Physics Commons^™

Sub-Micron Parallel Laser Direct-Write, Christina Othon, Arnoldo Laracuente, H Ladoucuer, Bradley Ringeisen

Christina M Othon

We have developed a modified laser induced forward transfer (LIFT) technique which allows for the parallel deposition of hundreds of sub-micron features. The approach utilizes a self-assembled monolayer of monodisperse polystyrene microspheres as the focusing element. A monolayer of close-packed microspheres is formed on top of an ultra-thin quartz support (25 m thick), and a metallic thin film is then deposited on the underside of the quartz. This approach is different from previous parallel microsphere-assisted LIFT experiments that required the deposition of metal directly onto the surface of the periodic microsphere structure. For this study, an 800 nm, 130 fs …

Is The Pamela Positron Excess Winos?, Scott Watson, Phill Grajek, Gordon L. Kane, Daniel J. Phalen, Aaron Pierce

Physics - All Scholarship

Recently the PAMELA satellite-based experiment reported an excess of galactic positrons that could be a signal of annihilating dark matter. The PAMELA data may admit an interpretation as a signal from a wino-like LSP of mass about 200 GeV, normalized to the local relic density, and annihilating mainly into W-bosons. This possibility requires the current conventional estimate for the energy loss rate of positrons be too large by roughly a factor of five. Data from anti-protons and gamma rays also provide tension with this interpretation, but there are significant astrophysical uncertainties associated with their propagation. It is not unreasonable to …

Gravitational Wave Burst Source Direction Estimation Using Time And Amplitude Information, J. Markowitz, M. Zanolin, L. Cadonati, E. Katsavounidis

Michele Zanolin

Self-Consistent Calculations Of Strain-Induced Band Gap Changes In Semiconducting (N, 0) Carbon Nanotubes, Pavan Kumar Valavala, Douglas R. Banyai, Max Seel, Ranjit Pati

Department of Physics Publications

First-principles density-functional calculations of the electronic structure, energy band gaps (E_g), and strain-induced band gap changes in moderate-gap single-walled (n,0) carbon nanotubes (SWNTs) are presented. It is confirmed that (n,0) SWNTs fall into two classes depending upon n mod 3=1 or 2. E_g is always lower for “mod 1” than for “mod 2” SWNTs of similar diameter. For n<10, strong curvature effects dominate E_g; from n=10 to 17, the E_g oscillations, amplified due to σ−π mixing, decrease and can be explained very well with a tight-binding model which includes trigonal warping. Under strain, the two families of semiconducting …

Drizzle Rates Versus Cloud Depths For Marine Stratocumuli, A. B. Kostinski

Department of Physics Publications

Marine stratocumuli make a major contribution to Earth’s radiation budget. Drizzle in such clouds can greatly affect their albedo, lifetime and fractional coverage, so drizzle rate prediction is important. Here we examine a question: does a drizzle rate (R) depend on cloud depth (H) and/or drop number concentration n in a simple way? This question was raised empirically in several recent publications and an approximate H3/n dependence was observed. Here we suggest a simple explanation for H3 scaling from viewing the drizzle rate as a sedimenting volume fraction ( f ) of water drops (radius r) in air, i.e. R …

Constructing Diabatic States From Adiabatic States: Extending Generalized Mulliken–Hush To Multiple Charge Centers With Boys Localization, Joseph E. Subotnik, Robert J. Cave, Sina Yeganeh, Mark A. Ratner

All HMC Faculty Publications and Research

This article shows that, although Boys localization is usually applied to single-electron orbitals, the Boys method itself can be applied to many electron molecular states. For the two-state charge-transfer problem, we show analytically that Boys localization yields the same charge-localized diabatic states as those found by generalized Mulliken–Hush theory. We suggest that for future work in electron transfer, where systems have more than two charge centers, one may benefit by using a variant of Boys localization to construct diabatic potential energy surfaces and extract electronic coupling matrix elements. We discuss two chemical examples of Boys localization and propose a generalization …

Search For The Standard Model Higgs Boson In The Missing Energy And Acoplanar B-Jet Topology At √S = 1.96 Tev, V. M. Abazov, Kenneth A. Bloom, Gregory R. Snow, D0 Collaboration

Kenneth Bloom Publications

We report a search for the standard model Higgs boson in the missing energy and acoplanar b-jet topology, using an integrated luminosity of 0.93 fb^-1 recorded by the D0 detector at the Fermilab Tevatron pp Collider. The analysis includes signal contributions from pp → ZH → ννbb, as well as from WH production in which the charged lepton from the W boson decay is undetected. Neural networks are used to separate signal from background. In the absence of a signal, we set limits on σ (pp → VH) x B(H → bb) at the 95% …

Matter-Wave Self-Imaging By Atomic Center-Of-Mass Motion Induced Interference, Ke Li, L. Deng, E. W. Hagley, Marvin G. Payne, M. S. Zhan

Marvin G. Payne

We demonstrate matter-wave self-imaging resulting from atomic center-of-mass motion-based interference. We show that non-negligible atomic center-of-mass motion and an instantaneous Doppler shift can drastically change the condensate momentum distribution, resulting in a periodic collapse and the recurrence of condensate diffraction probability as a function of the stationary light-field pulsing time. The observed matter-wave self-imaging is characterized by an atomic center-of-mass motion induced population amplitude interference in the presence of the light field that simultaneously minimizes all high (n≥1) diffraction orders and maximizes the zeroth diffraction component.

Switchable Polarization-Independent Liquid-Crystal Fabry-Perot Filter, Enkh-Amgalan Dorjgotov, Achintya K. Bhowmik, Philip J. Bos

Philip J. Bos

A new approach to a polarization-independent twisted liquid-crystal (LC) structure, where phase difference between orthogonal eigenmodes is tuned to be an integer multiple of 2 pi, is demonstrated with a numerical model. For select wavelengths, polarization-independent operation can be achieved by tuning the twist rate and thickness of the LC cavity Applications can be found in polarization-independent switches and field sequential wavelength selection devices.

Search For Third Generation Scalar Leptoquarks Decaying Into ΤB, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We have searched for third generation leptoquarks (LQ₃) using 1.05 fb^-1 of data collected with the D0 detector at the Fermilab Tevatron Collider operating at √s = 1.96 TeV. We set a 95% C.L. lower limit of 210 GeV on the mass of a scalar LQ₃ state decaying solely to a b quark and a τ lepton.

Measurement Of BS0 Mixing Parameters From The Flavor-Tagged Decay BS0 → J/Ψφ, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

From an analysis of the flavor-tagged decay B_s⁰ → J/ ψφ we obtain the width difference between the B_s⁰ light and heavy mass eigenstates, ΔΓ_s = 0.19 ± 0.07 (stat)_-0.01^+0.02 (syst) ps^-1, and the CP-violating phase, φ_s = -0.57_-0.30^+0.24(stat)_-0.02^+0.08(syst). The allowed 90% CL intervals of ΔΓ_s and φ_s are 0.06 < ΔΓ_s < 0.30 ps^-1 and -1.20< φ_s < 0.06, respectively. The data sample corresponds to an integrated luminosity of 2.8 fb^-1 accumulated with the D0 detector at the Fermilab Tevatron collider.

First Results From The Lick Agn Monitoring Project: The Mass Of The Black Hole In Arp 151, Misty C. Bentz, Jonelle L. Walsh, Aaron J. Barth, Nairn Baliber, Nicola Bennert, Gabriela Canalizo, Alexei V. Filippenko, Mohan Ganeshalingam, Elinor L. Gates, Jenny E. Greene, Marton G. Hidas, Kyle D. Hiner, Nicholas Lee, Weidong Li, Matthew A. Malkan, Takeo Minezaki, Frank J.D. Serduke, Joshua H. Shiode, Jeffrey M. Silverman, Thea N. Steele, Daniel Stern, Rachel A. Street, Carol E. Thornton, Tommaso Treu, Xiaofeng Wang, Jong-Hak Woo, Yuzuru Yoshii

Physics

We have recently completed a 64 night spectroscopic monitoring campaign at the Lick Observatory 3 m Shane telescope with the aim of measuring the masses of the black holes in 13 nearby (z < 0.05) Seyfert 1 galaxies with expected masses in the range ~10⁶-10⁷ M_☉. We present here the first results from this project—the mass of the central black hole in Arp 151. Strong variability throughout the campaign led to an exceptionally clean Hβ lag measurement in this object of 4.25_−0.66^+0.68 days in the observed frame. Coupled with the width of the Hβ emission line in the variable spectrum, we determine a black …

Rotational Quenching Rate Coefficients For H2 In Collisions With H2 From 2 To 10,000 K, T.-G. Lee, N. Balakrishnan, R. C. Forrey, P. C. Stancil, G. Shaw, D. R. Schultz, Gary J. Ferland

Physics and Astronomy Faculty Publications

Rate coefficients for rotational transitions in H₂ induced by H₂ impact are presented. Extensive quantum mechanical coupled-channel calculations based on a recently published (H₂)₂ potential energy surface were performed. The potential energy surface used here has been demonstrated to be more reliable than surfaces used in previous work. Rotational transition cross sections with initial levels of J≤8 were computed for collision energies ranging between 10^-4 and 2.5 eV, and the corresponding rate coefficients were calculated for the temperature range 2≤T≤10,000 K. In general, agreement with earlier calculations, which were limited to 100-6000 K, …

Formation Of Even-Numbered Hydrogen Cluster Cations In Ultracold Helium Droplets, S. Jaksch, A. Mauracher, A. Bacher, S. Denifl, F. Ferreira De Silva, H. Schoebel, Olof E. Echt, T. D. Maerk, M. Probst, D. K. Bohme, P. Scheier

Physics & Astronomy

Neutral hydrogen clusters are grown in ultracold helium nanodroplets by successive pickup of hydrogen molecules. Even-numbered hydrogen cluster cations are observed upon electron-impact ionization with and without attached helium atoms and in addition to the familiar odd-numbered H(n)(+). The helium matrix affects the fragmentation dynamics that usually lead to the formation of overwhelmingly odd-numbered H(n)(+). The use of high-resolution mass spectrometry allows the unambiguous identification of even-numbered H(n)(+) up to n congruent to 120 by their mass excess that distinguishes them from He(n)(+), mixed He(m)H(n)(+), and background ions. The large range in size of these hydrogen cluster ions is unprecedented, …

Lattice Super-Yang-Mills Using Domain Wall Fermions In The Chiral Limit, Simon Catterall, Joel Giedt, Richard Brower, George T. Fleming, Pavlos Vranas

Physics - All Scholarship

Lattice N=1 super-Yang-Mills theory formulated using Ginsparg-Wilson fermions provides a rigorous non-perturbative definition of the continuum theory that requires no fine-tuning as the lattice spacing is reduced to zero. Domain wall fermions are one explicit scheme for achieving this and using them we have performed large-scale Monte Carlo simulations of the theory for gauge group SU(2). We have measured the gaugino condensate, static potential, Creutz ratios and residual mass for several values of the domain wall separation L_s, four-dimensional lattice volume, and two values of the gauge coupling. With this data we are able to extrapolate the gaugino condensate to …

Observation Of The Doubly Strange B Baryon ΩB-, V. M. Abazov, Kenneth A. Bloom, Gregory Snow, D0 Collaboration

Kenneth Bloom Publications

We report the observation of the doubly strange b baryon Ω_b^- in the decay channel Ω_b^- → J/ψΩ^-, with J/ψ → μ⁺μ^- and Ω^- → ΛK^- → (pπ^-)K^-, in pp collisions at √s = 1.96 TeV. Using approximately 1.3 fb^-1 of data collected with the D0 detector at the Fermilab Tevatron Collider, we observe 17:8 ± 4.9(stat) ± 0.8(syst) Ω_b^- signal events at a mass of 6.165 ± 0.010(stat) ± 0.013(syst) GeV. The significance of …

The Thermoelectric Properties Investigation Of X0.05Mo3Sb7-YTeY (X=Mn, Fe, Ni, Co; Y=1.5, 1.6, 1.7), Tim Holgate

All Theses

With ever increasing energy costs, dwindling resources, and terms with the prefix 'green' filling headlines, the need for environmentally friendly energy sources has never been greater. Since the mid-20th century researchers have been pursuing greater efficiency in thermoelectric materials. Thermoelectric materials achieve energy conversion via the Seebeck effect (heat to electric power) and the Peltier effect (electricity to cooling power). Presented herein are the measured electrical and thermal transport properties and phenomenal analysis of the Ir₃Ge₇-type system: X_0.05Mo₃Sb_7-yTe_y (X=Mn, Fe, Ni, Co; y=1.5, 1.6, 1.7) where 'X' are interstitially …

Suppression Pattern Of Neutral Pions At High Transverse Momentum In Au + Au Collisions At Square Root Of Snn = 200 Gev And Constraints On Medium Transport Coefficients, Andrew Marshall Adare, Sergey V. Afanasiev, Christine A. Aidala, N. N. Ajitanand, Yasuyuki Akiba, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann, S. Rembeczki, Klaus Dehmelt

Aerospace, Physics, and Space Science Faculty Publications

For Au þ Au collisions at 200 GeV, we measure neutral pion production with good statistics for transverse momentum, pT, up to 20 GeV=c. A fivefold suppression is found, which is essentially constant for 5 < pT < 20 GeV=c. Experimental uncertainties are small enough to constrain any model-dependent parametrization for the transport coefficient of the medium, e.g., hq^i in the parton quenching model. The spectral shape is similar for all collision classes, and the suppression does not saturate in Au þ Au collisions.

Simulation And Analysis Of Cadmium Sulfide Nanoparticles, Chad Everett Junkermeier

Theses and Dissertations

I used ab initio molecular dynamics calculations to model cadmium sulfide nanoparticles. The nanoparticles were originaly spherical, bulk-like zinc-blende structures. Constant temperature molecular dynamics calculations reveals that CdS nanoparticles that are about 2 nm in diameter and have unpassivated surfaces are in an amorphous structure with short range order. The nearest neighbor distance on the surface of the nanoparticles being near the wurtzite nearest neighbor distance. I wrote the program xyzSTATS and used its results in justifying the amorphous nanoparticles claim. I also estimated the band gap of the CdS nanoparticles with unpassivated dangling bonds.

Structural And Magnetic Properties Of Manganites Pr1-XCa1+XMno4, Oxypnictides Cefeaso1-XFX, And Filled Skutterudite Pros4As12, Songxue Chi

Doctoral Dissertations

We present neutron scattering, with triple-axis and time-of-flight spectrometers, to study the structural and magnetic properties of the layered manganites Pr_1-xCa_1+xMnO₄ (PCMO), and to determine the crystalline electric field (CEF) levels in iron pnictides CeFeAsO_1-xF_x and filled skutterudite compound PrOs₄As₁₂.

For the single-layered manganites PCMO, four dopings (x=0.5, 0.45, 0.40 and 0.35) have been studied. At half-doping, the system first becomes charge- and orbital- ordered (CO/OO) near T_CO = 300 K and then develops CE-type antiferromagnetic (AF) order below T_N = 130 K. …

Explicit Methods In The Nuclear Burning Problem For Supernova Ia Models, Viktor Chupryna

Doctoral Dissertations

Most modern astrophysical problems such as supernova simulation require application of state-ofthe- art computational tools. Despite the fact that number of nuclei included in coupled simulations tends to be small, problems such as nuclear burning networks are often part of a large set of interconnected programs that require significant computing resources. Expansion of the nuclear reaction network to realistic sizes can easily make element and energy production the leading consumer of both time and memory in simulations. Therefore, in solving nuclear reaction networks coupled to (radiation) hydrodynamics in astrophysics simulations, the development of methods capable of improving on the traditional …

Collective Behavior Of Interacting Magnetic Nanoparticles, Noppi Widjaja

Doctoral Dissertations

In the past, Low Dimensional Materials by Design group at ORNL in collaboration with students from the University of Tennessee, have successfully tailored and studied magnetic nanostructures in 2D, 1D and 0D spatial confinement on Cu(111) substrates. They observed a striking collective ferromagnetic long-range order in Fe-nanodots on Cu(111) surface which can be stabilized through the indirect exchange interaction mediated by the substrate. This type of magnetic interaction was expected to have little effect on promoting a global ferromagnetic order in a randomly distributed dot assembly. It is for certain that we need a better understanding of the relative roles …

Emergent Phenomena In Spatially Confined Manganites, Thomas Z. Ward

Doctoral Dissertations

Rare earth manganites exhibit colossal magnetoresistance (CMR). There is evidence that alloyed single crystal materials in this class can display electronic inhomogeneity in which areas with vastly different electronic and magnetic properties can form and coexist in phase separated domains ranging in size from a few nanometers to micrometers. This phase separation (PS) is of particular interest, as it has been suggested that it is the central feature that leads to CMR in manganites, the Mott transition in VO₂ and may play a role in high-TC superconductivity in cuprates. However there is debate as to its precise role.

The …

Reconstructing Three-Dimensional Shape Envelopes From Time-Resolved Small-Angle X-Ray Scattering Data, Jessica Lamb, Lisa W. Kwok, Xiangyun Qiu, Kurt Andresen, Hye Yoon Park, Lois Pollack

Physics and Astronomy Faculty Publications

Modern computing power has made it possible to reconstruct low-resolution, three-dimensional shapes from solution small-angle X-ray scattering (SAXS) data on biomolecules without a priori knowledge of the structure. In conjunction with rapid mixing techniques, SAXS has been applied to time resolve conformational changes accompanying important biological processes, such as biomolecular folding. In response to the widespread interest in SAXS reconstructions, their value in conjunction with such time-resolved data has been examined. The group I intron from Tetrahymena thermophila and its P4–P6 subdomain are ideal model systems for investigation owing to extensive previous studies, including crystal structures. The goal of this …

Detection Of An So2 Plume Over Sapporo, Japan From The Eruption Of Mt. Kasatochi Using A Balloon Sounding Technique, Gary A. Morris, Jun Hirokawa, Masatomo Fujiwara, Fumio Hasebe, Keisuke Ishida, Nicholay Krotkov, Mark R. Schoeberl, Walter Komhyr, Barry Lefer, James Flynn

Physics and Astronomy Faculty Presentations

During the month of August 2008, 10 ozonesondes were launched from Hokkaido University in Sapporo, Japan as part of a study to examine regional pollution during the Olympic period. Seven of these soundings included a second instrument with a filter designed to remove SO2 from the intake air stream. SO2 interferes with the normal chemistry of the electrochemical cell (ECC) method for ozone detection, with the net result being that each molecule of SO2 registers as minus one molecule of O3. Thus the unfiltered sonde reports [O3] - [SO2] while the filtered sonde reports [O3]. Laboratory tests prior to launch …

Detection Of An So2 Plume Over Sapporo, Japan From The Eruption Of Mt. Kasatochi Using A Balloon Sounding Technique, Gary A. Morris, Jun Hirokawa, Masatomo Fujiwara, Fumio Hasebe, Keisuke Ishida, Nicholay Krotkov, Mark R. Schoeberl, Walter Komhyr, Barry Lefer, James Flynn

Gary A. Morris

During the month of August 2008, 10 ozonesondes were launched from Hokkaido University in Sapporo, Japan as part of a study to examine regional pollution during the Olympic period. Seven of these soundings included a second instrument with a filter designed to remove SO2 from the intake air stream. SO2 interferes with the normal chemistry of the electrochemical cell (ECC) method for ozone detection, with the net result being that each molecule of SO2 registers as minus one molecule of O3. Thus the unfiltered sonde reports [O3] - [SO2] while the filtered sonde reports [O3]. Laboratory tests prior to launch …

Analyzing The Catalytic Role Of Asp97 In The Methionine Aminopeptidase From Escherichia Coli, Sanghamitra Mitra, Kathleen M. Job, Lu Meng, Brian Bennett, Richard C. Holz

Physics Faculty Research and Publications

An active site aspartate residue, Asp97, in the methionine aminopeptidase (MetAPs) from Escherichia coli (EcMetAP-I) was mutated to alanine, glutamate, and asparagine. Asp97 is the lone carboxylate residue bound to the crystallographically determined second metal-binding site in EcMetAP-I. These mutant EcMetAP-I enzymes have been kinetically and spectroscopically characterized. Inductively coupled plasma–atomic emission spectroscopy analysis revealed that 1.0 ± 0.1 equivalents of cobalt were associated with each of the Asp97-mutated EcMetAP-Is. The effect on activity after altering Asp97 to alanine, glutamate or asparagine is, in general, due to a ∼ 9000-fold decrease in k_ca towards …

Anomalies In Electrostatic Calibrations For The Measurement Of The Casimir Force In A Sphere-Plane Geometry, W. J. Kim, M. Brown-Hayes, D. A.R. Dalvit, J. H. Brownell, R. Onofrio

Dartmouth Scholarship

We have performed precision electrostatic calibrations in the sphere-plane geometry, and observed anomalous behavior. Namely, the scaling exponent of the electrostatic signal with distance was found to be smaller than expected on the basis of the pure Coulombian contribution, and the residual potential found to be distance dependent. We argue that these findings affect the accuracy of the electrostatic calibrations and invite reanalysis of previous determinations of the Casimir force.

Establishment Of A Chebyshev-Dependent Inhomogeneous Second Order Differential Equation For The Applied Physics-Related Boubaker-Turki Polynomials, Micahel Dada, O. Bamidele Awojoyogbe, Maximilian Hasler, Karem B. Ben Mahmoud, Amine Bannour

Applications and Applied Mathematics: An International Journal (AAM)

This paper proposes Chebyshev-dependent inhomogeneous second order differential equation for the m-Boubaker polynomials (or Boubaker-Turki polynomials). This differential equation is also presented as a guide to applied physics studies. A concrete example is given through an attempt to solve the Bloch NMR flow equation inside blood vessels.

Calculations Of K-Shell Fluorescence Yields And Photoabsorption Cross Sections For Carbon Ions At The K-Edge, Muhammet Fatih Hasoglu

Dissertations

The advent of new space missions providing high-precision observations has engendered the need for reliable and precise K-shell atomic data in order to interpret these X-ray spectra. In response to this need, we focused on the calculation of K-shell fluorescence yields for 2 nd -row ions. A secondary project was undertaken in order to treat theoretically the K-shell X-ray absorption processes in carbon ions. These calculated fluorescence yields of 2nd -row ions and theX-ray photoabsorption cross sections of carbon are astrophysically important in determining (1) charge-changing probabilities, such as Auger vs. radiative decay, and (2) chemical abundances of the interstellar …