense of superconductivity. I reveal how the crystal structure of CaKFe4As4 leads to the observed hedgehog spin-vortex crystal magnetic order instead of the magnetic structures adopted by the other FeSCs. Finally, I propose a series of new magneto-elastic couplings in this new magnetic structure.

#### Measurement Of The Kaon Production Normalization In The Numi Target Using Uncontained Charged-Current Muon Neutrino Interactions In The Nova Far Detector, Jose Andres Sepulveda-Quiroz

NOvA is a long-baseline neutrino oscillation experiment that uses the NuMI beam from Fermilab.

Its physics goals include providing constraints to the neutrino mass hierarchy and the CP-violating phase $\delta$ by precision measurements of the electron (anti)neutrino

appearance in a muon (anti)neutrino beam.

Similarly, new limits on the values of $\sin^2{\theta_{23}}$ and $\Delta m^{2}_{32}$ will be achieved by measurements of the muon (anti)neutrino disappearance probabilities.

A combined analysis measurement will allow a better resolution of the $\theta_{23}$ octant.

The NuMI beam is produced by the collision of high energy protons ...

Exotic Phases In Strongly Correlated Materials, Guanghua Zhang Jan 2018

#### Exotic Phases In Strongly Correlated Materials, Guanghua Zhang

In strongly correlated materials, the electron-electron interaction is much stronger than the kinetic energy and plays a determining role in the properties of such materials. The strong electron-electron interaction often gives rise to exotic physical phenomena, such as high-temperature superconductivity, quantum Hall effects, Mott insulators, heavy fermion systems, and quantum criticality. There is no unified and effective approach to understand the physics in different materials, however, many of the same techniques generalize to different scenarios. In this thesis, we will discuss two types of exotic phases: the nematic order above the double-stripe magnetism, and hastatic order which originates from two-channel ...

Jan 2018

#### Interface Energy Transport Of Two-Dimensional (2d) Mos2, Pengyu Yuan

The bottleneck of most modern technologies and energy solutions has been attributed to the thermal problems at the nanoscale. Especially, the thermal transport across interfaces and in-plane direction can significantly influence the overall performance of 2D nanosystems. So accurate thermal-physical characterization of the 2D materials is very important for both fundamental research and industrial applications.

Focusing on 2D mechanically exfoliated MoS2, at first, we conduct a detailed temperature and laser power dependent micro-Raman spectroscopy study of FL MoS2 (4.2 to 45 nm thick) on c-Si substrate. We measured the interfacial thermal resistance (R) at room temperature decreases with increased ...

#### Biodetection And Biointerface Based On Nanostructured Aluminum Oxide (Nao): From Fluorescence Enhancement To Ms Effect On Single Neural Cells, Xiangchen Che

Anodic aluminum oxide (AAO) has been investigated and utilized in numerous products for almost a century. But the rapidly increasing interest in nanoscale materials and their outstanding properties has propelled nanoporous AAO to be used as a substrate for sensors and biosensors. Fluorescence-based biosensors are one type of optical biosensors which are very popular for detecting a variety of targets (DNA, RNA, glucose, enzyme, bacteria, etc.). The recent discovery of AAO fluorescence enhancement effect makes AAO more attractive since it has the great potential to be used in biosensing field to improve the sensor sensitivity. However, the mechanism of the ...

#### Structures And Dynamics Investigation Of Phase Selection In Metallic Alloy Systems, Lin Yang

Different phases of metallic alloys have a wide range of applications. However, the driving mechanisms of the phase selections can be complex. For example, the detailed pathways of the phase transitions in the devitrification process still lack a comprehensive interpretation. So, the understanding of the driving mechanisms of the phase selections is very important.

In this thesis, we focus on the study of the Al-Sm and other related metallic alloy systems by simulation and experiment. A procedure to evaluate the free energy has been developed within the framework of thermodynamic integration, coupled with extensive GPU-accelerated molecular dynamics (MD) simulations; The ...

Jan 2018

#### Biophysics Of Cadherin Interactions And Junction Assembly, Omer Shafraz

Desmosomes are robust cell adhesion junctions that are composed of two transmembrane desmosomal cadherin proteins: desmoglein (Dsg) and desmocollin (Dsc). The extracellular regions of Dsc and Dsg form an adhesive interface between cells while their cytoplasmic tails links to the intracellular keratin filament network. This dissertation investigates how Dsc and Dsg assemble into desmosomes using single molecule force measurements with an Atomic Force Microscope (AFM) and cell-based fluorescence assays. In Chapter 1, I give a brief over view of the content of this dissertation and the principles of AFM force measurements. In Chapter 2, I characterize the binding of isoform ...

Spin Polarization Of J/Ψ Through Lepton Decay, Nels Jacob Hotvedt Jan 2017

#### Spin Polarization Of J/Ψ Through Lepton Decay, Nels Jacob Hotvedt

This thesis presents a compilation of the latest research on J/Ψ polarization and bremsstrahlung along with the background surrounding the J/Ψ’s history. It covers the fundamentals of the standard model, quantum chromodynamics, deep inelastic scattering, and the calculations behind charm-anticharm production from hadron collisions. It shows research that’s centered on recombining identified bremsstrahlung with di-electron pairs to improve the J/Ψ invariant mass peak. The research for polarization studies simulated J/Ψ di-electron pairs with no polarization and pT between 0.0 to 1.5 GeV in the central arm. The PHENIX detector systems, namely the ...

Structural And Magnetic Properties Of Metastable Phases And Undercooled Liquids In Fe83b17, Dante Gabriel Quirinale Jan 2017

#### Structural And Magnetic Properties Of Metastable Phases And Undercooled Liquids In Fe83b17, Dante Gabriel Quirinale

Containerless processing techniques allow the exploration of several largely unexplored realms of materials science and physics. In particular, the formation of transient metastable phases is typically challenging to study \textit{in-situ}, and so information on high-temperature solidification pathways are often incomplete at best. Similarly, the structure and properties of the undercooled liquid regime are just now being explored. The wide variety of optical instrumentation and scattering techniques available for use with levitation based systems allow novel, multi-faceted approaches to \textit{in-situ} materials characterization.

Metastable phase formation in the Fe$_{83}$B$_{17}$ system was investigated through a wide ...

#### Regionally Implicit Discontinuous Galerkin Methods For Solving The Relativistic Vlasov-Maxwell System, Pierson Guthrey

The relativistic Vlasov-Maxwell system (RVM) models the behavior of collisionless plasma, where electrons and ions interact via the electromagnetic fields they generate. In the RVM system, electrons could accelerate to significant fractions of the speed of light. An idea that is actively being pursued by several research groups around the globe is to accelerate electrons to relativistic speeds by hitting a plasma with an intense laser beam. As the laser beam passes through the plasma it creates plasma wakes, much like a ship passing through water, which can trap electrons and push them to relativistic speeds. Such setups are known ...

Jan 2017

#### Hybrid Fs/Ps Coherent Anti-Stokes Raman Scattering For Multiparameter Measurements Of Combustion And Nonequilibrium, Chloe Elizabeth Dedic

Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) is developed for measuring internal energy distributions, species concentration, and pressure for highly dynamic gas-phase environments. Systems of interest include next-generation combustors, plasma-based manufacturing and plasma-assisted combustion, and high-speed aerodynamic flow. These challenging environments include spatial variations and fast dynamics that require the spatial and temporal resolution offered by hybrid fs/ps CARS.

A novel dual-pump fs/ps CARS approach is developed to simultaneously excite pure-rotational and rovibrational Raman coherences for dynamic thermometry (300--2400 K) and detection of major combustion species. This approach was also used to measure single-shot vibrational ...

Jan 2017