States

15.4% CuIn1-XGaXSe2-Based Photovoltaic Cells from Solution-Based Precursor Films (open access)

15.4% CuIn1-XGaXSe2-Based Photovoltaic Cells from Solution-Based Precursor Films

We have fabricated 15.4%- and 12.4%-efficient CuIn1-XGaXSe2 (CIGS)-based photovoltaic devices from solution-based electrodeposition (ED) and electroless-deposition (EL) precursors. As-deposited precursors are Cu-rich CIGS. Additional In, Ga, and Se are added to the ED and EL precursor films by physical vapor deposition (PVD) to adjust the final film composition to CuIn1-XGaXSe2. The ED and EL device parameters are compared with those of a recent world record, an 18.8%-efficient PVD device. The tools used for comparison are current voltage, capacitance voltage, and spectral response characteristics.
Date: May 25, 1999
Creator: Bhattacharya, R. N.; Batchelor, W.; Contreras, M. A.; Noufi, R. N. (National Renewable Energy Laboratory); Hiltner, J. F. & Sites, J. R. (Department of Physics, Colorado State University)
Object Type: Article
System: The UNT Digital Library
Advanced Lightning Location Interferometer: Final Report (open access)

Advanced Lightning Location Interferometer: Final Report

In January, 1994, New Mexico Institute for Mining and Technology (NM Tech) was commissioned by Los Alamos National Laboratories (LANL) to develop a three-axis interferometric lightning mapping system to be used in determining the source of certain frequency-dispersed pulse pairs which had been detected by spaceborne sensors. The existing NM Tech VHF Lightning Interferometer was a two axis system operating at 274 MHz with 6 MHz bandwidth. The third axis was to be added to refine estimates of the elevation angle to distant RF sources in that band. The system was to be initially deployed in support of an Air Force Technical Applications Center (AFTAC) effort planned for the Kennedy Space Center/Cape Canaveral AFS area in June-July of 1994. The project was, however, postponed until September of 1994. The interferometer was set up and operated at KSC near the Lightning Detection and Ranging (LDAR) central station. The initial setup was in two-axis configuration, and the third (vertical) axis was added at about mid-project. Though the storms were reduced in frequency and severity over what one would expect in mid-summer, several good data sets were obtained and delivered to AFTAC.
Date: May 25, 1995
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Audit of the Uranium Solidification Facility at the Savannah River Site (open access)

Audit of the Uranium Solidification Facility at the Savannah River Site

In the late 1980s, DOE decided to construct a Uranium Solidification Facility at the Savannah River Site to process liquid uranyl nitrate into powder. Since the need for weapons materials has been reduced, an audit was conducted to assess the need for this facility. The audit disclosed that DOE continued to construct the facility, because DOE`s procedures did not ensure that projects of this type were periodically reassessed when significant program changes occurred. The audit identified more economical alternatives for processing existing quantities of liquid uranyl nitrate at the Savannah River Site.
Date: May 25, 1994
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Biologic surveys for the Sandia National Laboratories, Coyote Canyon Test Complex, Kirtland Air Force Base, Albuquerque, New Mexico (open access)

Biologic surveys for the Sandia National Laboratories, Coyote Canyon Test Complex, Kirtland Air Force Base, Albuquerque, New Mexico

This report provides results of a comprehensive biologic survey performed in Coyote Canyon Test Complex (CCTC), Sandia National Laboratories (SNL), Bernalillo County, New Mexico, which was conducted during the spring and summer of 1992 and 1993. CCTC is sited on land owned by the Department of Energy (DOE) and Kirtland Air Force Base and managed by SNL. The survey covered 3,760 acres of land, most of which is rarely disturbed by CCTC operations. Absence of grazing by livestock and possibly native ungulates, and relative to the general condition of private range lands throughout New Mexico, and relative to other grazing lands in central New Mexico. Widely dispersed, low intensity use by SNL as well as prohibition of grazing has probably contributed to abundance of special status species such as grama grass cactus within the CCTC area. This report evaluates threatened and endangered species found in the area, as well as comprehensive assessment of biologic habitats. Included are analyses of potential impacts and mitigative measures designed to reduce or eliminate potential impacts. Included is a summary of CCTC program and testing activities.
Date: May 25, 1994
Creator: Sullivan, R.M. & Knight, P.J.
Object Type: Report
System: The UNT Digital Library
Book Review of State of Texas Environmental Priorities Project "Lawn Care Chemicals: Human Health Risks" (open access)

Book Review of State of Texas Environmental Priorities Project "Lawn Care Chemicals: Human Health Risks"

Letter from Robert Sielken Jr. of Sielken Inc. to Sylvia Amaya of the Texas Natural Resources Commission on May 25,1995, containing his answers to questions for a book review of "Lawn Care Chemicals: Human Health Risks"
Date: May 25, 1995
Creator: Sielken, Robert L., Jr.
Object Type: Letter
System: The Portal to Texas History
Calculation of unmitigated release from reverse circulation drilling of a borehole three meters south of borehole 41-15-09 near SST 241-SX-115 (open access)

Calculation of unmitigated release from reverse circulation drilling of a borehole three meters south of borehole 41-15-09 near SST 241-SX-115

It is known that underground, single shell tank (SST) 241-SX-115 leaked 50,000 gallons of contaminated liquid to the soil. Now there is a campaign to more fully characterize the plume from that leak. To determine radionuclide concentrations in the vadose zone, boring into the soil and collecting samples of it are needed. It was decided to bore a new hole 3 m (9.8 ft) from existing borehole number 41-15-09, located near the south edge of the tank. Drilling and sampling will be done with the use of reverse circulation drilling, which uses compressed air to power the drill bit and sweep out drillings into separation and sampling equipment. Prior to drilling, however, it was determined that safety assessment calculations were needed to find out if postulated releases from the drilling would pose unacceptable risk to onsite and offsite receptors. Unacceptable risk would require the design and construction of safety significant equipment for prevention or mitigation of the release.
Date: May 25, 1999
Creator: SCOTT, D.L.
Object Type: Report
System: The UNT Digital Library
E. Cartan moment of rotation in classical and quantum gravity. Final report (open access)

E. Cartan moment of rotation in classical and quantum gravity. Final report

The geometric construction of the E. Cartan moment of rotation associated to the spacetime curvature provides a geometric interpretation of the gravitational field sources and describes geometrically how the sources are ``wired`` to the field in standard geometrodynamics. E. Cartan moment of rotation yields an alternate way (as opposed to using variational principles) to obtain Einstein equations. The E. Cartan construction uses in an essential way the soldering structure of the frame bundle underlying the geometry of the gravitational field of general relativity. The geometry of Ashtekar`s connection formulation of gravitation theory is based on a complex-valued self-dual connection that is defined not on the frame bundle of spacetime but, rather, on its complexification. We show how to transfer the construction of the E. Cartan moment of rotation to Ashtekar`s theory of gravity and demonstrate that no spurious equations are produced via this procedure.
Date: May 25, 1994
Creator: Kheyfets, A.
Object Type: Report
System: The UNT Digital Library
Charged Local Defects in Extended Systems (open access)

Charged Local Defects in Extended Systems

The conventional approach to treating charged defects in extended systems in first principles calculations is via the supercell approximation using a neutralizing jellium background charge. I explicitly demonstrate shortcomings of this standard approach and discuss the consequences. Errors in the electrostatic potential surface over the volume of a supercell are shown to be comparable to a band gap energy in semiconductor materials, for cell sizes typically used in first principles simulations. I present an alternate method for eliminating the divergence of the Coulomb potential in supercell calculations of charged defects in extended systems that embodies a correct treatment of the electrostatic potential in the local viciniq of the a charged defect, via a mixed boundary condition approach. I present results of first principles calculations of charged vacancies in NaCl that illustrate the importance of polarization effects once an accurate representation of the local potential is obtained. These polarization effects, poorly captured in small supercells, also impact the energetic on the scale of typical band gap energies.
Date: May 25, 1999
Creator: Schultz, Peter A.
Object Type: Article
System: The UNT Digital Library
Coulomb Driven New Bound States at the Integer Quantum Hall States in GaAs/Al(0.3)Ga(0.7)As Single Heterojunctions (open access)

Coulomb Driven New Bound States at the Integer Quantum Hall States in GaAs/Al(0.3)Ga(0.7)As Single Heterojunctions

Coulomb driven, magneto-optically induced electron and hole bound states from a series of heavily doped GaAs/Al<sub>0.3</sub>Ga<sub>0.7</sub>As single heterojunctions (SHJ) are revealed in high magnetic fields. At low magnetic fields ({nu} >2), the photohuninescence spectra display Shubnikov de-Haas type oscillations associated with the empty second subband transition. In the regime of the Landau filling factor {nu} <1 and 1< {nu} <2, we found strong bound states due to Mott type Vocalizations. Since a SHJ has an open valence band structure, these bound states area unique property of the dynamic movement of the valence holes in strong magnetic fields.
Date: May 25, 1999
Creator: Jiang, H. W.; Kim, Yongmin; Lee, Kyu-Seok; Lee, X.; Munteanu, F. M.; Perry, C. H. et al.
Object Type: Article
System: The UNT Digital Library
Cratering rates from lunar xenospherules (open access)

Cratering rates from lunar xenospherules

The goal of this project is to obtain the time history of impacts on the moon, with emphasis on recent impacts. In particular, the project could prove (or disprove) the existence of comet sores and provide the dates when they occurred.
Date: May 25, 1993
Creator: Muller, R. A.
Object Type: Report
System: The UNT Digital Library
D0 Solenoid Upgrade Project: Pressure Ratings for Some Chimney and Control Dewar Componenets (open access)

D0 Solenoid Upgrade Project: Pressure Ratings for Some Chimney and Control Dewar Componenets

Pressure rating calculations were done for some of the chimney and control dewar components. This engineering note documents these calculations. The table below summarizes the components looked at, and what pressure rating are. The raw engineering calculations for each of the components is given.
Date: May 25, 1993
Creator: Rucinski, R.
Object Type: Report
System: The UNT Digital Library
Development of a membrane-based process for the treatment of oily waste waters. Final report, March 4, 1992--March 5, 1994 (open access)

Development of a membrane-based process for the treatment of oily waste waters. Final report, March 4, 1992--March 5, 1994

This is a final report from Bend Research, Inc., (BRI) to the U.S. Department of Energy (DOE) for work performed under Contract No. DE-AC22-92MT92005, titled {open_quotes}Development of a Membrane-Based Process for the Treatment of Oily Waste Waters.{close_quotes} This report covers the period from March 4, 1992, to March 5, 1994. The overall goal of this program was to develop an economical oily-water treatment system based on reverse osmosis (RO). The RO system would be used to (1) reduce oil production costs by reducing the volume of waste water that must be disposed of, (2) form the basis of a generic waste-water treatment system that can easily be integrated into oil-field operations, especially at production facilities that are small or in remote locations; and (3) produce water clean enough to meet existing and anticipated environmental regulations. The specific focus of this program was the development of a hollow-fiber membrane module capable of treating oily waste waters.
Date: May 25, 1994
Creator: McCray, S. B.
Object Type: Report
System: The UNT Digital Library
Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane. Quarterly technical progress report 8, January--March, 1995 (open access)

Development of vanadium-phosphate catalysts for methanol production by selective oxidation of methane. Quarterly technical progress report 8, January--March, 1995

Activities during this quarter focused on fine tuning of catalyst characterization and synthesis techniques. Improvements in catalyst activity test methods were also implemented but more remains to be done. Specific accomplishments include: improved characterization of vanadyl pyrophosphate (VPO) and Si promoted VPO by FTIR and FTIR of chemisorbed bases; several minor improvements in catalyst preparation technique resulting in enhanced catalyst yield, better control of catalyst composition, and generation of less waste; preliminary pulsed reaction data on methane oxidation were also acquired. Preliminary activity measurements for methane conversion (without oxygen) in a pulsed reactor over VPO indicate that the primary reaction product is CO. Carbon dioxide is also formed but selectivity to CO{sub 2} decreases with number of pulses. These results suggest that selectivity to partially oxidized products improves with catalyst reduction and suggest that some surface modification will be required to obtain oxidized hydrocarbon products. Note that catalyst activation (conversion from the precursor to VPO) has been carried out using air. For butane oxidation catalysts VPO is activated in a 1% butane/air mixture which produces a slightly reduced catalyst.
Date: May 25, 1995
Creator: McCormick, R.L.
Object Type: Report
System: The UNT Digital Library
The DOE Subsurface Microbial Culture Collection at Florida State University. Final Technical Report, January 16, 1996--February 15, 1997 (open access)

The DOE Subsurface Microbial Culture Collection at Florida State University. Final Technical Report, January 16, 1996--February 15, 1997

This report describes the research that supports the Subsurface Science Program by maintaining a culture collection of microorganisms isolated from deep terrestrial subsurface environments (the Subsurface Microbial Culture Collection, or SMCC). The general distribution of cultures and data was identified as an important function of the SMCC. The accomplishments related to this function of the culture collection are described.
Date: May 25, 1998
Creator: Balkwill, D. L.
Object Type: Report
System: The UNT Digital Library
Drug Control: Customs Can Do More To Prevent Drug-Related Employee Corruption (open access)

Drug Control: Customs Can Do More To Prevent Drug-Related Employee Corruption

A statement of record issued by the General Accounting Office with an abstract that begins "Pursuant to a congressional request, GAO discussed the Customs Service's efforts to combat drug-related corruption, focusing on: (1) the extent to which Customs has complied with policies and procedures for ensuring employee integrity; (2) an identification of the types of illegal drug-related activities of which Customs employees on the Southwest Border have been convicted; (3) an identification of the Department of the Treasury's organizational structures, policies, and procedures for handling allegations of drug-related employee misconduct and whether the policies and procedures were followed; and (4) the extent to which lessons learned from corruption cases closed in fiscal years 1992 through 1997 have led to changes in policies and procedures for preventing the drug-related corruption of Customs employees."
Date: May 25, 1999
Creator: United States. General Accounting Office.
Object Type: Text
System: The UNT Digital Library
Effects of He{sup +} ion implantation on optical and structural properties of MgAl{sub 2}O{sub 4} (open access)

Effects of He{sup +} ion implantation on optical and structural properties of MgAl{sub 2}O{sub 4}

Single crystals of magnesium-aluminate spinel were implanted with 170 keV He{sup +} ions to fluences ranging from 1 x 10{sup 16}--1 x 10{sup 21} ions/m{sup 2} at 120 K. The effects of ion implantation were studied using optical absorption spectroscopy, Rutherford Backscattering Spectroscopy and Ion Channeling (RBS/C) and Transmission Electron Microscopy (TEM). In absorption spectra obtained from the implanted samples, growth of an F-center band at 5.3 eV was observed. At the fluence of 3 x 10{sup 20} ions/m{sup 2}, the growth of this band not only ceases but the intensity suddenly decreases. This may be due to formation of a new phase at this fluence. This is partially confirmed by the fact that beginning at this dose, a modulated absorbance becomes apparent in the absorption spectrum of spinel. This effect is caused by formation of a buried layer with refraction index lower than that of an unimplanted sample. RBS/C and TEM measurements show that spinel is not amorphized over the fluence range examined in this study. TEM microdiffraction observations show that in the damaged region the intensities of superlattice spots decrease significantly, suggesting that ion beam irradiation induces either an order-disorder phase transition or a transformation into the so-called …
Date: May 25, 1999
Creator: Afanasyev-Charkin, I. V.; Cooke, D. W.; Gritsyna, V. T.; Ishimaru, M. & Sickafus, K. E.
Object Type: Article
System: The UNT Digital Library
Electric power monthly, May 1993 (open access)

Electric power monthly, May 1993

The Electric Power Monthly (EPM) is prepared by the Survey Management Division; Office of Coal, Nuclear, Electric and Alternate Fuels, Energy Information Administration (EIA), Department of Energy. This publication provides monthly statistics at the US, Census division, and State levels for net generation, fossil fuel consumption and stocks, quantity and quality of fossil fuels, cost of fossil fuels, electricity sales, revenue, and average revenue per kilowatthour of electricity sold. Data on net generation, fuel consumption, fuel stocks, quantity and cost of fossil fuels are also displayed for the North American Electric Reliability Council (NERC) regions.
Date: May 25, 1993
Creator: unknown
Object Type: Report
System: The UNT Digital Library
EMPACT: Electrons Muons Partons with Air Core Toroids (open access)

EMPACT: Electrons Muons Partons with Air Core Toroids

The EMPACT experiment utilizes a broad approach to maximize its discovery potential for new phenomena accessible at the SSC. The high resolution detector has a balances emphasis on, and large acceptance for, electrons, muons, jets, and noninteracting particles, and is capable of utilizing the ultimate luminosity of the SSC. The detector emphasizes excellent calorimetry augmented by TRD tracking, and employs an innovative system of superconducting air core toroids for muon measurements. Significant engineering effort has established the feasibility of a baseline detector concept and has addressed the related issues of support facilities, assembly, and detector integration. The design has been tested against the challenges of predicted phenomena, with the expectation that this will optimize the capacity for observing the unexpected. EMPACT's international collaboration has unprecedented support from major aerospace industries who are providing tools and expertise for project design and integration, which will assure that a detector optimized for performance and cost will be available for the first collisions at the new laboratory.
Date: May 25, 1990
Creator: Marx, M. D.
Object Type: Report
System: The UNT Digital Library
Estimation of contaminant transport in groundwater beneath radioactive waste disposal facilities (open access)

Estimation of contaminant transport in groundwater beneath radioactive waste disposal facilities

Performance assessments are required for low-level radioactive waste disposal facilities to demonstrate compliance with the performance objectives, consider human exposures from water, air, and inadvertent intruder pathways. Among these, the groundwater pathway analysis usually involves complex numerical simulations with results which are often difficult to verify and interpret. This paper presents a technique to identify and simplify the essential parts of the groundwater analysis. The transport process of radionuclides including infiltration of precipitation, leachate generation, and advection and dispersion in the groundwater is divided into several steps. For each step, a simple analytical model is constructed and refined to capture the dominant phenomena represented in the complex analysis included in a site-specific performance assessment. This step-wise approach provides a means for gaining insights into the transport process and obtaining reasonable estimates of relevant quantities for facility design and site evaluation.
Date: May 25, 1995
Creator: Wang, J. C.; Tauxe, J. D. & Lee, D. W.
Object Type: Article
System: The UNT Digital Library
An expression of interest in a Super Fixed Target Beauty Facility (SFT) at the Superconducting Super Collider (open access)

An expression of interest in a Super Fixed Target Beauty Facility (SFT) at the Superconducting Super Collider

The concept of a Super Fixed Target Beauty Facility (SFT) which uses a relatively low intensity 20 TeV proton beam as a generator of very high momenta B's is an exciting prospect which is very competitive with other B factory ideas. The yields of B's in such a facility are quite high (3 {times} 10{sup 10} {yields} 10{sup 11} B's per year). At this level of statistics, CP violation measurements will be possible in many modes. In addition, the fixed target configuration, because of the high momenta of the produced B's and the resulting long decay lengths, facilitates the detection and reconstruction of B's and offers unique opportunities for observation of the B decays. The limited solid angle coverage required for the fixed target spectrometer makes the cost of the facility much cheaper than other e{sup +}e{sup {minus}} or hadron collider options under consideration. The relatively low intensity 20 TeV beam (1 {yields} 2 {times} 10{sup 8} protons/second) needed for the SFT makes it possible to consider an extraction system which operates concurrently and in a non-interfering manner with the other collider experiments. One possible method for generating such a beam, crystal channeling, is discussed.
Date: May 25, 1990
Creator: unknown
Object Type: Report
System: The UNT Digital Library
FFTF Plant transition mission analysis report (open access)

FFTF Plant transition mission analysis report

FFTF (Fast Flux Test Facility) is a 400-MW(t) sodium-cooled, fast flux test reactor at Hanford, designed to test fuels and materials for advanced nuclear power plants; it has no capability for generating electric power. Since a long-term mission could not be found for FFTF, it was placed in standby, and a recommendation was made that it be shut down. Purpose of the FFTF Transition Project is to prepare it for Decontamination and Decommissioning; this will be accomplished by establishing a passively safe and environmentally secure configuration, that can be preserved for several decades. This report presents the results of the mission analysis, which is required by Hanford systems engineering procedures.
Date: May 25, 1995
Creator: Lund, D. P.
Object Type: Report
System: The UNT Digital Library
Gamma-ray array physics. (open access)

Gamma-ray array physics.

In this contribution I am going to discuss the development of large arrays of Compton Suppressed, High Purity Germanium (HpGe) detectors and the physics that has been, that is being, and that will be done with them. These arrays and their science have dominated low-energy nuclear structure research for the last twenty years and will continue to do so in the foreseeable future. John Sharpey Schafer played a visionary role in convincing a skeptical world that the development of these arrays would lead to a path of enlightenment. The extent to which he succeeded can be seen both through the world-wide propagation of ever more sophisticated devices, and through the world-wide propagation of his students. I, personally, would not be working in research if it were not for Johns inspirational leadership. I am eternally grateful to him. Many excellent reviews of array physics have been made in the past which can provide detailed background reading. The review by Paul Nolan, another ex-Sharpey Schafer student, is particularly comprehensive and clear.
Date: May 25, 1999
Creator: Lister, C. J.
Object Type: Article
System: The UNT Digital Library
Heat Transfer in Cane Fiberboard Exposed to Hypothetical Accident Conditions (open access)

Heat Transfer in Cane Fiberboard Exposed to Hypothetical Accident Conditions

Radioactive material packages containing fiberboard insulation have been subjected to Hypothetical Accident Condition (HAC) thermal tests for many years. Historically, the packages` thermal performance has always been difficult to grasp. A package designer needs to understand the effects of temperature and pyrolysis on the rate of heat transfer and performance. This paper describes in detail the one-dimensional HAC thermal tests performed on fiberboard to understand the effects of pyrolysis, its char and its gas products. The tests were conducted by the Packaging and Transportation Group at the Savannah River Site (SRS). Test fixtures were assembled at SRS and thermal testing conducted in the Radiant Heat Facility at the Sandia National Laboratories. Descriptions of the test fixtures are provided, as well as the time dependent temperature profiles. In addition, lessons learned are discussed.
Date: May 25, 1995
Creator: Gromada, R.J.
Object Type: Article
System: The UNT Digital Library
High temperature alkali corrosion of ceramics in coal gas. Quarterly progress report No. 7, March 1, 1993--June 1, 1993 (open access)

High temperature alkali corrosion of ceramics in coal gas. Quarterly progress report No. 7, March 1, 1993--June 1, 1993

Corrosion kinetics of SiC were investigated from 950 to 1100C at 0.63 vol% alkali vapor concentration. Corrosion rate in alkali is 10{sup 4} to 10{sup 5} times faster than oxidation rate of SiC in air. Activation energy of the alkali corrosion is 406 kj/mol, indicating a high sensitivity to temperature changes. Overall reaction appears to be controlled by the oxidation of SiC. The alkali corrosion kinetics of Si{sub 3}N{sub 4} from 950 to 1050{degrees}C were also examined in the same atmosphere (0.63 vol% alkali vapors). Reaction thickness of Si{sub 3}N{sub 4} appears to vary linearly with reaction time from 950 to 1050C, suggesting that the alkali corrosion process is controlled by the oxidation of Si{sub 3}N{sub 4}. At 1050{degrees}C, the alkali-enhanced oxidation of Si{sub 3}N{sub 4} is approximately 10{sup 7} times faster than the oxidation of Si{sub 3}N{sub 4} in dry oxygen. Compared to SiC corroded in the same alkali atmosphere, Si{sub 3}N{sub 4} seems to be less alkali-resistant than SiC. Phase relations of the Na{sub 2}O-Al{sub 2}TiO{sub 5} vertical section from 5--40 wt% Na{sub 2}O and 840-1100C were studied. Phase analysis indicates that this section is not a true binary system. A tentative phase diagram for the Na{sub 2}O-Al{sub …
Date: May 25, 1993
Creator: Pickrell, G. R.; Sun, T. & Brown, J. J.
Object Type: Report
System: The UNT Digital Library