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Accelerating Full Configuration Interaction Calculations for Nuclear Structure (open access)

Accelerating Full Configuration Interaction Calculations for Nuclear Structure

One of the emerging computational approaches in nuclear physics is the full configuration interaction (FCI) method for solving the many-body nuclear Hamiltonian in a sufficiently large single-particle basis space to obtain exact answers - either directly or by extrapolation. The lowest eigenvalues and correspondingeigenvectors for very large, sparse and unstructured nuclear Hamiltonian matrices are obtained and used to evaluate additional experimental quantities. These matrices pose a significant challenge to the design and implementation of efficient and scalable algorithms for obtaining solutions on massively parallel computer systems. In this paper, we describe the computational strategies employed in a state-of-the-art FCI code MFDn (Many Fermion Dynamics - nuclear) as well as techniques we recently developed to enhance the computational efficiency of MFDn. We will demonstrate the current capability of MFDn and report the latest performance improvement we have achieved. We will also outline our future research directions.
Date: April 14, 2008
Creator: Yang, Chao; Sternberg, Philip; Maris, Pieter; Ng, Esmond; Sosonkina, Masha; Le, Hung Viet et al.
System: The UNT Digital Library
Flashing Slurry Releases (open access)

Flashing Slurry Releases

The Hanford K Basin Closure Project involves the retrieval, transfer and processing of radioactive contaminated slurries containing partially corroded spent nuclear fuel from the K Basin spent fuel pools. The spent fuel is primarily metallic fuel from the operation of the Hanford reactors. The Sludge Treatment Project is being designed to treat and package this material in preparation for ultimate disposal. The processing of the contaminated slurries includes further corrosion of the remaining uncorroded uranium metal in a large heated vessel to form a more stable metal oxide for packaging and storage.
Date: March 14, 2007
Creator: Schmitt, Bruce E. & Young, Jonathan
System: The UNT Digital Library
Holographic optical elements for the extreme-ultravioletregime (open access)

Holographic optical elements for the extreme-ultravioletregime

As the development of extreme ultraviolet (EUV) lithography progresses, interest grows in the extension of traditional optical components to the EUV regime. The strong absorption of EUV by most materials and its extremely short wavelength, however, makes it very difficult to implement many components that are commonplace in the longer wavelength regimes. One such component is the diffractive optical element used, for example, in illumination systems to efficiently generate modified pupil fills. Here we demonstrate the fabrication and characterization of EUV binary phase-only computer-generated holograms allowing arbitrary far-field diffraction patterns to be generated.
Date: August 14, 2006
Creator: Naulleau, Patrick P.; Salmassi, Farhad; Gullikson, Eric M. & Anderson, Erik H.
System: The UNT Digital Library
New and Novel Nondestructive Neutron and Gamma-Ray Technologies Applied to Safeguards (open access)

New and Novel Nondestructive Neutron and Gamma-Ray Technologies Applied to Safeguards

None
Date: December 14, 2007
Creator: Dougan, A. D.; Snyderman, N. J.; Nakae, L. F.; Dietrich, D. D.; Kerr, P. L.; Wang, T. F. et al.
System: The UNT Digital Library
Optical Switching in VO2 films by below-gap excitation (open access)

Optical Switching in VO2 films by below-gap excitation

We study the photo-induced insulator-metal transition in VO2, correlating threshold and dynamic evolution with excitation wavelength. In high-quality single crystal samples, we find that switching can only be induced with photon energies above the 670-meV gap. This contrasts with the case of polycrystalline films, where formation of the metallic state can also be triggered with photon energies as low as 180 meV, well below the bandgap. Perfection of this process may be conducive to novel schemes for optical switches, limiters and detectors, operating at room temperature in the mid-IR.
Date: March 14, 2008
Creator: Dipartimento di Fisica, Universita?di Brescia, Italy
System: The UNT Digital Library
Investigating the Stability and Accuracy of the Phase Response for NOx Sensing 5% Mg-modified LaCrO3 Electrodes (open access)

Investigating the Stability and Accuracy of the Phase Response for NOx Sensing 5% Mg-modified LaCrO3 Electrodes

Impedance spectroscopy measurements were carried out on LaCr{sub 0.95}Mg{sub 0.05}O{sub 3} (LCM) asymmetric interdigitated electrodes supported on fully stabilized 8-mol% Y{sub 2}O{sub 3}-stabilized ZrO{sub 2} (YSZ) electrolytes. Experiments were carried out using 0-50 ppm NO{sub x}, 5-15% O{sub 2} with N{sub 2} as the balance, over temperatures ranging from 600-700 C. AC measurements taken at a constant frequency between 1-100 Hz indicated the phase response of the sensor was less sensitive to fluctuations in the O{sub 2} concentration and the baseline drift was limited. Specific frequencies were observed where the sensor response was essentially temperature independent.
Date: June 14, 2007
Creator: Murray, E. P.; Novak, R. F.; Kubinski, D. J.; Soltis, R. E.; Visser, J. H.; Woo, L. Y. et al.
System: The UNT Digital Library
The National Ignition Facility and the Golden Age of High Energy Density Science (open access)

The National Ignition Facility and the Golden Age of High Energy Density Science

The National Ignition Facility (NIF) is a 192-beam Nd:glass laser facility being constructed at the Lawrence Livermore National Laboratory (LLNL) to conduct research in inertial confinement fusion (ICF) and high energy density (HED) science. When completed, NIF will produce 1.8 MJ, 500 TW of ultraviolet light, making it the world's largest and highest-energy laser system. The NIF is poised to become the world's preeminent facility for conducting ICF and fusion energy research and for studying matter at extreme densities and temperatures.
Date: August 14, 2007
Creator: Moses, Edward
System: The UNT Digital Library
Investigating Inflation in Type IIA (open access)

Investigating Inflation in Type IIA

We prove that inflation is forbidden in the most well understood class of semi-realistic type IIA string compactifications: Calabi-Yau compactifications with only standard NS-NS 3-form flux, R-R fluxes, D6-branes and O6-planes at large volume and small string coupling. With these ingredients, the first slow-roll parameter satisfies {epsilon} {ge} 27/13 whenever V > 0, ruling out both inflation (including brane/anti-brane inflation) and de Sitter vacua in this limit. Our proof is based on the dependence of the 4-dimensional potential on the volume and dilaton moduli in the presence of fluxes and branes. We also describe broader classes of IIA models which may include cosmologies with inflation and/or de Sitter vacua. The inclusion of extra ingredients, such as NS 5-branes and geometric or non-geometric NS-NS fluxes, evades the assumptions used in deriving the no-go theorem. We focus on NS 5-branes and outline how such ingredients may prove fruitful for cosmology, but we do not provide an explicit model. We contrast the results of our IIA analysis with the rather different situation in IIB.
Date: December 14, 2007
Creator: Hertzberg, Mark P.; /MIT; Kachru, Shamit; /Stanford U., Phys. Dept. /SLAC; Taylor, Washington; Tegmark, Max et al.
System: The UNT Digital Library
Theoretical Overview on Recent Developments in Transverse Spin Physics (open access)

Theoretical Overview on Recent Developments in Transverse Spin Physics

Transverse-spin physics has been very active and rapidly developing in the last few years. In this talk, I will briefly summarize recent theoretical developments, focusing on the associated QCD dynamics in transverse spin physics.
Date: January 14, 2009
Creator: Yuan, Feng
System: The UNT Digital Library
Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid (open access)

Localized Pd Overgrowth on Cubic Pt Nanocrystals for Enhanced Electrocatalytic Oxidation of Formic Acid

Single crystalline surface such as (100), (111), (110) has been studied as an idealized platform for electrocatalytic reactions since the atomic arrangement affects a catalytic property. The secondary metal deposition on these surfaces also alters the catalytic property often showing improvement such as poisoning decrease. On the other hand, electrocatalysts used for practical purpose usually have a size on the order of nanometers. Therefore, linking the knowledge from single crystalline studies to nanoparticle catalysts is of enormous importance. Recently, the Pt nanoparticles which surface structure was preferentially oriented was synthesized and used as electrocatalysts. Here, we demonstrate a rational design of a binary metallic nanocatalyst based on the single crystalline study.
Date: December 14, 2007
Creator: Lee, Hyunjoo; Habas, Susan; Somorjai, Gabor & Yang, Peidong
System: The UNT Digital Library
Spontaneous Superlattice Formation in Nanorods through PartialCation Exchange (open access)

Spontaneous Superlattice Formation in Nanorods through PartialCation Exchange

Lattice mismatch strains are widely known to controlnanoscale pattern formation in heteroepitaxy, but such effects have notbeen exploited in colloidal nanocrystal growth. We demonstrate acolloidal route to synthesizing CdS-Ag2S nanorod superlattices throughpartial cation exchange. Strain induces the spontaneous formation ofperiodic structures. Ab initio calculations of the interfacial energy andmodeling of strain energies show that these forces drive theself-organization. The nanorod superlattices exhibit high stabilityagainst ripening and phase mixing. These materials are tunablenear-infrared emitters with potential applications as nanometer-scaleoptoelectronic devices.
Date: March 14, 2007
Creator: Robinson, Richard D.; Sadtler, Bryce; Demchenko, Denis O.; Erdonmez, Can K.; Wang, Lin-Wang & Alivisatos, A. Paul
System: The UNT Digital Library
Low-frequency asymptotic analysis of seismic reflection from afluid-saturated medium (open access)

Low-frequency asymptotic analysis of seismic reflection from afluid-saturated medium

Reflection of a seismic wave from a plane interface betweentwo elastic media does not depend on the frequency. If one of the mediais poroelastic and fluid-saturated, then the reflection becomesfrequency-dependent. This paper presents a low-frequency asymptoticformula for the reflection of seismic plane p-wave from a fluid-saturatedporous medium. The obtained asymptotic scaling of the frequency-dependentcomponent of the reflection coefficient shows that it is asymptoticallyproportional to the square root of the product of the reservoir fluidmobility and the frequency of the signal. The dependence of this scalingon the dynamic Darcy's law relaxation time is investigated as well.Derivation of the main equations of the theory of poroelasticity from thedynamic filtration theory reveals that this relaxation time isproportional to Biot's tortuosity parameter.
Date: April 14, 2004
Creator: Silin, D.B.; Korneev, V.A.; Goloshubin, G.M. & Patzek, T.W.
System: The UNT Digital Library
Decomposition of the Multistatic Response Matrix and Target Characterization (open access)

Decomposition of the Multistatic Response Matrix and Target Characterization

Decomposition of the time-reversal operator for an array, or equivalently the singular value decomposition of the multistatic response matrix, has been used to improve imaging and localization of targets in complicated media. Typically, each singular value is associated with one scatterer even though it has been shown in several cases that a single scatterer can generate several singular values. In this paper we review the analysis of the time-reversal operator (TRO), or equivalently the multistatic response matrix (MRM), of an array system and a small target. We begin with two-dimensional scattering from a small cylinder then show the results for a small non-spherical target in three dimensions. We show that the number and magnitudes of the singular values contain information about target composition, shape, and orientation.
Date: February 14, 2008
Creator: Chambers, D H
System: The UNT Digital Library
Erratum: High power impulse magnetron sputtering:Current-voltage-time characteristics indicate the onset of sustainedself-sputtering (open access)

Erratum: High power impulse magnetron sputtering:Current-voltage-time characteristics indicate the onset of sustainedself-sputtering

None
Date: December 14, 2007
Creator: Anders, Andre; Andersson, Joakim & Ehiasarian, Arutiun
System: The UNT Digital Library
Spectroscopic Characterization and Simulation of Chemical Sputtering Using the DiMES Porous Plug Injector in DIII-D (open access)

Spectroscopic Characterization and Simulation of Chemical Sputtering Using the DiMES Porous Plug Injector in DIII-D

None
Date: March 14, 2007
Creator: McLean, A. G.; Davis, J. W.; Stangeby, P. C.; Brooks, N. H.; Whyte, D. G.; Allen, S. L. et al.
System: The UNT Digital Library
Observation of B+ to b_1+K0 and Search for B-meson Decays to b_10K0 and b_1pi0 (open access)

Observation of B+ to b_1+K0 and Search for B-meson Decays to b_10K0 and b_1pi0

We present the results of searches for decays of B mesons to final states with a b{sub 1} meson and a neutral pion or kaon. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent 465 million B{bar B} pairs produced in e{sup +}e{sup -} annihilation. The results for the branching fractions are, in units of 10{sup -6}, {Beta}(B{sup +} {yields} b{sub 1}{sup +}K{sup 0}) = 9.6 {+-} 1.7 {+-} 0.9, {Beta}(B{sup 0} {yields} b{sub 1}{sup 0}K{sup 0}) = 5.1 {+-} 1.8 {+-} 0.5 (< 7.8), {Beta}(B{sup +} {yields} b{sub 1}{sup +} {pi}{sup 0}) = 1.8 {+-} 0.9 {+-} 0.2 (<3.3), and {Beta}(B{sup 0} {yields} b{sub 1}{sup 0}{pi}{sup 0}) = 0.4 {+-} 0.8 {+-} 0.2 (<1.9), with the assumption that {Beta}(b{sub 1} {yields} {omega}{pi}) = 1. They also measure the charge asymmetry {Alpha}{sub ch} (B{sup +} {yields} b{sub 1}{sup +}K{sup 0}) = -0.03 {+-} 0.15 {+-} 0.02. The first error quoted is statistical, the second systematic, and the upper limits in parentheses indicate the 90% confidence level.
Date: May 14, 2008
Creator: Aubert, B.
System: The UNT Digital Library
A Measurement of the Spatial Distribution of Diffuse TeV Gamma Ray Emission from the Galactic Plane with Milagro (open access)

A Measurement of the Spatial Distribution of Diffuse TeV Gamma Ray Emission from the Galactic Plane with Milagro

Diffuse {gamma}-ray emission produced by the interaction of cosmic-ray particles with matter and radiation in the Galaxy can be used to probe the distribution of cosmic rays and their sources in different regions of the Galaxy. With its large field of view and long observation time, the Milagro Gamma Ray Observatory is an ideal instrument for surveying large regions of the Northern Hemisphere sky and for detecting diffuse {gamma}-ray emission at very high energies. Here, the spatial distribution and the flux of the diffuse {gamma}-ray emission in the TeV energy range with a median energy of 15 TeV for Galactic longitudes between 30{sup o} and 110{sup o} and between 136{sup o} and 216{sup o} and for Galactic latitudes between -10{sup o} and 10{sup o} are determined. The measured fluxes are consistent with predictions of the GALPROP model everywhere except for the Cygnus region (l {element_of} [65{sup o}, 85{sup o}]). For the Cygnus region, the flux is twice the predicted value. This excess can be explained by the presence of active cosmic ray sources accelerating hadrons which interact with the local dense interstellar medium and produce gamma rays through pion decay.
Date: May 14, 2008
Creator: Abdo, A. A.; Allen, B.; Aune, T.; Berley, D.; Blaufuss, E.; Casanova, S. et al.
System: The UNT Digital Library
Plastic deformation in Al (Cu) interconnects stressed by electromigration and studied by synchrotron polychromatic X-ray microdiffraction (open access)

Plastic deformation in Al (Cu) interconnects stressed by electromigration and studied by synchrotron polychromatic X-ray microdiffraction

We report here an in-depth synchrotron radiation based white beam X-ray microdiffraction study of plasticity in individual grains of an Al (Cu) interconnect during the early stage of electromigration. The study shows a rearrangement of the geometrically necessary dislocations (GND) in bamboo typed grains during that stage. We find that about 90percent of the GNDs are oriented so that their line direction is the closest to the current flow direction. In non-bamboo typed grains, the Laue peak positions shift, indicating that the grains rotate. An analysis in terms of force directions has been carried out and is consistent with observed electromigration induced grain rotation and bending.
Date: May 14, 2008
Creator: Source, Advanced Light; UCLA; Chen, Kai; Chen, Kai; Tamura, Nobumichi; Valek, Bryan C. et al.
System: The UNT Digital Library
Searching for Gluinos at the Tevatron (open access)

Searching for Gluinos at the Tevatron

This letter describes how to perform model-independent searches for new pair-produced color octet particles that each subsequently decay into two jets plus missing energy at the Tevatron. Current searches are not sensitive to all regions of parameter space because they employ CMSSM-motivated cuts. Optimizing the H{sub T} and E{sub T} cuts expands the sensitivity of searches for all kinematically allowed decays.
Date: March 14, 2008
Creator: Alwall, Johan; Le, My-Phuong; Lisanti, Mariangela; Wacker, Jay G. & /SLAC /Stanford U., Phys. Dept.
System: The UNT Digital Library
The total charm cross section (open access)

The total charm cross section

We assess the theoretical uncertainties on the total charm cross section. We discuss the importance of the quark mass, the scale choice and the parton densities on the estimate of the uncertainty. We conclude that the uncertainty on the total charm cross section is difficult to quantify.
Date: September 14, 2007
Creator: Vogt, R
System: The UNT Digital Library
Simulating atmosphere flow for wind energy applications with WRF-LES (open access)

Simulating atmosphere flow for wind energy applications with WRF-LES

Forecasts of available wind energy resources at high spatial resolution enable users to site wind turbines in optimal locations, to forecast available resources for integration into power grids, to schedule maintenance on wind energy facilities, and to define design criteria for next-generation turbines. This array of research needs implies that an appropriate forecasting tool must be able to account for mesoscale processes like frontal passages, surface-atmosphere interactions inducing local-scale circulations, and the microscale effects of atmospheric stability such as breaking Kelvin-Helmholtz billows. This range of scales and processes demands a mesoscale model with large-eddy simulation (LES) capabilities which can also account for varying atmospheric stability. Numerical weather prediction models, such as the Weather and Research Forecasting model (WRF), excel at predicting synoptic and mesoscale phenomena. With grid spacings of less than 1 km (as is often required for wind energy applications), however, the limits of WRF's subfilter scale (SFS) turbulence parameterizations are exposed, and fundamental problems arise, associated with modeling the scales of motion between those which LES can represent and those for which large-scale PBL parameterizations apply. To address these issues, we have implemented significant modifications to the ARW core of the Weather Research and Forecasting model, including the …
Date: January 14, 2008
Creator: Lundquist, J K; Mirocha, J D; Chow, F K; Kosovic, B & Lundquist, K A
System: The UNT Digital Library
A Parameterization Invariant Approach to the Statistical Estimation of the CKM Phase alpha (open access)

A Parameterization Invariant Approach to the Statistical Estimation of the CKM Phase alpha

In contrast to previous analyses, we demonstrate a Bayesian approach to the estimation of the CKM phase {alpha} that is invariant to parameterization. We also show that in addition to computing the marginal posterior in a Bayesian manner, the distribution must also be interpreted from a subjective Bayesian viewpoint. Doing so gives a very natural interpretation to the distribution. We also comment on the effect of removing information about {beta}{sup 00}.
Date: April 14, 2008
Creator: Morris, Robin D.; /RIACS, Mtn. View & Cohen-Tanugi, Johann
System: The UNT Digital Library
Mask inspection microscopy with 13.2 nm table-top laser illumination (open access)

Mask inspection microscopy with 13.2 nm table-top laser illumination

We report the demonstration of a reflection microscope that operates at 13.2-nm wavelength with a spatial resolution of 55 {+-} 3 nm. The microscope uses illumination from a table-top EUV laser to acquire aerial images of photolithography masks with a 20 second exposure time. The modulation transfer function of the optical system was characterized.
Date: October 14, 2008
Creator: Brizuela, Fernando; Wang, Yong; Brewer, Courtney A.; Pedaci, Francesco; Chao, Weilun; Anderson, Erik H. et al.
System: The UNT Digital Library
Versatile microbial surface-display for environmental remediation and biofuels production (open access)

Versatile microbial surface-display for environmental remediation and biofuels production

Surface display is a powerful technique that utilizes natural microbial functional components to express proteins or peptides on the cell exterior. Since the reporting of the first surface-display system in the mid-1980s, a variety of new systems have been reported for yeast, Gram-positive and Gram-negative bacteria. Non-conventional display methods are emerging, eliminating the generation of genetically modified microorganisms. Cells with surface display are used as biocatalysts, biosorbents and biostimulants. Microbial cell-surface display has proven to be extremely important for numerous applications ranging from combinatorial library screening and protein engineering to bioremediation and biofuels production.
Date: February 14, 2008
Creator: Wu, Cindy H.; Mulchandani, Ashok & Chen, wilfred
System: The UNT Digital Library