Physical Sciences and Mathematics Commons^™

Charge Transfer In Slow Collisions Of C⁴⁺ With H Below 1 Kev/Amu, Chen-Nan Liu, Anh-Thu Le, C. D. Lin

Physics Faculty Research & Creative Works

We reexamined charge-transfer cross sections for C⁴⁺ + H collisions for energies from 1 meV/amu to 1 keV/amu using the recently developed hyperspherical close-coupling method. Our results agree with several previous theoretical calculations using molecular-orbital expansion. However, these converged theoretical predictions do not agree with total cross sections from the merged-beam experiments.

A High Shear-Rate Optical Rheometer For Complex Fluids, Khaled S. Mriziq

Doctoral Dissertations

A parallel-plate optical rheometer in a magnetic-disc drive configuration has been designed and constructed of optically transparent materials and operating with a very small gap to obtain rheological and structural measurements at very high shear rates.

The friction force at the disk-slider interface has been measured as a function of sliding speed while the film thickness was monitored in situ using a capacitance technique. The shear rate is calculated from the film thickness and the sliding speed. A thin film can be applied on the disk, which allows very high-shear-rate measurements at low sliding speeds with negligible viscous heating.

Both …

Isotropic Loop Quantum Cosmology With Matter. Ii. The Lorentzian Constraint, F. Hinterleitner, Seth Major

Articles

The Lorentzian Hamiltonian constraint is solved for isotropic loop quantum cosmology coupled to a massless scalar field. As in the Euclidean case, the discreteness of quantum geometry removes the classical singularity from the quantum Friedmann models. In spite of the absence of the classical singularity, a modified DeWitt initial condition is incompatible with a late-time smooth behavior. Further, the smooth behavior is recovered only for positive or negatives times but not both. An important feature, which is shared with the Euclidean case, is a minimal initial energy of the order of the Planck energy required for the system to evolve …

Monte Carlo Simulations And Analysis Of Single-Molecule Detection And Imaging, Peter Williams

Masters Theses

Computer modeling and analysis methods are developed for two modes of operation of an instrument for sensitive fluorescence detection of individual dye-labeled molecules in solution. First, Monte Carlo simulations of experiments for single-molecule imaging (SMI) are extended to include effects of sample flow, sticking of molecules to surfaces, and the finite depth-of-focus of the optics. The results have a bearing on a patented method for high-speed single-molecule DNA sequencing. They indicate that the imaging of freely moving fluorescent labels within a microfluidic flowcell will be considerably more involved than that of immobilized molecules at a surface, which is the usual …

Measurement Of High-Q2 Charged Current Cross Sections In E +P Deep Inelastic Scattering At Hera, S. Chekanov, M. Derrick, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan

Faculty Publications

Cross sections for e+p charged current deep inelastic scattering at a centre-of-mass energy of 318 GeV have been determined with an integrated luminosity of 60.9 pb-1 collected with the ZEUS detector at HERA. The differential cross sections dσ/dQ2, dσ/dx and dσ/dy for Q2 > 200 GeV2 are presented. In addition, d2σ/dxdQ2 has been measured in the kinematic range 280 GeV2 < Q2 < 17 000 GeV2 and 0.008 < x < 0.42. The predictions of the Standard Model agree well with the measured cross sections. The mass of the W boson propagator is determined to be MW = 78.9 ± 2.0 (stat.) ± 1.8 (syst.) -1.8+2.0 (PDF) GeV from a fit to dσ/dQ2. The chiral structure of the Standard Model is also investigated in terms of the (1-y)2 dependence of the double-differential cross section. The structure-function F2CC has been extracted by combining the measurements presented here with previous ZEUS results from e-p scattering, extending the measurement obtained in a neutrino-nucleus scattering experiment to a significantly higher Q2 region.

Objectivity, Information, And Maxwell's Demon, Steven Weinstein

Dartmouth Scholarship

This paper examines some common measures of complexity, structure, and information, with an eye toward understanding the extent to which complexity or information‐content may be regarded as objective properties of individual objects. A form of contextual objectivity is proposed which renders the measures objective, and which largely resolves the puzzle of Maxwell's Demon.

Physics First, Marcelo Alonso

Aerospace, Physics, and Space Science Faculty Publications

It is true that now most biology courses begin with the DNA molecule, and many chemistry courses introduce the notion of electronic orbitals in atoms and molecules, topics for which students are not well prepared, since most of them have not taken physics courses. Physics courses in turn relegate to the end some discussion of the structure of matter and electromagnetic interaction, or do not discuss that at all. Thus, students miss the overall picture.

Measurement Of Conductivity And Charge Storage In Insulators Related To Spacecraft Charging, A Robb Frederickson, Jr Dennison

Journal Articles

Improved experimental methods are discussed for laboratory measurement of conductivity and electric field in insulating spacecraft material intended for space radiation and plasma environments. These measurement techniques investigate the following features: 1) Measurements of conductivity are up to four orders of magnitude smaller than those determined by existing standard methods. 2) Conductivity is altered as radiation accumulates and trapping states fill with electrons. 3) With intense keV electron irradiation, electrons are continually emitted for hours from the irradiated surface after the irradiation ceases. 4) Charging induced by electron irradiation is strongly modified by the electron-hole pairs that the irradiation generates …

Low Latitude Ionospheric Disturbance Electric Field Effects Duringthe Recovery Phase Of The October 19-21, 1998 Magnetic Storm, Bela G. Fejer, J. T. Emmert

Bela G. Fejer

[1] Low-latitude ionospheric electric fields and currents are often strongly disturbed during periods of enhanced geomagnetic activity. These perturbations can last for several hours after geomagnetic quieting. We use incoherent scatter radar measurements from Jicamarca and Arecibo during 19–21 October 1998 to study, for the first time, the low-latitude disturbance electric fields during the recovery phase of a large magnetic storm. On 19 October the Jicamarca data showed initially large and short-lived (time scale of about 10–20 min) upward and westward drift perturbations in the early afternoon sector, due to the penetration of strong magnetospheric electric fields probably driven by …

Laser-Energy Transfer And Enhancement Of Plasma Waves And Electron Beams By Interfering High-Intensity Laser Pulses, P. Zhang, N. Saleh, Shouyuan Chen, Z.M. Sheng, Donald P. Umstadter

Donald Umstadter Publications

The effects of interference due to crossed laser beams were studied experimentally in the high-intensity regime. Two ultrashort (400 fs), high-intensity (4×10¹⁷ and 1.6×10¹⁸ W/cm²) and1µm wavelength laser pulses were crossed in a plasma of density 4×10¹⁹ cm³. Energy was observed to be transferred from the higher-power to the lower-power pulse, increasing the amplitude of the plasma wave propagating in the direction of the latter. This results in increased electron self-trapping and plasma-wave acceleration gradient, which led to an increased number of hot electrons (by 300%) and hot-electron temperature (by 70%) and a …

Criss-Crossing Laser Beams Zoom Electrons Along, P. Zhang, N. Saleh, Shouyuan Chen, Z.M. Sheng, Donald P. Umstadter

Donald Umstadter Publications

Crossing two high-intensity laser beams in a plasma (a collection of charged particles) can have some interesting effects. In a recent experiment performed by researchers at the University of Michigan and the Institute of Physics in China, energy from a higher-power laser pulse was transferred to a lower-power laser pulse. The lower-power pulse had been accelerating electrons with its "wakefield" (like a wave accelerating a surfer). The extra energy to this lower-power pulse enhanced the electron acceleration and decreased the divergence of the electron beam. These features are desirable for proposed "laser particle accelerators" that would be powered by relatively …

Giant Metamagnetic Moments In A Granular Fecl2-Fe Heterostructure, Sarbeswar Sahoo, Christian Binek, Wolfgang Kleemann

Christian Binek Publications

Giant moments are observed at low temperatures in a granular FeCl₂-Fe heterostructure owing to a local metamagnetic transformation of the antiferromagnetic (AF) FeCl₂ matrix due to dipolar interactions. A model of metamagnetically (MM) "dressed" single-domain Fe particles is suggested to explain the observations. These include polydispersive ac susceptibility induced by AF-MM domain configurations and weak exchange bias due to non-spin-flipped AF crystallites.

Search For The Flavor-Changing Neutral Current Decay D0→Μ +Μ - In Pp̅ Collisions At √S =1.96 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report on a search for the flavor-changing neutral current decay D⁰→µ⁺µ^- in pp̅ collisions at √s =1.96 TeV using 65 pb^-1 of data collected by the CDF II experiment at the Fermilab Tevatron Collider. A displaced-track trigger selects long-lived D⁰ candidates in the D⁰→µ⁺µ^- search channel, the kinematically similar D⁰→ π⁺ π^- channel used for normalization, the Cabibbo-favored D⁰→ K^-π⁺ channel used to optimize the selection criteria in an unbiased manner, and their charge conjugates. Finding no signal …

Twin-Rainbow Metrology. I. Measurement Of The Thickness Of A Thin Liquid Film Draining Under Gravity, Charles L. Adler, James A. Lock, Ian P. Rafferty, Wayne Hickok

Physics Faculty Publications

We describe twin-rainbow metrology, a new optical technique used to measure the thickness of thin films in a cylindrical geometry. We also present an application of the technique: measurement of the thickness of a Newtonian fluid draining under gravity. We compare these measurements with fluid mechanics models. (C) 2003 Optical Society of America.

Exclusive Electrodisintegration Of Three-Nucleon Systems, Tigran Abrahamyan

FIU Electronic Theses and Dissertations

The purpose of this research was to develop a theory of high-energy exclusive electrodisintegration of three-nucleon systems on the example of 3He(e, e'NN)N reaction with knocked-out nucleon in the final state.

The scattering amplitudes and differential cross section of the reaction were calculated in details within the Generalized Eikonal Approximation(GEA). The manifestly covariant nature of Feynman diagrams derived in GEA allowed us to preserve both the relativistic dynamics and kinematics of the scattering while identifying the low momentum nuclear part of the amplitude with a nonrelativistic nuclear wave function. Numerical calculations of the residual system's total and relative momentum distribution …

Domain Wall Solutions With Abelian Gauge Fields, J. S. Rozowsky, R. R. Volkas, K. C. Wali

Physics - All Scholarship

We study kink (domain wall) solutions in a model consisting of two complex scalar fields coupled to two independent Abelian gauge fields in a Lagrangian that has $U(1)\times U(1)$ gauge plus $\mathbb{Z}_2$ discrete symmetry. We find consistent solutions such that while the U(1) symmetries of the fields are preserved while in their respective vacua, they are broken on the domain wall. The gauge field solutions show that the domain wall is sandwiched between domains with constant magnetic fields.

Long Coherence Times At 300 K For Nitrogen-Vacancy Center Spins In Diamond Grown By Chemical Vapor Deposition, John S. Colton, T. A. Kennedy, J. E. Butler, R. C. Linares, P.J. Doering

Faculty Publications

Electron-spin-echo experiments reveal phase-memory times as long as 58 μs at 300 K for nitrogen-vacancy centers in chemical vapor deposition (CVD) single crystals. The spins were optically polarized and optically detected. Two high-quality CVD samples were studied. From the current results, it is not clear whether these phase-memory times represent a fundamental limit or are limited by an external source of decoherence.

Structural Order And Disorder In Co-Based Layered Cuprates Cosr2(Y,Ce)Scu2o5+2s (S=1-3), T. Nagai, V. P.S. Awana, E. Takayama-Muromachi, A. Yamazaki, M. Karppinen, H. Yamauchi, S. K. Malik, William B. Yelon, Y. Matsui

Physics Faculty Research & Creative Works

Crystal structures of a homologous series of Co-Based layered cuprates, CoSr₂(Y,Ce)_sCu₂O_5+2s (s=1-3), have been investigated by high-resolution electron microscopy (HREM) and electron diffraction (ED) techniques. for all the three phases ED patterns showed double periodicity along a direction parallel to the CoO layers, indicating a regular alternation of two types of CoO_4- tetrahedra chains within the layers. Also seen was ordering of the chains along the layer-stacking direction for the s=1 phase (Co-1212); ED patterns simulated based on the proposed superstructure model well reproduced the observed patterns. for the s=2 (Co-1222) and …

Labview Interface For School-Network Daq Card, Hans Berns, T. H. Burnett, Richard Gran, Graham Wheel, R. Jeffrey Wilkes, Daniel R. Claes, Jared Kite, Gregory R. Snow

Gregory Snow Publications

A low-cost DAQ card has been developed for school-network cosmic ray detector projects, providing digitized data from photomultiplier tubes via a standard serial interface. To facilitate analysis of these data and to provide students with a starting point for custom readout systems, a model interface has been developed using the National Instruments LabVIEW(R) system. This user-friendly interface allows one to initialize the trigger coincidence conditions for data-taking runs and to monitor incoming or pre-recorded data sets with updating singles- and coincidence-rate plots and other user-selectable histograms.

Low-Cost Data Acquisition Card For School-Network Cosmic Ray Detectors, Sten Hansen, Thomas Jordan, Daniel R. Claes, Gregory R. Snow, Hans Berns, T. H. Burnett, Richard Gran, R. Jeffrey Wilkes

Gregory Snow Publications

The Cosmic Ray Observatory Project (CROP) at University of Nebraska/Lincoln and the Washington Area Large-scale Time coincidence Array (WALTA) at University of Washington/Seattle are among several outreach projects siting cosmic-ray detectors at local high schools in cities around North America, to study the origins and interactions of highenergy cosmic rays. In a collaboration between QuarkNet, the outreach program based at Fermilab, CROP, and WALTA, a low-cost data acquisition electronics card has been developed to collect and synchronize the data from each detector site. The cost for each card is under US$500 for parts, functionally replacing much more expensive electronics crates …

Mean Field Theory Of Collective Transport With Phase Slips, Alan Middleton, Karl Saunders, J. M. Schwarz, M. Cristina Marchetti

Physics - All Scholarship

The driven transport of plastic systems in various disordered backgrounds is studied within mean field theory. Plasticity is modeled using non-convex interparticle potentials that allow for phase slips. This theory most naturally describes sliding charge density waves; other applications include flow of colloidal particles or driven magnetic flux vortices in disordered backgrounds. The phase diagrams exhibit generic phases and phase boundaries, though the shapes of the phase boundaries depend on the shape of the disorder potential. The phases are distinguished by their velocity and coherence: the moving phase generically has finite coherence, while pinned states can be coherent or incoherent. …

Measurement Of The Open-Charm Contribution To The Diffractive Proton Structure Function, S. Chekanov, M. Derrick, D. Krakauer, J. H. Loizides, S. Magill, B. Musgrave, J. Repond, R. Yoshida, Margarita C. K. Mattingly, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, A. Margotti, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli, A. Zichichi, G. Aghuzumtsyan

Faculty Publications

Production of D*±(2010) mesons in diffractive deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 82 pb-1. Diffractive events were identified by the presence of a large rapidity gap in the final state. Differential cross sections have been measured in the kinematic region 1.5

Mode Structure Of Diffusive Transport In Hydroxypropylcellulose:Water, George D.J. Phillies, Robert O. Connell, Paul Whitford, Kiril A. Streletzky

Physics Faculty Publications

A systematic analysis of the mode structure of diffusive relaxations in 1 MDa hydroxypropylcellulose(HPC):water is presented. New methods and data include (1) use of integral spectral moments to characterize nonexponential decays, (2) spectra of small probes in concentrated HPC solutions, (3) temperature dependence of the mode structure, and (4) comparison of optical probe spectra and spectra of probe-free polymer solutions. We find that (1) probe and polymer relaxations are in general not the same; (2) the apparent viscometric crossover near ct≈6 g/l is echoed by probe behavior; (3) our HPC solutions have a characteristic dynamic length, namely the 50 nm …

State-To-State Rotational Rate Constants For Co+He: Infrared Double Resonance Measurements And Simulation Of The Data Using The Sapt Theoretical Potential Energy Surface, Tony C. Smith, David A. Hostutler, Gordon D. Hager, Michael C. Heaven, George C. Mcbane

Peer Reviewed Articles

An extensive data set of 54 time-resolved pump-probe measurements was used to examine CO+He rotational energy transfer within the CO v=2 rotational manifold. Rotational levels in the range J_i=2-9 were excited and collisional energy transfer of population to the levels J_f=1-10 was monitored. The resulting data set was analyzed by fitting to numerical solutions of the master equation. State-to-state rate constant matrices were generated using fitting law functions and ab initio theoretical calculations that employed the SAPT potential energy surface of Heijmen et al. [J. Chem. Phys. 107, 9921 (1997)]. Fitting laws based on …

Magnetoresistance In Boron Carbide Junctions, L. Bernard, J. Monson, Andrei Sokolov, Zong-Yuan Liu, C.S. Yang, Peter A. Dowben, Bermard Doudin, A. Harken, P. Welsch, B. W. Robertson

Peter Dowben Publications

Photoemission and electric transport properties of ferromagnet–insulator–ferromagnet junctions with boron carbide (C₂B₁₀) dielectric barrier are presented. Using a non-oxide barrier confidence avoids oxidation of the interfaces with the ferromagnetic layers. Photoemission confirms chemical abruptness of the interface. Magnetoresistance ratios reaching 50% are observed at low temperatures, and large nonlinearity in the current–voltage curves show that impurities in the junctions play a key role. © 2003 American Institute of Physics.

Evidence Of The Zn Vacancy Acting As The Dominant Acceptor In N-Type Zno, F. Tuomisto, V. Ranki, K. Saarinen, David C. Look

Physics Faculty Publications

We have used positron annihilation spectroscopy to determine the nature and the concentrations of the open volume defects in as-grown and electron irradiated (E_el=2   MeV, fluence 6×10¹⁷   cm^-2) ZnO samples. The Zn vacancies are identified at concentrations of [V_Zn]≃2×10¹⁵   cm^-3 in the as-grown material and [V_Zn]≃2×10¹⁶   cm^-3 in the irradiated ZnO. These concentrations are in very good agreement with the total acceptor density determined by temperature dependent Hall experiments. Thus, the Zn vacancies are dominant acceptors in both as-grown and irradiated ZnO.

Review Of "Liquid Crystals: Fundamentals" By S. Singh, Peter J. Collings

Physics & Astronomy Faculty Works

No abstract provided.

Ecotoxicological Research At Dit, Maria Davoren, Colm O'Dowd, Sharon Ni Shuilleabhain

Articles

The term ecotoxicology first defined by Rene Truhart in 1969, essentially describes the study of the harmful effects of chemicals upon ecosystems.

Test Particle Acceleration In Three-Dimensional Magnetohydrodynamic Turbulence, P. Dmitruk, W. H. Matthaeus, N. Seenu, Michael R. Brown

Physics & Astronomy Faculty Works

We perform numerical experiments of test particle acceleration on turbulent magnetic and electric fields obtained from pseudospectral direct numerical solutions of the compressible three-dimensional MHD equations. We find consistent acceleration of the particles to many times the plasma characteristic (Alfven) speed and extended power laws in the density distribution of energies. Scaling laws of maximum and mean energy of particles with the nominal gyrofrequency and the MHD electric field are observed and a simple estimate is presented.

The Spectra Of Type Ii Cepheids. Ii. The Hα Line In Intermediate-Period Stars, Edward G. Schmidt, Shawn Langan, Kevin M. Lee, Dale Johnston, Peter R. Newman, Stephanie A. Snedden

Edward Schmidt Publications

We present 98 Hα profiles for 21 pulsating variable stars with periods from 3 to 8 days. The strength, depth, and shape of Hα vary throughout the cycles of the stars in a way consistent with the temperature changes. Otherwise, they are quite uniform among all the stars, with a single exception. In FM Del, Hα is weaker and has a smaller central depth than in the other stars. This and the wavelength shifts of the core are attributed to incipient emission. The differential velocity of Hα relative to the metal lines is less than 25 km s^-1 for …