The Microbial DNA Index System (MiDIS): A tool for microbial pathogen source identification (open access)

The Microbial DNA Index System (MiDIS): A tool for microbial pathogen source identification

None
Date: August 9, 2010
Creator: Velsko, S P
Object Type: Report
System: The UNT Digital Library
MiniBooNE "Windows on the Universe" (open access)

MiniBooNE "Windows on the Universe"

Progress in the last few decades has left neutrino physics with several vexing issues. Among them are the following questions: (1) Why are lepton mixing angles so different from those in the quark sector? (2) What is the most probable range of the reactor mixing angle? (3) Is the atmospheric mixing angle maximal? (4) What is the number of fermion generations? These are some of the issues that neutrino science hopes to study; this article will explore these questions as part of a more general scientific landscape, and will discuss the part MiniBooNE might play in this exploration. We discuss the current state of measurements taken by MiniBooNE, and emphasize the uniqueness of neutrino oscillations as an important probe into the 'Windows on the Universe.'
Date: December 9, 2010
Creator: Stefanski, Ray
Object Type: Article
System: The UNT Digital Library
Model verification: synthetic single pattern simulations using seismic reflection data (open access)

Model verification: synthetic single pattern simulations using seismic reflection data

None
Date: July 9, 2010
Creator: Ramirez, A; Dyer, K; White, D; Hao, Y & Yang, X
Object Type: Report
System: The UNT Digital Library
Molecular Interactions of Plutonium(VI) with Synthetic Manganese-Substituted Goethite (open access)

Molecular Interactions of Plutonium(VI) with Synthetic Manganese-Substituted Goethite

Plutonium(VI) sorption on the surface of well-characterized synthetic manganese-substituted goethite minerals (Fe1-xMnxOOH) was studied using X-ray absorption spectroscopy. We chose to study the influence of manganese as a minor component in goethite, because goethite rarely exists as a pure phase in nature. Manganese X-ray absorption near-edge structure measurements indicated that essentially all the Mn in the goethite existed as Mn(III), even though Mn was added during mineral synthesis as Mn(II). Importantly, energy dispersive X-ray analysis demonstrated that Mn did not exist as discrete phases and that it was homogeneously mixed into the goethite to within the limit of detection of the method. Furthermore, Mössbauer spectra demonstrated that all Fe existed as Fe(III), with no Fe(II) present. Plutonium(VI) sorption experiments were conducted open to air and no attempt was made to exclude carbonate. The use of X-ray absorption spectroscopy allows us to directly and unambiguously measure the oxidation state of plutonium in situ at the mineral surface. Plutonium X-ray absorption near-edge structure measurements carried out on these samples showed that Pu(VI) was reduced to Pu(IV) upon contact with the mineral. This reduction appears to be strongly correlated with mineral solution pH, coinciding with pH transitions across the point of zero charge …
Date: March 9, 2010
Creator: Hu, Yung-Jin; Schwaiger, Luna Kestrel; Booth, Corwin H.; Kukkadapu, Ravi K.; Cristiano, Elena; Kaplan, Daniel et al.
Object Type: Article
System: The UNT Digital Library
Nanograting-based compact VUV spectrometer and beam profiler for in-situ characterization of high-order harmonic generation light sources (open access)

Nanograting-based compact VUV spectrometer and beam profiler for in-situ characterization of high-order harmonic generation light sources

A compact, versatile device for VUV beam characterization is presented. It combines the functionalities of a VUV spectrometer and a VUV beam profiler in one unit and is entirely supported by a standard DN200 CF flange. The spectrometer employs a silicon nitride transmission nanograting in combination with a micro-channel plate based imaging detector. This enables the simultaneous recording of wavelengths ranging from 10 nm to 80 nm with a resolution of 0.25 nm to 0.13 nm. Spatial beam profiles with diameters up to 10 mm are imaged with 0.1 mm resolution. The setup is equipped with an in-vacuum translation stage that allows for in situ switching between the spectrometer and beam profiler modes and for moving the setup out of the beam. The simple, robust design of the device is well suited for non-intrusive routine characterization of emerging laboratory- and accelerator-based VUV light sources. Operation of the device is demonstrated by characterizing the output of a femtosecond high-order harmonic generation light source.
Date: July 9, 2010
Creator: Kornilov, Oleg; Wilcox, Russell & Gessner, Oliver
Object Type: Article
System: The UNT Digital Library
Nanostructured Lanthanum Halides and CeBr3 for Nuclear Radiation and Detection (open access)

Nanostructured Lanthanum Halides and CeBr3 for Nuclear Radiation and Detection

Scintillator materials are used to detect, and in some cases identify, gamma rays. Higher performance scintillators are expensive, hard to manufacture, fragile, and sometimes require liquid nitrogen or cooling engines. But whereas lower-quality scintillators are cheap, easy to manufacture, and more rugged, their performance is lower. At issue: can the desirable qualities of high-and low-performance scintillators be combined to achieve better performance at lower cost? Preliminary experiments show that a LaF{sub 3}:Ce oleic acid-based nanocomposite exhibits a photopeak when exposed to {sup 137}Cs source gamma-radiation. The chemical synthesis of the cerium-doped lanthanum halide nanoparticles are scalable and large quantities of material can be produced at a time, unlike typical crystal growth processes such as the Bridgeman process. Using a polymer composite (Figure 1), produced by LANL, initial measurements of the unloaded and 8% LaF{sub 3}:Ce-loaded sample have been made using {sup 137}Cs sources. Figure 2 shows an energy spectrum acquired for CeF{sub 3}. The lighter plot is the measured polymer-only spectrum and the black plot is the spectrum from the nanocomposite scintillator. As the development of this material continues, the energy resolution is expected to improve and the photopeak-to-Compton ratio will become greater at higher loadings. These measurements show the …
Date: June 9, 2010
Creator: Paul Guss, Sanjoy Mukhopadhyay, Ron Guise, Ding Yuan
Object Type: Article
System: The UNT Digital Library
New Classes of Quasi-helically Symmetric Stellarators (open access)

New Classes of Quasi-helically Symmetric Stellarators

New classes of quasi-helically symmetric stellarators with aspect ratios ≤ 10 have been found which are stable to the perturbation of magnetohydrodynamic modes at plasma pressures of practical interest. These configurations have large rotational transform and good quality of flux surfaces. Characteristics of some selected examples are discussed in detail. The feasibility of using modular coils for these stellarators has been investigated. It is shown that practical designs for modular coils can be achieved.
Date: August 9, 2010
Creator: Ku, L. P.
Object Type: Report
System: The UNT Digital Library
NIF Target Assembly Metrology and Results (open access)

NIF Target Assembly Metrology and Results

None
Date: February 9, 2010
Creator: Alger, E T; Kroll, J J; Hughes, J; Dzenitis, E G; Montesanti, R; Swisher, M et al.
Object Type: Article
System: The UNT Digital Library
On The Anomalous Fast Ion Energy Diffusion in Toroidal Plasmas Due to Cavity Modes (open access)

On The Anomalous Fast Ion Energy Diffusion in Toroidal Plasmas Due to Cavity Modes

An enormous wave-particle diffusion coefficient along paths suitable for alpha channeling had been deduced in mode converted ion Bernstein wave experiments on Tokamak Fusion Test Reactor (TFTR) the only plausible explanation advanced for such a large diffusion coefficient was the excitation of internal cavity modes which induce particle diffusion along identical diffusion paths, but at much higher rates. Although such a mode was conjectured, it was never observed. However, recent detailed observations of high frequency compressional Alfven eigenmodes (CAEs) on the National Spherical torus Experiment (NSTX) indirectly support the existence of the related conjectured modes on TFTR. The eigenmodes responsible for the high frequency magnetic activity can be identified as CAEs through the polarization of the observed magnetic field oscillations in NSTX and through a comparison with the theoretically derived freuency dispersion relation. Here, we show how these recent observations of high frequency CAEs lend support to this explanation of the long-standing puzzle of anomalous fast ion energy diffusion on TFTR. The support of the conjecure that these internal modes could have caused the remarkable ion energy diffusion on TFTR carries significant and favorable implications for the possibilities in achieving the alpha channeling effect with small injected power in a …
Date: March 9, 2010
Creator: Gorelenkov, N. N.; Fisch, N. J. & Fredrickson, E.
Object Type: Report
System: The UNT Digital Library
Optimization Studies for Radiation Shielding of a Superconducting RF Cavity Test Facility (open access)

Optimization Studies for Radiation Shielding of a Superconducting RF Cavity Test Facility

Test facilities for high-gradient superconducting RF cavities must be shielded for particle radiation, which is generated by field emitted electrons in the cavities. A major challenge for the shielding design is associated with uncertainty in modeling the field emission. In this work, a semi-empirical method that allows us to predict the intensity of the generated field emission is described. Spatial, angular and energy distributions of the generated radiation are calculated with the FISHPACT code. The Monte Carlo code MARS15 is used for modeling the radiation transport in matter. The detailed distributions of the generated field emission are used for studies with 9-cell 1.3 GHz superconducting RF cavities in the Fermilab Vertical Cavity Test Facility. This approach allows us to minimize the amount of shielding inside cryostat which is an essential operational feature.
Date: July 9, 2010
Creator: Ginsburg, Camille M. & Rakhno, Igor
Object Type: Article
System: The UNT Digital Library
PERFORMANCE OF A CONTAINMENT VESSEL CLOSURE FOR RADIOACTIVE GAS CONTENTS (open access)

PERFORMANCE OF A CONTAINMENT VESSEL CLOSURE FOR RADIOACTIVE GAS CONTENTS

This paper presents a summary of the design and testing of the containment vessel closure for the Bulk Tritium Shipping Package (BTSP). This package is a replacement for a package that has been used to ship tritium in a variety of content configurations and forms since the early 1970s. The containment vessel closure incorporates features specifically designed for the containment of tritium when subjected to the normal and hypothetical conditions required of Type B radioactive material shipping Packages. The paper discusses functional performance of the containment vessel closure of the BTSP prototype packages and separate testing that evaluated the performance of the metallic C-Rings used in a mock BTSP closure.
Date: July 9, 2010
Creator: Blanton, P. & Eberl, K.
Object Type: Article
System: The UNT Digital Library
Phase Segregation in Polystyrene?Polylactide Blends (open access)

Phase Segregation in Polystyrene?Polylactide Blends

Spun-cast films of polystyrene (PS) blended with polylactide (PLA) were visualized and characterized using atomic force microscopy (AFM) and synchrotron-based X-ray photoemission electron microscopy (X-PEEM). The composition of the two polymers in these systems was determined by quantitative chemical analysis of near-edge X-ray absorption signals recorded with X-PEEM. The surface morphology depends on the ratio of the two components, the total polymer concentration, and the temperature of vacuum annealing. For most of the blends examined, PS is the continuous phase with PLA existing in discrete domains or segregated to the air?polymer interface. Phase segregation was improved with further annealing. A phase inversion occurred when films of a 40:60 PS:PLA blend (0.7 wt percent loading) were annealed above the glass transition temperature (Tg) of PLA.
Date: June 9, 2010
Creator: Leung, Bonnie; Hitchcock, Adam; Brash, John; Scholl, Andreas & Doran, Andrew
Object Type: Article
System: The UNT Digital Library
Photoacoustically Measured Speeds of Sound and the Equation of State of HBO2: On Understanding Detonation with Boron Fuel (open access)

Photoacoustically Measured Speeds of Sound and the Equation of State of HBO2: On Understanding Detonation with Boron Fuel

Elucidation of geodynamic, geochemical, and shock induced processes is limited by challenges to accurately determine molecular fluid equations of state (EOS). High pressure liquid state reactions of carbon species underlie physiochemical mechanisms such as differentiation of planetary interiors, deep carbon sequestration, propellant deflagration, and shock chemistry. In this proceedings paper we introduce a versatile photoacoustic technique developed to measure accurate and precise speeds of sound (SoS) of high pressure molecular fluids and fluid mixtures. SoS of an intermediate boron oxide, HBO{sub 2} are measured up to 0.5 GPa along the 277 C isotherm. A polarized exponential-6 interatomic potential form, parameterized using our SoS data, enables EOS determinations and corresponding semi-empirical evaluations of >2000 C thermodynamic states including energy release from bororganic formulations. Our thermochemical model propitiously predicts boronated hydrocarbon shock Hugoniot results.
Date: March 9, 2010
Creator: Zaug, J M; Bastea, S; Crowhurst, J; Armstrong, M; Fried, L & Teslich, N
Object Type: Article
System: The UNT Digital Library
Plasma Channel Diagnostic Based on Laser Centroid Oscillations (open access)

Plasma Channel Diagnostic Based on Laser Centroid Oscillations

A technique has been developed for measuring the properties of discharge-based plasma channels by monitoring the centroid location of a laser beam exiting the channel as a function of input alignment offset between the laser and the channel. The centroid position of low-intensity (<10{sup 14}Wcm{sup -2}) laser pulses focused at the input of a hydrogen-filled capillary discharge waveguide was scanned and the exit positions recorded to determine the channel shape and depth with an accuracy of a few %. In addition, accurate alignment of the laser beam through the plasma channel can be provided by minimizing laser centroid motion at the channel exit as the channel depth is scanned either by scanning the plasma density or the discharge timing. The improvement in alignment accuracy provided by this technique will be crucial for minimizing electron beam pointing errors in laser plasma accelerators.
Date: September 9, 2010
Creator: Gonsalves, Anthony; Nakamura, Kei; Lin, Chen; Osterhoff, Jens; Shiraishi, Satomi; Schroeder, Carl et al.
Object Type: Article
System: The UNT Digital Library

Practical Issues when Selecting PV Technologies

Presentation highlighting practical considerations for photovoltaic technologies and strategies for future reductions in cost and increases in efficiency.
Date: September 9, 2010
Creator: Kurtz, S.
Object Type: Presentation
System: The UNT Digital Library
Probabilistic Threshold Criterion (open access)

Probabilistic Threshold Criterion

The Probabilistic Shock Threshold Criterion (PSTC) Project at LLNL develops phenomenological criteria for estimating safety or performance margin on high explosive (HE) initiation in the shock initiation regime, creating tools for safety assessment and design of initiation systems and HE trains in general. Until recently, there has been little foundation for probabilistic assessment of HE initiation scenarios. This work attempts to use probabilistic information that is available from both historic and ongoing tests to develop a basis for such assessment. Current PSTC approaches start with the functional form of the James Initiation Criterion as a backbone, and generalize to include varying areas of initiation and provide a probabilistic response based on test data for 1.8 g/cc (Ultrafine) 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and LX-17 (92.5% TATB, 7.5% Kel-F 800 binder). Application of the PSTC methodology is presented investigating the safety and performance of a flying plate detonator and the margin of an Ultrafine TATB booster initiating LX-17.
Date: March 9, 2010
Creator: Gresshoff, M & Hrousis, C A
Object Type: Article
System: The UNT Digital Library
PROBABILITY BASED CORROSION CONTROL FOR LIQUID WASTE TANKS - PART III (open access)

PROBABILITY BASED CORROSION CONTROL FOR LIQUID WASTE TANKS - PART III

The liquid waste chemistry control program is designed to reduce the pitting corrosion occurrence on tank walls. The chemistry control program has been implemented, in part, by applying engineering judgment safety factors to experimental data. However, the simple application of a general safety factor can result in use of excessive corrosion inhibiting agents. The required use of excess corrosion inhibitors can be costly for tank maintenance, waste processing, and in future tank closure. It is proposed that a probability-based approach can be used to quantify the risk associated with the chemistry control program. This approach can lead to the application of tank-specific chemistry control programs reducing overall costs associated with overly conservative use of inhibitor. Furthermore, when using nitrite as an inhibitor, the current chemistry control program is based on a linear model of increased aggressive species requiring increased protective species. This linear model was primarily supported by experimental data obtained from dilute solutions with nitrate concentrations less than 0.6 M, but is used to produce the current chemistry control program up to 1.0 M nitrate. Therefore, in the nitrate space between 0.6 and 1.0 M, the current control limit is based on assumptions that the linear model developed from …
Date: December 9, 2010
Creator: Hoffman, E. & Edwards, T.
Object Type: Report
System: The UNT Digital Library
PROBABILITY BASED CORROSION CONTROL FOR WASTE TANKS - PART II (open access)

PROBABILITY BASED CORROSION CONTROL FOR WASTE TANKS - PART II

As part of an ongoing study to evaluate the discontinuity in the corrosion controls at the SRS tank farm, a study was conducted this year to assess the minimum concentrations below 1 molar nitrate, see Figure 1. Current controls on the tank farm solution chemistry are in place to prevent the initiation and propagation of pitting and stress corrosion cracking in the primary steel waste tanks. The controls are based upon a series of experiments performed with simulated solutions on materials used for construction of the tanks, namely ASTM A537 carbon steel (A537). During FY09, an experimental program was undertaken to investigate the risk associated with reducing the minimum molar nitrite concentration required to confidently inhibit pitting in dilute solutions (i.e., less than 1 molar nitrate). The experimental results and conclusions herein provide a statistical basis to quantify the probability of pitting for the tank wall exposed to various solutions with dilute concentrations of nitrate and nitrite. Understanding the probability for pitting will allow the facility to make tank-specific risk-based decisions for chemistry control. Based on previous electrochemical testing, a statistical test matrix was developed to refine and solidify the application of the statistical mixture/amount model to corrosion of A537 …
Date: December 9, 2010
Creator: Hoffman, E. & Edwards, T.
Object Type: Report
System: The UNT Digital Library
Probing the evolution of antiferromagnetism in multiferroics (open access)

Probing the evolution of antiferromagnetism in multiferroics

This study delineates the evolution of magnetic order in epitaxial films of the room-temperature multiferroic BiFeO3 system. Using angle- and temperature-dependent dichroic measurements and spectromicroscopy, we have observed that the antiferromagnetic order in the model multiferroic BiFeO3 evolves systematically as a function of thickness and strain. Lattice-mismatch-induced strain is found to break the easy-plane magnetic symmetry of the bulk and leads to an easy axis of magnetization which can be controlled through strain. Understanding the evolution of magnetic structure and how to manipulate the magnetism in this model multiferroic has significant implications for utilization of such magnetoelectric materials in future applications.
Date: June 9, 2010
Creator: Holcomb, M.; Martin, L.; Scholl, A.; He, Q.; Yu, P.; Yang, C. H. et al.
Object Type: Article
System: The UNT Digital Library

Questions Utilities Should Ask to Mitigate PV Technology Risk

This presentation outlines utility concerns when evaluating PV technologies for risk.
Date: November 9, 2010
Creator: Wohlgemuth, J.
Object Type: Presentation
System: The UNT Digital Library
Reactor Physics Modeling of Spent Nuclear Research Reactor Fuel for Snm Attribution and Nuclear Forensics (open access)

Reactor Physics Modeling of Spent Nuclear Research Reactor Fuel for Snm Attribution and Nuclear Forensics

Nuclear research reactors are the least safeguarded type of reactor; in some cases this may be attributed to low risk and in most cases it is due to difficulty from dynamic operation. Research reactors vary greatly in size, fuel type, enrichment, power and burnup providing a significant challenge to any standardized safeguard system. If a whole fuel assembly was interdicted, based on geometry and other traditional forensics work, one could identify the material's origin fairly accurately. If the material has been dispersed or reprocessed, in-depth reactor physics models may be used to help with the identification. Should there be a need to attribute research reactor fuel material, the Savannah River National Laboratory would perform radiochemical analysis of samples of the material as well as other non-destructive measurements. In depth reactor physics modeling would then be performed to compare to these measured results in an attempt to associate the measured results with various reactor parameters. Several reactor physics codes are being used and considered for this purpose, including: MONTEBURNS/ORIGEN/MCNP5, CINDER/MCNPX and WIMS. In attempt to identify reactor characteristics, such as time since shutdown, burnup, or power, various isotopes are used. Complexities arise when the inherent assumptions embedded in different reactor physics …
Date: June 9, 2010
Creator: Sternat, M.; Beals, D.; Webb, R. & Nichols, T.
Object Type: Article
System: The UNT Digital Library
RESULTS FOR THE THIRD QUARTER 2010 TANK 50 WAC SLURRY SAMPLE: CHEMICAL AND RADIONUCLIDE CONTAMINANT RESULTS (open access)

RESULTS FOR THE THIRD QUARTER 2010 TANK 50 WAC SLURRY SAMPLE: CHEMICAL AND RADIONUCLIDE CONTAMINANT RESULTS

This report details the chemical and radionuclide contaminant results for the characterization of the 2010 Third Quarter sampling of Tank 50 for the Saltstone Waste Acceptance Criteria (WAC). Information from this characterization will be used by Liquid Waste Operations (LWO) to support the transfer of low-level aqueous waste from Tank 50 to the Salt Feed Tank in the Saltstone Facility in Z-Area, where the waste will be immobilized. This information is also used to update the Tank 50 Waste Characterization System. The following conclusions are drawn from the analytical results provided in this report: (i) The concentrations of the reported chemical and radioactive contaminants were less than their respective WAC targets or limits unless noted in this section. (ii) The reported detection limits for {sup 94}Nb, {sup 247}Cm and {sup 249}Cf are above the requested limits from Reference 4. However, they are below the limits established in Reference 3. (iii) The reported detection limit for {sup 242m}Am is greater than the requested limit from Attachment 8.4 of the WAC. (iv) The reported detection limit for Isopar L is greater than the limit from Table 3 of the WAC. (v) The reported concentration of Isopropanol is greater than the limit from …
Date: December 9, 2010
Creator: Reigel, M. & Bibler, N.
Object Type: Report
System: The UNT Digital Library
Room Temperature Magnetic Barrier Layers in Magnetic Tunnel Junctions (open access)

Room Temperature Magnetic Barrier Layers in Magnetic Tunnel Junctions

We investigate the spin transport and interfacial magnetism of magnetic tunnel junctions with highly spin polarized LSMO and Fe3O4 electrodes and a ferrimagnetic NiFe2O4 (NFO) barrier layer. The spin dependent transport can be understood in terms of magnon-assisted spin dependent tunneling where the magnons are excited in the barrier layer itself. The NFO/Fe3O4 interface displays strong magnetic coupling, while the LSMO/NFO interface exhibits clear decoupling as determined by a combination of X-ray absorption spectroscopy and X-ray magnetic circular dichroism. This decoupling allows for distinct parallel and antiparallel electrode states in this all-magnetic trilayer. The spin transport of these devices, dominated by the NFO barrier layer magnetism, leads to a symmetric bias dependence of the junction magnetoresistance at all temperatures.
Date: March 9, 2010
Creator: Nelson-Cheeseman, B. B.; Wong, F. J.; Chopdekar, R. V.; Arenholz, E. & Suzuki, Y.
Object Type: Article
System: The UNT Digital Library
SIGMA WEB INTERFACE FOR REACTOR DATA APPLICATIONS (open access)

SIGMA WEB INTERFACE FOR REACTOR DATA APPLICATIONS

We present Sigma Web interface which provides user-friendly access for online analysis and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The interface includes advanced browsing and search capabilities, interactive plots of cross sections, angular distributions and spectra, nubars, comparisons between evaluated and experimental data, computations for cross section data sets, pre-calculated integral quantities, neutron cross section uncertainties plots and visualization of covariance matrices. Sigma is publicly available at the National Nuclear Data Center website at http://www.nndc.bnl.gov/sigma.
Date: May 9, 2010
Creator: Pritychenko,B. & Sonzogni, A.A.
Object Type: Report
System: The UNT Digital Library