Digital Commons Network^™

Optical Metrology Of Adaptive Membrane Mirrors, John W. Wagner

Theses and Dissertations

Current space-based imaging platforms are significantly constrained in both size and weight by the launch vehicle. Increased payload size and weight results in increased cost and a decrease in launch responsiveness. The USAF Scientific Advisory Board (SAB) identified "Large lightweight structures for optics and antennas" as a revolutionary primary technology to be developed for the Air Force of the 21st Century. A membrane primary mirror in a space-based imaging system has the ability to overcome current payload constraints and meet evolutionary needs of the future. The challenge of membrane optics in space is the process of implementing adaptive optics technology …

Interactive Worksheets In Large Introductory Physics Courses, Diandra Leslie-Pelecky

Diandra Leslie-Pelecky Publications

Physics education research indicates that interactive instruction techniques improve student performance. ¹ A variety of methods have been developed to promote interactivity, including peer instruction, ² tutorials, ³ ranking tasks, ⁴ and in-class worksheets.5 These techniques are attractive because they are adaptable to classes of all sizes and rarely require the instructor to make radical changes in the course content or pedagogical approach. Our Physics 151 is a one-semester algebra-based course for which the primary audience is architecture, construction management, natural resources, and business majors. Eighty to 140 students are in each section. The course has three hours of lecture …

Topologically Ordered Phases Of Smectics Confined In Anisotropic Random Media: Smectic Bragg Glasses, Karl Saunders, Brad Jacobsen, Leo Radzihovsky, John Toner

Physics

We report the existence of two new topologically ordered glass phases of smectics in strained aerogel. In contrast to the case of unstrained aerogel, we find compelling theoretical arguments that a smectic in uniaxially stretched aerogel exhibits, for homeotropic nematic-aerogel alignment, a `smectic Bragg glass' in the universality class of the `XY Bragg glass'. On the other hand, a uniaxial compression, with homeotropic alignment, leads to an entirely novel type of anisotropic smectic elastic glass phase that we call the `m = 1 Bragg glass'. This latter phase exhibits anomalous elasticity, characterized by exponents that we calculate to high precision. …

Measurement Of B-Quark Fragmentation Fractions In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have studied the production of B hadrons in 1.8-TeV pp̅ collisions. We present measurements of the fragmentation fractions, f_u, f_d, f_s, and f_baryon, of produced b quarks that yield B⁺, B⁰, B_s⁰, and Λ̅_b⁰ hadrons. Reconstruction of five electron-charm final states yields f_s/(f_u+ f_d)= 0.213 ± 0.068 and f_baryon/(f_u+ f_d)= 0.118 ± 0.042, assuming f_u=f_d. If all B hadrons produced in pp̅ collisions …

Phase Transition In The Surface Structure In Copolymer Films Of Vinylidene Fluoride (70%) With Trifluoroethylene (30%), Jaewu Choi, C.N. Borca, Peter A. Dowben, A. Bune, Matt Poulsen, Shane Pebley, Shireen Adenwalla, Stephen Ducharme, Lee Robertson, V.M. Fridkin, N.N. Petukhova, S.G. Yudin

Peter Dowben Publications

Surface structures and a surface structure phase transition are identified that are distinct from the known bulk ferroelectric-paraelectric phase transition of crystalline copolymer films of vinylidene fluoride (70%) with trifluoroethylene (30%). The temperature-dependent changes in the surface structure are accompanied by the physical rotation of the polar group (CH₂-CF₂). These changes in the surface structure are compared to the bulk phase transition. We show that the bulk structural transition, while distinct from the surface, is qualitatively similar in both thick and thin Langmuir-Blodgett-grown films.

Method For Depositing Rare-Earth Boride Onto A Substrate, Peter A. Dowben, Zhenchen Zhong, David J. Sellmyer

Peter Dowben Publications

Disclosed is a method for depositing rare-earth boride onto the surface of a substrate which is submerged in an organic solution of borane and a rare-earth halide. Application of electromagnetic radiation, preferably in the visible wavelength range, near the surface of the submerged substrate drives the formation and deposition of rare-earth boride onto a substrate.

Boron-Carbide And Boron Rich Rhobohedral Based Transistors And Tunnel Diodes, Peter A. Dowben

Peter Dowben Publications

The present invention relates to the fabrication of a boron carbideboron diode on an aluminum substrate, and a boron carbideboron junction field effect transistor. Our results suggest that with respect to the approximately 2 eV band gap pure boron material, 0.9 eV band gap boron carbide (B₅C) acts as a p-type material. Both boron and boron carbide (B₅C) thin films were fabricated from single source borane cage molecules using plasma enhanced chemical vapor deposition (PECVD). Epitaxial growth does not appear to be a requirement. We have doped boron carbide grown by plasma enhanced chemical vapor deposition. …

Measurement Of The E(T,Jet)/ 2 /Q 2 Dependence Of Forward-Jet Production At Hera, J. Breitweg, S. Chekanov, M. Derrick, D. Krakauer, S. Magill, B. Musgrave, A. Pellegrino, J. Repond, R. Stanek, R. Yoshida, Margarita C. K. Mattingly, G. Abbiendi, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, N. Coppola, M. Corradi, S. De Pasquale, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

The forward-jet cross section in deep inelastic e + p scattering has been measured using the ZEUS detector at HERA with an integrated luminosity of 6.36 pb -1 . The jet cross section is presented as a function of jet transverse energy squared, E(T,jet)/ 2 , and Q 2 in the kinematic ranges 10 -2 < E(T,jet)/ 2 /Q 2 < 10 2 and 2.5 · 10 -4 < x < 8.0 · 10 -2 . Since the perturbative QCD predictions for this cross section are sensitive to the treatment of the log(E(T,jet)/ 2 /Q2) terms, this measurement provides an important test. The measured cross section is compared to the predictions of a next-to-leading order pQCD calculation as well as to various leading-order Monte Carlo models. Whereas the predictions of all models agree with the measured cross section in the region of small E(T,jet/ 2 /Q 2 only one model, which includes a resolved photon component, describes the data over the whole kinematic range. (C) 2000 Elsevier Science B.V.

Pion-Induced Transport Of Π Mesons In Nuclei, S. G. Mashnik, R. J. Peterson, A. J. Sierk, Michael R. Braunstein

All Faculty Scholarship for the College of the Sciences

A large body of data for pion-induced neutral pion continuum spectra spanning outgoing energies near 180 MeV shows no dip there that might be ascribed to internal strong absorption processes involving the formation of Δ’s. This is the same observation previously made for the charged pion continuum spectra. Calculations in an intranuclear cascade model or a cascade exciton model with free-space parameters predict such a dip for both neutral and charged pions. We explore several medium modifications to the interactions of pions with internal nucleons that are able to reproduce the data for nuclei from ⁷Li through Bi.

Search For Color Singlet Technicolor Particles In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We search for color singlet technirho and technipion production in pp̅ collisions at √s = 1.8 TeV recorded with the Collider Detector at Fermilab. These exotic technimesons are present in a model of walking technicolor. The signatures studied are lepton plus two jets plus E/_T and multijet final states. No excess of events is seen in either final state. We set an upper limit on the technirho production cross section and exclude a region in the technipion mass versus technirho mass plane.

Exact Analytic Relation Between Quantum Defects And Scattering Phases With Applications To Green’S Functions In Quantum Defect Theory, V. E. Chernov, N. L. Manakov, Anthony F. Starace

Anthony F. Starace Publications

The relation between the quantum defects, μ_λ, and scattering phases, δ_λ, in the single-channel Quantum Defect Theory (QDT) is discussed with an emphasis on their analyticity properties for both integer and noninteger values of the orbital angular momentum parameter λ. To derive an accurate relation between μ_λ and δ_λ for asymptotically-Coulomb potentials, the QDT is formally developed for the Whittaker equation in its general form “perturbed” by an additional short-range potential. The derived relations demonstrate that μ_λ is a complex function for above-threshold energies, which is analogous to the fact that δ …

The Statistical Mechanics Of Membranes, Mark Bowick, Alex Travesset

Physics - All Scholarship

The fluctuations of two-dimensional extended objects membranes is a rich and exciting field with many solid results and a wide range of open issues. We review the distinct universality classes of membranes, determined by the local order, and the associated phase diagrams. After a discussion of several physical examples of membranes we turn to the physics of crystalline (or polymerized) membranes in which the individual monomers are rigidly bound. We discuss the phase diagram with particular attention to the dependence on the degree of self-avoidance and anisotropy. In each case we review and discuss analytic, numerical and experimental predictions of …

Fluctuation Properties Of Precipitation. Part Vi: Observations Of Hyperfine Clustering And Drop Size Distribution Structures In Three-Dimensional Rain, A. R. Jameson, Alexander Kostinski

Department of Physics Publications

In past work it is argued that rain consists of patches of coherent, physical drop size distributions passing in an unpredictable fashion for an unknown duration over a sensor. This leads to the detection both of correlations among drops and of clustering. While the analyses thus far support this characterization, in this final paper in this series, techniques are developed demonstrating that clustering of drops of a specific size in rain is occurring even on scales as small as a few centimeters. Moreover, using video disdrometer data processed to achieve high temporal resolution, it is shown that drops of different …

Simulation Of Dc Resistivity Data: Questioning Critical Scaling For The High-Tc Copper Oxides, Brandon R. Brown

Physics and Astronomy

We simulate dc V-I data using Gaussian distributions of depinning currents for the mixed state of a copper-oxide superconductor and subsequently submit the data to a critical scaling analysis. Though the simple model for simulation assumes no phase transition for the vortex matter, the generated data exhibit a collapse matching those in the experimental literature. The resulting would-be critical parameters depend on the simulated sensitivity level, reinforcing doubts concerning the utility of the scaling analysis for these systems.

Disorder-Induced Desynchronization In A 2x2 Circular Josephson Junction Array, Adam S. Landsberg

WM Keck Science Faculty Papers

Analytical results are presented which characterize the behavior of a dc-biased, two-dimensional circular array of overdamped Josephson junctions subject to increasing levels of disorder. It is shown that high levels of disorder can abruptly destroy the synchronous functioning of the array. We identify the transition boundary between synchronized and desynchronized behavior, along with the mechanism responsible for the loss of frequency locking. Comparisons with recent results for arrays with rectangular lattice geometries are described.

Factorized Representation For Parity-Projected Wigner DJ (Β) Matrices, N.L. Manakov, A.V. Meremianin, Anthony F. Starace

Anthony F. Starace Publications

An alternative representation for the parity-projected Wigner d^j(β) rotation matrix is derived as the product of two triangular matrices composed of Gegenbauer polynomials with negative and positive upper indices, respectively. We relate this representation for d^j(β) to the one presented by Matveenko [Phys. Rev. A 59, 1034 (1999)], which, in contrast with our result, requires for its evaluation a matrix inversion. In addition, identities for bilinear sums of Gegenbauer polynomials are derived. This work is based on our recently introduced invariant representations for finite rotation matrices [Phys. Rev. A 57, 3233 (1998)].

Characteristics Of Driven Polymer Surfaces: Growth And Roughness, Grace M. Foo, Ras B. Pandey

Faculty Publications

Using a Monte Carlo simulation, the growth and roughness characteristics of polymer surfaces are studied in 2 + 1 dimensions. Kink-jump and reptation dynamics are used to move polymer chains under a driving field where they deposit onto an impenetrable attractive wall. Effects of field (E) chain length (L_c) and the substrate size (L) on the growing surfaces are studied. In low field, the interface width (W) shows a crossover from one power-law growth in time (W∼t^β₁) to another (W∼t^{β_{2 …}}

Effect Of Slow Compression On The Linear Stability Of An Accelerated Shear Layer, John D. Ramshaw

Physics Faculty Publications and Presentations

An analysis is given of the effect of a slow uniform anisotropic compression or expansion on the linear stability of a normally accelerated planar interface between two fluids with different densities and tangential velocities, i.e., a combined Kelvin-Helmholtz and Rayleigh-Taylor instability, but generalized to an arbitrary time-dependent acceleration history. The compression is presumed to be sufficiently slow that the density remains uniform within each fluid and hence depends only on time. The perturbation is taken to be sinusoidal with amplitude h(t). The time evolution of h is determined by requiring pressure continuity across the interface in the usual way. The …

Lifetime Effects On The Dissociation Of Core-Excited N2 And Co Molecules, N. Saito, A. Hempelmann, F. Heiserq, Oliver Hemmers, K. Wieliczek, J. Viefhaus, U. Becker

Environmental Studies Faculty Publications

Vibrational-resolved ion and ion-pair yield spectra of N₂ and CO taken at their 1s⃗π^* resonance excitations reveal decay-channel-dependent core hole lifetimes. The linewidths of the yield spectra tend to be shortened when the number of electrons ejected in the deexcitation process increases, finally becoming narrower than the total ion yield or absorption natural lifetime width of the core-excited states of N₂ and CO, respectively. In contrast to this, the linewidths of the yield spectra for the singly charged molecular ions, N₂⁺ and CO⁺, are shown to be broader than their corresponding natural linewidths. …

Measurement Of Bb̅ Rapidity Correlations In Pp̅ Collisions At √S =1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report the first direct measurement of bb̅ rapidity correlations in pp̅ collisions at √s =1.8 TeV. We select events with a high transverse momentum muon accompanied by a jet, and a second jet associated with a decay vertex displaced from the pp̅ interaction vertex. Two independent samples are obtained corresponding to events with a forward (2.0<|η|bb̅ production to be 0.361±0.033(stat) _-0.031^+0.015(syst), in good agreement with the next-to-leading order QCD prediction 0.338_-0.097^+0.014

Electronic Structure Of Cu1-Xnixrh2s4 And Curh2se4: Band-Structure Calculations, X-Ray Photoemission, And Fluorescence Measurements, Gus L. W. Hart, W. E. Pickett, E. Z. Kurmaev, M. Neumann, D. Hartmann, A. Moewes, D. L. Ederer, R. Endoh, K. Taniguchi, S. Nagata

Faculty Publications

The electronic structure of spinel-type Cu1-xNixRh2S4 (x=0.0, 0.1, 0.3, 0.5, 1.0) and CuRh2Se4 compounds has been studied by means of x-ray photoelectron (SPS) and fluorescent spectroscopy. Cu L3, Ni L3, S L2,3, and Se M2,3 x-ray emission spectra (XES) were measured near thresholds at Beamline 8.0 of the Lawrence Berkeley Laboratory's Advanced Light Source. XES measurements of the constituent atoms of these compounds, reduced to the same binding energy scale, are found to be in excellent agreement with XPS valence bands. The calculated XES spectra which include dipole matrix elements show that the partial density of states reproduce experimental spectra …

Quantum Gravity Corrections To The Schwarzschild Mass, Marco Cavaglia, Carlo Ungarelli

Physics Faculty Research & Creative Works

Vacuum spherically symmetric Einstein gravity in (N≥4) dimensions can be cast in a two-dimensional conformal nonlinear sigma model form by first integrating on the (N - 2)-dimensional (hyper)sphere and then performing a canonical transformation. The conformal sigma model is described by two fields which are related to the Arnowitt-Deser-Misner (ADM) mass and to the radius of the (N - 2)-dimensional (hyper)sphere, respectively. By quantizing perturbatively the theory we estimate the quantum corrections to the ADM mass of a black hole.

Observations Of Particulates Within The North Atlantic Flight Corridor: Polinat 2, September-October 1997, J. D. Paladino, Donald E. Hagen, Philip D. Whitefield, Alfred Raymond Hopkins, Otmar Schmid, M. R. Wilson, Hans Schlager, Peter Schulte

Physics Faculty Research & Creative Works

This paper discusses particulate concentration and size distribution data gathered using the University of Missouri-Rolla Mobile Aerosol Sampling System (UMR-MASS), and used to investigate the southern extent of the eastern end of the North Atlantic Flight Corridor (NAFC) during project Pollution From Aircraft Emissions in the North Atlantic Flight Corridor/Subsonic Assessment (SASS) Ozone and Nitrogen Oxide Experiment (POLINAT 2/SONEX) from September 19 to October 23, 1997. The analysis presented in this paper focuses on "the corridor effect," or enhancement of pollutants by jet aircraft combustion events. To investigate the phenomena, both vertical and horizontal profiles of the corridor, and regions …

Excitation Of Ar 3p⁵4s-3p⁵4p Transitions By Electron Impact, Colette M. Maloney, Jerry Peacher, Klaus Bartschat, Don H. Madison

Physics Faculty Research & Creative Works

Electron-impact excitation of argon from the 3p⁵4s (J=0,2) metastable states to the 3p⁵4p (J=0,1,2,3) manifold has been investigated in the semirelativistic first-order distorted-wave and plane-wave Born approximations. The results are compared with recent experimental data of Boffard et al. [Phys. Rev. A 59, 2749 (1999)] and R-matrix predictions by Bartschat and Zeman [Phys. Rev. A 59, R2552 (1999)]. In cases for which perturbative approaches are expected to be valid, the plane-wave Born approximation is found to be sufficiently accurate and thus allows for an efficient calculation of results over a wide range of collision energies.

Correlated Three-Electron Continuum States In Triple Ionization By Fast Heavy-Ion Impact, Michael Schulz, Robert Moshammer, Wayne M. Schmitt, Holger Kollmus, Rido Mann, Siegbert Hagmann, Ronald E. Olson, Joachim Hermann Ullrich

Physics Faculty Research & Creative Works

We have performed a kinematically complete experiment for triple ionization in atomic collisions. Data were obtained for 3.6-MeV/amu Au⁵³⁺ impact on Ne. A specific Dalitz representation was developed allowing one to plot in a single spectrum the energy of all three ionized electrons and, simultaneously, obtain information on their emission angles with respect to the projectile direction. The data show distinct fragmentation patterns favoring very asymmetric energy partitionings with one fast and two slow electrons. They are compared to various Classical Trajectory Monte Carlo (CTMC) models. The experimental results are well described only if the electron-electron interaction is included …

How Big Is Our Sun?, Mark Moldwin

Aerospace, Physics, and Space Science Faculty Publications

Putting large numbers into human perspective by using ratios of a known quantity to an unknown quantity is an important scientific skill. An astronomy activity that encourages the use of estimation and helps students get a handle on large numbers is the making of a scale model of Earth and Sun that is relative in both size and distance.

Experimental And Phenomenological Study Of Persistent Photoconductivity In Yba2cu3o6 Thin Films, Daniel-Dennis Mcalevy Bubb

Dissertations

Persistent Photoconductivity in YBa₂Cu₃O_6+x thin films is studied by means of infrared photoconductivity measurements after the films have been illuminated with visible light at low temperature. Experimentally, the effect is characterized by the samples' electrical response to infrared light, either causing the resistance to decrease or increase.

A cellular automata model is proposed in explanation of these results and is shown to be consistent with current experimental understanding of this unusual effect, both our results and those of others. The cellular automata model may have application to other unusual optical phenomena exhibited by YBa_{2 …}

Search For A Fourth-Generation Quark More Massive Than The Z0 Boson In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present the results of a search for pair production of a fourth-generation charge -⅓ quark (b′) in √s =1.8 TeV pp collisions using 88 pb^-1 of data obtained with the Collider Detector at Fermilab. We assume that both quarks decay via the flavor-changing neutral current process b′ → bZ⁰ and that the b′ mass is greater than m_z+ m_b. We studied the decay mode b′b̅′→ Z⁰Z⁰ bb̅ where one Z⁰ decays into e⁺e^- or μ⁺μ^-and the other decays hadronically, …

Transverse Momentum And Total Cross Section Of E+E- Pairs In The Z-Boson Region, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

The transverse momentum and total cross section of e⁺e^- pairs in the Z-boson region of 66 < M_ee < 116 GeV/c² from pp̅ collisions at √s =1.8 TeV are measured using 110 pb^-1 of collisions taken by the Collider Detector at Fermilab during 1992–1995. The total cross section is measured to be 248 ± 11 pb. The differential transverse momentum cross section is compared with calculations that match quantum chromodynamics perturbation theory at high transverse momentum with the gluon resummation formalism at low transverse momentum.

Parity Violation In 232th Neutron Resonances Above 250 Ev, E I. Sharapov, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, L Y. Lowie, J E. Lynch, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, Sharon L. Stephenson, Y-F Yen, V W. Yuan

Physics and Astronomy Faculty Publications

The analysis of parity nonconservation (PNC) measurements performed on ²³²Th by the TRIPLE Collaboration has been extended to include the neutron energy range of 250 to 1900 eV. Below 250 eV all ten statistically significant parity violations have the same sign. However, at higher energies PNC effects of both signs were observed in the transmission of longitudinally polarized neutrons through a thick thorium target. Although the limited experimental energy resolution precluded analysis in terms of the longitudinal asymmetry, parity violations were observed and the cross section differences for positive and negative neutron helicities were obtained. For comparison, a similar …