Recent US target-physics-related research in heavy-ion inertial fusion: simulations for tamped targets and for disk experiments in accelerator test facilities (open access)

Recent US target-physics-related research in heavy-ion inertial fusion: simulations for tamped targets and for disk experiments in accelerator test facilities

Within the last few years, there have also appeared in the Heavy-Ion Fusion literature several studies of targets which have outer tampers. One-dimensional simulations indicate higher target gains with a judicious amount of tamping. But for these targets, a full investigation has not been carried through in regards to conservative criteria for fluid instabilities as well as reasonable imperfections in target fabrication and illumination symmetry which all affect target ignition and burn. Comparisons of these results with the gain survey of Part I would have to be performed with care. These calculations suggest that experiments relating to high temperature disk heating, as well as beam deposition, focusing and transport can be performed within the context of current design proposals for accelerator test-facilities. Since the test-facilities have lower ion kinetic energy and beam pulse power as compared to reactor drivers, we achieve high-beam intensities at the focal spot by using short focal distance and properly designed beam optics.
Date: June 24, 1982
Creator: Mark, J.W.K.
Object Type: Article
System: The UNT Digital Library
Control of pyrite surface chemistry in physical coal cleaning (open access)

Control of pyrite surface chemistry in physical coal cleaning

The successful separation of pyrite from coal by flotation is dependent to a large extent upon the selectivity of the process, and the use of a pyrite depressant is one of the most important and cost-effective techniques for achieving this. This report evaluates the effects of three factors on the floatability of pyrite. These are (1) the superficial oxidation of pyrite, (2) the contamination of pyrite surfaces by carbonaceous matter, and (3) pulp redox potentials. XPS (x-ray photoelectron spectroscopy) and IR spectrometry have been used to identify surface reaction products. Microflotation, laboratory-scale conventional flotation and microbubble column flotation were used to quantify the effects of these factors. It was found that low (reducing) pulp potentials are effective depressants of pyrite (more so for fresh, unoxidized samples than for oxidized samples), whilst at the same time do not materially affect coal flotation.
Date: June 24, 1992
Creator: Luttrell, G. H.; Yoon, R. H. & Ou, Z. S.
Object Type: Report
System: The UNT Digital Library
Control of pyrite surface chemistry in physical coal cleaning (open access)

Control of pyrite surface chemistry in physical coal cleaning

To better understand the surface chemical properties of coal and mineral pyrite, studies on the effect of flotation surfactants (frother and kerosene) on the degree of hydrophobicity have been conducted. The presence of either frother or kerosene enhanced the flotability of coal and mineral pyrite with a corresponding decrease in induction time over the pH range examined. Scanning electron microscopy (SEM) results indicate a correlation exists between the sample surface morphology and crystal structure and the observed hydrophobicity. As a result of the data obtained from the surface characterization studies, controlled surface oxidation was investigated as a possible pyrite rejection scheme in microbubble column flotation.
Date: June 24, 1992
Creator: Luttrell, G. H.; Yoon, R. H.; Zachwieja, J. & Lagno, M.
Object Type: Report
System: The UNT Digital Library
Master oscillator stability requirements considerations (open access)

Master oscillator stability requirements considerations

This note attempts to point out some ideas about the required stability of the 476 MHz master oscillator, assuming that the phase noise of the oscillator is the only source of noise in the accelerator system.
Date: June 24, 1986
Creator: Schwarz, H. & Vancraeynest, J.
Object Type: Report
System: The UNT Digital Library
Early history of computer simulations in statistical mechanics (open access)

Early history of computer simulations in statistical mechanics

A history of the early use of the Monte Carlo method is presented.
Date: June 24, 1985
Creator: Wood, W.W.
Object Type: Article
System: The UNT Digital Library
Control of pyrite surface chemistry in physical coal cleaning (open access)

Control of pyrite surface chemistry in physical coal cleaning

One of the most difficult separations in minerals processing involves the differential flotation of pyrite and coal. Under practical flotation conditions, they are both hydrophobic and no cost-effective method has been developed to efficiently reject the pyrite. The problem arises from inherent floatability of coal and pyrite. Coal is naturally hydrophobic and remains so under practical flotation. Although pyrite is believed to be naturally hydrophilic under practical flotation conditions it undergoes a relatively rapid incipient oxidation reaction that causes self-induced'' flotation. The oxidation product responsible for self-induced'' flotation is believed to be a metal polysulfide, excess sulfur in the lattice, or in some cases elemental sulfur. It is believed that if incipient oxidation of pyrite could be prevented, good pyrite rejection could be obtained. In order to gain a better understanding of how pyrite oxidizes, a new method of preparing fresh, unoxidized pyrite surfaces and a new method of studying pyrite oxidation have been developed this reporting period.
Date: June 24, 1992
Creator: Yoon, R. H. & Richardson, P. R.
Object Type: Report
System: The UNT Digital Library
General Chemistry Division quarterly report, January--March 1977 (open access)

General Chemistry Division quarterly report, January--March 1977

Reported are: development of analytical capabilities of a submillimeter spectrometer; improved minimum detectibility of laser-induced molecular fluorescence; use of laser photoionization sources for analytical mass spectrometry; photoacoustic spectroscopy of solids; development of time-resolved spectroscopy for multicomponent mixtures; excited-state reactions of Ba/sup +/ + N/sub 2/O ..-->.. BaO +N/sub 2/; development of an ion-cyclotron-resonance spectrometer; development of glow-discharge multielement analytical systems; analysis of deposits on exploding gold bridgeware detonators; results of /sup 13/C-NMR study of toluene-2,4-diisocyanate polymers; analysis of 1,6-hexanediamine and 1,3-dipiperiodylpropane; studies of discrepancies between chromatographic and mass spectrometric data. (JRD)
Date: June 24, 1977
Creator: Harrar, J.E. (ed.)
Object Type: Report
System: The UNT Digital Library
324 building safety analysis report supplement (open access)

324 building safety analysis report supplement

Process engineering designs, major equipment and plant facilities to be utilized in commercial nuclear waste preparation and vitrification in the 324 Radiochemical Engineering Building are reviewed with regard to accident potential and consequences. This Safety Analysis Report Supplement compares calculated environmental doses anticipated from the Commercial Nuclear Waste Vitrification Project (CNWVP) routine operations with the average doses from past waste management operations conducted at the Hanford Project and finds them to be significantly less. The calculated CNWVP environmental doses are found to be far below presently applicable ERDA standards and standards proposed by the EPA for nuclear power operations. (DLC)
Date: June 24, 1977
Creator: Dodd, A. O. & Wittenbrock, N. G.
Object Type: Report
System: The UNT Digital Library
Sigma: Web Retrieval Interface for Nuclear Reaction Data (open access)

Sigma: Web Retrieval Interface for Nuclear Reaction Data

The authors present Sigma, a Web-rich application which provides user-friendly access in processing and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The main interface includes browsing using a periodic table and a directory tree, basic and advanced search capabilities, interactive plots of cross sections, angular distributions and spectra, comparisons between evaluated and experimental data, computations between different cross section sets. Interactive energy-angle, neutron cross section uncertainties plots and visualization of covariance matrices are under development. Sigma is publicly available at the National Nuclear Data Center website at www.nndc.bnl.gov/sigma.
Date: June 24, 2008
Creator: Pritychenko,B. & Sonzogni, A.A.
Object Type: Article
System: The UNT Digital Library
A High Repetition Rate VUV-Soft X-Ray FEL Concept (open access)

A High Repetition Rate VUV-Soft X-Ray FEL Concept

We report on design studies for a seeded FEL light source that is responsive to the scientific needs of the future. The FEL process increases radiation flux by several orders of magnitude above existing incoherent sources, and offers the additional enhancements attainable by optical manipulations of the electron beam: control of the temporal duration and bandwidth of the coherent output, reduced gain length in the FEL, utilization of harmonics to attain shorter wavelengths, and precise synchronization of the x-ray pulse with seed laser systems. We describe an FEL facility concept based on a high repetition rate RF photocathode gun, that would allow simultaneous operation of multiple independent FEL's, each producing high average brightness, tunable over the VUV-soft x-ray range, and each with individual performance characteristics determined by the configuration of the FEL. SASE, enhanced-SASE (ESASE), seeded, harmonic generation, and other configurations making use of optical manipulations of the electron beam may be employed, providing a wide range of photon beam properties to meet varied user demands.
Date: June 24, 2007
Creator: Corlett, J.; Byrd, J.; Fawley, W. M.; Gullans, M.; Li, D.; Lidia, S. M. et al.
Object Type: Article
System: The UNT Digital Library
The impact of retail rate structures on the economics of commercial photovoltaic systems in California (open access)

The impact of retail rate structures on the economics of commercial photovoltaic systems in California

This article examines the impact of retail electricity rate design on the economic value of grid-connected photovoltaic (PV) systems, focusing on commercial customers in California. Using 15-min interval building load and PV production data from a sample of 24 actual commercial PV installations, we compare the value of the bill savings across 20 commercial-customer retail electricity rates currently offered in the state. Across all combinations of customers and rates, we find that the annual bill savings from PV, per kWh generated, ranges from $0.05 to $0.24/kWh. This sizable range in rate-reduction value reflects differences in rate structures, revenue requirements, the size of the PV system relative to building load, and customer load shape. The most significant rate design issue for the value of commercial PV is found to be the percentage of total utility bills recovered through demand charges, though a variety of other factors are also found to be of importance. The value of net metering is found to be substantial, but only when energy from commercial PV systems represents a sizable portion of annual customer load. Though the analysis presented here is specific to California, our general results demonstrate the fundamental importance of retail rate design for the …
Date: June 24, 2008
Creator: Mills, Andrew D.; Wiser, Ryan; Barbose, Galen & Golove, William
Object Type: Article
System: The UNT Digital Library
Can cross sections be accurately known for priori? (open access)

Can cross sections be accurately known for priori?

Distinct maxima and minima in the neutron total cross section uncertainties were observed in our large scale covariance calculations using a spherical optical potential. In this contribution we investigate the physical origin of this oscillating structure. Specifically, we analyze the case of neutron reactions on {sup 56}Fe, for which total cross section uncertainties are characterized by the presence of five distinct minima at 0.1, 1.1, 5, 25, and 70 MeV. To investigate their origin, we calculated total cross sections by perturbing the real volume depth V{sub v} by its expected uncertainty {+-}{Delta}V{sub v}. Inspecting the effect of this perturbation on the partial wave cross sections we found that the first minimum (at 0.1 MeV) is exclusively due to the contribution of the s-wave. On the other hand, the same analysis at 1.1 MeV showed that the minimum is the result of the interplay between s-, p-, and d-waves; namely the change in the s-wave happens to be counterbalanced by changes in the p- and d-waves. Similar considerations can be extended for the third minimum, although it can be also explained in terms of the Ramsauer effect as well as the other ones (at 25 and 70 MeV). We discuss the …
Date: June 24, 2008
Creator: Pigni, M. T.; Dietrich, F. S.; Herman, M. & Oblozinsky, P.
Object Type: Article
System: The UNT Digital Library
Energy dependence of jet transport parameter and parton saturationin quark-gluon plasma (open access)

Energy dependence of jet transport parameter and parton saturationin quark-gluon plasma

We study the evolution and saturation of the gluondistribution function in the quark-gluon plasma as probed by apropagating parton and its effect on the computation of jet quenching ortransport parameter $\hat q $. For thermal partons, the saturation scale$Q2_s$ is found to be proportional to the Debye screening mass $\mu_D2$.For hard probes, evolution at small $x=Q2_s/6ET$ leads to jet energydependence of hat q. We study this dependence for both a conformal gaugetheory in weak and strong coupling limit and for (pure gluon) QCD. Theenergy dependence can be used to extract the shear viscosity $\eta$ ofthe medium since $\eta$ can be related to the transport parameter forthermal partons in a transport description. We also derive upper boundson the transport parameter for both energetic and thermal partons. Thelater leads to a lower bound on shear viscosity-to-entropy density ratiowhich is consistent with the conjectured lower bound $\eta/s\geq 1/4\pi$.Implications on the study of jet quenching at RHIC and LHC and the bulkproperties of the dense matter are discussed.
Date: June 24, 2007
Creator: Casalderrey-Solana, Jorge & Wang, Xin-Nian
Object Type: Article
System: The UNT Digital Library
Neutron Cross Section Uncertainties in the Thermal and Resonance Regions (open access)

Neutron Cross Section Uncertainties in the Thermal and Resonance Regions

In the 'Atlas of Neutron Resonances', special care was expended to ensure that the resonance parameter information reproduces the various measured thermal cross sections, as well as the infinite dilute resonance integrals for Z = 1-100. In contrast, the uncertainties of the recommended quantities do not match those generated from the uncertainties of the resonance parameters. To address this problem, the present study was initiated to achieve consistency for 15 actinides and 21 structural and coolant moderator materials. This is realized by assigning uncertainties to the parameters of the negative-energy resonances and changing, if necessary, significantly the uncertainties of the low-lying positive-energy resonances. The influence of correlations between parameters on the derived uncertainties is examined and discussed.
Date: June 24, 2008
Creator: Mughabghab, S. F. & Oblozinsky, P.
Object Type: Article
System: The UNT Digital Library
The Progress on Low-Cost, High-Quality, High-Temperature Superconducting Tapes Deposited by the Combustion Chemical Vapor Deposition Process (open access)

The Progress on Low-Cost, High-Quality, High-Temperature Superconducting Tapes Deposited by the Combustion Chemical Vapor Deposition Process

The innovative Combustion Chemical Vapor Deposition (CCVD) process is a non-vacuum technique that is being investigated to enable next generation products in several application areas including high-temperature superconductors (HTS). In combination with the Rolling Assisted Biaxially Textured Substrate (RABiTS) technology, the CCVD process has significant promise to provide low-cost, high-quality lengths of YBCO coated conductor. Over 100 meter lengths of both Ni and Ni-W (3 at. Wt.%) substrates with a surface roughness of 12-18 nm were produced. The CCVD technology has been used to deposit both buffer layer coatings as well as YBCO superconducting layers. Buffer layer architecture of strontium titanate (SrTiO{sub 3}) and ceria (CeO{sub 2}) have been deposited by CCVD on textured nickel substrates and optimized to appropriate thicknesses and microstructures to provide templates for growing PLD YBCO with a J{sub c} of 1.1 MA/cm{sup 2} at 77 K and self-field. The CCVD buffer layers have been scaled to meter plus lengths with good epitaxial uniformity along the length. A short sample cut from one of the lengths enabled high critical current density PLD YBCO. Films of CCVD YBCO superconductors have been grown on single crystal substrates with critical current densities over 1 MA/cm{sup 2}. In addition, superconducting …
Date: June 24, 2008
Creator: Shoup, S. S.; White, M. K.; Krebs, S. L.; Darnell, N.; King, A. C.; Mattox, D. S. et al.
Object Type: Report
System: The UNT Digital Library
Development of covariance capabilities in EMPIRE code (open access)

Development of covariance capabilities in EMPIRE code

The nuclear reaction code EMPIRE has been extended to provide evaluation capabilities for neutron cross section covariances in the thermal, resolved resonance, unresolved resonance and fast neutron regions. The Atlas of Neutron Resonances by Mughabghab is used as a primary source of information on uncertainties at low energies. Care is taken to ensure consistency among the resonance parameter uncertainties and those for thermal cross sections. The resulting resonance parameter covariances are formatted in the ENDF-6 File 32. In the fast neutron range our methodology is based on model calculations with the code EMPIRE combined with experimental data through several available approaches. The model-based covariances can be obtained using deterministic (Kalman) or stochastic (Monte Carlo) propagation of model parameter uncertainties. We show that these two procedures yield comparable results. The Kalman filter and/or the generalized least square fitting procedures are employed to incorporate experimental information. We compare the two approaches analyzing results for the major reaction channels on {sup 89}Y. We also discuss a long-standing issue of unreasonably low uncertainties and link it to the rigidity of the model.
Date: June 24, 2008
Creator: Herman, M.; Pigni, M. T.; Oblozinsky, P.; Mughabghab, S. F.; Mattoon, C. M.; Capote, R. et al.
Object Type: Article
System: The UNT Digital Library
The Next Generation Air Particle Detectors for the United States Navy (open access)

The Next Generation Air Particle Detectors for the United States Navy

Design and testing of the United States Navy’s next generation air particle detector (NGAPD) is presently underway. The NGAPD is intended for use in nuclear applications for the United States Navy and is being designed to detect airborne Co-60 with a reduction in false alarms and improved ease of use. Features being developed include gamma compensation, low maintenance, commercial off-the-shelf electronics, and spectrum simulation for quality assurance and functional testing applications. By supplying a spectrum simulator, the radon stripping algorithm can be running when a simulated anthropogenic source spectrum (e.g., from Co-60 or transuranics) is superimposed on the radon progeny spectrum. This will allow alarm levels to be tested when the air flow is running and the radon stripping algorithm is providing the instrument response output. Modern units evaluate source spectra with the air flow off and the radon spectrum absent thereby not testing the true system performance which comes out of the radon stripping algorithm. Testing results of the preliminary prototype show promise along with computer simulations of source spectra. Primary testing results taken to date include gamma compensation, thermal insults, vibration and spectrum simulation.
Date: June 24, 2007
Creator: Hayes, Robert & Marianno, Craig
Object Type: Article
System: The UNT Digital Library
Energy Star Concepts for Highway Vehicles (open access)

Energy Star Concepts for Highway Vehicles

The authors of this report, under the sponsorship of the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) Weatherization and Intergovernmental Program, have investigated the possible application of Energy Star ratings to passenger cars and light trucks. This study establishes a framework for formulating and evaluating Energy Star rating methods that is comprised of energy- and environmental-based metrics, potential vehicle classification systems, vehicle technology factors, and vehicle selection criteria. The study tests several concepts and Energy Star rating methods using model-year 2000 vehicle data--a spreadsheet model has been developed to facilitate these analyses. This study tests two primary types of rating systems: (1) an outcome-based system that rates vehicles based on fuel economy, GHG emissions, and oil use and (2) a technology-based system that rates vehicles based on the energy-saving technologies they use. Rating methods were evaluated based on their ability to select vehicles with high fuel economy, low GHG emissions, and low oil use while preserving a full range of service (size and acceleration) and body style choice. This study concludes that an Energy Star rating for passenger cars and light trucks is feasible and that several methods could be used to achieve reasonable …
Date: June 24, 2003
Creator: Greene, D. L.
Object Type: Report
System: The UNT Digital Library
POLARIZATION IN PROTON-PROTON SCATTERING USING A POLARIZED TARGET.Part I. 0.330 to 0.740 GeV Part II 1.70 to 6.15 GeV (open access)

POLARIZATION IN PROTON-PROTON SCATTERING USING A POLARIZED TARGET.Part I. 0.330 to 0.740 GeV Part II 1.70 to 6.15 GeV

Using the Berkeley polarized-proton target, we have measured the polarization parameter P({theta}) for proton-proton (p-p) scattering. The measurements were obtained at beam kinetic energies of 0.330, 0.680, and 0.740 GeV at the 184-in. synchrocyclotron and 1.70, 2.85, 3.50, 4.00, 5.05, and 6.15 GeV at the Bevatron. The angular regions measured were from 20 to 100 degrees center of mass; the square of the four-momentum transfer ranged from 0.1 to 0.8 (GeV/c){sup 2}.
Date: June 24, 1964
Creator: Betz, F. W.; Arens, J. F.; Dost, H. E.; Hansroul, M. J.; Holloway, L. E.; Schultz, C. H. et al.
Object Type: Article
System: The UNT Digital Library
Modeling and Simulation of Fluid Mixing Laser Experiments and Supernova (open access)

Modeling and Simulation of Fluid Mixing Laser Experiments and Supernova

The three year plan for this project is to develop novel theories and advanced simulation methods leading to a systematic understanding of turbulent mixing. A primary focus is the comparison of simulation models (both Direct Numerical Simulation and subgrid averaged models) to experiments. The comprehension and reduction of experimental and simulation data are central goals of this proposal. We will model 2D and 3D perturbations of planar interfaces. We will compare these tests with models derived from averaged equations (our own and those of others). As a second focus, we will develop physics based subgrid simulation models of diffusion across an interface, with physical but no numerical mass diffusion. We will conduct analytic studies of mix, in support of these objectives. Advanced issues, including multiple layers and reshock, will be considered.
Date: June 24, 2008
Creator: Glimm, James
Object Type: Report
System: The UNT Digital Library
Estimated 55Mn and 90Zr cross section covariances in the fast neutron energy region (open access)

Estimated 55Mn and 90Zr cross section covariances in the fast neutron energy region

We completed estimates of neutron cross section covariances for {sup 55}Mn and {sup 90}Zr, from keV range to 25 MeV, considering the most important reaction channels, total, elastic, inelastic, capture, and (n,2n). The nuclear reaction model code EMPIRE was used to calculate sensitivity to model parameters by perturbation of parameters that define the optical model potential, nuclear level densities and strength of the pre-equilibrium emission. The sensitivity analysis was performed with the set of parameters which reproduces the ENDF/B-VII.0 cross sections. The experimental data were analyzed and both statistical and systematic uncertainties were extracted from almost 30 selected experiments. Then, the Bayesian code KALMAN was used to combine the sensitivity analysis and the experiments to obtain the evaluated covariance matrices.
Date: June 24, 2008
Creator: Pigni, M. T.; Herman, M. & Oblozinsky, P.
Object Type: Article
System: The UNT Digital Library
Progress in Finite Temperature Lattice Qcd. (open access)

Progress in Finite Temperature Lattice Qcd.

I review recent progress in finite temperature lattice calculations, including the determination of the transition temperature, equation of state, screening of static quarks and meson spectral functions.
Date: June 24, 2007
Creator: Petreczky, P.
Object Type: Article
System: The UNT Digital Library
Determining Exchange Splitting in a Magnetic Semiconductor by Spin-Filter Tunneling (open access)

Determining Exchange Splitting in a Magnetic Semiconductor by Spin-Filter Tunneling

A large exchange splitting of the conduction band in ultrathin films of the ferromagnetic semiconductor EuO was determined quantitatively, by using EuO as a tunnel barrier and fitting the current-voltage characteristics and temperature dependence to tunneling theory. This exchange splitting leads to different tunnel barrier heights for spin-up and spin-down electrons, and is large enough to produce a near fully spin-polarized current. Moreover, the magnetic properties of these ultrathin films (<6 nm) show a reduction in Curie temperature with decreasing thickness, in agreement with theoretical calculation [R. Schiller et al., Phys. Rev. Lett. 86, 3847 (2001)].
Date: June 24, 2008
Creator: Santos, T. S.; Moodera, J. S.; Venkataraman, K.; Negusse, E.; Holroyd, J.; Dvorak, J. et al.
Object Type: Article
System: The UNT Digital Library
PERI - Auto-tuning Memory Intensive Kernels for Multicore (open access)

PERI - Auto-tuning Memory Intensive Kernels for Multicore

We present an auto-tuning approach to optimize application performance on emerging multicore architectures. The methodology extends the idea of search-based performance optimizations, popular in linear algebra and FFT libraries, to application-specific computational kernels. Our work applies this strategy to Sparse Matrix Vector Multiplication (SpMV), the explicit heat equation PDE on a regular grid (Stencil), and a lattice Boltzmann application (LBMHD). We explore one of the broadest sets of multicore architectures in the HPC literature, including the Intel Xeon Clovertown, AMD Opteron Barcelona, Sun Victoria Falls, and the Sony-Toshiba-IBM (STI) Cell. Rather than hand-tuning each kernel for each system, we develop a code generator for each kernel that allows us to identify a highly optimized version for each platform, while amortizing the human programming effort. Results show that our auto-tuned kernel applications often achieve a better than 4X improvement compared with the original code. Additionally, we analyze a Roofline performance model for each platform to reveal hardware bottlenecks and software challenges for future multicore systems and applications.
Date: June 24, 2008
Creator: Bailey, David H.; Williams, Samuel; Datta, Kaushik; Carter, Jonathan; Oliker, Leonid; Shalf, John et al.
Object Type: Article
System: The UNT Digital Library