Physics Commons^™

Diode Lasers For Use In Experiments On Cold Rydberg Atoms, Bill Whitledge

Honors Theses

This project was to measure the atomic density of (85)Rb atoms in a magneto optical trap using a low-intensity probe laser. Additionally, a dark spontaneous force optical trap was constructed in an attempt to boost the trap density. The dark spot failed to appreciably increase the overall trap density (which remained steady at - N = 10^10 atoms/cm^3) but it did increase the density of dark-state atoms in the trap by an order of magnitude. This is a useful result since many experiments on cold Rydberg atoms involve exciting atoms starting in the ground state rather than the first excited …

Search For Novel Molecular Species Formed By Cold Rydberg Atoms In A Magneto-Optical Trap, Alexander Gill

Honors Theses

This describes a search for novel ultra-long-range molecular resonances between rubidium Rydberg atoms in a magneto-optical trap (MOT). We use the technique of photoassociative spectroscopy by directly scanning the wavelength of our Rydberg excitation laser about a 5p3/2 - 90p3/2 transition in a weak electric field and by scanning mm-waves about a 39sl/2 - 39p3/2 transition. The results of both of these surveys are inconclusive.

Hamiltonian Constraint Analysis Of Vector Field Theories With Spontaneous Lorentz Symmetry Breaking, Nolan L. Gagne

Honors Theses

Recent investigations of various quantum-gravity theories have revealed a variety of possible mechanisms that lead to Lorentz violation. One of the more elegant of these mechanisms is known as Spontaneous Lorentz Symmetry Breaking (SLSB), where a vector or tensor field acquires a nonzero vacuum expectation value. As a consequence of this symmetry breaking, massless Nambu-Goldstone modes appear with properties similar to the photon in Electromagnetism. This thesis considers the most general class of vector field theories that exhibit spontaneous Lorentz violation-known as bumblebee models-and examines their candidacy as potential alternative explanations of E&M, offering the possibility that Einstein-Maxwell theory could …

Search For Gravitational Waves From Binary Inspirals In S3 And S4 Ligo Data, B. P. Abbott, R. Abbott, Mario C. Diaz, R. Grosso, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres

Physics and Astronomy Faculty Publications and Presentations

We report on a search for gravitational waves from the coalescence of compact binaries during the third and fourth LIGO science runs. The search focused on gravitational waves generated during the inspiral phase of the binary evolution. In our analysis, we considered three categories of compact binary systems, ordered by mass: (i) primordial black hole binaries with masses in the range 0.35M⊙

Search For Gravitational Waves Associated With 39 Gamma-Ray Bursts Using Data From The Second, Third, And Fourth Ligo Runs, B. P. Abbott, R. Abbott, Mario C. Diaz, R. Grosso, Wm. R. Johnston, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres

Physics and Astronomy Faculty Publications and Presentations

We present the results of a search for short-duration gravitational-wave bursts associated with 39 gamma-ray bursts (GRBs) detected by gamma-ray satellite experiments during LIGO’s S2, S3, and S4 science runs. The search involves calculating the crosscorrelation between two interferometer data streams surrounding the GRB trigger time. We search for associated gravitational radiation from single GRBs, and also apply statistical tests to search for a gravitational-wave signature associated with the whole sample. For the sample examined, we find no evidence for the association of gravitational radiation with GRBs, either on a single-GRB basis or on a statistical basis. Simulating gravitational-wave bursts …

All-Sky Search For Periodic Gravitational Waves In Ligo S4 Data, B. P. Abbott, R. Abbott, Mario C. Diaz, R. Grosso, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres

Physics and Astronomy Faculty Publications and Presentations

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50–1000 Hz and with the frequency’s time derivative in the range −1×10−8  Hz s−1 to zero. Data from the fourth LIGO science run (S4) have been used in this search. Three different semicoherent methods of transforming and summing strain power from short Fourier transforms (SFTs) of the calibrated data have been used. The first, known as StackSlide, averages normalized power from each SFT. A “weighted Hough” scheme is also developed and used, which also allows for a multi-interferometer search. The third method, …

Driving The Ting Model With Gaim Electron Densities: Ionospheric Effects On The Thermosphere, G. Jee, A. G. Burns, W. Wang, S. C. Solomon, Robert W. Schunk, L. Scherliess, D. C. Thompson, Jan Josef Sojka, Lie Zhu

All Physics Faculty Publications

In order to study the effects of ionospheric plasma densities on the thermosphere, the electron and O+ densities in the Thermosphere Ionosphere Nested Grid (TING) model were replaced by electron densities from the Global Assimilation of Ionospheric Measurements (GAIM) model at pressure level z = 0 (about 210 ~ 230 km altitude) and above. This GAIM-derived TING model (G-TING) was then run for the period 1–4 April 2004. The TING model was also run as a stand-alone coupled model (S-TING), without using the GAIM electron densities, for the same period. The resulting thermospheric responses from the two simulations were compared …

Performance Comparison Of Pb(Zr0.52Ti0.48)O3-Only And Pb(Zr0.52Ti0.48)O3-On-Silicon Resonators, Hengky Chandrahalim, Sunil A. Bhave, Ronald G. Polcawich, Jeff Pulskamp, Dan Judy, Roger Kaul, Madan Dubey

Faculty Publications

This paper provides a quantitative comparison and explores the design space of lead zirconium titanate (PZT)–only and PZT-on-silicon length-extensional mode resonators for incorporation into radio frequency microelectromechanical system filters and oscillators. We experimentally measured the correlation of motional impedance (R_X) and quality factor (Q) with the resonators’ silicon layer thickness (t_Si). For identical lateral dimensions and PZT-layer thicknesses (t_PZT), the PZT-on-silicon resonator has higher resonant frequency (f_C), higher Q (5100 versus 140), lower R_X (51 Ω versus 205 Ω), and better linearity [third-order input intercept …

Evanescent Microwave Microscopy Of Porcine Skin Tissue, Richard A. Kleismit

Browse all Theses and Dissertations

This thesis describes the application of a custom designed λ/4 resonant coaxial probe to measurements of the complex permittivity of in vitro freshly excised porcine skin tissue. The dielectric properties of the organic material within the near field of the tip of the probe frustrates the electric field and measurably changes the resonant frequency and quality factor Q of the coaxial sensor, where the change in resonant frequency and quality factor of a tuned resonance is measured as a function of tip-sample separation. The design of the probe enables better spatial resolution than previously developed probes. The following studies were …

Denaturation Transition Of Stretched Dna, Andreas Hanke, Martha G. Ochoa, Ralf Metzler

Physics and Astronomy Faculty Publications and Presentations

We generalize the Poland-Scheraga model to consider DNA denaturation in the presence of an external stretching force. We demonstrate the existence of a force-induced DNA denaturation transition and obtain the temperature-force phase diagram. The transition is determined by the loop exponent c, for which we find the new value c=4ν−1/2 such that the transition is second order with c=1.85DNA, corresponding to a lower melting temperature T(F), in agreement with single-molecule DNA stretching experiments.

Search Of S3 Ligo Data For Gravitational Wave Signals From Spinning Black Hole And Neutron Star Binary Inspirals, B. P. Abbott, R. Grosso, Mario C. Diaz, Soumya Mohanty, Soma Mukherjee, Cristina V. Torres

Physics and Astronomy Faculty Publications and Presentations

We report on the methods and results of the first dedicated search for gravitational waves emitted during the inspiral of compact binaries with spinning component bodies. We analyze 788 hours of data collected during the third science run (S3) of the LIGO detectors. We searched for binary systems using a detection template family specially designed to capture the effects of the spin-induced precession of the orbital plane. We present details of the techniques developed to enable this search for spin-modulated gravitational waves, highlighting the differences between this and other recent searches for binaries with nonspinning components. The template bank we …

Hypersonic Boundary Layer Receptivity To Acoustic Disturbances Over Cones, Kursat Kara

Mechanical & Aerospace Engineering Theses & Dissertations

The receptivity mechanisms of hypersonic boundary layers to free stream acoustic disturbances are studied using both linear stability theory (LST) and direct numerical simulations (DNS). A computational code is developed for numerical simulation of steady and unsteady hypersonic flow over cones by combining a fifth-order weighted essentially non-oscillatory (WENO) scheme with third-order total-variation-diminishing (TVD) Runge-Kutta method. Hypersonic boundary layer receptivity to free-stream acoustic disturbances in slow and fast modes over 5-degree, half-angle blunt cones and wedges are numerically investigated. The free-stream Mach number is 6.0, and the unit Reynolds number is 7.8×106/ft. Both the steady and unsteady solutions are obtained …

Comparison Of Two Methods Of External Scatter Dose Contributions To The Contralateral Breast, James Cutlip

Browse all Theses and Dissertations

The treatment outcomes of many forms of breast cancer have become very favorable. The usual standard of successful treatment of five years without a recurrence is not adequate any longer for breast cancer. Many patients live well beyond this time interval only to have a second malignancy develop in the contralateral breast ten or twenty years later. Boice et al (1992) found that there was a correlation between the amount of dose to the contralateral breast and the likelihood of a secondary malignancy forming.

The normal practice today is to use multi-leaf collimators (MLC) to modulate the photon beam in …

Color Transparency In Qcd And Post-Selection In Quantum Mechanics, Shmuel Nussinov, Jeff Tollaksen

Mathematics, Physics, and Computer Science Faculty Articles and Research

We discuss color transparency in the nuclear QCD context from the perspective of pre- and post-selected ensembles. We show that the small size of the hadronic states can be explained by the peculiar "force of post-selection," in contrast to the more standard explanation based on external forces.

Quantum Graphical Models And Belief Propagation, Matthew S. Leifer, D. Poulin

Mathematics, Physics, and Computer Science Faculty Articles and Research

Belief Propagation algorithms acting on Graphical Models of classical probability distributions, such as Markov Networks, Factor Graphs and Bayesian Networks, are amongst the most powerful known methods for deriving probabilistic inferences amongst large numbers of random variables. This paper presents a generalization of these concepts and methods to the quantum case, based on the idea that quantum theory can be thought of as a noncommutative, operator-valued, generalization of classical probability theory. Some novel characterizations of quantum conditional independence are derived, and definitions of Quantum n-Bifactor Networks, Markov Networks, Factor Graphs and Bayesian Networks are proposed. The structure of Quantum Markov …

Li- And B-Decorated Cis-Polyacetylene: A Computational Study, S. Li, Puru Jena

Physics Publications

By using density functional theory and the generalized gradient approximation, we show that Li-decorated cis-polyacetylene meets some of the requirements of an ideal hydrogen storage material. Unlike Ti-doped cis-polyacetylene, Li resists clustering and can reversibly store up to 10.8 wt %hydrogen in molecular form. However, molecular dynamics simulations show that Li can retain hydrogen only at cryogenic temperatures. On the other hand, B-doped cis-polyacetylene can store up to 7.5 wt % hydrogen, but it binds to hydrogen too strongly to be suitable for room temperature applications. The results are compared to those in Ti-doped cis-polyacetylene.

Yellow Luminescence In Zno Layers Grown On Sapphire, M. A. Reshchikov, J. Q. Xie, B. Hertog, A. Osinsky

Physics Publications

We conducted a detailed study of the yellow luminescence (YL) band that has a maximum of 2.19eV at 10K in undoped and N-doped ZnO layers grown on sapphire substrates. Important characteristics of this band and the related defect are established. The YL band is attributed to a transition between a shallow donor and an acceptor with an energy level ∼0.4eV above the valence band. Quenching of the YL intensity with activation energies of 85meV and 0.4eV is observed at temperatures above 100 and 320K, respectively. The YL band is possibly due to a defect complex that may include a Znvacancy.

Alignment Memory Of A Nematic Liquid Crystal And Thermal Isotropization Of The Surface Adsorbed Layer, A. B. Nych, D. Yu. Reznikov, O. P. Boiko, V. G. Nazarenko, V. M. Pergamenshchik, Philip Bos

Philip J. Bos

We use a digital image analysis of the schlieren textures to study the effect of memory of the surface anisotropy in a nematic-liquid-crystal cell and establish its relation to the surface adsorbed molecular layer. The anisotropy is induced on an isotropic glass surface by a flow of the nematic liquid. The proposed technique allows us to quantify the alignment and its changes under the effect of temperature. The temperature at which the memory of the alignment texture is lost is interpreted as the temperature of the full isotropization of the initial anisotropic surface layer adsorbed during the flow: the molecules …

Cavity Resonances Of Metal-Dielectric-Metal Nanoantennas, Bhuwan Joshi, Qi-Huo Wei

Qi-Huo Wei

We propose a new design of optical nanoantennas and numerically study their optical properties. The nanoantennas are composed of two cylindrical metal nanorods stacked vertically with a circular dielectric disk spacer. Simulation results show that when the dielectric disk is less than 5nm in thickness, such nanoantennas exhibit two types of resonances: one corresponding to antenna resonance, the other corresponding to cavity resonances. The antenna resonance generates a peak in scattering spectra, while the cavity resonances lead to multiple dips in the scattering spectra. The cavity resonant frequency can be tuned by varying the size of the dielectric disk. The …

Hierarchies Of Networked Phases Induced By Multiple Liquid-Liquid Critical Points, C. W. Hsu, J. Largo, F. W. Sciortino, Francis Starr

Francis Starr

No abstract provided.

Bond Stiffening In Small Nanoclusters And Its Consequences For Mechanical And Thermal Properties, Pushpa Raghani, Umesh Waghmare, Shobhana Narasimhan

Pushpa Raghani

We have used density functional perturbation theory to investigate the stiffness of interatomic bonds in small clusters of Si, Sn, and Pb. As the number of atoms in a cluster is decreased, there is a marked shortening and stiffening of bonds. The competing factors of fewer but stiffer bonds in clusters result in softer elastic moduli but higher #1;average#2; frequencies as size is decreased, with clear signatures of universal scaling relationships. The stiffness of bonds is found to scale as the inverse tenth power of length. A significant role in understanding trends is played by the coordination number of the …

Improvement Of Ferroelectric Fatigue Endurance In Multiferroic (Ba(0.5)Sr(0.5))Tio(3)/(Bi(1.05)La(0.05))Feo(3)/(Ba(0.5)Sr(0.5))Tio(3) Sandwich Structures, Chew Khian Hooi, Miao J., Zhang B. P., Wang Y.

Chew Khian Hooi

We report the improved ferroelectric properties in dielectric/multiferroic/dielectric sandwich structures composed of Ba(0.5)Sr(0.5)TiO(3) (BST) and Bi(1.05)La(0.05)FeO(3) (BLF). Compared with the single BLF film, the trilayer structures exhibit a lower dielectric loss and weaker frequency dependence of dielectric properties. At room temperature, the remnant polarization and saturation polarization of the trilayer structures are 34.3 and 46.9 mu C/cm(2), respectively. More interestingly, the polarization of BST/BLF/BST trilayer exhibits a fatigue-free characteristic of up to 10(9) switching cycles. Applying Dawber's model, the concentration of oxygen vacancies and barrier energy of oxygen vacancies migration in BST/BLF/BST trilayer are calculated as 6.1x10(17) cm(-3) and 1.33 …

How Deep Is The Irrationalism In The Science?, Pal R. Molnar

Pal R. Molnar

In the last decades a strong skeptic movement started against the para-sciences or irrationalism. We welcome this endeavor and we would like to extend the target of this movement into the field of scientific irrationalism too. In this article we try to discuss some of the clear and evident contradiction in the physics. Most of these problems were published in the last 20 years [1], and here we try to collect the biggest and stunk bugs. With this paper we try to break out the wall of silence about the inner problems of scientific world view. We believe that the …

Generation Of Laser-Polarized Xenon Using Fiber-Coupled Laser-Diode Arrays Narrowed With Integrated Volume Holographic Gratings, Panayiotis Nikolaou, Nicholas Whiting, Neil A. Eschmann, Kathleen E. Chaffee, Michael J. Barlow, Boyd M. Goodson

Nicholas Whiting

Cascading Infrastructure Failures: Avoidance And Response, George H. Baker, Cheryl J. Elliott

George H Baker

No critical infrastructure is self-sufficient. The complexity inherent in the interdependent nature of infrastructure systems complicates planning and preparedness for system failures. Recent wide-scale disruption of infrastructure on the Gulf Coast due to weather, and in the Northeast due to electric power network failures, dramatically illustrate the problems associated with mitigating cascading effects and responding to cascading infrastructure failures once they have occurred.

The major challenge associated with preparedness for cascading failures is that they transcend system, corporate, and political boundaries and necessitate coordination among multiple, disparate experts and authorities. This symposium brought together concerned communities including government and industry …

Thermal Roots Of Correlation-Based Complexity, Philip Fraundorf

Phil Fraundorf

The Formation Of Sporadic E Layers By A Vortical Perturbation Excited In A Horizontal Wind Shear Flow, G. G. Didebulidze, Levan Lomidze

Levan Lomidze

The formation of the mid-latitude sporadic E layers (Es layers) by an atmospheric vortical perturbation excited in a horizontal shear flow (horizontal wind with a horizontal linear shear) is investigated. A three-dimensional atmospheric vortical perturbation (atmospheric shear waves), whose velocity vector is in the horizontal plane and has a vertical wavenumber kz≠0, can provide a vertical shear of the horizontal wind. The shear waves influence the vertical transport of heavy metallic ions and their convergence into thin and dense horizontal layers. The proposed mechanism takes into account the dynamical influence of the shear wave velocity in the horizontal wind on …

Different Long-Term Trends Of The Oxygen Red 630.0 Nm Line Nightglow Intensity As The Result Of Lowering The Ionosphere F2 Layer, N. B. Gudadze, G. G. Didebulidze, Levan Lomidze, G. Sh. Javakhishvili, M. A. Marsagishvili, M. Todua

Levan Lomidze

Long-term observations of total nightglow intensity of the atomic oxygen red 630.0 nm line at Abastumani (41.75° N, 42.82° E) in 1957–1993 and measurements of the ionosphere F2 layer parameters from the Tbilisi ionosphere station (41.65° N, 44.75° E) in 1963–1986 have been analyzed. It is shown that a decrease in the long-term trend of the mean annual red 630.0 nm line intensity from the pre-midnight value (+0.770±1.045 R/year) to its minimum negative value (−1.080±0.670 R/year) at the midnight/after midnight is a possible result of the observed lowering of the peak height of the ionosphere F2 layer electron density hmF2 …