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Full-Text Articles in Physical Sciences and Mathematics
Isotope Shifts In Francium Isotopes Fr206-213 And Fr-221, R. Collister, G. Gwinner, M. Tandecki, Seth Aubin
Isotope Shifts In Francium Isotopes Fr206-213 And Fr-221, R. Collister, G. Gwinner, M. Tandecki, Seth Aubin
Arts & Sciences Articles
We present the isotope shifts of the 7s(1/2) to 7p(1/2) transition for francium isotopes Fr206-213 with reference to Fr-221 collected from two experimental periods. The shifts are measured on a sample of atoms prepared within a magneto-optical trap by a fast sweep of radio-frequency sidebands applied to a carrier laser. King plot analysis, which includes literature values for 7s(1/2) to 7p(3/2) isotope shifts, provides a field shift constant ratio of 1.0520(10) and a difference between the specific mass shift constants of 170(100) GHz amu between the D-1 and D-2 transitions, of sufficient precision to differentiate between ab initio calculations.
Matter, Energy, And Heat Transfer In A Classical Ballistic Atom Pump, Tommy A. Byrd, Kunal K. Das, Kevin Mitchell, Seth Aubin, John B. Delos
Matter, Energy, And Heat Transfer In A Classical Ballistic Atom Pump, Tommy A. Byrd, Kunal K. Das, Kevin Mitchell, Seth Aubin, John B. Delos
Arts & Sciences Articles
A ballistic atom pump is a system containing two reservoirs of neutral atoms or molecules and a junction connecting them containing a localized time-varying potential. Atoms move through the pump as independent particles. Under certain conditions, these pumps can create net transport of atoms from one reservoir to the other. While such systems are sometimes called “quantum pumps,” they are also models of classical chaotic transport, and their quantum behavior cannot be understood without study of the corresponding classical behavior. Here we examine classically such a pump's effect on energy and temperature in the reservoirs, in addition to net particle …
Ballistic Atom Pumps, Megan K. Ivory, Tommy A. Byrd, Andrew J. Pyle, Et Al., John B. Delos
Ballistic Atom Pumps, Megan K. Ivory, Tommy A. Byrd, Andrew J. Pyle, Et Al., John B. Delos
Arts & Sciences Articles
We examine a classically chaotic system consisting of two reservoirs of particles connected by a channel containing oscillating potential-energy barriers. We investigate whether such a system can preferentially pump particles from one reservoir to the other, a process often called “quantum pumping.” We show how to make a “particle diode” which under specified conditions permits net particle pumping in only one direction. Then we examine systems having symmetric barriers. We find that if all initial particle energies are considered, a system with symmetric barriers cannot preferentially pump particles. However, if only finite initial energy bands are considered, the system can …
Early Results From The Qweak Experiment, D. Androic, David S. Armstrong, A. Asaturyan, Todd Averett
Early Results From The Qweak Experiment, D. Androic, David S. Armstrong, A. Asaturyan, Todd Averett
Arts & Sciences Articles
A subset of results from the recently completed Jefferson Lab Qweak experiment are reported. This experiment, sensitive to physics beyond the Standard Model, exploits the small parity-violating asymmetry in elastic ~ep scattering to provide the first determination of the proton’s weak charge Q p w. The experiment employed a 180 µA longitudinally polarized 1.16 GeV electron beam on a 35 cm long liquid hydrogen target. Scattered electrons in the angular range 6◦ < θ < 12◦ corresponding to Q2 = 0.025 GeV2 were detected in eight Cerenkov detectors arrayed symmetrically around the beam axis. The goals of the experiment were to provide a measure of Q p w to 4.2% (combined statistical and systematic error), which implies a measure of sin2 (θw) at the level of 0.3%, and to help constrain the vector weak quark charges C1u and C1d. The experimental method is described, with particular focus on the challenges associated with the world’s highest power LH2 target. The new constraints on C1u and C1d provided by the subset of the experiment’s data analyzed to date will also be shown, together with the extracted weak charge of the neutron.
Topological Analysis Of Chaotic Transport Through A Ballistic Atom Pump, Tommy A. Byrd, John B. Delos
Topological Analysis Of Chaotic Transport Through A Ballistic Atom Pump, Tommy A. Byrd, John B. Delos
Arts & Sciences Articles
We examine a system consisting of two reservoirs of particles connected by a channel. In the channel are two oscillating repulsive potential-energy barriers. It is known that such a system can transport particles from one reservoir to the other, even when the chemical potentials in the reservoirs are equal. We use computations and the theory of chaotic transport to study this system. Chaotic transport is described by passage around or through a heteroclinic tangle. Topological properties of the tangle are described using a generalization of homotopic lobe dynamics, which is a theory that gives some properties of intermediate-time behavior from …
Photodetachment Near A Repulsive Center: Closed-Orbit Theory For The Total Cross Section, B. C. Yang, John B. Delos, M. L. Du
Photodetachment Near A Repulsive Center: Closed-Orbit Theory For The Total Cross Section, B. C. Yang, John B. Delos, M. L. Du
Arts & Sciences Articles
The total photodetachment cross section of a negative ion near a repulsive center is studied based on the closed-orbit theory. An analytical expression, written as a product of the zero-field photodetachment cross section and a modulation function, is obtained for energy above and below threshold. The expression also incorporates the different wave sources produced by different negative ions. The present results are shown to be accurate by comparing with quantum calculations based on the exact Coulomb Green's function. We also compared the photodetachment cross section near a repulsive center with that in a homogeneous electric field and found interesting connections …
Magneto-Optics And Magneto-Transport Studies On Thin Films For Sensor Applications, Kaida Yang
Magneto-Optics And Magneto-Transport Studies On Thin Films For Sensor Applications, Kaida Yang
Dissertations, Theses, and Masters Projects
Recent progress and interest have bought considerable effort to bear on the synthesis and opportunities of magnetic thin films in different fields. There are applications in many fields, including remote sensing, waveguide applications, hard drive applications, etc. at the College of William and Mary, we have focused on utilizing magnetic thin films in some of these applications and are deeply involved in the optimization process of the thin films.
Superconducting Thin Films For Srf Cavity Applications: A Route To Higher Field Gradient Linacs, Wiliam Michael Roach
Superconducting Thin Films For Srf Cavity Applications: A Route To Higher Field Gradient Linacs, Wiliam Michael Roach
Dissertations, Theses, and Masters Projects
Many linear accelerator (linac) applications rely on the use of superconducting radio frequency (SRF) cavities. In order to overcome the current field gradient limits imposed by the use of bulk niobium, a model involving the deposition of alternating superconducting-insulating-superconducting (SIS) thin films onto the interior surface of SRF cavities has been proposed. Since SRF performance is a surface phenomenon, the critical surface of these cavities is less than 1 micron thick, thus enabling the use of thin films. Before such approach can successfully be implemented fundamental studies correlating the microstructure and superconducting properties of thin films are needed. to this …
Nonlinear Optical Studies Of Photoelastic Effect And Magneto-Plasmonics, Wei Zheng
Nonlinear Optical Studies Of Photoelastic Effect And Magneto-Plasmonics, Wei Zheng
Dissertations, Theses, and Masters Projects
Nonlinear optical (NLO) processes are optical phenomena involving a nonlinear response to an applied light field. Two kinds of nonlinearities are studied in this dissertation: magnetic-induced second-harmonic generation (MSHG) interacting with surface plasmon, called "nonlinear magnetoplasmonics" (NMP), and the nonlinear index induced by a strong pump beam in Titanium doped sapphire crystal, referred to as population-induced nonlinear index effect.;The fundamentals of the major effects involved are discussed, which include: surface plasmon and its field enhancement effect, MSHG technique and phenomenological calculations, the contrast ratio of magnetic switching, the calculation of lensing effects, population induced strain, and photoelastic effect. Furthermore, the …
Enhancement Of Ms Signal Processing For Improved Cancer Biomarker Discovery, Qian Si
Enhancement Of Ms Signal Processing For Improved Cancer Biomarker Discovery, Qian Si
Dissertations, Theses, and Masters Projects
Technological advances in proteomics have shown great potential in detecting cancer at the earliest stages. One way is to use the time of flight mass spectroscopy to identify biomarkers, or early disease indicators related to the cancer. Pattern analysis of time of flight mass spectra data from blood and tissue samples gives great hope for the identification of potential biomarkers among the complex mixture of biological and chemical samples for the early cancer detection. One of the keys issues is the pre-processing of raw mass spectra data. A lot of challenges need to be addressed: unknown noise character associated with …
Exploring A Novel Approach To Technical Nuclear Forensics Utilizing Atomic Force Microscopy, Richard Scot Peeke
Exploring A Novel Approach To Technical Nuclear Forensics Utilizing Atomic Force Microscopy, Richard Scot Peeke
Dissertations, Theses, and Masters Projects
No abstract provided.
Dynamical Monodromy, C. Chen, Megan K. Ivory, Seth Aubin, John B. Delos
Dynamical Monodromy, C. Chen, Megan K. Ivory, Seth Aubin, John B. Delos
Arts & Sciences Articles
Integrable Hamiltonian systems are said to display nontrivial monodromy if fundamental action-angle loops defined on phase-space tori change their topological structure when the system is carried around a circuit. In an earlier paper it was shown that this topological change can occur as a result of time evolution under certain rather abstract flows in phase space. In the present paper, we show that the same topological change can occur as a result of application of ordinary forces. We also show how this dynamical phenomenon could be observed experimentally in classical or in quantum systems.