Digital Commons Network^™

Casimir Force Between Eccentric Cylinders, D. A. R. Dalvit, F. C. Lombardo, F. D D. Mazzitelli, R Onofrio

Dartmouth Scholarship

We consider the Casimir interaction between a cylinder and a hollow cylinder, both conducting, with parallel axis and slightly different radii. The Casimir force, which vanishes in the coaxial situation, is evaluated for both small and large eccentricities using the proximity approximation. The cylindrical configuration offers various experimental advantages with respect to the parallel planes or the plane-sphere geometries, leading to favourable conditions for the search of extra-gravitational forces in the micrometer range and for the observation of finite-temperature corrections.

Measurement Of The Polar-Angle Distribution Of Leptons From W Boson Decay As A Function Of The W Transverse Momentum In P̅P Collisions At √S=1.8 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a measurement of the polar-angle distribution of leptons from W boson decay, as a function of the W transverse momentum. The measurement uses an 80±4 pb^-1 sample of pp̅ collisions at √s =1.8 TeV collected by the CDF detector and includes data from both the W→e+ν and W→µ+ν decay channels. We fit the W boson transverse mass distribution to a set of templates from a Monte Carlo event generator and detector simulation in several ranges of the W transverse momentum. The measurement agrees with the standard model expectation, whereby the ratio of longitudinally to transversely …

Inclusive Search For Anomalous Production Of High-PT Like-Sign Lepton Pairs In Pp̅ Collisions At √S =1.8 Tev, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report on a search for anomalous production of events with at least two charged, isolated, like-sign leptons, each with -p_T>11 GeV/c using a 107 pb^-1 sample of 1.8 TeV pp̅ collisions collected by the CDF detector. We define a signal region containing low background from standard model processes. To avoid bias, we fix the final cuts before examining the event yield in the signal region using control regions to test the Monte Carlo predictions. We observe no events in the signal region, consistent with an expectation of 0.63_-0.07^+0.84 events. We present 95% confidence …

Dna Strand Breaks Induced By 0–4 Ev Electrons: The Role Of Shape Resonances, Frédéric Martin, Paul Burrow, Zhongli Cai, Pierre Cloutier, Darel Hunting, Léon Sanche

Paul Burrow Publications

Collisions of 0– 4 eV electrons with thin DNA films are shown to produce single strand breaks. The yield is sharply structured as a function of electron energy and indicates the involvement of π* shape resonances in the bond breaking process. The cross sections are comparable in magnitude to those observed in other compounds in the gas phase in which π* electrons are transferred through the molecule to break a remote bond. The results therefore support aspects of a theoretical study by Barrios et al. [J. Phys. B 106, 7991 (2002)] indicating that such a mechanism could produce strand breaks …

Quantitative Analysis Of Nanoscale Switching In Srbi2Ta2O9 Thin Films By Piezoresponse Force Microscopy, Sergei V. Kalinin, Alexei Gruverman, Dawn Bonnell

Alexei Gruverman Publications

Local switching properties in SrBi₂Ta₂O₉ thin films have been studied by spatially resolved piezoresponse force microscopy (PFM) and spectroscopy. Variations in PFM contrast of individual grains due to their random crystallographic orientation are consistent with the grain switching behavior examined via vertical and lateral hysteresis loops. Theoretical description of vertical hysteresis loop shape obtained in the point-charge approximation is shown to be in good agreement with the experimental data. Dependence of the hysteresis loop parameters on the grain crystallographic orientation is analyzed. It has been found that grain deviation from the ideal (010) orientation when …

High-Resolution Kinetic Energy Release Distributions And Dissociation Energies For Fullerene Ions C(N)(+), 42 <= N <= 90, K. Gluch, S. Matt-Leubner, Olof E. Echt, B. Concina, P. Scheier, T. D. Mark

Physics & Astronomy

We have measured the kinetic energy released in the unimolecular dissociation of fullerene ions, C(n)(+)-->C(n-2)(+)+C(2), for sizes 42less than or equal tonless than or equal to90. A three-sector-field mass spectrometer equipped with two electric sectors has been used in order to ensure that contributions from isotopomers of different masses do not distort the experimental kinetic energy release distributions. We apply the concept of microcanonical temperature to derive from these data the dissociation energies of fullerene cations. They are converted to dissociation energies of neutral fullerenes with help of published adiabatic ionization energies. The results are compared with literature values. …

First Nearglobal Retrievals Of Oh Rotational Temperatures From Satellite-Based Meinel Band Emission Measurements, C. Von Savigny, C. U. Eichmann, E. J. Llewellyn, H. Bovensmann, J. P. Burrows, M. Bittner, K. Hoppner, D. Offermann, Michael J. Taylor, Y. Zhao, W. Steinbrecht, P. Winkler

All Physics Faculty Publications

For the first time near-global retrievals of mesopause OH rotational temperatures from satellite-borne Meinel band emission measurements are presented. The measurements of the OH (3-1) Meinel band near 1.5 micron were performed with the SCIAMACHY instrument on the European Space Agency’s environmental satellite Envisat. The derived OH (3-1) rotational temperatures are shown to be in reasonable agreement with the CIRA (1986) atmosphere temperatures for the seasons and latitudes considered. The derived temperatures are in good agreement with groundbased measurements of the OH rotational temperature performed with a CEDAR Mesospheric Temperature Mapper (MTM) at Maui, Hawaii (21N/204E), with the GRound based …

How We Think About And Prepare To Teach Physics, Dewey I. Dykstra

Physics Faculty Publications and Presentations

We have been preparing physics teachers in the same manner for many decades. Yet, physics education research reveals for some observers disturbing evidence of little or no change in understanding the phenomena occurs as a direct result of physics instruction from elementary school through the college years. The apparent compatibility between these learning results and prevailing paradigm enables the construction of a description the paradigm. If it can be demonstrated that there is even just one alternative paradigm from which powerful alternative pedagogical practice is derived, are we not obligated to change how we prepare to teach physics?

Co2+ Dissociative Recombination: A Source Of Thermal And Nonthermal C On Mars, Jane L. Fox

Physics Faculty Publications

CO₂ ⁺ dissociative recombination has been assumed in the past to proceed overwhelmingly by the channel that produces CO + O. Although the channel that leads to the products C + O₂ is energetically possible, the significant rearrangement of bonds that is required has led to the belief that this channel contributes minimally. Seiersen et al. [2003] have recently measured the branching ratio for the latter channel, and they have reported a value of ∼9% of the total. We have constructed both low and high solar activity models of the Martian thermosphere, and we have tested the effect …

Hot Carbon Densities In The Exosphere Of Venus, Michael W. Liemohn, Jane L. Fox, Andrew F. Nagy, Xiaohua Fang

Physics Faculty Publications

The results of calculations of hot carbon densities in the exosphere of Venus are presented. The calculation is a two-step process. First a two-stream transport code is used to solve for the distribution function at the exobase, and then these results are used in a Liouville equation solution above the exobase. It is found that generally, photodissociation of carbon monoxide is the largest source of hot carbon atoms in the upper atmosphere of Venus, larger than dissociative recombination of CO⁺ and significantly larger than the creation of hot carbon through collisions with hot oxygen atoms. It is also found …

Measurement Of Charge Storage Decay Time And Resistivity Of Spacecraft Insulators, Prasanna V. Swaminathan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Insulators used in the construction of spacecraft are irradiated with high-energy electrons in the space environment and this sometimes causes the insulators to charge to very high voltages. Such charged insulators can generate spontaneous electric partial-discharge pulses of the order of mA to tens of A. These pulses sometimes last enough time to destroy the expensive micro-circuitry present in the spacecraft. In evaluating the threat to the spacecraft due to these discharges, calculation of the resistivity becomes a critical parameter since it determines how accumulated charge will distribute across the spacecraft and how rapidly charge imbalance will dissipate. So far, …

Approximately Self-Similar Critical Collapse In 2+1 Dimensions, Marco Cavaglia, Gerard Clement, Alessandro Fabbri

Physics Faculty Research & Creative Works

Critical collapse of a self-gravitating scalar field in a (2+1)-dimensional spacetime with negative cosmological constant seems to be dominated by a continuously self-similar solution of the field equations without cosmological constant. However, previous studies of linear perturbations in this background were inconclusive. We extend the continuously self-similar solutions to solutions of the field equations with negative cosmological constant, and analyze their linear perturbations. The extended solutions are characterized by a continuous parameter. A suitable choice of this parameter seems to improve the agreement with the numerical results. We also study the dynamics of the apparent horizon in the extended background.

Erratum: Test Of The Pluvinage Wave Function For The Helium Ground State (Physical Review A - Atomic, Molecular, And Optical Physics (2004) 70 (012712)), Darryl B. Jones, Joseph H. Macek, Don H. Madison

Physics Faculty Research & Creative Works

No abstract provided.

Test Of The Pluvinage Wave Function For The Helium Ground State, S. Jones, Joseph H. Macek, Don H. Madison

Physics Faculty Research & Creative Works

The accuracy of the Pluvinage wave function for the ground state of helium is investigated by considering a number of different physical processes including double ionization by photoabsorption, Compton scattering, and electron impact. In the high-energy limit of these processes, the accuracy of the initial ground state can be ascertained without reference to the final double-continuum state. In this limit, we find that a Hylleraas description is superior to the Pluvinage one. For intermediate energies, final-state correlation becomes important, so we employ a 3C description of the final state (the 3C wave function is the double-continuum analog of the Pluvinage …

Circular Dichroism At Equal Energy Sharing In Photo-Double-Ionization Of He, Andrei Y. Istomin, N. L. Manakov, A. V. Meremianin, Anthony F. Starace

Department of Physics and Astronomy: Faculty Publications

Interference between dipole and quadrupole transition amplitudes in photo-double-ionization of He by an elliptically polarized vuv photon is shown to induce circular dichroism in the case of equal energy sharing. The magnitude of this retardation-induced dichroic effect is estimated and its impact on the nondipole asymmetries of the triply differential cross section is demonstrated.

Reactor Physics Studies For The Afci Race Project: Reactor-Accelerator Coupling Experiments Project, Denis Beller

Transmutation Sciences Physics (TRP)

In the RACE Project of the U.S. Advanced Fuel Cycle Initiative (AFCI), a series of accelerator driven subcritical systems (ADSS) experiments will be conducted at the Idaho State University’s Idaho Accelerator Center (ISU-IAC), at the University of Texas (UT) at Austin, and at the Texas A&M University. In these experiments we will use electron accelerators to induce bremsstrahlung photon-neutron reactions in heavy-metal targets; this source of about 10¹² to 10¹³ n/s will then initiate fission reactions in the subcritical systems. These systems will include a compact, transportable assembly at ISU and TRIGA reactors at UT-Austin and Texas A&M. …

Search For BS0 Μ+Μ- And BD0 Μ+Μ- Decays 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 B_s⁰→ µ⁺µ^- and B_d⁰→ µ⁺µ^- decays in p collisions at =1.96 TeV using 171 pb–1 of data collected by the CDF II experiment at the Fermilab Tevatron Collider. The decay rates of these rare processes are sensitive to contributions from physics beyond the standard model. One event survives all our selection requirements, consistent with the background expectation. We derive branching ratio limits of Ɓ (B_s⁰→µ⁺µ^-)B_d⁰→µ+µ–)<1.5×10^-7 at 90% confidence level.

On The Variability Of The Fine Structure Constant, Jason Lott Evans

Theses and Dissertations

This thesis addresses the issue of the time variability of the fine structure constant, alpha. Recent claims of a varying alpha are set against the established standards of quantum electrodynamical theory and experiments. A study of the feasibility of extracting data on the time dependence of alpha using particles in Penning traps is compared to the results obtained by existing methods, including those using astrophysical data and those obtained in atomic clock experiments. Suggestions are made on the nature of trapped particles and the trapping fields.

National Academy Of Sciences Study On The Comprehensive Nuclear Test Ban Treaty, David W. Hafemeister

Physics

No abstract provided.

Bottom Photoproduction Measured Using Decays Into Muons In Dijet Events In Ep Collisions At √S=318 Gev, S. Chekanov, M. Derrick, D. Krakauer, J. H. Loizides, S. Magill, S. Miglioranzi, 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, A. Montanari, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli

Faculty Publications

The photoproduction of bottom quarks in events with two jets and a muon has been measured with the ZEUS detector at HERA using an integrated luminosity of 110 pb-1. The fraction of jets containing b quarks was extracted from the transverse momentum distribution of the muon relative to the closest jet. Differential cross sections for bottom production as a function of the transverse momentum and pseudorapidity of the muon, of the associated jet and of xγjets, the fraction of the photon's momentum participating in the hard process, are compared with MC models and QCD predictions made at next-to-leading order. The …

Physical Conditions In Orion's Veil, N. P. Abel, C. L. Brogan, Gary J. Ferland, C. R. O'Dell, G. Shaw, Thomas H. Troland

Physics and Astronomy Faculty Publications

Orion's veil consists of several layers of largely neutral gas lying between us and the main ionizing stars of the Orion Nebula. It is visible in 21 cm H I absorption and in optical and UV absorption lines of H I and other species. Toward θ¹ Ori C, the veil has two remarkable properties, a high magnetic field (~100 μG) and a surprising lack of H₂, given its total column density. Here we compute photoionization models of the veil to establish its gas density and its distance from θ¹ Ori C. We use a greatly improved …

Dynamical Studies Of Model Membrane And Cellular Response To Nanosecond, High-Intensity Pulsed Electric Fields, Qin Hu

Electrical & Computer Engineering Theses & Dissertations

The dynamics of electroporation of biological cells subjected to nanosecond, high intensity pulses are studied based on a coupled scheme involving the current continuity and Smoluchowski equations. The improved pore formation energy model includes a dependence on pore population and density. It also allows for variable surface tension and incorporates the effects of finite conductivity on the electrostatic correction term, which was not considered by the simple energy models in the literature. It is shown that E(r) becomes self-adjusting with variations in its magnitude and profile. The whole scheme is self-consistent and dynamic.

An electromechanical analysis based on thin-shell theory …

Excitation Energies From Time-Dependent Density-Functional Theory Beyond The Adiabatic Approximation, Carsten A. Ullrich, Kieron Burke

Physics Faculty Research & Creative Works

The nonadiabatic effects for excitation energies from time-dependent density-functional theory (TDDFT) were analyzed. a general analytic expression for nonadiabatic corrections to excitation energies of finite systems was derived and singlet s→s and s→p excitations of closed-shell atoms were calculated. It is observed that as the Vignale, Ullrich and Conti (VUC) functional is based on frequency-dependent xc kernel of homogeneous electron gas so it produces excitation energies with small but finite imaginary parts. the results show that the VUC approach determines excitation energies for atomic and molecular systems as well as for plasmon-like excitations in solids.

Optical Variability Of Narrow-Line Seyfert 1 Galaxies, Elizabeth S. Klimek, C. Martin Gaskell, Cecilia H. Hedrick

Department of Physics and Astronomy: Faculty Publications

We present results of a broadband photometric study of the optical variability of six narrow-line Seyfert 1 (NLS1) galaxies observed at 172 epochs. We searched for microvariability on 33 nights. Strong evidence for microvariability was found only for our lowest luminosity object, NGC 4051, on one night. Weaker evidence suggests such variability on a few other nights for two other objects, but the data are not as convincing. Intranight variability in NLS1’s is thus concluded to be rare and of low amplitude. We give illustrations of how variable image quality can produce spurious variability. We find that for well-studied non-NLS1’s …

Hysteresis Of Granular Fept:Ag Films With Perpendicular Anisotropy, M. L. Yan, Ralph Skomski, Arti Kashyap, L. Gao, Sy-Hwang Liou, David J. Sellmyer

Department of Physics and Astronomy: Faculty Publications

Intergranular interactions in nanostructured FePt:Ag thin films and their effect on magnetic hysteresis are investigated. The films, produced by multilayer deposition plus rapid thermal annealing, consist of FePt nanoparticles embedded in a silver matrix. They are investigated by magnetization measurements and magnetic force microscopy. Analytical model calculations, supported by micromagnetic simulations, are used to elucidate the relation between coercivity, hysteresis-loop slope, and spatial correlations during magnetization reversal. The analytical calculations yield simple expressions for the loop slope and the coercivity as a function of the intergranular exchange. Small intergranular exchange enhances the coercivity, but for strong exchange there is a …

Mesospheric Mid-Latitude Density Climatology Above Utah State University, Eric M. Lundell, Vincent B. Wickwar

Posters

Lidars have been used extensively to derive temperatures, but not absolute densities, in the mesospheric region of the atmosphere. We used observations since 1993 with the Rayleigh- scatter lidar at the Atmospheric Lidar Observatory (ALO) at Utah State University (41.7oN, 111.8oW) to create an absolute density climatology between 45 and ~95 km. The observations provide profiles of relative density to which an absolute scale is attached by normalizing the profiles at 45 km to the densities in the MSISe00 empirical model. We examine the density variations on several time scales—during the climatological year, from year to year, and over several …

Another Noctilucent Cloud At 41.7ºn, Joshua P. Herron, Vincent B. Wickwar

Posters

On June 23, 1995, a noctilucent cloud (NLC) was detected with the Rayleigh-scatter lidar at the Atmospheric Lidar Observatory (ALO) on the campus of Utah State University (USU) located in Logan, UT (41.7° N 111.8° W). This observation preceded, by four years, the one from 1999 that was previously reported [Wickwar et al., 2002]. These are both important because of their occurrence significantly equatorward of 50° latitude. The NLC was observed for 45 minutes shortly after local midnight. This was well past the twilight period when NLCs are visible to the naked eye. Several parameters of the NLC were …

Photoproduction Of D*± Mesons Associated With A Leading Neutron, S. Chekanov, M. Derrick, D. Krakauer, J. H. Loizides, S. Magill, S. Miglioranzi, 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, A. Montanari, R. Nania, F. Palmonari, A. Pesci, G. Sartorelli

Faculty Publications

The photoproduction of D*±(2010) mesons associated with a leading neutron has been observed with the ZEUS detector in ep collisions at HERA using an integrated luminosity of 80 pb-1. The neutron carries a large fraction, xL>0.2, of the incoming proton beam energy and is detected at very small production angles, θn< 0.8 mrad, an indication of peripheral scattering. The D* meson is centrally produced with pseudorapidity η1.9 GeV, which is large compared to the average transverse momentum of the neutron of 0.22 GeV. The ratio of neutron-tagged to inclusive D* production is 8.85±0.93(stat.) +0.48-0.61(syst.)% in the photon-proton center-of-mass energy range 130

An Experimental Study Of Micron-Scale Droplet Aerosols Produced Via Ultrasonic Atomization, Thomas D. Donnelly, J. Hogan '03, A. Mugler '04, N. Schommer '04, M. Schubmehl '02, Andrew J. Bernoff, B. Forrest '02

All HMC Faculty Publications and Research

In the last 10 years, laser-driven fusion experiments performed on atomic clusters of deuterium have shown a surprisingly high neutron yield per joule of input laser energy. Results indicate that the optimal cluster size for maximizing fusion events should be in the 0.01–μm diameter range, but an appropriate source of droplets of this size does not exist. In an attempt to meet this need, we use ultrasonic atomization to generate micron-scale droplet aerosols of high average density, and we have developed and refined a reliable droplet sizing technique based on Mie scattering. Harmonic excitation of the fluid in …

Study Of Leptonic Cp Violation, Joseph Schechter, Salah Nasri, Sherif Moussa

Physics - All Scholarship

The "complementary" Ansatz, Tr(M_\nu)=0, where M_\nu is the prediagonal neutrino mass matrix, seems a plausible approximation for capturing in a self-contained way some of the content of Grand Unification. We study its consequences in the form of relations between the neutrino masses and CP violation phases.