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Physics Faculty Publications

2008

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Articles 1 - 30 of 71

Full-Text Articles in Physical Sciences and Mathematics

Contamination Cannot Explain The Lack Of Large-Scale Power In The Cosmic Microwave Background Radiation, Emory F. Bunn, Austin Bourdon Dec 2008

Contamination Cannot Explain The Lack Of Large-Scale Power In The Cosmic Microwave Background Radiation, Emory F. Bunn, Austin Bourdon

Physics Faculty Publications

Several anomalies appear to be present in the large-angle cosmic microwave background (CMB) anisotropy maps of the Wilkinson Microwave Anisotropy Probe. One of these is a lack of large-scale power. Because the data otherwise match standard models extremely well, it is natural to consider perturbations of the standard model as possible explanations. We show that, as long as the source of the perturbation is statistically independent of the source of the primary CMB anisotropy, no such model can explain this large-scale power deficit. On the contrary, any such perturbation always reduces the probability of obtaining any given low value of …

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Scattering Of An Electromagnetic Plane Wave By A Luneburg Lens. Iii. Finely Stratified Sphere Model, James A. Lock Dec 2008

Scattering Of An Electromagnetic Plane Wave By A Luneburg Lens. Iii. Finely Stratified Sphere Model, James A. Lock

Physics Faculty Publications

The parallel iteration procedure for computing scattering by a multilayer sphere is described. The procedure uses a successive doubling strategy applied to four sets of multiple-scattering amplitudes, which is reminiscent of the fast Fourier transform (FFT) algorithm. The procedure is then used to calculate scattering of a plane wave by a modified Luneburg lens. The evolution of the transmission rainbow for the Luneburg lens parameter f > 1 into an orbiting ray for f = 1 and into a series of morphology-dependent resonances for f < 1 is studied, and various features of the scattered intensity as a function of scattering angle are commented on. It is found that some resonances are formed without the presence of an exterior centrifugal barrier to confine them. (C) 2008 Optical Society of America

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Rainbows In The Grass. Ii. Arbitrary Diagonal Incidence, Charles L. Adler, James A. Lock, Richard W. Fleet Dec 2008

Rainbows In The Grass. Ii. Arbitrary Diagonal Incidence, Charles L. Adler, James A. Lock, Richard W. Fleet

Physics Faculty Publications

We consider external reflection rainbow caustic,,; due to the reflection of light from a pendant droplet where the light rays are at an arbitrary angle with respect to the horizontal. We compare this theory to observation of glare spots from, pendant drops on grass; we also consider the potential application of this theory to the determination of liquid surface tension. (C) 2008 Optical Society of America

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Scattering Of An Electromagnetic Plane Wave By A Luneburg Lens. I. Ray Theory, James A. Lock Dec 2008

Scattering Of An Electromagnetic Plane Wave By A Luneburg Lens. I. Ray Theory, James A. Lock

Physics Faculty Publications

For a plane wave incident on either a Luneburg lens or a modified Luneburg lens, the magnitude and phase of the transmitted electric field are calculated as a function of the scattering angle in the context of ray theory. It is found that the ray trajectory and the scattered intensity are not uniformly convergent in the vicinity of edge ray incidence on a Luneburg lens, which corresponds to the semiclassical phenomenon of orbiting. In addition, it is found that rays transmitted through a large-focal-length modified Luneburg lens participate in a far-zone rainbow, the details of which are exactly analytically soluble …

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Scattering Of An Electromagnetic Plane Wave By A Luneburg Lens. Ii. Wave Theory, James A. Lock Dec 2008

Scattering Of An Electromagnetic Plane Wave By A Luneburg Lens. Ii. Wave Theory, James A. Lock

Physics Faculty Publications

The partial wave scattering and interior amplitudes for the interaction of an electromagnetic plane wave with a modified Luneburg lens are derived in terms of the exterior and interior radial functions of the scalar radiation potentials evaluated at the lens surface. A Debye series decomposition of these amplitudes is also performed and discussed. The effective potential inside the lens for the transverse electric polarization is qualitatively examined, and the approximate lens size parameters of morphology-dependent resonances are determined. Finally, the physical optics model is used to calculate wave scattering in the vicinity of the ray theory orbiting condition in order …

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Rainbows In The Grass. I. External Reflection Rainbows From Pendant Droplets, James A. Lock, Charles L. Adler, Richard W. Fleet Dec 2008

Rainbows In The Grass. I. External Reflection Rainbows From Pendant Droplets, James A. Lock, Charles L. Adler, Richard W. Fleet

Physics Faculty Publications

In the mid-morning on a sunny day one can sometimes see glare spots associated with uncolored "rainbow" (i.e., fold) caustics due to the sunlight reflected from the surface of dew or guttation drops. We show that these dewdrop reflection rainbows are due to places on the droplet (i.e., from an "inflection circle") where its Gaussian curvature becomes zero. We work out the theory of such caustics with horizontally incident light and present a comparison of the theory to measurements made in the laboratory. (C) 2008 Optical Society of America

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Spectral Time Moment Analysis Of Microgel Deswelling: Effect Of The Heating Rate, Kiril A. Streletzky, John T. Mckenna Nov 2008

Spectral Time Moment Analysis Of Microgel Deswelling: Effect Of The Heating Rate, Kiril A. Streletzky, John T. Mckenna

Physics Faculty Publications

Microgel nanoparticles were synthesized in aqueous solutions of neutral polymer hydroxypropylcellulose (HPC) through the self-association of amphiphilic HPC molecules and the subsequent cross linking at room temperature. Dynamic Light Scattering was used to study the transport properties of HPC microgels below and above the volume phase transition. Highly nonexponential, multimodal microgel spectra were observed and successfully analyzed by spectral time moment analysis. This article expands earlier results and focuses on the effect of the heating rate on microgel deswelling. During the fast heating two identified microgel modes with apparent hydrodynamic radii (RH) of 25–30 nm and 400–650 nm collapse into …

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Nonlinear Magneto-Optic Polarization Rotation With Intense Laser Fields, Paul S. Hsu, Anil K. Patnaik, George R. Welch Nov 2008

Nonlinear Magneto-Optic Polarization Rotation With Intense Laser Fields, Paul S. Hsu, Anil K. Patnaik, George R. Welch

Physics Faculty Publications

We have studied the nonlinear Faraday effect with intense linear polarized light in an optically thick atomic rubidium vapor. We demonstrate that the polarization rotation rate (rotation angle per unit magnetic field, in the limit of low field) has a maximum value as the intensity and density are increased. We also show that the optimal sensitivity of an optical magnetometer based on this system reaches a saturation value as the intensity and density are increased.

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Morphology Of The Dayside Ionosphere Of Venus: Implications For Ion Outflows, Jane L. Fox Nov 2008

Morphology Of The Dayside Ionosphere Of Venus: Implications For Ion Outflows, Jane L. Fox

Physics Faculty Publications

The nightside ionosphere of Venus is formed mostly by day-to-night transport of ions below the ionopause, with a small contribution from precipitation of energetic electrons from the wake. This nightward flux of ions should result in dayside ionospheres that are characterized by smaller electron density scale heights at high altitudes than those that are characteristic of diffusive equilibrium. In order to determine both the maximum possible values of the upward fluxes and the upward fluxes implied by comparison of our computed ion and electron density profiles to measurements, we have constructed more than 60 models of the high solar activity …

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Turbulent Dispersion In Cloudy Boundary Layers, Remco A. Verzijlbergh, Harmen J.J. Jonker, Thijs Heus, J. Vilà-Guerau De Arellano Nov 2008

Turbulent Dispersion In Cloudy Boundary Layers, Remco A. Verzijlbergh, Harmen J.J. Jonker, Thijs Heus, J. Vilà-Guerau De Arellano

Physics Faculty Publications

Compared to dry boundary layers, dispersion in cloud-topped boundary layers has received less attention. In this LES based numerical study we investigate the dispersion of a passive tracer in the form of Lagrangian particles for four kinds of atmospheric boundary layers: 1) a dry convective boundary layer (for reference), 2) a "smoke" cloud boundary layer in which the turbulence is driven by radiative cooling, 3) a stratocumulus topped boundary layer and 4) a shallow cumulus topped boundary layer. We show that the dispersion characteristics of the smoke cloud boundary layer as well as the stratocumulus situation can be well understood …

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Metal Modulation Epitaxy Growth For Extremely High Hole Concentrations Above 10(19) Cm(-3) In Gan, Gon Namkoong, Elaissa Trybus, Kyung Kuen Lee, Michael Moseley, W. Alan Doolittle, David C. Look Oct 2008

Metal Modulation Epitaxy Growth For Extremely High Hole Concentrations Above 10(19) Cm(-3) In Gan, Gon Namkoong, Elaissa Trybus, Kyung Kuen Lee, Michael Moseley, W. Alan Doolittle, David C. Look

Physics Faculty Publications

The free hole carriers in GaN have been limited to concentrations in the low 1018 cm−3 range due to the deep activation energy, lower solubility, and compensation from defects, therefore, limiting doping efficiency to about 1%. Herein, we report an enhanced doping efficiency up to ∼ 10% in GaN by a periodic doping, metal modulation epitaxy growth technique. The hole concentrations grown by periodically modulating Ga atoms and Mg dopants were over ∼ 1.5×1019 cm−3.

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Electron Tunneling In A Strained N-Type Si1−Xgex/Si/Si1−Xgex Double-Barrier Structure, K. M. Hung, T. H. Cheng, W. P. Huang, K. Y. Wang, H. H. Cheng, Greg Sun, R. A. Soref Sep 2008

Electron Tunneling In A Strained N-Type Si1−Xgex/Si/Si1−Xgex Double-Barrier Structure, K. M. Hung, T. H. Cheng, W. P. Huang, K. Y. Wang, H. H. Cheng, Greg Sun, R. A. Soref

Physics Faculty Publications

We report electrical measurements on an n-type Si1−xGex/Si/Si1−xGex double-barrier structure grown on a partially relaxed Si1−yGey buffer layer. Resonance tunneling of Δ4band electrons is demonstrated. This is attributed to the strain splitting in the SiGe buffer layer where the Δ4 band is lowest in energy at the electrode. Since the Δ4 band electrons have a much lighter effective mass along the direction of tunneling current in comparison with that of the Δ2 band electrons, this work presents an advantage over those …

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Surface Magnetoelectric Effect In Ferromagnetic Metal Films, Chun-Gang Duan, Julian P. Velev, Renat F. Sabirianov, Zigiang Zhu, Junhao Chu, Sitaram Jaswal, Evgeny Y. Tsymbal Sep 2008

Surface Magnetoelectric Effect In Ferromagnetic Metal Films, Chun-Gang Duan, Julian P. Velev, Renat F. Sabirianov, Zigiang Zhu, Junhao Chu, Sitaram Jaswal, Evgeny Y. Tsymbal

Physics Faculty Publications

A surface magnetoelectric effect is revealed by density-functional calculations that are applied to ferromagnetic Fe(001), Ni(001), and Co(0001) films in the presence of an external electric field. The effect originates from spin-dependent screening of the electric field which leads to notable changes in the surface magnetization and the surface magnetocrystalline anisotropy. These results are of considerable interest in the area of electrically controlled magnetism and magnetoelectric phenomena.

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Investigation Into The B(E2) Anomaly In 144Nd Using Coulomb Excitation, C. R. Fitzpatrick, V. Werner, R. F. Casten, E. Williams, H. Ai, C. W. Beausang, R. Cakirli, G. Gurdal, A. Heinz, E. A. Mccutchan, D. A. Meyer, E. Novitski, J. Qian, R. Winkler Sep 2008

Investigation Into The B(E2) Anomaly In 144Nd Using Coulomb Excitation, C. R. Fitzpatrick, V. Werner, R. F. Casten, E. Williams, H. Ai, C. W. Beausang, R. Cakirli, G. Gurdal, A. Heinz, E. A. Mccutchan, D. A. Meyer, E. Novitski, J. Qian, R. Winkler

Physics Faculty Publications

The ratio of B(E2) strengths between the lowest lying members of the ground state band in 144Nd, B4/2 = B(E2; 4+1 → 2+1)/B(E2; 2+1 → 0+1), which is used to quantify collectivity in nonmagic nuclei, has been remeasured by means of Coulomb excitation. Ambiguities in literature values for this ratio have been resolved. The results are discussed in terms of the interplay of collective and single-particle degrees of freedom, and in the context of the formation of collective structures in the A = 140 mass region, and more …

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Emissions Scenarios In The Face Of Fossil-Fuel Peaking, Robert J. Brecha Sep 2008

Emissions Scenarios In The Face Of Fossil-Fuel Peaking, Robert J. Brecha

Physics Faculty Publications

Emissions scenarios used by the Intergovernmental Panel on Climate Change (IPCC) are based on detailed energy system models in which demographics, technology and economics are used to generate projections of future world energy consumption, and therefore, of greenhouse gas emissions. We propose in this paper that it is useful to look at a qualitative model of the energy system, backed by data from short- and medium-term trends, to gain a sense of carbon emission bounds. Here we look at what may be considered a lower bound for 21st century emissions given two assumptions: first, that extractable fossil-fuel resources follow the …

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Variation Of The Martian Ionospheric Electron Density From Mars Express Radar Soundings, D. D. Morgan, D. A. Gurnett, D. L. Kirchner, Jane L. Fox, E. Nielsen, J. J. Plaut Sep 2008

Variation Of The Martian Ionospheric Electron Density From Mars Express Radar Soundings, D. D. Morgan, D. A. Gurnett, D. L. Kirchner, Jane L. Fox, E. Nielsen, J. J. Plaut

Physics Faculty Publications

The Mars Advanced Radar for Subsurface and Ionospheric Sounding aboard Mars Express has been in operation for over 2 years. Between 14 August 2005 and 31 July 2007, we obtain 34,492 ionospheric traces, of which 14,060 yield electron density profiles and 12,291 yield acceptable fits to the Chapman ionospheric model. These results are used to study the Martian ionosphere under changing conditions: the presence or absence of solar energetic particles, solar EUV flux, season, solar zenith angle, and latitude. The 2-year average subsolar maximum electron density n 0 is 1.62 × 105 cm−3, the average subsolar electron …

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Surface Traps In Vapor-Phase-Grown Bulk Zno Studied By Deep Level Transient Spectroscopy, Z-Q. Fang, B. Claflin, David C. Look, Y. F. Dong, H. L. Mosbacker, L. J. Brillson Sep 2008

Surface Traps In Vapor-Phase-Grown Bulk Zno Studied By Deep Level Transient Spectroscopy, Z-Q. Fang, B. Claflin, David C. Look, Y. F. Dong, H. L. Mosbacker, L. J. Brillson

Physics Faculty Publications

Deep level transient spectroscopy, current-voltage, and capacitance-voltage measurements are used to study interface traps in metal-on-bulk-ZnO Schottky barrier diodes (SBDs). c-axis-oriented ZnO samples were cut from two different vapor-phase-grown crystals, and Au- and Pd-SBDs were formed on their (0001) surfaces after remote oxygen-plasma treatment. As compared to Au-SBDs, the Pd-SBDs demonstrated higher reverse-bias leakage current and forward-bias current evidently due to higher carrier concentrations, which might have been caused by hydrogen in-diffusion through the thin Pd metal. The dominant traps included the well-known bulk traps E3 (0.27 eV) and E4 (0.49 eV). In addition, a surface-related trap, …

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Two-Layer Hall-Effect Model With Arbitrary Surface-Donor Profiles: Application To Zno, David C. Look Sep 2008

Two-Layer Hall-Effect Model With Arbitrary Surface-Donor Profiles: Application To Zno, David C. Look

Physics Faculty Publications

A complete two-layer Hall-effect model, allowing arbitrary donor and acceptor profiles, is presented and applied to the problem of conductive surface layers in ZnO. Temperature-dependent mobility and carrier concentration data in the temperature range of 20–320 K are fitted with an efficient algorithm easily implemented in commercial mathematics programs such as MATHCAD. The model is applied to two ZnO samples, grown by the melt (MLT) and hydrothermal (HYD) processes, respectively. Under the assumption of a “square” surface-donor profile, the fitted surface-layer thicknesses are 48 and 2.5 nm, respectively, for the MLT and HYD samples. The surface-donor concentrations are 7.6×1017 …

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Active And Passive Imaging In The Thz Spectral Region: Phenomenology, Dynamic Range, Modes, And Illumination, Douglas T. Petkie, Corey Casto, Frank C. De Lucia, Steven R. Murrill, Brian Redman, Richard L. Espinola, Charmaine C. Franck, Eddie L. Jacobs, Steven T. Griffin, Carl E. Halford, Joe Reynolds, Sean O'Brien, David Tofsted Sep 2008

Active And Passive Imaging In The Thz Spectral Region: Phenomenology, Dynamic Range, Modes, And Illumination, Douglas T. Petkie, Corey Casto, Frank C. De Lucia, Steven R. Murrill, Brian Redman, Richard L. Espinola, Charmaine C. Franck, Eddie L. Jacobs, Steven T. Griffin, Carl E. Halford, Joe Reynolds, Sean O'Brien, David Tofsted

Physics Faculty Publications

The useful compromise between resolution and penetration power of the submillimeter or terahertz (THz) spectral region has long made it attractive for a variety of imaging applications. However, many of the demonstrations of imaging in this spectral region have used strategically oriented targets, especially favorable concealment materials, proximate imaging geometries, etc. This paper reports the results of studies aimed at better understanding the phenomenology of targets, the impact of this phenomenology on various active and passive imaging strategies, and most importantly, the development of imaging strategies that do not require the aforementioned special circumstances. Particular attention is paid to the …

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Structure Of The Catalytic Trimer Of Methanococcus Jannaschii Aspartate Transcarbamoylase In An Orthorhombic Crystal Form, Jacqueline Vitali, Michael J. Colaneri Sep 2008

Structure Of The Catalytic Trimer Of Methanococcus Jannaschii Aspartate Transcarbamoylase In An Orthorhombic Crystal Form, Jacqueline Vitali, Michael J. Colaneri

Physics Faculty Publications

Crystals of the catalytic subunit of Methanococcus jannaschii aspartate transcarbamoylase in an orthorhombic crystal form contain four crystallographically independent trimers which associate in pairs to form stable staggered complexes that are similar to each other and to a previously determined monoclinic C2 form. Each subunit has a sulfate in the central channel. The catalytic subunits in these complexes show flexibility, with the elbow angles of the monomers differing by up to 7.4 degrees between crystal forms. Moreover, there is also flexibility in the relative orientation of the trimers around their threefold axis in the complexes, with a difference of 4 …

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Zn- And O-Face Polarity Effects At Zno Surfaces And Metal Interfaces, Yufeng Dong, Z-Q. Fang, David C. Look, G. Cantwell, J. Zhang, J. J. Song, L. J. Brillson Aug 2008

Zn- And O-Face Polarity Effects At Zno Surfaces And Metal Interfaces, Yufeng Dong, Z-Q. Fang, David C. Look, G. Cantwell, J. Zhang, J. J. Song, L. J. Brillson

Physics Faculty Publications

Depth-resolved cathodoluminescence spectroscopy, current-voltage, capacitance-voltage, and deep level transient spectroscopy of ZnO (0001) Zn- and (000) O-polar surfaces and metal interfaces show systematically higher Zn-face near band edge emission and lower near-surface defect emission. Even with remote plasma decreases of the 2.5 eV near-surface defect emission, (0001)-Zn face emission quality still exceeds that of (000)-O face. Ultrahigh vacuum-deposited Au and Pd diodes on as-received and O2/He plasma-cleaned surfaces display a strong polarity dependence that correlates with defect emissions, traps, and interface chemistry. A comprehensive model accounts for the polarity-dependent transport properties and their correlations with carrier concentration profiles.

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Very High Channel Conductivity In Low-Defect Aln/Gan High Electron Mobility Transistor Structures, A. M. Dabiran, A. M. Wowchak, A. Osinsky, J. Xie, Brian Hertzog, David C. Look, P. P. Chow Aug 2008

Very High Channel Conductivity In Low-Defect Aln/Gan High Electron Mobility Transistor Structures, A. M. Dabiran, A. M. Wowchak, A. Osinsky, J. Xie, Brian Hertzog, David C. Look, P. P. Chow

Physics Faculty Publications

Low defect AlN/GaN high electron mobility transistor (HEMT) structures, with very high values of electron mobility (>1800 cm2/V s) and sheet charge density (>3×1013 cm−2), were grown by rf plasma-assisted molecular beam epitaxy (MBE) on sapphire and SiC, resulting in sheet resistivity values down to ∼ 100 Ω/◻ at room temperature. Fabricated 1.2 μm gate devices showed excellent current-voltage characteristics, including a zero gate saturation current density of ∼ 1.3 A/mm and a peak transconductance of ∼ 260 mS/mm. Here, an all MBE growth of optimized AlN/GaN HEMT structures plus the results …

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Mixing In Shallow Cumulus Clouds Studied By Lagrangian Particle Tracking, Thijs Heus, Gertjan Van Dijk, Harmen J.J. Jonker, Harry E.A. Van Den Akker Aug 2008

Mixing In Shallow Cumulus Clouds Studied By Lagrangian Particle Tracking, Thijs Heus, Gertjan Van Dijk, Harmen J.J. Jonker, Harry E.A. Van Den Akker

Physics Faculty Publications

Mixing between shallow cumulus clouds and their environment is studied using large-eddy simulations. The origin of in-cloud air is studied by two distinct methods: 1) by analyzing conserved variable mixing diagrams (Paluch diagrams) and 2) by tracing back cloud-air parcels represented by massless Lagrangian particles that follow the flow. The obtained Paluch diagrams are found to be similar to many results in the literature, but the source of entrained air found by particle tracking deviates from the source inferred from the Paluch analysis. Whereas the classical Paluch analysis seems to provide some evidence for cloud-top mixing, particle tracking shows that …

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Electroluminescence Efficiency Enhancement Using Metal Nanoparticles, Jacob B. Khurgin, Greg Sun, R. A. Soref Jul 2008

Electroluminescence Efficiency Enhancement Using Metal Nanoparticles, Jacob B. Khurgin, Greg Sun, R. A. Soref

Physics Faculty Publications

We apply the “effective mode volume” theory to evaluate enhancement of the electroluminescence efficiency of semiconductor emitters placed in the vicinity of isolated metal nanoparticles and their arrays. Using the example of an InGaN/GaN quantum-well active region positioned in close proximity to Ag nanospheres, we show that while the enhancement due to isolated metal nanoparticles is large, only modest enhancement can be obtained with ordered array of those particles. We further conclude that random assembly of isolated particles holds an advantage over the ordered arrays for light emitting devices of finite area.

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Reproducible Increased Mg Incorporation And Large Hole Concentration In Gan Using Metal Modulated Epitaxy, Shawn D. Burnham, Gon Namkoong, David C. Look, Bruce Claflin, W. Alan Doolittle Jul 2008

Reproducible Increased Mg Incorporation And Large Hole Concentration In Gan Using Metal Modulated Epitaxy, Shawn D. Burnham, Gon Namkoong, David C. Look, Bruce Claflin, W. Alan Doolittle

Physics Faculty Publications

The metal modulated epitaxy (MME) growth technique is reported as a reliable approach to obtain reproducible large hole concentrations in Mg-doped GaN grown by plasma-assisted molecular-beam epitaxy on c-plane sapphire substrates. An extremely Ga-rich flux was used, and modulated with the Mg source according to the MME growth technique. The shutter modulation approach of the MME technique allows optimal Mg surface coverage to build between MME cycles and Mg to incorporate at efficient levels in GaN films. The maximum sustained concentration of Mg obtained in GaN films using the MME technique was above 7×1020 cm−3, leading …

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Observations Of Neutral Depletion And Plasma Acceleration In A Flowing High-Power Argon Helicon Plasma, C. Mark Denning, Matt Wiebold, John E. Scharer Jul 2008

Observations Of Neutral Depletion And Plasma Acceleration In A Flowing High-Power Argon Helicon Plasma, C. Mark Denning, Matt Wiebold, John E. Scharer

Physics Faculty Publications

Neutral depletion effects are observed in a steady-state flowing argon helicon plasma with a magnetic nozzle for high rf input powers (up to 3 kW). Noninvasive diagnostics including 105 GHz microwave interferometry and optical spectroscopy with collisional-radiative modeling are used to measure the electron density (ne), electron temperature (Te), and neutral density (nn). A region of weak neutral depletion is observed upstream of the antenna where increasing rf power leads to increased electron density (up to ne = 1.6×1013 cm-3) while Te remains essentially constant and …

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3he Spin-Dependent Cross Sections And Sum Rules, K. Slifer, M. Amarian, L. Auerbach, T. Averett, J. Berthot, P. Bertin, B. Bertozzi, K. Mccormick, F. Sabatié, L. Todor Jul 2008

3he Spin-Dependent Cross Sections And Sum Rules, K. Slifer, M. Amarian, L. Auerbach, T. Averett, J. Berthot, P. Bertin, B. Bertozzi, K. Mccormick, F. Sabatié, L. Todor

Physics Faculty Publications

We present a measurement of the spin-dependent cross sections for the 3→He(→e,e′)X reaction in the quasielastic and resonance regions at a four-momentum transfer 0.1≤Q2≤0.9  GeV2. The spin-structure functions have been extracted and used to evaluate the nuclear Burkhardt-Cottingham and extended Gerasimov-Drell-Hearn sum rules for the first time. The data are also compared to an impulse approximation calculation and an exact three-body Faddeev calculation in the quasielastic region.

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Radiation Torque Exerted On A Spheroid: Analytical Solution, Feng Xu, James A. Lock, Gérard Gouesbet, Cameron Tropea Jul 2008

Radiation Torque Exerted On A Spheroid: Analytical Solution, Feng Xu, James A. Lock, Gérard Gouesbet, Cameron Tropea

Physics Faculty Publications

As a companion work to our previous study [F. Xu, , Phys. Rev. E. 75, 026613 (2007)] on radiation force prediction for a homogeneous spheroid, we provide in this paper the analytical solution to the radiation torque exerted by an arbitrarily shaped beam on a spheroid, which can be prolate or oblate, transparent or absorbing. Calculations based upon this theoretical development are performed for both linearly and circularly polarized incident beams, and the results are compared to those of a sphere. Stable orientations of spheroids inside a linearly and a circularly polarized Gaussian beam are predicted. We analyze two physical …

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Three-Dimensional Seismic Array Characterization Study: Experiment And Modeling, Arslan M. Tashmukhambetov, George E. Ioup, Juliette W. Ioup, Natalia A. Sidorovskaia, Joal J. Newcomb Jun 2008

Three-Dimensional Seismic Array Characterization Study: Experiment And Modeling, Arslan M. Tashmukhambetov, George E. Ioup, Juliette W. Ioup, Natalia A. Sidorovskaia, Joal J. Newcomb

Physics Faculty Publications

In the summer of 2003, the Littoral Acoustic Demonstration Center conducted an acoustic characterization experiment for a 21-element marine seismic exploration airgun array of total volume of 0.0588 m3 (3590 in.3). Two Environmental Acoustic Recording System buoys, one with a desensitized hydrophone, were deployed at a depth of 758 m in a water depth of 990 m, near Green’s Canyon in the Gulf of Mexico. Shots over a grid were recorded and calibrated to produce absolute broadband (up to 25 kHz) pressure-time dependencies for a wide range of offsets and arrival angles in the water column. Experimental …

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The Rotational Spectrum Of Chlorine Nitrate (Ciono2): V6 And The V5/V6V9 Dyad, Zbigniew Kisiel, Ewa Bialkowska-Jaworska, Rebecca A. H. Butler, Douglas T. Petkie, Paul Helminger, Frank C. De Lucia Jun 2008

The Rotational Spectrum Of Chlorine Nitrate (Ciono2): V6 And The V5/V6V9 Dyad, Zbigniew Kisiel, Ewa Bialkowska-Jaworska, Rebecca A. H. Butler, Douglas T. Petkie, Paul Helminger, Frank C. De Lucia

Physics Faculty Publications

No abstract provided.

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