R-MATRIX RESONANCE ANALYSIS AND STATISTICAL PROPERTIES OF THE RESONANCE PARAMETERS OF 233U IN THE NEUTRON ENERGY RANGE FROM THERMAL TO 600 eV (open access)

R-MATRIX RESONANCE ANALYSIS AND STATISTICAL PROPERTIES OF THE RESONANCE PARAMETERS OF 233U IN THE NEUTRON ENERGY RANGE FROM THERMAL TO 600 eV

The R-matrix resonance analysis of experimental neutron transmission and cross sections of {sup 233}U, with the Reich-Moore Bayesian code SAMMY, was extended up to the neutron energy of 600 eV by taking advantage of new high resolution neutron transmission and fission cross section measurements performed at the Oak Ridge Electron Linear Accelerator (ORELA). The experimental data base is described. In addition to the microscopic data (time-of-flight measurements of transmission and cross sections), some experimental and evaluated integral quantities were included in the data base. Tabulated and graphical comparisons between the experimental data and the SAMMY calculated cross sections are given. The ability of the calculated cross sections to reproduce the effective multiplication factors k{sub eff} for various thermal, intermediate, and fast systems was tested. The statistical properties of the resonance parameters were examined and recommended values of the average s-wave resonance parameters are given.
Date: February 27, 2001
Creator: Leal, L.C.
Object Type: Report
System: The UNT Digital Library
Radial Patterns of Instability and Transport in JT-60U Internal Transport Barrier Discharges (open access)

Radial Patterns of Instability and Transport in JT-60U Internal Transport Barrier Discharges

One class of internal transport barrier discharges in the JT-60U tokamak is characterized by two relatively flatter regions of the pressure separated by a region with very large pressure gradient. Linear growth rates for toroidal drift-type modes are calculated for discharges in this class, without and with sheared E x B rotation effects. For cases with fully-developed barriers, the results with rotation are consistent with a picture in which the radial electric field generated in part by the steep pressure gradient causes local stabilization, and thus reduction of the local anomalous transport, which allows the steep pressure gradient to persist. If rotation is omitted from the calculation for these cases, or if rotation is included for cases without barriers or with partially developed barriers, the unstable region spreads into the steep pressure gradient region.
Date: February 27, 2001
Creator: Rewoldt, G.; Hill, K.W.; Nazikian, R.; Tang, W.M.; Shirai, H; Sakamoto, Y. et al.
Object Type: Report
System: The UNT Digital Library
USE OF PERFLUOROCARBON TRACER (PFT) TECHNOLOGY FOR SUBSURFACE BARRIER INTEGRITY VERIFICATION AT THE WALDO TEST SITE (open access)

USE OF PERFLUOROCARBON TRACER (PFT) TECHNOLOGY FOR SUBSURFACE BARRIER INTEGRITY VERIFICATION AT THE WALDO TEST SITE

Researchers from Brookhaven National Laboratory (BNL) tested perfluorocarbon (PFT) gas tracers on a subsurface barrier with known flaws at the Waldo test facility [operated by Science and Engineering Associates, Inc (SEA)]. The tests involved the use of five unique PFT tracers with a different tracer injected along the interior of each wall of the barrier. A fifth tracer was injected exterior to the barrier to examine the validity of diffusion controlled transport of the PFTs. The PFTs were injected for three days at a nominal flow rate of 15 cm{sup 3}/min and a concentrations in the range of a few hundred ppm. Approximately 65 liters of air laced with tracer was injected for each tracer. The tracers were able to accurately detect the presence of the engineered flaws. Two flaws were detected on the north and east walls and lane flaw was detected on the south and west walls. In addition, one non-engineered flaw at the seam between the north and east walls was also detected. The use of multiple tracers provided independent confirmation of the flaws and permitted a distinction between tracers arriving at a monitoring port after being released from a nearby flaw and non-engineered flaws. The PFTs …
Date: February 27, 2000
Creator: Sullivan, T.; Heiser, J.; Senum, G. & Millian, L.
Object Type: Article
System: The UNT Digital Library
Optical spectroscopy of strongly correlated electron systems (open access)

Optical spectroscopy of strongly correlated electron systems

In this thesis, both time-resolved, nonlinear optical spectroscopy and linear spectroscopy are used to investigate the interactions and dynamics of elementary excitations in strongly correlated electron systems. In the first part, we investigate the renormalization of magnetic elementary excitations in the transition metal oxide Cr{sub 2}O{sub 3}. We have created a non-equilibrium population of antiferromagnetic spin waves and characterized its dynamics, using frequency- and time-resolved optical spectroscopy of the exciton-magnon transition. We observed a time-dependent pump-probe line shape, which results from excitation induced renormalization of the spin wave band structure. We present a model that reproduces the basic characteristics of the data, in which we postulate the optical nonlinearity to be dominated by interactions with long-wavelength spin waves, and the dynamics due to spin wave thermalization. Using linear spectroscopy, coherent third-harmonic generation and pump-probe experiments, we measured the optical properties of the charge-transfer (CT) gap exciton in Sr{sub 2}CuO{sub 2}Cl{sub 2}, an undoped model compound for high-temperature superconductors. A model is developed which explains the pronounced temperature dependence and newly observed Urbach tail in the linear absorption spectrum by a strong, phonon-mediated coupling between the charge-transfer exciton and ligand field excitations of the Cu atoms. The third-order nonlinear optical susceptibility …
Date: February 27, 2001
Creator: Schumacher, Andreas B.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Regulatory issues affecting management of produced water from coal bed methane wells. (open access)

Regulatory issues affecting management of produced water from coal bed methane wells.

Coal bed methane (CBM) wells are being developed in increasing numbers throughout the United States. These are wells that are drilled into coal seams to withdraw ground water (produced water) to reduce the hydrostatic pressure on the coal seam. The reduced pressure allows methane gas to migrate to the well bore where it moves to the surface and is collected. Where possible, operators prefer to discharge the produced water into nearby streams, rivers, or other surface water bodies. Depending on the chemical characteristics of the produced water, different levels of treatment are applied to the produced water before discharge. In some locations, produced water cannot be discharged and is injected, reused, or evaporated. Although the CBM industry is producing ''natural'' gas, such gas may not necessarily be covered under the existing national regulations for discharges from the oil and gas industry. This paper describes the existing national discharge regulations, the ways in which CBM produced water is currently being managed, the current CBM discharge permitting practices, and how these options might change as the volume of produced water increases because of the many new wells being developed.
Date: February 27, 2002
Creator: Veil, J. A.
Object Type: Report
System: The UNT Digital Library
Synthesis and Magnetic, Thermal, and Electrical Measurements on Complex non-Cuprate Superconductors (open access)

Synthesis and Magnetic, Thermal, and Electrical Measurements on Complex non-Cuprate Superconductors

The project investigated superconductivity in non-cuprate materials with critical temperatures, T{sub c}, in excess of 20 K in order to understand the thermodynamics of several of these materials. The project is a cooperative effort between investigators at Southern University (SU), Louisiana State University (LSU), and Los Alamos National Laboratory (LANL). It involved synthesis of high quality samples, and subsequent detailed magnetic, thermal and electrical measurements on them. The project provided a PhD Thesis research experience and training for a graduate student, Ms. Robin Macaluso. High quality, single crystal samples were synthesized by Ms. Macaluso under the direction of one of the CO-PIS, John Sarao, during the summer while she was a visitor at LANL being supported by this grant. On these samples magnetic measurements were performed at SU, thermal and electrical measurements were made in the LSU Physics and Astronomy Department. The crystallographic properties were determined in the LSU Chemistry Department by Ms. Macaluso under the direction of her dissertation advisor, Dr. Julia Chan. Additional high field magnetic measurements on other samples were performed at the National High Magnetic Field Laboratory (NHMFL) both in Tallahassee and at LANL. These measurements involved another graduate student, Umit Alver, who used some of …
Date: February 27, 2006
Creator: Henry, Laurence L
Object Type: Report
System: The UNT Digital Library
High Resolution Radionuclide Imaging Using Focusing Gamma-Ray Optics (open access)

High Resolution Radionuclide Imaging Using Focusing Gamma-Ray Optics

Significant effort is being devoted to the development of noninvasive imaging systems that allow in vivo assessment of biological and biomolecular interactions in mice and other small animals. Although single-photon emission tomography (SPECT) and positron emission tomography (PET) are well-matched to the study of physiological function in small animals, the spatial resolutions of 1-2 mm currently achievable with these techniques limits the types of research possible. For this reason, we are developing a small animal radionuclide imaging system using grazing incidence optics to focus the low-energy gamma-rays emitted by {sup 125}I, {sup 95m}Tc, {sup 96}Tc, and {sup 99m}Tc. We compare this approach to the more traditional use of absorptive collimation.
Date: February 27, 2004
Creator: Pivovaroff, Michael; Craig, William; Ziock, Klaus; Barber, William; Funk, Tobias; Hasegawa, Bruce et al.
Object Type: Article
System: The UNT Digital Library
Experience From Two Small Quantity RH-TRU Waste Sites in Navigating Through an Evolving Regulatory Landscape (open access)

Experience From Two Small Quantity RH-TRU Waste Sites in Navigating Through an Evolving Regulatory Landscape

Two small quantity transuranic (TRU) waste generator sites have gained considerable experience in navigating through a changing regulatory landscape in their efforts to remove the TRU waste from their sites and proceed with site remediation. The Battelle Columbus Laboratories Decommissioning Project (BCLDP) has the objectives of decontaminating nuclear research buildings and associated grounds and remediating to a level of residual contamination allowing future use without radiological restrictions. As directed by Congress, BCLDP must complete decontamination and decommissioning activities by the end of Fiscal Year (FY) 2006. This schedule requires the containerization of all TRU waste in 2002. BCLDP will generate a total of approximately 27 cubic meters (m3) of remote-handled (RH) TRU waste. Similarly, the Energy Technology Engineering Center (ETEC) is scheduled to close in 2006 pursuant to an agreement between the U.S. Department of Energy (DOE) and Boeing Canoga Park, the management and operating contractor for ETEC. ETEC had 11.0 m3 of RH-TRU and contact-handled (CH) TRU waste in storage, with the requirement to remove this waste in 2002 in order to meet their site closure schedule. The individual milestones for BCLDP and ETEC necessitated the establishment of site-specific programs to direct packaging and characterization of RH-TRU waste before …
Date: February 27, 2003
Creator: Biedscheid, Jennifer; Devarakonda, Murthy; Eide, Jim & Kneff, Dennis
Object Type: Article
System: The UNT Digital Library