Controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers (open access)

Controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers

This article discusses controlled terahertz frequency response and transparency of Josephson chains and superconducting multilayers.
Date: January 26, 2007
Creator: Yampol'skii, V. A.; Savel'ev, Sergey; Usatenko, O. V.; Mel'nik, S. S.; Kusmartsev, F. V.; Krokhin, Arkadii A. et al.
System: The UNT Digital Library
Biodiversity Of Southernmost Forests And Tundra Ecosystems (open access)

Biodiversity Of Southernmost Forests And Tundra Ecosystems

Article discussing research on the biodiversity of the dominant vegetation in the world's southernmost forests and tundra ecosystems.
Date: October 26, 2007
Creator: Rozzi, Ricardo, 1960-; Massardo, Francisca; Anderson, Christopher B.; Armesto, Juan J., 1953-; Goffinet, Bernard; Silander, John August, 1945- et al.
System: The UNT Digital Library
Characterization of Room-Temperature Ionic Liquids by the Abraham Model with Cation-Specific and Anion-Specific Equation Coefficients (open access)

Characterization of Room-Temperature Ionic Liquids by the Abraham Model with Cation-Specific and Anion-Specific Equation Coefficients

Article on the characterization of room-temperature ionic liquids by the Abraham model with cation-specific and anion-specific equation coefficients.
Date: April 26, 2007
Creator: Sprunger, Laura M.; Clark, Michael; Acree, William E. (William Eugene) & Abraham, M. H. (Michael H.)
System: The UNT Digital Library
Prediction of drug solubility in ethanol-ethyl acetate mixtures at various temperatures using the Jouyban-Acree model (open access)

Prediction of drug solubility in ethanol-ethyl acetate mixtures at various temperatures using the Jouyban-Acree model

Article on the prediction of drug solubility in ethanol-ethyl acetate mixtures at various temperatures using the Jouyban-Acree model.
Date: December 26, 2007
Creator: Jouyban, Abolghasem & Acree, William E. (William Eugene)
System: The UNT Digital Library
Side extraction duoPIGatron-type ion source. (open access)

Side extraction duoPIGatron-type ion source.

We have designed and constructed a compact duoPIGatron-type ion source, for possible use in ion implanters, in such the ion can be extracted from side aperture in contrast to conventional duoPIGatron sources with axial ion extraction. The size of the side extraction aperture is 1x40 mm. The ion source was developed to study physical and technological aspects relevant to an industrial ion source. The side extraction duoPIGatron has stable arc, uniformly bright illumination, and dense plasma. The present work describes some of preliminary operating parameters of the ion source using Argon, BF3. The total unanalyzed beam currents are 23 mA using Ar at an arc current 5 A and 13 mA using BF3 gas at an arc current 6 A.
Date: August 26, 2007
Creator: Gushenets, V. I.; Oks, E. M.; Herschovitch, A. & Johnson, B. M.
System: The UNT Digital Library
SAFETY INSTRUMENTED FUNCTIONS AS CRITICALITY DEFENSES (open access)

SAFETY INSTRUMENTED FUNCTIONS AS CRITICALITY DEFENSES

The objective of this paper is to share the SRS methodology for identifying the reliability requirements and documenting the expected performance of Safety Instrumented Functions (SIFs) used as criticality defenses. Nuclear Criticality SIFs are comprised of sensors, logic solvers, and final control elements, which may be either automatic or manual, to detect a process hazard and respond to prevent a criticality. The Savannah River Site (SRS) has invoked the chemical process industry safety standard (ANSI/ISA 84.00.01) for the design of safety significant instrumented systems. The ISA standard provides a graded approach to design based on the amount of risk reduction that is required of an SIF. SRS is embarking on application of this standard to nuclear criticality defenses, thus integrating criticality safety requirements with verifiable design methodology. Per the DOE G 421.1-1 discussion of the double contingency principle, guidance for a single contingency barrier includes, ''The estimated probability that the control will fail (when called upon for protection) is not greater than 1 in 100 demands''. The application of this standard to nuclear criticality SIFs will provide clear requirements in terms of safety availability and testing to assure that the instrumented criticality system as designed, installed, and maintained will meet …
Date: March 26, 2007
Creator: Suttinger, L & William Hearn, W
System: The UNT Digital Library
A Hypothesis of the Magnetostatic Turbulence and its Implications for Astrophysics (open access)

A Hypothesis of the Magnetostatic Turbulence and its Implications for Astrophysics

Arguments are presented in favor of a possible existence of a random, force-free magnetic field. Ponderomotive forces in such a field are small, and the evolutionary time is much longer than Alfven crossing time over the vortex scale, whence the suggested term ''magnetostatic''. The presence of this long-lived random magnetic field provides stiffness with respect to large-scale compressional motions. On the other hand, such a field cannot be detected by techniques involving line-of-sight averaging. It may therefore be a source of stiffness for various astrophysical objects, ranging from plasmas in clusters of galaxies to the interiors of molecular clouds in HII regions, and remaining at the same time undetectable. Analysis of large-scale motions on the background of the magnetostatic turbulence is presented; it is concluded that these large-scale motions can be roughly described by a usual hydrodynamics for the matter with an isotropic pressure; the adiabatic index is 4/3.
Date: February 26, 2007
Creator: Ryutov, D. D. & Remington, B. A.
System: The UNT Digital Library
Deep Sub-Micron FD-SOI for Front-End Application (open access)

Deep Sub-Micron FD-SOI for Front-End Application

In order to confirm benefits of a deep sub-micron FD-SOI and to identify possible issues concerning front-end circuits with the FD-SOI, we have submitted a small design to Oki Electric Industry Co., Ltd. via the multi-chip project service of VDEC, the University of Tokyo. The initial test results and future plans for development are presented.
Date: October 26, 2007
Creator: Ikeda, H.; Arai, Y.; Hara, K.; Hayakawa, H.; Hirose, K.; Ikegami, Y. et al.
System: The UNT Digital Library
RAPID ANALYSIS OF EMERGENCY URINE AND WATER SAMPLES (open access)

RAPID ANALYSIS OF EMERGENCY URINE AND WATER SAMPLES

There is a need for fast, reliable methods for the determination of actinides and Sr-89/90 analysis on environmental and bioassay samples in response to an emergency radiological incident. The SRS (Savannah River Site) Environmental Bioassay Laboratory participated in the National Institute of Standards and Technology Radiochemistry Intercomparison Program (NRIP-06) and analyzed water and urine samples within 8 hours of receipt. The SRS Environmental Laboratory was the only lab that participated in the program that analyzed these samples for both actinides and Sr-89/90 within the requested 8 hour turnaround time. A new, rapid actinide and strontium 89/90 separation method was used for both urine and water samples. This method uses stacked TEVA Resin{reg_sign}, TRU Resin{reg_sign} and Sr-Resin{reg_sign} cartridges from Eichrom Technologies (Darien, IL, USA) that allows the rapid separation of plutonium (Pu), neptunium (Np), uranium (U), and americium (Am), curium (Cm) and thorium (Th) using a single multi-stage column combined with alpha spectrometry. By using vacuum box cartridge technology and stacked cartridges with rapid flow rates, sample preparation time was minimized. This paper discusses the technology and conditions employed for both water and urine samples and presents the SRS performance data on the NRIP-06 samples.
Date: February 26, 2007
Creator: Maxwell, S
System: The UNT Digital Library
HYDROGEN TECHNOLOGY RESEARCH AT THE SAVANNAH RIVER NATIONAL LABORATORY, CENTER FOR HYDROGEN RESEARCH, AND THE HYDROGEN TECHNOLOGY RESEARCH LABORATORY (open access)

HYDROGEN TECHNOLOGY RESEARCH AT THE SAVANNAH RIVER NATIONAL LABORATORY, CENTER FOR HYDROGEN RESEARCH, AND THE HYDROGEN TECHNOLOGY RESEARCH LABORATORY

The Savannah River National Laboratory (SRNL) is a U.S. Department of Energy research and development laboratory located at the Savannah River Site (SRS) near Aiken, South Carolina. SRNL has over 50 years of experience in developing and applying hydrogen technology, both through its national defense activities as well as through its recent activities with the DOE Hydrogen Programs. The hydrogen technical staff at SRNL comprises over 90 scientists, engineers and technologists, and it is believed to be the largest such staff in the U.S. SRNL has ongoing R&D initiatives in a variety of hydrogen storage areas, including metal hydrides, complex hydrides, chemical hydrides and carbon nanotubes. SRNL has over 25 years of experience in metal hydrides and solid-state hydrogen storage research, development and demonstration. As part of its defense mission at SRS, SRNL developed, designed, demonstrated and provides ongoing technical support for the largest hydrogen processing facility in the world based on the integrated use of metal hydrides for hydrogen storage, separation and compression. The SRNL has been active in teaming with academic and industrial partners to advance hydrogen technology. A primary focus of SRNL's R&D has been hydrogen storage using metal and complex hydrides. SRNL and its Hydrogen Technology …
Date: February 26, 2007
Creator: Danko, E
System: The UNT Digital Library
Osiris: A Modern, High-Performance, Coupled, Multi-Physics Code For Nuclear Reactor Core Analysis (open access)

Osiris: A Modern, High-Performance, Coupled, Multi-Physics Code For Nuclear Reactor Core Analysis

To meet the simulation needs of the GNEP program, LLNL is leveraging a suite of high-performance codes to be used in the development of a multi-physics tool for modeling nuclear reactor cores. The Osiris code project, which began last summer, is employing modern computational science techniques in the development of the individual physics modules and the coupling framework. Initial development is focused on coupling thermal-hydraulics and neutral-particle transport, while later phases of the project will add thermal-structural mechanics and isotope depletion. Osiris will be applicable to the design of existing and future reactor systems through the use of first-principles, coupled physics models with fine-scale spatial resolution in three dimensions and fine-scale particle-energy resolution. Our intent is to replace an existing set of legacy, serial codes which require significant approximations and assumptions, with an integrated, coupled code that permits the design of a reactor core using a first-principles physics approach on a wide range of computing platforms, including the world's most powerful parallel computers. A key research activity of this effort deals with the efficient and scalable coupling of physics modules which utilize rather disparate mesh topologies. Our approach allows each code module to use a mesh topology and resolution that …
Date: February 26, 2007
Creator: Procassini, R. J.; Chand, K. K.; Clouse, C. J.; Ferencz, R. M.; Grandy, J. M.; Henshaw, W. D. et al.
System: The UNT Digital Library
Cosmological Constraints From SDSS MaxBCG Cluster Abundances (open access)

Cosmological Constraints From SDSS MaxBCG Cluster Abundances

We perform a maximum likelihood analysis of the cluster abundance measured in the SDSS using the maxBCG cluster finding algorithm. Our analysis is aimed at constraining the power spectrum normalization {sigma}{sub 8}, and assumes flat cosmologies with a scale invariant spectrum, massless neutrinos, and CMB and supernova priors {Omega}{sub m}h{sup 2} = 0.128 {+-} 0.01 and h = 0.72 {+-} 0.05 respectively. Following the method described in the companion paper Rozo et al. (2007), we derive {sigma}{sub 8} = 0.92 {+-} 0.10 (1{sigma}) after marginalizing over all major systematic uncertainties. We place strong lower limits on the normalization, {sigma}{sub 8} > 0.76 (95% CL) (> 0.68 at 99% CL). We also find that our analysis favors relatively low values for the slope of the Halo Occupation Distribution (HOD), {alpha} = 0.83 {+-} 0.06. The uncertainties of these determinations will substantially improve upon completion of an ongoing campaign to estimate dynamical, weak lensing, and X-ray cluster masses in the SDSS maxBCG cluster sample.
Date: March 26, 2007
Creator: Rozo, Eduardo; Wechsler, Risa H.; Koester, Benjamin P.; McKay, Timothy A.; Evrard, August E.; Johnston, David et al.
System: The UNT Digital Library
Magnetic Fields above the Surface of aSuperconductor with Internal Magnetism (open access)

Magnetic Fields above the Surface of aSuperconductor with Internal Magnetism

The author presents a method for calculating the magnetic fields near a planar surface of a superconductor with a given intrinsic magnetization in the London limit. He computes solutions for various magnetic domain boundary configurations and derives relations between the spectral densities of the magnetization and the resulting field in the vacuum half space, which are useful if the magnetization can be considered as a statistical quantity and its features are too small to be resolved individually. The results are useful for analyzing and designing magnetic scanning experiments. Application to existing data from such experiments on Sr{sub 2}RuO{sub 4} show that a domain wall would have been detectable, but the magnetic field of randomly oriented small domains and small defects may have been smaller than the experimental noise level.
Date: June 26, 2007
Creator: Bluhm, Hendrik & /Stanford U., Phys. Dept. /SLAC, SSRl
System: The UNT Digital Library
On One Master Integral for Three-loop On-shell HQET Propagator Diagrams with Mass (open access)

On One Master Integral for Three-loop On-shell HQET Propagator Diagrams with Mass

An exact expression for the master integral I{sub 2} [1] arising in three-loop on-shell HQET propagator diagrams with mass is derived and its analytical expansion in the dimensional regularization parameter {var_epsilon} is given.
Date: June 26, 2007
Creator: Grozin, A. G.; Huber, T. & Maitre, D.
System: The UNT Digital Library
Validation of Hadronic Models in GEANT4 (open access)

Validation of Hadronic Models in GEANT4

Geant4 is a software toolkit for the simulation of the passage of particles through matter. It has abundant hadronic models from thermal neutron interactions to ultra relativistic hadrons. An overview of validations in Geant4 hadronic physics is presented based on thin target measurements. In most cases, good agreement is available between Monte Carlo prediction and experimental data; however, several problems have been detected which require some improvement in the models.
Date: September 26, 2007
Creator: Koi, Tatsumi; Wright, Dennis H.; Folger, Gunter; Ivanchenko, Vladimir; Kossov, Mikhail; Starkov, Nikolai et al.
System: The UNT Digital Library
Development of Semiconductor Imaging Detectors for a Si/CdTe Compton Camera (open access)

Development of Semiconductor Imaging Detectors for a Si/CdTe Compton Camera

None
Date: October 26, 2007
Creator: Watanabe, S.; Takeda, S.; Ishikawa, S. N.; Odaka, H.; Ushio, M.; Tanaka, T. et al.
System: The UNT Digital Library
GRB 060714: No Clear Dividing Line Between Prompt Emission and X-Ray Flares (open access)

GRB 060714: No Clear Dividing Line Between Prompt Emission and X-Ray Flares

The long gamma-ray burst GRB 060714 was observed to exhibit a series of five X-ray flares beginning {approx} 70 s after the burst trigger T{sub 0} and continuing until {approx} T{sub 0} + 200 s. The first two flares were detected by the Burst Alert Telescope (BAT) on the Swift satellite, before Swift had slewed to the burst location, while the last three flares were strongly detected by the X-Ray Telescope (XRT) but only weakly detected by the BAT. This burst provides an unusual opportunity to track a complete sequence of flares over a wide energy range. The flares were very similar in their light curve morphology, showing power-law rise and fall components, and in most cases significant sub-structure. The flares also showed strong evolution with time, both spectrally and temporally. The small time scale and large amplitude variability observed are incompatible with an external shock origin for the flares, and support instead late time sporadic activity either of the central source or of localized dissipation events within the outflow. We show that the flares in GRB 060714 cannot be the result of internal shocks in which the contrast in the Lorentz factor of the colliding shells is very small, …
Date: February 26, 2007
Creator: Krimm, Hans A.; Granot, J.; Marshal, F.; Perri, M.; Barthelmy, S. D.; Burrows, D. N. et al.
System: The UNT Digital Library
Performance Study of Si/CdTe Semiconductor Compton Telescopes With Monte Carlo Simulation (open access)

Performance Study of Si/CdTe Semiconductor Compton Telescopes With Monte Carlo Simulation

None
Date: October 26, 2007
Creator: Odaka, H.; Takeda, S.; /JAXA, Tokyo /Tokyo U.; Watanabe, S.; /JAXA, Tokyo; Ishikawa, S.N. et al.
System: The UNT Digital Library
Constraints on the Low-Energy Cutoff in the Electron Distributionof the PKS 0637--752 Jet (open access)

Constraints on the Low-Energy Cutoff in the Electron Distributionof the PKS 0637--752 Jet

We re-analyze the Chandra X-ray spectrum of the kpc-scale jet in PKS 0637-752 to investigate the possible low energy cutoff in the relativistic electron spectrum producing the non-thermal radiation in the scenario of inverse Compton emission off the cosmic microwave background. This was among the first objects targeted by the Chandra Observatory and gives a unique opportunity to study the low energy X-ray emission free of contamination. As previously noted, the spectrum can be fit by a power law, with the slope predicted by the radio spectrum, modified by low energy absorption through the Galaxy as determined from the spectrum of the quasar core and by HI 21 cm observations. We report evidence for a broad excess of emission below 1 keV, but are unable to constrain the shape very well. If we assume that this soft excess is unrelated to the electron population responsible for the power law emission, and that the electron spectrum cuts off at an energy of {gamma}{sub min}m{sub e}c{sup 2}, then we must have {gamma}{sub min} ({Lambda}/10) {approx}< 75 due to the absence of any low energy turn-over in the X-ray spectrum. This predicts that the observed radio spectrum should extend unbroken down below 2 …
Date: June 26, 2007
Creator: Mueller, M. & /SLAC /KIPAC, Menlo Park
System: The UNT Digital Library
Development of Hfe Sections of Dg-1145. (open access)

Development of Hfe Sections of Dg-1145.

For the licensing of the current fleet of commercial nuclear power plants (NPPs), the Nuclear Regulatory Commission (NRC) used two key documents, NUREG-0800 and Regulatory Guide (RG) 1.70. RG 1.70 provided guidance to applicants on the contents needed in their Safety Analysis Reports (SARs) submitted as part of their application to construct or operate an NPP. NUREG-0800, the NRC Standard Review Plan (SRP), provides guidance to the NRR staff reviewers on performing their safety reviews of these applications. As part of the preparation for a new wave of improved NPP designs the NRC is in the process of updating the SRP and is also developing a new RG designated as draft RG or DG-1145, ''Combined License Applications for Nuclear Power Plants (LWR Edition).'' This will eventually become RG 1.206 and will take the place of RG 1.70. This will provide guidance for combined license (COL) applicants, as well as for other 10CFR Part 52 variations that are permitted.
Date: March 26, 2007
Creator: Higgins, J. C.; Ohara, J. M. & Bongarra, J.
System: The UNT Digital Library
Prospects for Electron Imaging with Ultrafast Time Resolution (open access)

Prospects for Electron Imaging with Ultrafast Time Resolution

Many pivotal aspects of material science, biomechanics, and chemistry would benefit from nanometer imaging with ultrafast time resolution. Here we demonstrate the feasibility of short-pulse electron imaging with t10 nanometer/10 picosecond spatio-temporal resolution, sufficient to characterize phenomena that propagate at the speed of sound in materials (1-10 kilometer/second) without smearing. We outline resolution-degrading effects that occur at high current density followed by strategies to mitigate these effects. Finally, we present a model electron imaging system that achieves 10 nanometer/10 picosecond spatio-temporal resolution.
Date: January 26, 2007
Creator: Armstrong, M R; Reed, B W; Torralva, B R & Browning, N D
System: The UNT Digital Library
Evaluation of Neutron Irradiated Silicon Carbide and Silicon Carbide Composites (open access)

Evaluation of Neutron Irradiated Silicon Carbide and Silicon Carbide Composites

The effects of fast neutron irradiation on SiC and SiC composites have been studied. The materials used were chemical vapor deposition (CVD) SiC and SiC/SiC composites reinforced with either Hi-Nicalon{trademark} Type-S, Hi-Nicalon{trademark} or Sylramic{trademark} fibers fabricated by chemical vapor infiltration. Statistically significant numbers of flexural samples were irradiated up to 4.6 x 10{sup 25} n/m{sup 2} (E>0.1 MeV) at 300, 500 and 800 C in the High Flux Isotope Reactor at Oak Ridge National Laboratory. Dimensions and weights of the flexural bars were measured before and after the neutron irradiation. Mechanical properties were evaluated by four point flexural testing. Volume increase was seen for all bend bars following neutron irradiation. Magnitude of swelling depended on irradiation temperature and material, while it was nearly independent of irradiation fluence over the fluence range studied. Flexural strength of CVD SiC increased following irradiation depending on irradiation temperature. Over the temperature range studied, no significant degradation in mechanical properties was seen for composites fabricated with Hi-Nicalon{trademark} Type-S, while composites reinforced with Hi-Nicalon{trademark} or Sylramic fibers showed significant degradation. The effects of irradiation on the Weibull failure statistics are also presented suggesting a reduction in the Weibull modulus upon irradiation. The cause of this potential …
Date: March 26, 2007
Creator: Newsome G, Snead L, Hinoki T, Katoh Y, Peters D
System: The UNT Digital Library
Future GLAST Observations of Supernova Remnants And Pulsar Wind Nebulae (open access)

Future GLAST Observations of Supernova Remnants And Pulsar Wind Nebulae

Shell-type Supernova remnants (SNRs) have long been known to harbour a population of ultra-relativistic particles, accelerated in the Supernova shock wave by the mechanism of diffusive shock acceleration. Experimental evidence for the existence of electrons up to energies of 100 TeV was first provided by the detection of hard X-ray synchrotron emission as e.g. in the shell of the young SNR SN1006. Furthermore using theoretical arguments shell-type Supernova remnants have long been considered as the main accelerator of protons - Cosmic rays - in the Galaxy; definite proof of this process is however still missing. Pulsar Wind Nebulae (PWN) - diffuse structures surrounding young pulsars - are another class of objects known to be a site of particle acceleration in the Galaxy, again through the detection of hard synchrotron X-rays such as in the Crab Nebula. Gamma-rays above 100 MeV provide a direct access to acceleration processes. The GLAST Large Area telescope (LAT) will be operating in the energy range between 30 MeV and 300 GeV and will provide excellent sensitivity, angular and energy resolution in a previously rather poorly explored energy band. We will describe prospects for the investigation of these Galactic particle accelerators with GLAST.
Date: September 26, 2007
Creator: Funk, S.
System: The UNT Digital Library
Development of Double-Sided Silicon Strip Detectors (DSSD) for a Compton Telescope (open access)

Development of Double-Sided Silicon Strip Detectors (DSSD) for a Compton Telescope

None
Date: October 26, 2007
Creator: Takeda, S.; Watanabe, S.; Tanaka, T.; Nakazawa, K.; Takahashi, T.; Fukazawa, Y. et al.
System: The UNT Digital Library