RAPID SEPARATION METHOD FOR ACTINIDES IN EMERGENCY AIR FILTER SAMPLES (open access)

RAPID SEPARATION METHOD FOR ACTINIDES IN EMERGENCY AIR FILTER SAMPLES

A new rapid method for the determination of actinides and strontium in air filter samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used in emergency response situations. The actinides and strontium in air filter method utilizes a rapid acid digestion method and a streamlined column separation process with stacked TEVA, TRU and Sr Resin cartridges. Vacuum box technology and rapid flow rates are used to reduce analytical time. Alpha emitters are prepared using cerium fluoride microprecipitation for counting by alpha spectrometry. The purified {sup 90}Sr fractions are mounted directly on planchets and counted by gas flow proportional counting. The method showed high chemical recoveries and effective removal of interferences. This new procedure was applied to emergency air filter samples received in the NRIP Emergency Response exercise administered by the National Institute for Standards and Technology (NIST) in April, 2009. The actinide and {sup 90}Sr in air filter results were reported in {approx}4 hours with excellent quality.
Date: February 3, 2010
Creator: Maxwell, S.; Noyes, G. & Culligan, B.
Object Type: Article
System: The UNT Digital Library
Angle-resolved photoemission studies of lattice polaron formation in the cuprate Ca2CuO2Cl2 (open access)

Angle-resolved photoemission studies of lattice polaron formation in the cuprate Ca2CuO2Cl2

To elucidate the nature of the single-particle excitations in the undoped parent cuprates, we have performed a detailed study of Ca{sub 2}CuO{sub 2}Cl{sub 2} using photoemission spectroscopy. The photoemission lineshapes of the lower Hubbard band are found to be well-described by a polaron model. By comparing the lineshape and temperature dependence of the lower Hubbard band with additional O 2p and Ca 3p states, we conclude that the dominant broadening mechanism arises from the interaction between the photohole and the lattice. The strength of this interaction was observed to be strongly anisotropic and may have important implications for the momentum dependence of the first doped hole states.
Date: May 3, 2010
Creator: Shen, K.M.
Object Type: Article
System: The UNT Digital Library
Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters (open access)

Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters

Integrated energy, environment and economics modeling suggests electrical energy use will increase from 2.4 TWe today to 12 TWe in 2100. It will be challenging to provide 40% of this electrical power from combustion with carbon sequestration, as it will be challenging to provide 30% from renewable energy sources. Thus nuclear power may be needed to provide ~30% by 2100. Calculations of the associated stocks and flows of uranium, plutonium and minor actinides indicate that the proliferation risks at mid-century, using current light-water reactor technology, are daunting. There are institutional arrangements that may be able to provide an acceptable level of risk mitigation, but they will be difficult to implement. If a transition is begun to fast-spectrum reactors at mid-century, without a dramatic change in the proliferation risks of such systems, at the end of the century proliferation risks are much greater, and more resistant to mitigation. The risks of nuclear power should be compared with the risks of the estimated 0.64oC long-term global surface-average temperature rise predicted if nuclear power were replaced with coal-fired power plants without carbon sequestration. Fusion energy, if developed, would provide a source of nuclear power with much lower proliferation risks than fission.
Date: March 3, 2010
Creator: Goldston, Robert J.
Object Type: Report
System: The UNT Digital Library
Investigation of Electron Bernstein Wave (EBW) Coupling and its Critical Dependence on EBW Collisional Loss in High-β, H-mode ST Plasmas (open access)

Investigation of Electron Bernstein Wave (EBW) Coupling and its Critical Dependence on EBW Collisional Loss in High-β, H-mode ST Plasmas

High-β spherical tokamak (ST) plasma conditions cut off propagation of electron cyclotron (EC) waves used for heating and current drive in conventional aspect ratio tokamaks. The electron Bernstein wave (EBW) has no density cutoff and is strongly absorbed and emitted at the EC harmonics, allowing EBWs to be used for heating and current drive in STs. However, this application requires efficient EBW coupling in the high-β, H-mode ST plasma regime. EBW emission (EBE) diagnostics and modelling have been employed on the National Spherical Torus Experiment (NSTX) to study oblique EBW to O-mode (B–X–O) coupling and propagation in H-mode plasmas. Efficient EBW coupling was measured before the L–H transition, but rapidly decayed thereafter. EBE simulations show that EBW collisional damping prior to mode conversion (MC) in the plasma scrape off reduces the coupling efficiency during the H-mode phase when the electron temperature is less than 30 eV inside the MC layer. Lithium evaporation during H-mode plasmas was successfully used to reduce this EBW collisional damping by reducing the electron density and increase the electron temperature in the plasma scrape off. Lithium conditioning increased the measured B–X–O coupling efficiency from less than 10% to 60%, consistent with EBE simulations.
Date: February 3, 2010
Creator: Diem, S. J.; Caughman, J. B.; Efthimion, P. C.; Kugel, H.; LeBlanc, B. P.; Phillips, C. K. et al.
Object Type: Article
System: The UNT Digital Library
Summary of Shock Initiation Data for TATB-based Explosives (open access)

Summary of Shock Initiation Data for TATB-based Explosives

This short summary of previously published data was compiled to provide the actual in-situ gauge data to allow modeling of these experiments. Although the purpose here is to fulfill a deliverable for a JOWOG 9 Focused Exchange (09-006), it is just as applicable to other exchanges as well. The TATB materials described here are Ultra Fine (UF) TATB and LX-17 (92.5% TATB and 7.5% Kel-F by weight), with the details of the experiments provided in the prior publications. The data is provided in the appendices of the document, but will be provided electronically as text files due to being amenable to importing into the code in that manner for comparison.
Date: April 3, 2010
Creator: Vandersall, K S
Object Type: Report
System: The UNT Digital Library
Merged Sounding Value-Added Product (open access)

Merged Sounding Value-Added Product

The Merged Sounding value-added product (VAP) uses a combination of observations from radiosonde soundings, the microwave radiometer (MWR), surface meteorological instruments, and European Centre for Medium-Range Weather Forecasts (ECMWF) model output with a sophisticated scaling/interpolation/smoothing scheme in order to define profiles of the atmospheric thermodynamic state at one-minute temporal intervals and a total of 266 altitude levels.
Date: March 3, 2010
Creator: Troyan, D.
Object Type: Report
System: The UNT Digital Library
Anomalous Fermi-Surface Dependent Pairing in a Self-Doped High-Tc Superconductor (open access)

Anomalous Fermi-Surface Dependent Pairing in a Self-Doped High-Tc Superconductor

We report the discovery of a self-doped multi-layer high T{sub c} superconductor Ba{sub 2}Ca{sub 3}Cu{sub 4}O{sub 8}F{sub 2} (F0234) which contains distinctly different superconducting gap magnitudes along its two Fermi surface(FS) sheets. While formal valence counting would imply this material to be an undoped insulator, it is a self-doped superconductor with a T{sub c} of 60K, possessing simultaneously both electron- and hole-doped FS sheets. Intriguingly, the FS sheet characterized by the much larger gap is the electron-doped one, which has a shape disfavoring two electronic features considered to be important for the pairing mechanism: the van Hove singularity and the antiferromagnetic ({pi}/a, {pi}/a) scattering.
Date: May 3, 2010
Creator: Chen, Y.
Object Type: Article
System: The UNT Digital Library
Doping Dependent Charge Transfer Gap and Realistic Electronic Model of n-type Cuprate Superconductors (open access)

Doping Dependent Charge Transfer Gap and Realistic Electronic Model of n-type Cuprate Superconductors

Based on the analysis of the measurement data of angle-resolved photoemission spectroscopy (ARPES) and optics, we show that the charge transfer gap is significantly smaller than the optical one and is reduced by doping in electron doped cuprate superconductors. This leads to a strong charge fluctuation between the Zhang-Rice singlet and the upper Hubbard bands. The basic model for describing this system is a hybridized two-band t-J model. In the symmetric limit where the corresponding intra- and inter-band hopping integrals are equal to each other, this two-band model is equivalent to the Hubbard model with an antiferromagnetic exchange interaction (i.e. the t-U-J model). The mean-field result of the t-U-J model gives a good account for the doping evolution of the Fermi surface and the staggered magnetization.
Date: May 3, 2010
Creator: Xiang, T.
Object Type: Article
System: The UNT Digital Library
Doping Evolution of the Underlying Fermi Surface in La_2&#8722xSr_xCuO_4 (open access)

Doping Evolution of the Underlying Fermi Surface in La_2&#8722xSr_xCuO_4

We have performed a systematic doping dependent study of La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO) (0.03 {le} x {le} 0.3) by angle-resolved photoemission spectroscopy. In the entire doping range, the underlying 'Fermi surface' determined from the low energy spectral weight approximately satisfies Luttinger's theorem, even down to the lightly-doped region. This is in strong contrast to the result on Ca{sub 2-x}Na{sub x}CuO{sub 2}Cl{sub 2} (Na-CCOC), which shows a strong deviation from Luttinger's theorem. The differences between LSCO and Na-CCOC are correlated with the different behaviors of the chemical potential shift and spectral weight transfer induced by hole doping.
Date: May 3, 2010
Creator: Yoshida, T.
Object Type: Article
System: The UNT Digital Library
Development of Regenerable High Capacity Boron Nitrogen Hydrides as Hydrogen Storage Materials (open access)

Development of Regenerable High Capacity Boron Nitrogen Hydrides as Hydrogen Storage Materials

The objective of this three-phase project is to develop synthesis and hydrogen extraction processes for nitrogen/boron hydride compounds that will permit exploitation of the high hydrogen content of these materials. The primary compound of interest in this project is ammonia-borane (NH{sub 3}BH{sub 3}), a white solid, stable at ambient conditions, containing 19.6% of its weight as hydrogen. With a low-pressure on-board storage and an efficient heating system to release hydrogen, ammonia-borane has a potential to meet DOE's year 2015 specific energy and energy density targets. If the ammonia-borane synthesis process could use the ammonia-borane decomposition products as the starting raw material, an efficient recycle loop could be set up for converting the decomposition products back into the starting boron-nitrogen hydride. This project is addressing two key challenges facing the exploitation of the boron/nitrogen hydrides (ammonia-borane), as hydrogen storage material: (1) Development of a simple, efficient, and controllable system for extracting most of the available hydrogen, realizing the high hydrogen density on a system weight/volume basis, and (2) Development of a large-capacity, inexpensive, ammonia-borane regeneration process starting from its decomposition products (BNHx) for recycle. During Phase I of the program both catalytic and non-catalytic decomposition of ammonia borane are being investigated …
Date: February 3, 2010
Creator: Damle, A.
Object Type: Report
System: The UNT Digital Library
LX-17 and ufTATB Data for Corner-Turning, Failure and Detonation (open access)

LX-17 and ufTATB Data for Corner-Turning, Failure and Detonation

Data is presented for the size (diameter) effect for ambient and cold confined LX-17, unconfined ambient LX-17, and confined ambient ultrafine TATB. Ambient, cold and hot double cylinder corner-turning data for LX-17, PBX 9502 and ufTATB is presented. Transverse air gap crossing in ambient LX-17 is studied with time delays given for detonations that cross.
Date: February 3, 2010
Creator: Souers, P C; Lauderbach, L; Garza, R; Vitello, P & Hare, D E
Object Type: Article
System: The UNT Digital Library
A Pilot Plant: The Fastest Path to Commercial Fusion Energy (open access)

A Pilot Plant: The Fastest Path to Commercial Fusion Energy

Considerable effort has been dedicated to determining the possible properties of a magneticconfinement fusion power plant, particularly in the U.S.1, Europe2 and Japan3. There has also been some effort to detail the development path to fusion energy, particularly in the U.S.4 Only limited attention has been given, in Japan5 and in China6, to the options for a specific device to form the bridge from the International Thermonuclear Experimental Reactor, ITER, to commercial fusion energy. Nor has much attention been paid, since 2003, to the synergies between magnetic and inertial fusion energy development. Here we consider, at a very high level, the possibility of a Qeng ≥ 1 Pilot Plant, with linear dimensions ~ 2/3 the linear dimensions of a commercial fusion power plant, as the needed bridge. As we examine the R&D needs for such a system we find significant synergies between the needs for the development of magnetic and inertial fusion energy.
Date: March 3, 2010
Creator: Goldston, Robert J.
Object Type: Report
System: The UNT Digital Library
Enhanced superconducting pairing interaction in indium-doped tin telluride (open access)

Enhanced superconducting pairing interaction in indium-doped tin telluride

The ferroelectric degenerate semiconductor Sn{sub 1-{delta}}Te exhibits superconductivity with critical temperatures, T{sub c}, of up to 0.3 K for hole densities of order 10{sup 21} cm{sup -3}. When doped on the tin site with greater than x{sub c} = 1.7(3)% indium atoms, however, superconductivity is observed up to 2 K, though the carrier density does not change significantly. We present specific heat data showing that a stronger pairing interaction is present for x > x{sub c} than for x < x{sub c}. By examining the effect of In dopant atoms on both T{sub c} and the temperature of the ferroelectric structural phase transition, T{sub SPT}, we show that phonon modes related to this transition are not responsible for this T{sub c} enhancement, and discuss a plausible candidate based on the unique properties of the indium impurities.
Date: May 3, 2010
Creator: Erickson, A.S.
Object Type: Article
System: The UNT Digital Library
Analysis of the Spectral Function of Nd1.85Ce0.15CuO4, Obtained by Angle Resolved Photoemission Spectroscopy (open access)

Analysis of the Spectral Function of Nd1.85Ce0.15CuO4, Obtained by Angle Resolved Photoemission Spectroscopy

Samples of Nd{sub 2-x}Ce{sub x}CuO{sub 4}, an electron-doped high temperature superconducting cuprate (HTSC), near optimal doping at x = 0.155 were measured via angle resolved photoemission (ARPES). We report a renormalization feature in the self energy ('kink') in the band dispersion at {approx} 50-60 meV present in nodal and antinodal cuts across the Fermi surface. Specifically, while the kink had been seen in the antinodal region, it is now observed also in the nodal region, reminiscent of what has been observed in hole-doped cuprates.
Date: May 3, 2010
Creator: Schmitt, F.
Object Type: Article
System: The UNT Digital Library
Direct observation of the mass renormalization in SrVO3 by angle resolved photoemission spectroscopy (open access)

Direct observation of the mass renormalization in SrVO3 by angle resolved photoemission spectroscopy

We have performed an angle-resolved photoemission study of the three-dimensional perovskite-type SrVO{sub 3}. Observed spectral weight distribution of the coherent part in the momentum space shows cylindrical Fermi surfaces consisting of the V 3d t{sub 2g} orbitals as predicted by local-density approximation (LDA) band-structure calculation. The observed energy dispersion shows a moderately enhanced effective mass compared to the LDA results, corresponding to the effective mass enhancement seen in the thermodynamic properties. Contributions from the bulk and surface electronic structures to the observed spectra are discussed based on model calculations.
Date: May 3, 2010
Creator: Yoshida, t.
Object Type: Article
System: The UNT Digital Library
High Temperature, Low Relative Humidity, Polymer-type Membranes Based on Disulfonated Poly(arylene ether) Block and Random Copolymers Optionally Incorporating Protonic Conducting Layered Water insoluble Zirconium Fillers (open access)

High Temperature, Low Relative Humidity, Polymer-type Membranes Based on Disulfonated Poly(arylene ether) Block and Random Copolymers Optionally Incorporating Protonic Conducting Layered Water insoluble Zirconium Fillers

Our research group has been engaged in the past few years in the synthesis of biphenol based partially disulfonated poly(arylene ether sulfone) random copolymers as potential PEMs. This series of polymers are named as BPSH-xx, where BP stands for biphenol, S stands for sulfonated, H stands for acidified and xx represents the degree of disulfonation. All of these sulfonated copolymers phase separate to form nano scale hydrophilic and hydrophobic morphological domains. The hydrophilic phase containing the sulfonic acid moieties causes the copolymer to absorb water. Water confined in hydrophilic pores in concert with the sulfonic acid groups serve the critical function of proton (ion) conduction and water transport in these systems. Both Nafion and BPSH show high proton conductivity at fully hydrated conditions. However proton transport is especially limited at low hydration level for the BPSH random copolymer. It has been observed that the diffusion coefficients of both water and protons change with the water content of the pore. This change in proton and water transport mechanisms with hydration level has been attributed to the solvation of the acid groups and the amount of bound and bulk-like water within a pore. At low hydration levels most of the water is …
Date: June 3, 2010
Creator: McGrath, James E. & Baird, Donald G.
Object Type: Report
System: The UNT Digital Library
On the Theory of the Modulation Instability in Optical Fiber and Laser Amplifiers (open access)

On the Theory of the Modulation Instability in Optical Fiber and Laser Amplifiers

The modulation instability (MI) in optical fiber amplifiers and lasers with anomalous dispersion leads to CW beam breakup and the growth of multiple pulses. This can be both a detrimental effect, limiting the performance of amplifiers, and also an underlying physical mechanism in the operation of MI-based devices. Here we revisit the analytical theory of MI in fiber optical amplifiers. The results of the exact theory are compared with the previously used adiabatic approximation model, and the range of applicability of the latter is determined. The same technique is applicable to the study of spatial MI in solid state laser amplifiers and MI in non-uniform media.
Date: November 3, 2010
Creator: Rubenchik, A M; Turitsyn, S K & Fedoruk, M P
Object Type: Article
System: The UNT Digital Library
Final Report: Human Capacity Building Grant for Renewable Energy Development (open access)

Final Report: Human Capacity Building Grant for Renewable Energy Development

Warm Springs Power and Water Enterprise (WSPWE), a Corporate Entity of the Confederated Tribes of Warm Springs Oregon, developed and distributed written materials, held workshops and field trips to educate tribal members on renewable energy projects that are a possibility utilizing resources on reservation. In order to build stronger public and Tribal Council support for the development of renewable energy projects on the reservation, WSPWE conducted a 12 month public education and technical expertise development program. The objectives of this program were to: • To build a knowledge base within the tribal community regarding renewable energy development potential and opportunities on reservation lands. • To educate the tribal community regarding development process, impacts and benefits. • To increase the technical expertise of tribal government and Tribal Council.
Date: January 3, 2010
Creator: Sando, Wil
Object Type: Report
System: The UNT Digital Library
DATA QUALITY OBJECTIVES FOR SELECTING WASTE SAMPLES FOR THE BENCH STEAM REFORMER TEST (open access)

DATA QUALITY OBJECTIVES FOR SELECTING WASTE SAMPLES FOR THE BENCH STEAM REFORMER TEST

This document describes the data quality objectives to select archived samples located at the 222-S Laboratory for Fluid Bed Steam Reformer testing. The type, quantity and quality of the data required to select the samples for Fluid Bed Steam Reformer testing are discussed. In order to maximize the efficiency and minimize the time to treat Hanford tank waste in the Waste Treatment and Immobilization Plant, additional treatment processes may be required. One of the potential treatment processes is the fluid bed steam reformer (FBSR). A determination of the adequacy of the FBSR process to treat Hanford tank waste is required. The initial step in determining the adequacy of the FBSR process is to select archived waste samples from the 222-S Laboratory that will be used to test the FBSR process. Analyses of the selected samples will be required to confirm the samples meet the testing criteria.
Date: August 3, 2010
Creator: DL, BANNING
Object Type: Report
System: The UNT Digital Library
Impact of substrate surface scratches on the laser damage resistance of multilayer coatings (open access)

Impact of substrate surface scratches on the laser damage resistance of multilayer coatings

Substrate scratches can limit the laser resistance of multilayer mirror coatings on high-peak-power laser systems. To date, the mechanism by which substrate surface defects affect the performance of coating layers under high power laser irradiation is not well defined. In this study, we combine experimental approaches with theoretical simulations to delineate the correlation between laser damage resistance of coating layers and the physical properties of the substrate surface defects including scratches. A focused ion beam technique is used to reveal the morphological evolution of coating layers on surface scratches. Preliminary results show that coating layers initially follow the trench morphology on the substrate surface, and as the thickness increases, gradually overcoat voids and planarize the surface. Simulations of the electrical-field distribution of the defective layers using the finite-difference time-domain (FDTD) method show that field intensification exists mostly near the top surface region of the coating near convex focusing structures. The light intensification could be responsible for the reduced damage threshold. Damage testing under 1064 nm, 3 ns laser irradiation over coating layers on substrates with designed scratches show that damage probability and threshold of the multilayer depend on substrate scratch density and width. Our preliminary results show that damage occurs …
Date: November 3, 2010
Creator: Qiu, S; Wolfe, J; Monterrosa, A; Teslich, N; Feit, M; Pistor, T et al.
Object Type: Article
System: The UNT Digital Library
Neutron Cross Section Covariances in the Resonance Region: 52Cr, 56Fe, 58Ni (open access)

Neutron Cross Section Covariances in the Resonance Region: 52Cr, 56Fe, 58Ni

We evaluated covariances for neutron capture and elastic scattering cross sections on major structural materials, {sup 52}Cr, {sup 56}Fe and {sup 58}Ni, in the resonance region which extends beyond 800 keV for each of them. Use was made of the recently developed covariance formalism based on kernel approximation along with data in the Atlas of Neutron Resonances. The data of most interest for AFCI applications, elastic scattering cross section uncertainties at energies above about few hundred keV, are on the level of about 12% for {sup 52}Cr, 7-8% for {sup 56}Fe and 5-6% for {sup 58}Ni.
Date: August 3, 2010
Creator: Oblozinsky, P.; Cho, Y.-S.; Mattoon, C. M. & Mughabghab, S. F.
Object Type: Report
System: The UNT Digital Library
BASSET: Scalable Gateway Finder in Large Graphs (open access)

BASSET: Scalable Gateway Finder in Large Graphs

Given a social network, who is the best person to introduce you to, say, Chris Ferguson, the poker champion? Or, given a network of people and skills, who is the best person to help you learn about, say, wavelets? The goal is to find a small group of 'gateways': persons who are close enough to us, as well as close enough to the target (person, or skill) or, in other words, are crucial in connecting us to the target. The main contributions are the following: (a) we show how to formulate this problem precisely; (b) we show that it is sub-modular and thus it can be solved near-optimally; (c) we give fast, scalable algorithms to find such gateways. Experiments on real data sets validate the effectiveness and efficiency of the proposed methods, achieving up to 6,000,000x speedup.
Date: November 3, 2010
Creator: Tong, H; Papadimitriou, S; Faloutsos, C; Yu, P S & Eliassi-Rad, T
Object Type: Article
System: The UNT Digital Library
Form CJ-8, Annual Probation Survey: 2010 (open access)

Form CJ-8, Annual Probation Survey: 2010

Blank probation data survey containing a series of questions related to the probationary population in a particular location, with instructions for filling out the survey.
Date: November 3, 2010
Creator: United States. Bureau of Justice Statistics.
Object Type: Text
System: The UNT Digital Library
Superconductivity-Induced Self-Energy Evolution of the Nodal Electron in Optimally-Doped Bi2212 (open access)

Superconductivity-Induced Self-Energy Evolution of the Nodal Electron in Optimally-Doped Bi2212

The temperature dependent evolution of the renormalization effect in optimally-doped Bi2212 along the nodal direction has been studied via angle-resolved photoemission spectroscopy. Fine structure is observed in the real part of the self-energy (Re{Sigma}), including a subkink and maximum, suggesting that electrons couple to a spectrum of bosonic modes, instead of just one mode. Upon cooling through the superconducting phase transition, the fine structures of the extracted Re{Sigma} exhibit a two-processes evolution demonstrating an interplay between kink renormalization and superconductivity. We show that this two-process evolution can be qualitatively explained by a simple Holstein model in which a spectrum of bosonic modes is considered.
Date: May 3, 2010
Creator: Lee, W.S.
Object Type: Article
System: The UNT Digital Library