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Full-Text Articles in Physics
Ac Zeeman Force With Ultracold Atoms, Charles Fancher
Ac Zeeman Force With Ultracold Atoms, Charles Fancher
Dissertations, Theses, and Masters Projects
Ultracold atom experiments use a gas of neutral atoms with temperatures less than 100 µK above absolute zero and offer unmatched experimental control of quantum states and coherence, which has allowed ultracold atom-based measurements to be some of the most precise to date. While ultracold atom experiments can control almost all atomic degrees of freedom, spin-dependent trapping and spatial manipulation has remained difficult if not inaccessible. We are developing a method of spin-dependent trapping and spatial manipulation for ultracold neutral atoms using the AC Zeeman force produced by a microwave magnetic near-field gradient generated by an atom chip. We measure …
An Improved Measurement Of The Muon Neutrino Charged Current Quasi-Elastic Cross-Section On Hydrocarbon At Minerva, Dun Zhang
Dissertations, Theses, and Masters Projects
Neutrino interactions in the detectors of long baseline oscillation experiments are analyzed to determine the neutrino flavor and energy spectrum, allowing the neutrino mass ordering and mixing parameters to be determined. For neutrino interactions below the pion production threshold, the dominant reaction is charged current quasi-elastic (CCQE) scattering. Oscillation experiments are made of heavy nuclei so the QE process occurs on nucleons that are embedded in the nuclear environment. Predictions of the QE cross-section suffer from significant uncertainties due to our understanding of that nuclear environment and the way it is probed by the weak interaction. I have developed a …
Electron Neutrino Appearance In The Nova Experiment, Ji Liu
Electron Neutrino Appearance In The Nova Experiment, Ji Liu
Dissertations, Theses, and Masters Projects
The NuMI off-Axis $\nu_e$ Appearance (NO$\nu$A) experiment is a long baseline, off-axis neutrino oscillation experiment. It is designed to search for oscillations of $\nu_\mu$ to $\nu_e$ by comparing measurements of the NuMI beam composition in two detectors. These two detectors are functionally identical, nearly fully-active liquid-scintillator tracking calorimeters and located at two points along the beam line to observe the neutrinos. The Near Detector (ND), situated \unit[1]{km} away from the proton target at Fermilab, measures neutrinos prior to oscillation. Then the Far Detector (FD), located 810 km away at Ash River, Minnesota, measures the neutrinos after they have traveled and …
Study Of Variations Of The Dynamics Of The Metal-Insulator Transition Of Thin Films Of Vanadium Dioxide With An Ultra-Fast Laser, Elizabeth Lee Radue
Study Of Variations Of The Dynamics Of The Metal-Insulator Transition Of Thin Films Of Vanadium Dioxide With An Ultra-Fast Laser, Elizabeth Lee Radue
Dissertations, Theses, and Masters Projects
Vanadium dioxide is an intensely studied material, since it goes through an insulator-metal transition at a critical temperature just above room temperature at 340~K. The dramatic change in conductivity and the easily accessible transition temperature makes it an attractive material for novel technologies. Thin films of VO2 have a reversible transition without any significant degradation in contrast, and depending on the microstructure of the films, the properties of the transition are tunable. In this work, I study the dynamics of the insulator-transition in thin films grown on different substrates using a pump-probe configuration. The energy needed to trigger the transition, …
A Measurement Of The Parity-Violating Asymmetry In Aluminum And Its Contribution To A Measurement Of The Proton's Weak Charge, Joshua Allen Magee
A Measurement Of The Parity-Violating Asymmetry In Aluminum And Its Contribution To A Measurement Of The Proton's Weak Charge, Joshua Allen Magee
Dissertations, Theses, and Masters Projects
The Qweak experiment, which ran at the Thomas Je↵erson National Accelerator Facility, made a precision measurement of the proton’s weak charge, Q_p^W . The weak charge is extracted via a measurement of the parity-violating asymmetry in elastic electron-proton scattering from hydrogen at low momentum transfer (Q^2=0.025 GeV^2). This result is directly related to the electroweak mixing angle, sin2 (theta_W ), a fundamental parameter in the Standard Model of particle physics. This provides a precision test sensitive to new, as yet unknown, fundamental physics. This dissertation focuses on two central corrections to the Qweak measurement: the target window contribution and sub-percent …
Applications Of High Energy Theory To Superconductivity And Cosmic Inflation, Zhen Wang
Applications Of High Energy Theory To Superconductivity And Cosmic Inflation, Zhen Wang
Dissertations, Theses, and Masters Projects
This dissertation examines applications of methods of high-energy theory to other physical systems: unconventional superconductors on the one hand, and cosmology on the other. Extra-dimensional models of superconductors, motivated by gauge/gravity duality in string theory, have proven remarkably successful in reproducing qualitative, and sometimes quantitative, aspects of unconventional superconductors. We analyze the universality of some of these predictions, and discover a universal relation between certain superconducting observables. The second part of this dissertation is about cosmic inflation. The evolution of the universe is sensitive to the fundamental particles and their interactions. We investigate models of cosmic inflation which involve the …
Solving Problems Of The Standard Model Through Scale Invariance, Dark Matter, Inflation And Flavor Symmetry, Raymundo Alberto Ramos
Solving Problems Of The Standard Model Through Scale Invariance, Dark Matter, Inflation And Flavor Symmetry, Raymundo Alberto Ramos
Dissertations, Theses, and Masters Projects
Through beyond standard model formulations we are able to suggest solutions to some of the current shortcomings of the standard model. In this thesis we focus in particular on inflation, the hierarchy of fermion masses, scale invariant extensions and dark matter candidates. First we present a model of hybrid natural inflation based on the discrete group S_3, the smallest non-Abelian group. The S_3 potential has an accidental symmetry whose breaking results in a pseudo-Goldstone boson with the appropriate potential for a slow-rolling inflaton. The hybrid adjective comes from the fact that inflation is ended by additional scalar fields interacting with …
Compton Scattering Polarimetry For The Determination Of The Proton’S Weak Charge Through Measurements Of The Parity-Violating Asymmetry Of 1h(E,E')P, Juan Carlos Cornejo
Compton Scattering Polarimetry For The Determination Of The Proton’S Weak Charge Through Measurements Of The Parity-Violating Asymmetry Of 1h(E,E')P, Juan Carlos Cornejo
Dissertations, Theses, and Masters Projects
The Standard Model has been a theory with the greatest success in describing the fundamental interactions of particles. as of the writing of this dissertation, the Standard Model has not been shown to make a false prediction. However, the limitations of the Standard Model have long been suspected by its lack of a description of gravity, nor dark matter. its largest challenge to date, has been the observation of neutrino oscillations, and the implication that they may not be massless, as required by the Standard Model. The growing consensus is that the Standard Model is simply a lower energy effective …
Neutrino Flux Prediction For The Numi Beamline, Leonidas Aliaga Soplin
Neutrino Flux Prediction For The Numi Beamline, Leonidas Aliaga Soplin
Dissertations, Theses, and Masters Projects
The determination of the neutrino flux in any conventional neutrino beam presents a challenge for the current and future short and long baseline neutrino experiments. The uncertainties associated with the production and attenuation of the hadrons in the beamline materials along with those associated with the beam optics have a big effect in the flux spectrum knowledge. For experiments like MINERvA, understanding the flux is crucial since it enters directly into every neutrino-nucleus cross-section measurements. The foundation of this work is predicting the neutrino flux at MINERvA using dedicated measurements of hadron production in hadron-nucleus collisions and incorporating in-situ MINERvA …
Turbulent Particle Transport In H-Mode Plasmas On Diii-D, Xin Wang
Turbulent Particle Transport In H-Mode Plasmas On Diii-D, Xin Wang
Dissertations, Theses, and Masters Projects
Particle transport is an important topic in plasma physics. It determines the density profile of a burning plasma within a tokamak – a magnetic confinement device. Microscopic turbulent particle transport is two orders of magnitude larger than other transport mechanisms for electrons and small ions. In order to confine a plasma in a tokamak with a core density that exceeds the fusion criteria, it is essential to study turbulent particle transport. This thesis investigates how different plasma parameters such as the toroidal rotation and microscopic instabilities affect turbulent particle transport in the DIII-D tokamak. First, we show how toroidal rotation …
Investigating Proton Spin Structure: A Measurement Of G_2^P At Low Q^2, Melissa Ann Cummings
Investigating Proton Spin Structure: A Measurement Of G_2^P At Low Q^2, Melissa Ann Cummings
Dissertations, Theses, and Masters Projects
The $g_2^p$ collaboration performed the first measurement of the reaction $\vec{p}(\vec{e},e')X$ in the kinematic range 0.02 $ < $ Q$^2$ $ < $ 0.2 GeV$^2$ in the resonance region. Experiment E08-027 took place in Hall A at the Thomas Jefferson National Accelerator Facility from March-May of 2012. Data was taken with a longitudinally polarized electron beam, using an NH$_3$ target polarized in both parallel and perpendicular configurations. Very preliminary results for $g_1^p$ and $g_2^p$ are shown in this thesis. to extract the spin structure functions, asymmetries are calculated from data taken with a 2.2 GeV electron beam and a 5 T target field, and combined with the Bosted model proton cross section. Preliminary dilution factors and preliminary radiative corrections are included in the asymmetry analysis. Sum rules and $\chi$PT allow us to test the Burkhardtt-Cottingham (BC) sum rule and obtain the spin polarizability quantities $\gamma_0$ and $\delta_{LT}$. The BC sum rule, valid for all values of $Q^2$, says that the integral of $g_2$ over all Bjorken $x$ vanishes. The very preliminary result presented here shows the contribution to the integral from the measured kinematic region. Although the contribution from the resonance region is not consistent with the expected result of zero, an extrapolation to high and low $x$ must be included to test whether the BC sum rule is satisfied. The difficulty in $\chi$PT calculations of $\gamma_0$ and $\delta_{LT}$ is how to include the resonance contributions, particularly the $\Delta$-resonance, which dominates. Recent developments have found better agreement with neutron experimental results, however this is little proton data to compare with the calculations, particularly at low $Q^2$. The very preliminary results shown here do not show agreement with any of the current $\chi$PT predictions. However, as this is only the contribution from the measured kinematic region, it is necessary to include the extrapolation outside the resonance region to draw a stronger conclusion. Further analysis is ongoing, and preliminary results, including a cross section extracted from data instead of a model prediction, are expected within the next year.
Study Of Spatial Structure Of Squeezed Vacuum Field, Mi Zhang
Study Of Spatial Structure Of Squeezed Vacuum Field, Mi Zhang
Dissertations, Theses, and Masters Projects
Squeezed states of light, with field fluctuations smaller than the coherent state fluctuations (or shot noise), are used for improving accuracy of quantum-noise limited measurements, like the detection of gravitational waves. They are also essential resources for quantum information transfer protocols. We studied a squeezed vacuum field generated in hot Rb vapor via the polarization self-rotation effect. We studied the mode structure of the squeezed field by spatially-masking the laser beam after its interaction with the Rb atomic vapor. From analysis of the data we developed a multi-mode theory to simulate the mode composition of the squeezed vacuum field. Our …
Thin Film Approaches To The Srf Cavity Problem: Fabrication And Characterization Of Superconducting Thin Films, Douglas Beringer
Thin Film Approaches To The Srf Cavity Problem: Fabrication And Characterization Of Superconducting Thin Films, Douglas Beringer
Dissertations, Theses, and Masters Projects
Superconducting Radio Frequency (SRF) cavities are responsible for the acceleration of charged particles to relativistic velocities in most modern linear accelerators, such as those employed at high-energy research facilities like Thomas Jefferson National Laboratory’s CEBAF and the LHC at CERN. Recognizing SRF as primarily a surface phenomenon enables the possibility of applying thin films to the interior surface of SRF cavities, opening a formidable tool chest of opportunities by combining and designing materials that offer greater benefit. Thus, while improvements in radio frequency cavity design and refinements in cavity processing techniques have improved accelerator performance and efficiency – 1.5 GHz …
Resolution Limits Of Time-Of-Flight Mass Spectrometry With Pulsed Source, Guangzhi Qu
Resolution Limits Of Time-Of-Flight Mass Spectrometry With Pulsed Source, Guangzhi Qu
Dissertations, Theses, and Masters Projects
Matrix Assisted Laser Desorption/Ionization (MALDI) is a time-of-flight mass spectrometry commonly used to detect a wide mass range of biomarkers. However, MALDI requires a high laser pulse energy to create ions with a mass higher than 50,000 Daltons. That high laser energy increases the net ion production but it also degrades the instrument's mass resolution. This project uses a Room Temperature Ionization Liquid (RTIL) as a liquid matrix with a self healing surface instead of a standard crystal matrix to increase shot to shot reproducibility, enabling a systematic study of the origin of the resolution degradation. This study shows that …
A Precision Measurement Of The Weak Charge Of Proton At Low Q^2: Kinematics And Tracking, Siyuan Yang
A Precision Measurement Of The Weak Charge Of Proton At Low Q^2: Kinematics And Tracking, Siyuan Yang
Dissertations, Theses, and Masters Projects
The Standard Model of particle physics represents our present best understanding of the elementary particles and three of the four fundamental forces. One of the most important and challenging tasks of modern particle physics is to test, and perhaps, to find the evidence for new physics not contained in the Standard Model. One such test, the $Q_{weak}$ experiment, was conducted at JLab in Newport News, VA, from 2010 to 2012. The goal of the experiment is to measure the value of the weak charge of proton, $Q_{weak}$ to a 4\% precision, which, if it confirms the Standard Model prediction, will …
Disorder Effects In Dirac Heterostructures, Martin Alexander Rodriguez-Vega
Disorder Effects In Dirac Heterostructures, Martin Alexander Rodriguez-Vega
Dissertations, Theses, and Masters Projects
In this dissertation, we study theoretically heterostructures based on Dirac mate- rials, i.e. materials, such as graphene in which the electrons behave as massless Dirac fermions at low energies. We first examine how the presence of long-range disorder affects the electronic ground state of a double layer graphene heterostruc- ture formed by two graphene layers separated by a thin dielectric film. We then identify the necessary conditions for the formation of an interlayer exciton conden- sate in such a system. We also comment on the effect of long-range disorder on the broken symmetry ground state induced by electron-electron interactions in …
Quantitative Analysis Of Periodic Breathing And Very Long Apnea In Preterm Infants., Mary A. Mohr
Quantitative Analysis Of Periodic Breathing And Very Long Apnea In Preterm Infants., Mary A. Mohr
Dissertations, Theses, and Masters Projects
No abstract provided.
Experimental Apparatus For Quantum Pumping With A Bose-Einstein Condensate., Megan K. Ivory
Experimental Apparatus For Quantum Pumping With A Bose-Einstein Condensate., Megan K. Ivory
Dissertations, Theses, and Masters Projects
No abstract provided.