Digital Commons Network^™

Optimization Of A Multilayer Photothermal Sensor For Infrared Spectroscopy, Janine O.J. Wiggins

Theses and Dissertations

Tri-layer thermal diffusion modeling was applied to the optimization of a multi-layer reed sensor for use in a photothermal infrared detector. The multi-layer reed sensor deflects in response to increased temperature. Deflection, of angstroms or larger, is measured using an atomic force microscope. A newly developed thermal diffusion model for three layer reeds was combined with an existing two-layer cantilever model, in order to explore the effects of length, operating frequency, and layer thickness on signal to noise ratio. Model behavior is presented, and compared to laboratory results.

Active Multispectral Band Selection And Reflectance Measurement System, Bradley D. Rennich

Theses and Dissertations

Due to system design requirements, an active multispectral laser radar system may be limited in the number of spectral bands that can be integrated into the system. To aid in the selection of these bands, a novel multispectral band selection technique is presented based on the cross-correlation of the material class reflectance spectra over a wavelength range of 1 - 5 microns. The algorithm uses directional hemispherical reflectance data from the Nonconventional Exploitation Factors database to select a number of spectral bands for classification purposes. Because the target material spectral reflectance is so important to the performance of an active …

Geometrodynamical Formulation Of Two-Dimensional Dilaton Gravity, Marco Cavaglia

Physics Faculty Research & Creative Works

Two-dimensional matterless dilaton gravity with an arbitrary dilatonic potential can be discussed in a unitary way, both in the Lagrangian and canonical frameworks, by introducing suitable field redefinitions. The new fields are directly related to the original spacetime geometry and in the canonical picture they generalize the well-known geometrodynamical variables used in the discussion of the Schwarzschild black hole. So the model can be quantized using the techniques developed for the latter case. The resulting quantum theory exhibits the Birkhoff theorem at the quantum level.

Measurement Of ZT0 And Drell-Yan Production Cross Sections Using Dimuons In P̅P Collisions At √S =1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a measurement of Z⁰ boson and Drell-Yan production cross sections in p̅p collisions at √s =1.8 TeV using a sample of 107 pb^-1 accumulated by the Collider Detector at Fermilab. The Drell-Yan cross section is measured in the mass range of M_μμ>40 GeV/c². We compare the measurements with the predictions of quantum chromodynamics in both leading order and next-to-leading order, incorporating the recent parton distribution functions. The measurements are consistent with the standard model expectations.

Kinetic Model Of A Space-Based, Br (4 2P1/2 → 4 2P3/2) Laser Pumped By Solar Photolysis Of Ibr, Barry N. Behnken

Theses and Dissertations

A kinetic model of the directly solar-pumped, atomic bromine laser-operating on the Br (4 ²P_1/2 → 4 ²P_3/2) transition under IBr photolysis-was developed, executed, and interpreted. In recognition of an evolving national interest in space-based laser development, the model presumed operation on a space station platform. Results indicate that a well-engineered IBr laser is capable of generating 1.2 kilowatts of continuous-wave (CW) power under a pumping concentration of 20,000 solar units. Such performance translates to an efficiency of roughly 0.29%, appreciably better than the 0.1% ascribed to the heretofore leading solar-pumped competitor. An extensive analysis …

The Cleo-Iii Ring Imaging Cherenkov Detector, Raymond Mountain, Marina Artuso, R. Ayad, F. Azfar

Physics - All Scholarship

The CLEO-III Detector upgrade for charged particle identification is discussed. The RICH design uses solid LiF crystal radiators coupled with multi-wire chamber photon detectors, using TEA as the photosensor, and low-noise Viking readout electronics. Results from our beam test at Fermilab are presented.

Computational Complexity Of Determining The Barriers To Interface Motion In Random Systems, Alan Middleton

Physics - All Scholarship

The low-temperature driven or thermally activated motion of several condensed matter systems is often modeled by the dynamics of interfaces (co-dimension-1 elastic manifolds) subject to a random potential. Two characteristic quantitative features of the energy landscape of such a many-degree-of-freedom system are the ground-state energy and the magnitude of the energy barriers between given configurations. While the numerical determination of the former can be accomplished in time polynomial in the system size, it is shown here that the problem of determining the latter quantity is NP-complete. Exact computation of barriers is therefore (almost certainly) much more difficult than determining the …

He I 2.06 Micron Emission From Nebulae, Gary J. Ferland

Physics and Astronomy Faculty Publications

The spectrum emitted by any astronomical plasma is sensitive to a variety of details, some of which may not be obviously important. This paper describes the sensitivity of the He I 2.06 μm line to the gas opacity at ionizing energies. The intensity of the line relative to a hydrogen line depends on the He⁺/H⁺ ratio, but also on the ratio of continuous to He I Lyα line opacity, since this determines whether the Lyα line can scatter often enough to be converted to the 2.06 μm line. The intensity of the infrared line relative to Hβ …

Parity Violation In Neutron Resonances In 107,109ag, L Y. Lowie, J D. Bowman, J Corvi, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, H M. Shimizu

Physics and Astronomy Faculty Publications

Parity nonconservation (PNC) was studied in p-wave resonances in Ag by measuring the helicity dependence of the neutron total cross section. Transmission measurements on natural Ag were performed in the energy range 32 to 422 eV with the time-of-flight method at the Manuel Lujan Neutron Scattering Center at Los Alamos National Laboratory. A total of 15 p-wave neutron resonances were studied in ¹⁰⁷Ag and ninep-wave resonances in ¹⁰⁹Ag. Statistically significant asymmetries were observed for eight resonances in ¹⁰⁷Ag and for four resonances in¹⁰⁹Ag. An analysis treating the PNC matrix elements as random variables yields a …

Search For Parity Violation In 93nb Neutron Resonances, E I. Sharapov, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, K Fukuda, M Iinuma, J N. Knudsen, J Lokitz, L Y. Lowie, A Masaike, Y Matsuda, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, H M. Shimizu, Sharon L. Stephenson, Y-F Yen, V W. Yuan

Physics and Astronomy Faculty Publications

A new search has been performed for parity violation in the compound nuclear states of ⁹⁴Nb by measuring the helicity dependence of the neutron total cross section. Transmission measurements on a thick niobium target were performed by the time-of-flight method at the Manuel Lujan Neutron Scattering Center with a longitudinally polarized neutron beam in the energy range 32 to 1000 eV. A total of 18 p-wave resonances in ⁹³Nb were studied with none exhibiting a statistically significant parity-violating longitudinal asymmetry. An upper limit of 1.0×10^-7 eV (95% confidence level) was obtained for the weak spreading widthΓ_{w …}

Exposure To Atmospheric Radon, Daniel J. Steck, R. William Field, Charles F. Lynch

Physics Faculty Publications

We measured radon (²²²Rn) concentrations in Iowa and Minnesota and found that unusually high annual average radon concentrations occur outdoors in portions of central North America. In some areas, outdoor concentrations exceed the national average indoor radon concentration. The general spatial patterns of outdoor radon and indoor radon are similar to the spatial distribution of radon progeny in the soil. Outdoor radon exposure in this region can be a substantial fraction of an individual's total radon exposure and is highly variable across the population. Estimated lifetime effective dose equivalents for the women participants in a radon-related lung cancer …

Dislocation Scattering In Gan, David C. Look, J. R. Sizelove

Physics Faculty Publications

A theory of charged-dislocation-line scattering is developed within the framework of the Boltzmann transport equation. A fit of the theory to temperature-dependent Hall-effect data in GaN gives dislocation densities which are in excellent agreement with those measured by transmission electron microscopy. This work shows that threading edge dislocations in GaN indeed are electrically active, in agreement with recent theoretical predictions.

Anisotropic Magnetoresistance In The Organic Superconductor Β″–(Bedt-Ttf)2sf5ch2cf2so3, X. Su, F. Zuo, J. A. Schlueter, Jack M. Williams, P. G. Nixon, Rolf Walter Winter, Gary L. Gard

Chemistry Faculty Publications and Presentations

In this paper, we report transport measurements of interlayer magnetoresistance with field parallel and perpendicular to the current direction in an all organic superconductor β″–(BEDT-TTF)₂SF₅CH₂CF₂SO₃. For H∥I, the isothermal magnetoresistance R(H) at low temperatures (T

Measurement Of The Mass Splittings Between The Bb̅ΧB,J(1P) States, K. W. Edwards, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

We present new measurements of photon energies and branching fractions for the radiative transitions Υ(2S) → γχ_b(J=0,1,2)(1P). The masses of the χ_b states are determined from the measured radiative photon energies. The ratio of mass splittings between the χ_b substates, r ≡ [(M_J=2 -M_J=1)/( M_J=1 - M_J=0), with M the χ_b mass, provides information on the nature of the bb̅ confining potential. We find r(1P)=0.542 ±0.022±0.024. This value is somewhat lower than the previous world average, but more consistent with …

Impact Parameter Related Final N-Level Splitting Observed In Aligned Ion-Rydberg Collisions, K. R. Cornelius, Ronald E. Olson

Physics Faculty Research & Creative Works

The classical trajectory Monte Carlo method has been used to calculate the final product principal quantum state n f-distributions in electron capture collisions involving a proton incident on a Rydberg hydrogen atom in an ni = 25 state. The generalized eccentricity, defined by orienting the classical eccentricity of the electron's orbit relative to the incident ion, was varied to show how the final state n f-levels depended on this quantity over the range of reduced collision speeds v* = vp/ve = 1.0-2.4. Plots of the final product n f-distributions at low reduced velocities show a resonance peak near n f …

Oh 1720 Megahertz Masers In Supernova Remnants: C-Shock Indicators, Phil Lockett, Eric Gauthier, Moshe Elitzur

Physics and Astronomy Faculty Publications

Recent observations show that the OH 1720 MHz maser is a powerful probe of the shocked region where a supernova remnant strikes a molecular cloud. We perform a thorough study of the pumping of this maser and find tight constraints on the physical conditions needed for its production. The presence of the maser implies moderate temperatures (50-125 K) and densities (~10⁵ cm^-3) and OH column densities of order 10¹⁶ cm^-2. We show that these conditions can exist only if the shocks are of C-type. J-shocks fail by such a wide margin that the presence …

Influence Of Dynamical Scattering In Crystalline Poly„Vinylidene, C.N. Borca, Jaewu Choi, Shireen Adenwalla, Stephen Ducharme, Peter A. Dowben, Lee Robertson, V.M. Fridkin, S.P. Palto, N. Petukhova

Stephen Ducharme Publications

The effective Debye temperature of poly(vinylidene fluoride-trifluoroethylene) copolymers was measured using photoemission and neutron diffraction techniques. An effective Debye temperature of 53611K is obtained from the photoemission data and 6963.5K from neutron diffraction measurements. This effective Debye temperature is a consequence of the temperature-dependent dynamic motions perpendicular to the surface of these crystalline polymer films.

Evidence Of Dynamic Jahn-Teller Distortions In Two-Dimensional Crystalline Molecular Films, Jaewu Choi, Peter A. Dowben, C.N. Borca, Shireen Adenwalla, A.V. Bune, Stephen Ducharme, V.M. Fridkin, S.P. Palto, N. Petukhova

Peter Dowben Publications

The surface electronic structure in crystalline copolymer films of vinylidene fluoride (70%) with trifluoroethylene (30%) has been studied by photoemission and inverse photoemission as a function of alkali metal (sodium) doping. Sodium doping introduces at least two new states into the band (HOMO-LUMO) gap well away from the Fermi level. While the sodium-doped copolymer is observed to resemble an n-type semiconductor, the change in electronic structure with temperature suggests that dynamic distortions lead to a photoemission initial state splitting of the lower Hubbard-like bands. There is a decrease in the effective Debye temperature with sodium doping which may, in turn, …

Measurement Of The Top Quark Mass With The Collider Detector At Fermilab, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a new measurement of the top quark mass in tt̅ events in which both W bosons from top quarks decay into leptons (eν, μν). We use events collected by the CDF experiment from pp̅ collisions at √s =1.8 TeV at the Tevatron collider. We measure a top quark mass of 167.4 ± 10.3(stat) ± 4.8(syst) GeV/c² from a sample of eight events. We combine this result with previous CDF measurements in other decay channels to obtain a final mass value of 176.0 ± 6.5 GeV/c².

Structural Domain Growth Of Strained Gadolinium On Mo(112), C. Waldfried, Peter A. Dowben, O. Zeybek, T. Bertrams, S. D. Barrett

Peter Dowben Publications

The growth mode of domains of the hexagonal lattice of strained gadolinium deposited on Mo(112) has been investigated with low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The molybdenum substrate corrugations and the expansive strain within the gadolinium films dominate the growth of the thin Gd films, which is characterized by a preferential domain growth direction of the hexagonal Gd crystal structure, unlike the more uniform, epitaxial growth of ‘unstrained’ gadolinium, grown on W(110).

Fluctuation Properties Of Precipitation. Part Iv: Finescale Clustering Of Drops In Variable Rain, A. R. Jameson, Alexander Kostinski, A Kruger

Department of Physics Publications

In recent studies it is shown that in variable rain the spatial distribution of drops is not Poissonian. However, these past studies were limited to 1-min drop counts, which likely correspond to spatial scales of a few hundred to several hundreds of meters.

In this work results based on 1-s drop counts using a video disdrometer are reported. It is shown that the clustering of raindrops previously found during intervals of 1 min also occurs during 1 s as well in convective rain. These latter temporal scales likely correspond to spatial features having dimensions from only a few to tens …

Does N-2(-) Exist? A Coupled-Cluster Study, Gennady L. Gutsev, Piotr B. Rozyczko, Rodney J. Bartlett, Charles A. Weatherford

Physics Publications

Potential energy curves of the ground-state N2 molecule and its doublet N−2 anion are calculated at the coupled-cluster level with single and double excitations and with noniterative triples [CCSD(T)] as well as with the multireference averaged-quadratic coupled-cluster (MR-AQCC) method. The N−2 anion is shown to be temporary and decays to its neutral parent plus a free electron at bond lengths shorter than ≈1.4 and larger than ≈2.5 Å. Thus, the N−2 anion exists within the 1.4⩽R(N–N)⩽2.5 Å range at the Born–Oppenheimer approximation.

Tracks To Therapy, Robert Katz, F. A. Cucinotta

Robert Katz Publications

Studies of the structure of particle tracks have led to models of track effects based on radial dose and radiobiological target theory that have been very successful in describing and predicting track effects in physical, chemical, and biological systems. For describing mammalian cellular inactivation two inactivation modes are required, called gamma-kill aid ion-kill, the first due to synergistic effects of delta rays from adjacent ion paths thus resembling the effects from gamma rays, and the second to the effects of single ion transits through a cell nucleus. The ion-kill effect is more severe, where the fraction of cells experiencing ion …

Thermodynamical Stability Of Ch3ono And Ch3ono-: A Coupled-Cluster And Hartree-Fock-Density-Functional-Theory Study, Gennady L. Gutsev, Puru Jena, Rodney J. Bartlett

Physics Publications

The structure and thermodynamic stability of methylnitrite and its anion are studied by the infinite-order coupled-cluster method with all singles and doubles and noniterative inclusion of triple excitations [CCSD(T)] and Hartree–Fock-density-functional theory (HFDFT). We have optimized the geometries and computed the harmonic vibrational frequencies of major fragments, H2, CH, NH, OH, CN, N2, CO, NO, O2, CH2, NH2, H2O, HCN, HNC, HCO, HNO, O2H, CO2, NO2, CH3, NH3, CNH2, HCO2, HNO2, CH3N, CH3O, CH3NO, CH3ON, CH2NO2, and their anions, when the latter exist. Fragmentation energies obtained at both levels of theory are rather close to each other, except for channels …

Search For Exchange-Antisymmetric Two-Photon States, D. Demille, D. Budker, N. Derr, Edward Deveney

Physics Faculty Publications

Atomic two-photon J = 0↔J^′ = 1 transitions are forbidden for photons of the same energy. This selection rule is related to the fact that photons obey Bose-Einstein statistics. We have searched for small violations of this selection rule by studying transitions in atomic Ba. We set a limit on the probability v that photons are in exchange-antisymmetric states: v<1.2×10^-7.

Neutron Stars And Black Holes As Machos, Aparna Venkatesan, Angela V. Olinto, James W. Truran

Physics and Astronomy

We consider the contribution of neutron stars and black holes to the dynamical mass of galactic halos. In particular, we show that if these compact objects were produced by an early generation of stars with initial metallicity 10^-4 Z_☉, they can contribute at most 30%-40% of the Galactic halo mass without creating supersolar levels of enrichment. We show that the case for halo neutron stars and black holes cannot be rejected on metal overproduction arguments alone because of the critical factor of the choice of progenitor metallicity in determining the yields. We show that this scenario satisfies …

Midisuperspace Models Of Canonical Quantum Gravity, Charles G. Torre

All Physics Faculty Publications

A midisuperspace model is a field theory obtained by symmetry reduction of a parent gravitational theory. Such models have proven useful for exploring the classical and quantum dynamics of the gravitational field. I present three recent classes of results pertinent to canonical quantization of vacuum general relativity in the context of midisuperspace models. (1) I give necessary and sufficient conditions such that a given symmetry reduction can be performed at the level of the Lagrangian or Hamiltonian.(2) I discuss the Hamiltonian formulation of models based upon cylindrical and toroidal symmetry. In particular, I explain how these models can be identified …

Evolution Of The Electronic Structure And Properties Of Neutral And Charged Aluminum Clusters: A Comprehensive Analysis, B. K. Rao, P. Jena

Physics Publications

Density-functional theory with generalized gradient approximation for the exchange-correlation potential has been used to calculate the global equilibrium geometries and electronic structure of neutral, cationic, and anionic aluminumclusters containing up to 15 atoms. The total energies of these clusters are then used to study the evolution of their binding energy, relative stability, fragmentation channels, ionization potential, and vertical and adiabatic electron affinities as a function of size. The geometries are found to undergo a structural change from two dimensional to three dimensional when the cluster contains 6 atoms. An interior atom emerges only when clusters contain 11 or more atoms. …

The Non-Local Universe: The New Physics And Matters Of The Mind, Robert Nadeau, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Books and Book Chapters

Classical physics states that physical reality is local, or that a measurement at one point in space cannot cannot influence what occurs at another beyond a fairly short distance. Until recently this seemed like an immutable truth in nature. However, in 1997 experiments were conducted in which light particles (photons) originated under certain conditions and traveled in opposite directions to detectors located about seven miles apart. The amazing results indicated that the photons "interacted" or "communicated" with one another instantly or "in no time," leading to the revelation that physical reality is non-local--a discovery that Robert Nadeau and Menas Kafatos …

Structure And Stability Of The Alx And Alx- Species, Gennady L. Gutsev, Puru Jena, Rodney J. Bartlett

Physics Publications

The electronic and geometrical structures of the ground and low-lying excited states of the diatomic AlX and AlX− series (X=H, Li, Be, B, C, N, O, and F) are calculated by the coupled-cluster method with all singles and doubles and noniterative inclusion of triples using a large atomic natural orbital basis. All the ground-state AlX molecules except for AlF can attach an additional electron and form ground-state AlX− anions. The ground-state AlBe−, AlB−, AlC−, AlN−, and AlO− anions possess excited states that are stable toward autodetachment of an extra electron; AlBe− also has a second excited state. Low-lying excited states …