PHD, Kent State University, 2022, College of Arts and Sciences / Department of Physics

Strongly correlated electron systems are at the borderline of competing phases and can be tuned through different ground states by slight modifications. Therefore, they are good examples to study a quantum phase transition (QPT), to reveal how a quan tum critical point (QCP) at zero temperature is responsible for the unconventional properties observed at finite temperatures. QPTs are zero-temperature phase tran sitions, they are more complex and less understood than common phase transitions at finite temperatures. Examples are lacking, especially in the case where disorder is involved. Recent theories predict the possibility of an exotic quantum critical point in itinerant magnets with induced disorder that is accompanied by a quantum Grif- fiths phase. To explore such unconventional properties in close neighborhood to a magnetic phase, we aim to reveal the relevant quantum critical fluctuations with neutron scattering. We select systems with different magnetic order and choose as tuning parameter chemical substitution to study the effect of disorder. Such exper imental study aims to find key elements of a QCP with disorder. The two systems are the ferromagnetic (FM) alloy, Ni-V, tuned by the V-concentration into a para magnetic phase, and the non-magnetic Kondo semimetal, Ce(Cu,Ni)Sn, tuned by Cu concentration into an antiferromagnetic state. We apply different neutron scat- tering techniques and simple models to get essential characteristics of the magnetic correlations and fluctuations close to the QCP. Ni-V is a simple FM-alloy with a random atomic distribution that undergoes a quantum phase transition from a ferromagnetic to a paramagnetic state with sufficient substitution of Ni by V. First indication of a quantum Griffiths phase came from magnetization and μSR data, but the scale of the magnetic clusters remained elusive. Optimized small angle neutron scattering (SANS) data on different polycrystalline Ni- V samples close to the QCP (open full item for complete abstract)

Committee: Almut Schroeder (Advisor); Carmen Almasan (Committee Member); Gokarna Sharma (Committee Member); Maxim Dzero (Committee Member); Sanjaya Abeysirigunawardena (Committee Member) Subjects: Condensed Matter Physics

Master of Science (MS), Wright State University, 2020, Physics

This work was an investigation of nanosecond repetitively pulsed discharges in air by measuring the evolution of electron density and electron temperature between pulses using Thomson scattering of laser light. Bursts of repetitive pulses within several microseconds after the initial pulse were found to exhibit a coupling effect and create an even higher electron density than the initial pulse. The wide range of temperatures and densities of the electrons existing between pulses allow an opportunity to explore both the collective and non-collective regimes of Thomson scattering. By measuring electron density and temperature at a variety of times, an accurate description of the coupling between discharges can been formulated which provides insight into the behavior and potential applications of nanosecond repetitive pulse discharges.

Committee: Steven Adams Ph.D. (Committee Co-Chair); Amit Sharma Ph.D. (Committee Co-Chair); Jason Deibel Ph.D. (Committee Member) Subjects: Physics

Master of Science (MS), Wright State University, 2018, Physics

The Generalized Harvey-Shack (GHS) surface scatter theory claims to predict the scatter from rough surfaces over a wide domain of validity but has not been widely implemented or tested. The focus of this research is to provide a documented implementation and experimental validation of the GHS theory for the prediction of the bidirectional reflectance distribution function (BRDF) from real rough surfaces. First, the GHS theory was developed for the MATLAB software and the details of its implementation and application to experimental comparison are discussed. Next, a BRDF measurement system was designed, built, and validated. The BRDF of the Spectralon reflectance standard was measured with high agreement. Sample surfaces were characterized via atomic force microscopy as inputs to the GHS theory. The BRDF of each surface was then measured and simulated with the assumption of Gaussian autocovariance. When this assumption held, the GHS theory predictions matched well with experimental results.

Committee: Jason Deibel Ph.D. (Advisor); Brent Foy Ph.D. (Committee Member); Jerry Clark Ph.D. (Committee Member) Subjects: Optics; Physics

Doctor of Philosophy, The Ohio State University, 2015, Mechanical Engineering

Kinetic processes controlling N2 vibrational distribution, electron temperature and electron density in nanosecond pulse, nonequilibrium plasma, electric discharges are studied through laser scattering diagnostic techniques. The experiments are conducted in high pulse energy (≥4 mJ/pulse), nanosecond pulse gas discharge plasmas at moderate pressures (75-200 torr) in nitrogen, air, helium, H2-He and O2-He mixtures. In electric discharges, local energy loading is a function of the electron number density (ne) and electron temperature (Te). Furthermore, electron temperature, and more specifically, electron energy distribution function (EEDF) control the electron energy partition in nonequilibrium plasmas by controlling the rates of critical kinetic processes including ionization, vibrational and electronic excitation, and recombination of molecules, atoms and electrons in the gas discharge. Thus, obtaining time-resolved, quantitative measurements for these values (ne, Te, and EEDF) is critical in understanding the energy requirements for sustaining these discharges, as well as discerning how electron energy is partitioned among different molecular energy modes, and which excited species and radicals are generated in the plasma. Furthermore, in molecular plasmas, significant electron energy is loaded into vibrational modes. Study of temporally resolved vibrational distribution function (VDF) and vibrational temperature (Tv) is important in quantifying vibrational energy loading and relaxation in these plasmas. This affects the rate of temperature rise in nanosecond pulse discharges and the afterglow, as well as rates of vibrationally stimulated chemical reactions, such as NO formation. Applications of these studies include plasma flow control (PFC), plasma assisted combustion (PAC), electrically excited laser development and various plasma bio-medical applications. Time-resolved N2 vibrational distribution function (VDF) and first-level N2 vibrational tempe (open full item for complete abstract)

Committee: Igor Adamovich Professor (Advisor); Jeffrey Sutton Professor (Committee Member); Vishwanath Subramaniam Professor (Committee Member); J. William Rich Professor Emeritus (Committee Member) Subjects: Aerospace Engineering; Chemistry; Engineering; Mechanical Engineering; Molecular Chemistry; Molecular Physics; Optics; Physical Chemistry; Plasma Physics

PhD, University of Cincinnati, 2007, Engineering : Materials Science

The phenomenon of structural branching is ubiquitous in a wide array of materials such as polymers, ceramic aggregates, networks and gels. These materials with structural branching are a unique class of disordered materials and often display complex architectures. Branching has a strong influence over the structure-property relationships of these materials. Despite the generic importance across a wide spectrum of materials, our physical understanding of the scientific nature of branching and the analytic description and quantification of branching is at an early stage, though many decades of effort have been made. For polymers, branching is conventionally characterized by hydrodynamic radius (size exclusion chromatography, SEC, rheology) or by counting branch sites (nuclear magnetic resonance spectroscopy, NMR). SEC and rheology are, at best, qualitative; and quantitative characterization techniques like NMR and transmission electron microscopy (TEM) (for ceramic nanoparticulate aggregates) have limitations in providing routine quantification. Effective structure characterization, though an important step in understanding these materials, remains elusive. For ceramic aggregates, theoretical work has dominated and only a few publications on analytic studies exist to support theory. A new generic scaling model is proposed in Chapter I, which encompasses the critical structural features associated with these complex architectures. The central theme of this work is the application of this model to describe a variety of disordered structures like aggregated nano-particulates, long chain branched polymers like polyethylene, hyperbranched polymers, multi-arm star polymers, and cyclic macromolecules. The application of the proposed model to these materials results in a number of fundamental structural parameters, like the mass-fractal dimension, df, the minimum path dimension, dmin, connectivity dimension, c, and the mole fraction branch content, φbr. These dimensions refl (open full item for complete abstract)

Committee: Dr. Gregory Beaucage (Advisor) Subjects: Engineering, Materials Science

Doctor of Philosophy, The Ohio State University, 2003, Chemistry

Laser light scattering diagnostic techniques, for characterization of weakly ionized molecular plasmas, are developed and demonstrated in high pressure, low temperature air-like molecular plasmas sustained by a continuous wave CO laser. Highly non-Boltzmann vibrational distribution functions (VDFs) of neutral species in the plasmas, which is created by anharmonic vibration-to-vibration up-pumping, are measured by spontaneous Raman scattering. Vibrational levels of all molecular species are significantly overpopulated compared to a Boltzmann distribution, and corresponding vibrational temperatures of molecular species (> 2000 K) are much higher than the translational/rotational temperature (< 500 K). Spatial distributions of the VDFs are also measured, and compared to master equation calculations. An instrumental system for filtered Thomson/rotational Raman scattering is developed. A single mode pulsed titanium:sapphire laser in combination with a rubidium vapor filter is employed in order to completely attenuate strong Rayleigh scattering/stray light, which causes severe interference because of the weak intensity and small wavelength shift of Thomson/rotational Raman scattering. The spectral purity of the titanium:sapphire laser has been increased to over 0.99999 using injection seeding, active cavity locking and a stimulated Brillouin scattering cell, greatly reducing the broadband residual component of the laser. When the wavelength of the laser is precisely tuned to the strong absorption line of rubidium at 780nm, the Rayleigh/stray light signal is absorbed essentially completely by the filter, placed in the detection path, while the Doppler broadened/wavelength shifted signal is transmitted. In order to optimize the instrument, the spectral purity as a function of circulating seed power in the laser cavity, as well as the effect of seed wavelength – cavity wavelength mismatch, is also studied. The utility of the instrument is demonstrated in measurements of elec (open full item for complete abstract)

Committee: Walter Lempert (Advisor) Subjects: Chemistry, Physical

Bachelor of Sciences, Ohio University, 2024, Physics and Astronomy

Nuclear cross section is a tool used by physicists to characterize scattering interactions between particles. It relates the probability of a reaction occurring to an effective “size” of the target particle's cross sectional area. For electron-nucleon collisions, the elastic cross section values are well supported by experimental evidence for a wide range of Q^2 measurements. Because of this, comparing one's own experimental data to the known values can highlight possible issues with the data collection process. This makes elastic cross section an effective tool to safeguard against oversights when analyzing more complex interactions. This project analyzed elastic data from the Pion LT experiment run at Jefferson Lab in 2021-2022. Using the scattering analysis software ROOT and Jefferson Lab's Monte Carlo simulator SIMC, the measured elastic cross sections were able to be verified to the 10% level of their expected values.

Committee: Julie Roche (Advisor) Subjects: Nuclear Physics; Physics

Master of Science (M.S.), University of Dayton, 2023, Electro-Optics

There are an increasing number of applications for high power lasers in medicine, industry and the military. Fiber lasers present an attractive alternative to traditional laser types; however, when operating at high power levels, fiber lasers are subject to detrimental nonlinear effects. Stimulated Brillouin scattering (SBS) is a nonlinear acousto-optic interaction where a stimulated acoustic wave scatters light, which limits the laser output. This thesis presents a theoretical and experimental framework for Brillouin scattering in continuous wave and pulsed beam regimes. Stimulated Brillouin scattering was observed in optical fibers in stationary and transient beam excitations and Brillouin frequencies are presented for different optical fibers with pulsed beam widths ranging from 15 ns to 500 ns.

Committee: Imad Agha (Advisor); Said Elhamri (Committee Co-Chair); David Zelmon (Committee Member); Andrew Sarangan (Committee Member) Subjects: Optics; Physics

Doctor of Philosophy, The Ohio State University, 2023, Electrical and Computer Engineering

Rough surface scattering is an essential aspect of modern remote sensing research, as virtually all real-world surfaces exhibit some degree of roughness whose effects cannot be adequately accounted for using simple planar surfaces. However, knowledge of what each rough surface model is capable of is critical, as choosing an appropriate model will aid in providing accurate results while minimizing the computational cost incurred. To explore these capabilities, four studies were conducted to assess how various rough surface scattering models fare in scenarios of current interest to the remote sensing community. The first two studies involve the Kirchhoff approximation (KA), with the first study assessing its applicability when the normalized coherent reflected field (which the KA is commonly used to model) is -20dB or lower, and the second study comparing it to a second-order correction term based on the second-order small slope approximation (SSA2) for ocean surface scattering. The first study shows that the KA continues to be applicable for such low amplitude cases, and the second study shows that the second-order correction shows no marked improvement over the base KA overall. The third study uses the SSA2 to validate retrieved zero-Doppler delay waveforms as part of a campaign to explore off-specular ocean scattering, and found the model waveforms to match the retrieved waveforms well in most cases considered. The fourth and final study uses simulated SAR imagery to determine under what conditions a monostatic radar system will observe the same surface scattering as a bistatic radar system, and revealed that cases with near-normal incidence angles and minor roughness yield the best agreement, with effects such as shadowing and multiple reflections accounting for most of the disagreements.

Committee: Joel Johnson (Advisor); Fernando Teixeira (Committee Member); Robert Burkholder (Committee Member) Subjects: Electrical Engineering; Electromagnetics; Physics; Remote Sensing

Doctor of Philosophy, University of Akron, 2021, Polymer Engineering

The control of ice crystallization is desired in biology, food industries, renewable wind power, and food packaging. Nature has designed countermeasures to control ice crystallization, like antifreeze proteins found in fauna and flora that allowed the biological specimen to survive extreme low-temperature conditions. Antifreeze proteins inhibit ice crystallization by surface absorption into the ice crystal by forming hydrogen bonds between protein hydroxyl groups and water molecules. Another possible mechanism is the confinement of water molecules in the antifreeze protein hydrophobic segments. Due to the low quantity extraction of antifreeze proteins in their native source and inability to be successfully synthesize by bacterial recombination, other forms of ice inhibition technologies have been sought after. Polyvinyl alcohol (PVA) is a synthetic antifreeze protein analog. PVA can inhibit ice nucleation by forming hydrogen bonds between the hydroxyl group of the polymer and ice nuclei. The control of ice crystallization has also been achieved by confining water molecules in rigid materials with well-defined nanoscale porous structures. Nanoscale confinement prevents the alignment of hydrogen bonds into a crystalline structure. The hydrogels polymer network structure size tunability and large water content represent an alternative to rigid porous materials and synthetic antifreeze proteins for antifreeze applications. Modifying the hydrogel chemical composition directly impacts the size of the polymer nanostructure, hydration level, water dynamics, and the degree of ice crystallization of water within the hydrogel. Therefore, it is hard to decouple the water content and ice inhibition properties. In the first part of this dissertation, we demonstrate a route to decouple hydrogel water content and ice inhibition properties by synthesizing copolymer hydrogel using a crystalline hydrophobic crosslinker and kinetically controlled processing of the dry copolyme (open full item for complete abstract)

Committee: Bryan Vogt (Advisor); Kevin Cavicchi (Committee Member); Bi-min Newby (Committee Member); Fardin Khabaz (Committee Chair); Mark Foster (Committee Member) Subjects: Engineering; Physical Chemistry; Polymer Chemistry

Master of Science (M.S.), University of Dayton, 2020, Aerospace Engineering

Velocity measurement inside of a wind tunnel is an extremely useful quantitative data for a multitude of reasons. One major reason is that velocity has a mathematical relationship with dynamic pressure which in turn influences all the aerodynamic forces on the test model. Many devices and methods exist for measuring velocity inside wind tunnels. At the same time, Doppler wind lidar (light detection and ranging) has been used for decades to make air speed measurements outdoors at long ranges. Lidar has been proven effective for many applications, and it has the potential to solve many of the problems faced by current velocimetry techniques inside wind tunnels. Despite this, minimal research has been performed with Doppler wind lidars inside wind tunnels. While multiple commercial systems exist for making air speed measurements at longer ranges, there are currently no widely available commercial devices designed to work well inside wind tunnels. In this research, initial work is described for the design and development of a continuous wave (CW), coherent wind lidar system. The system is for use as an alternative non-intrusive velocimetry method inside wind tunnels relying on the Doppler effect. A scaled down wind lidar designed to operate at much shorter ranges than current commercial wind lidars can be simpler, less expensive, and require less power. A first iteration of the design was constructed for proof of concept testing with a small-scale wind tunnel at low speeds (7.5-9 m/s). Testing showed that the lidar system could take one-dimensional speed measurements of seeded flow that closely matched Pitot static tube data. When not adding tracer particles to the flow, the lidar return signal was not strong enough for the photodetector used to measure the beat frequency. This research is focused on the process for designing the Doppler wind lidar system, constructing the experimental setup, and studying methods for data analysis. Results of testing presente (open full item for complete abstract)

Committee: Sidaard Gunasekaran (Advisor); Aaron Altman (Committee Member); Paul McManamon (Committee Member) Subjects: Aerospace Engineering; Atmosphere; Atmospheric Sciences; Engineering; Optics; Technology

Doctor of Philosophy (PhD), Ohio University, 2019, Physics and Astronomy (Arts and Sciences)

The work presented in this thesis is based on the g10 experiment performed at the Hall B of the Jefferson Laboratory, where tagged photons with beam energies between 0.8 and 3.5 GeV were incident on a deuterium target. With three final state particles detected (two charged pions and a deuteron), various reaction channels can be studied. This work focuses on three of many possible processes using the same reaction sample: γ d → ρ d → ϖ+ϖ- d γ d → ω d → ϖ+ϖ- d (ϖ0) γ d → NΔ ≡ d∗ϖ±→ ϖ+ϖ- d. The first two channels deal with the photoproduction of vector mesons. Differential cross sections as a function of the momentum transfer, t, are calculated for various photon energies. Using a phenomenological model based on the theory of Vector Meson Dominance, the Vector Meson-Nucleon scattering cross section (ςVN) were extracted for ρ and ω. The third reaction, on the other hand primarily focuses on the production of possible dibaryon resonances. This work establishes the possibility of three dibaryonic charge states (possible NΔ configuration) and presents a preliminary differential cross section for one of the charged states.

Committee: Kenneth Hicks (Advisor) Subjects: Particle Physics

Master of Science (MS), Ohio University, 2018, Physics and Astronomy (Arts and Sciences)

Previous data for the elastic scattering of Lambda hyperons from the nucleon dates back to the bubble chamber era of the 1960s and 1970s. Data for Lambda-N scattering is very limited in comparison with other elastic scattering processes, such as N-N, K-N or pi-N. Using the high luminosity photon beam incident on a long (40 cm) liquid hydrogen target at Hall B of Jefferson Lab, the CLAS detector was used to identify a final state with a proton in coincidence with a scattered Lambda baryon. The Lambda, before elastic scattering, were produced via the gamma p -> K+ Lambda reaction, for which the cross section is well known. This allows us to determine the flux of Lambda particles, with which we can then measure the Lambda-p elastic scattering cross section in the momentum range between 0.6 and 1.6 GeV/c. Results from the analysis of this reaction are discussed as well as future work for the direction of this analysis.

Committee: Kenneth Hicks Ph.D. (Advisor); Horacio Castillo Ph.D. (Committee Chair); Daniel Phillips Ph.D. (Committee Member) Subjects: Particle Physics; Physics

Doctor of Philosophy (PhD), Ohio University, 2018, Physics and Astronomy (Arts and Sciences)

A complete description of nucleon structure requires the simultaneous knowledge of both the spatial and momentum information of the ultimate constituents of the nucleon, the quarks and gluons. Generalized Parton Distributions (GPDs) provide such tools to describe nucleon structure. GPDs are measurable through hard exclusive processes like Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP). GPDs can describe hard exclusive processes only if Bjorken factorization is achieved during the hard scattering process. While DVCS data have given hints of the factorization regime being attained, such hints have not been observed for DVMP data. Testing for factorization in DVMP processes is the topic of this thesis. Exclusive p 0 electroproduction has been measured by experiment E12-06-114 in Hall A of JLab. Cross sections have been measured at three fixed Bjorken-x (x_B ): 0.35, 0.48 and 0.6 in the Q^2 range 3 to 9 GeV 2 . In this document we present an analysis of a subset of the data: x_B = 0.35 in the Q^2 range 3.1 to 4.5 GeV^2 . The different structure functions: unseparated cross section (sigma_T + sigma_L ), longitudinal-transverse interference(sigma_LT ), transverse-transverse interference (sigma_TT ), and the polarized response (sigma_LT' ) terms were extracted. The data was compared to a transversity GPD model. The model fails to reproduce the data even though the order of magnitude is in agreement for both model and data. We observe a strong disagreement between the data and the model for sigma_LT in terms of both magnitude and the cross section sign. Our results are in a larger and wider Q^2 domain but they are in agreement with existing measurements.

Committee: Julie Roche (Advisor) Subjects: Physics

MS, University of Cincinnati, 2018, Pharmacy: Pharmaceutical Sciences

It is established that the cleansing properties and irritation potential of surfactants can be managed with the addition of other surfactants or polymers. However, the mechanism of the surfactant-induced irritation is not fully understood. In 2003, the Blankschtein group used 14C-radiolabelling assay and dynamic light scattering (DLS) to study the penetration of sodium dodecyl sulfate (SDS) and a system of SDS with polyethylene glycol (PEG) through porcine skin. They concluded that the micelles and monomers contributed to skin irritation and the irritation potential of a surfactant was dependent on the size of the assembly body (this is referred to as the “Blankschtein Hypothesis” within this body of work). Herein, we use combined small-angle neutron scattering (SANS), DLS, and proton nuclear magnetic resonance (1H-NMR) spectroscopy to investigate the shape, size, and solution dynamics of the surfactant systems to further elaborate the “Blankschtein Hypothesis”. The results revealed that shape and inter-micellar interactions, in addition to size, serve as important factors in determining surfactant skin penetration. The validity of the Blankschtein Hypothesis was furthered explored by adding a clinical component to the study. Part of Nicole McCardy's MS thesis work was to determine if pre-clinical assays, including 14C-radiolabeled skin penetration assay and DLS, could be used to predict the clinical results observed with human subjects. A model was built to predict the harshness of mixed surfactant and surfactant-polymer composition on human skin, as measured by corneometry and visual dryness scores in a five-day forearm controlled application test (FCAT). A similar method was applied to another set of formulations, simplified to contain only one anionic surfactant. All of the surfactants in this set were structurally similar, differing only slightly in chain lengths and functional groups. The pre-clinical assays in this study were correlated with clinical resu (open full item for complete abstract)

Committee: Harshita Kumari Ph.D. (Committee Chair); Gerald Kasting Ph.D. (Committee Member); Michael Weaver Ph.D. (Committee Member) Subjects: Pharmaceuticals

MS, University of Cincinnati, 2017, Engineering and Applied Science: Materials Science

Antifoams are utilized as an industrial additive to control undesired foam during processing. This study focuses on the impact of silica on the antifoam stability. Antifoam stability refers to the ability to maintain efficiency in foam destruction after prolonged shelf storage. Common antifoams are a mixture of hydrophobic silica particles and silicone oil. Based on the general mechanisms of antifoam action discussed in Chapter 1, silica particles play a significant role in foam destruction. Silica particles contribute to foam control by facilitating the entry and the penetration depth of oil-silica globules into surfactant-water films (foam bubble walls). The size, morphology and hydrophobicity of silica can be manipulated to generate optimal antifoam globules. For example, the two silicas with good shelf life performance (8375 and 9512) had the largest silica particles and both showed a tendency to aggregate in toluene solution. We conclude that improved shelf life is related to the propensity of PDMS oil to adsorb on silica, which leads to aggregation and particle size increase. We measured the time-evolution of dynamic light scattering (DLS) from 3-vol% antifoam dissolved in toluene (Chapter 2). For the sample with the largest hydrodynamic radius (9512) the scattered intensity decreased significantly after applying ultrasonic dispersion. Decreasing intensity also occurred for 8375 albeit at later times. The decrease of intensity is attributed to the growth and precipitation of oil-silica globules. The concentration dependence of light scattering confirmed the growth-precipitation hypothesis. FT-IR (Chapter 3) was consistent with precipitation due to oil adsorption, but the data were not definitive. Chapter 4 examines the time-evolution of silica structures by static light scattering and X-ray scattering. The combined data are consistent with a hierarchical structure for silica. Agglomeration occurred fastest for 9512, which is co (open full item for complete abstract)

Committee: Dale Schaefer Ph.D. (Committee Chair); Gregory Beaucage Ph.D. (Committee Member); Yoonjee Park Ph.D. (Committee Member) Subjects: Materials Science

Doctor of Philosophy, The Ohio State University, 1984, Graduate School

Committee: Not Provided (Other) Subjects: Chemistry

Doctor of Philosophy, The Ohio State University, 2017, Physics

In this thesis, we present lambda baryon femtoscopy measured by the ALICE collaboration in √sNN = 2.76 TeV Pb-Pb collision. Correlation functions are shown in three centrality ranges for lambda-antilambda and two for the combined lambda-lambda ⊕ antilambda-antilambda results. Femtoscopy is capable of measuring the femtometer-scale spatial and temporal aspects of particle collisions by looking at relative momentum correlations among pairs of particles. In addition, femtoscopy can extract information about the final state interactions of the strong nuclear forces that occur between those particles. The femtoscopic radii and scattering parameters (scattering length and effective range of interaction) of lambda-lambda ⊕ antilambda-antilambda and lambda-antilambda are presented. Following recent measurements of proton-antilambda and antiproton-antiproton, we have expanded the standard femtoscopic fitting process to account for the correlated effects of particles that decay into lambdas. We have estimated the λ parameters that describe the relative contribution of each residual correlation. Residual correlation effects are included in the fitting process by estimating their correlation strength and then smearing the relative momentum of their contribution according to the kinematics of their decay.

Committee: Thomas Humanic (Advisor); Michael Lisa (Committee Member); Yuri Kovchegov (Committee Member); Fengyuan Yang (Committee Member); Michael Bond (Committee Member) Subjects: Physics

Doctor of Philosophy, The Ohio State University, 2016, Physics

In systems of ultracold atoms, pairwise interactions are resonantly enhanced by the application of an oscillating magnetic field that is parallel to the spin-quantization axis of the atoms. The resonance occurs when the frequency of the applied field is precisely tuned near the transition frequency between the scattering atoms and a diatomic molecule. The resulting cross section can be made more than two orders of magnitude larger than the cross section in the absence of the oscillating field. The low momentum resonance properties have a universal description that is independent of the atomic species. To arrive at these conclusions, we first develop a formal extension of Floquet theory to describe scattering of atoms with time-periodic, short-range interaction potentials. We then calculate the atomic scattering properties by modeling the atomic interactions with a square well potential with oscillating depth and then explicitly solving the time-dependent Schrodinger equation. We then apply the Floquet formalism to the case of atoms scattering with a contact interaction described by a time-periodic scattering length, obtaining analytic results that agree with those obtained by solving the time-dependent Schrodinger equation.

Committee: Eric Braaten PhD (Advisor); Louis DiMauro PhD (Committee Member); Ilya Gruzberg PhD (Committee Member); Ulrich Heinz PhD (Committee Member) Subjects: Physics

Doctor of Philosophy (PhD), Ohio University, 1987, Physics and Astronomy (Arts and Sciences)

The specific purpose of this work is to provide a better understanding of the 14C level structure; the general purpose is to provide the details for using shell model calculations in R-matrix analyses. Using the TOF facilities of the Ohio University Accelerator Laboratory, the elastic and first 3 inelastic differential scattering cross sections for 13C+n were measured at 69 energies for 4.5 ≤ En ≤ 11 MeV. A multiple scattering code was developed which provided a simulation of the experimental scattering process allowing accurate corrections to the small inelastic data. The integrated 13C(n,α)10Be cross section is estimated. The sequential 2n-decay of 14C states populated by 13C+n was observed. A shell model code was developed. Normal and non-normal parity calculations were made for the lithium isotopes using a new two-body interaction. The results for 5Li predict the 2s1/2 and 1d5/2 single-particle states to be located below the 3/2+ (Ex = 16.66 MeV) state. Similar calculations were made for 13C,13N, and 14C. Results for 13C and 13N show for Ex < 10 MeV the Thomas-Ehrman shifts are related to the 2s1/2 single-particle energies. For 7Li and 14C, 2ℏω calculations were done. Shell model calculations generated the R-matrix parameters for the elastic and first 3 inelastic channels of 13C+n. After adjusting some energies, the predicted structure generally agrees with experiment for En < 4 MeV. Previous elastic 13C+n data were refit to replace Ro background terms by more realistic broad states and to get better agreement with model calculations. R-matrix fitting of the full data set produced new 14C level information. For En > 4 MeV (Ex > 12 MeV), 5 states are given defining Jϖ assignments; 3, tentative assignments. The procedure for using shell model calculations in R-matrix analyses is given. New and more consistent 14C level information is obtained.

Committee: Raymond Lane (Advisor) Subjects: Nuclear Physics