CRYOSYSTEM FOR THE AHF SINGLE AXIS, PROTON-RADIOGRAPHY FACILITY. (open access)

CRYOSYSTEM FOR THE AHF SINGLE AXIS, PROTON-RADIOGRAPHY FACILITY.

None
Date: July 12, 2002
Creator: BROWN, DONALD P; KELLEY, J PATRICK; JANKOWSKI, TODD A & WAYNERT, JOSEPH A
Object Type: Article
System: The UNT Digital Library
Impact of the Wall Conditioning Program on Plasma Performance in NSTX (open access)

Impact of the Wall Conditioning Program on Plasma Performance in NSTX

High performance operating regimes have been achieved on NSTX (National Spherical Torus Experiment) through impurity control and wall-conditioning techniques. These techniques include HeGDC-aided boronization using deuterated trimethylboron, inter-discharge HeGDC, 350 C PFC bake-out followed by D2 and HeGDC, and experiments to test fueling discharges with either a He-trimethylboron mixture or pure trimethylboron. The impact of this impurity and density control program on recent advances in NSTX plasma performance is discussed.
Date: July 12, 2002
Creator: Kuge, H. W.; Soukhanovskii, V.; Bell, M.; Blanchard, W.; Gates, D.; LeBlanc, B. et al.
Object Type: Report
System: The UNT Digital Library
Constraining hydrologic models using thermal analysis (open access)

Constraining hydrologic models using thermal analysis

Starting with regional geographic, geologic, hydrologic, geophysical, and meteorological data for the Tono area in Gifu, Japan, we develop a numerical model to simulate subsurface flow and transport in a 4 km by 6 km by 3 km thick fractured granite rock mass overlain by sedimentary layers. Individual fractures are not modeled explicitly. Rather, continuum permeability and porosity distributions are assigned stochastically, based on well-test data and fracture density measurements. The primary goal of the study is to simulate steady-state groundwater flow through the site, then calculate travel times to the model boundaries from specified monitoring points. The lateral boundaries of the model follow topographic features such as ridgelines and rivers. Assigning lateral boundary conditions is a major point of uncertainty in model construction. We evaluate two models with opposing boundary conditions: mostly closed and mostly open boundaries. The two models show vastly different spatial distributions of groundwater flow, so we would like to find a means of choosing the more realistic model. Surface recharge is much larger for the closed model, but field recharge data are of too limited spatial extent to provide a definitive model constraint. Temperature profiles in 16 boreholes show consistent trends with conduction-dominated (linear) temperature …
Date: December 12, 2002
Creator: Doughty, Christine & Karasaki, Kenzi
Object Type: Article
System: The UNT Digital Library
Fission Multiplicity Detection with Temporal Gamma-Neutron Discrimination from Higher-Order Time Correlation Statistics (open access)

Fission Multiplicity Detection with Temporal Gamma-Neutron Discrimination from Higher-Order Time Correlation Statistics

The current practice of nondestructive assay (NDA) of fissile materials using neutrons is dominated by the {sup 3}He detector. This has been the case since the mid 1980s when Fission Multiplicity Detection (FMD) was replaced with thermal well counters and neutron multiplicity counting (NMC). The thermal well counters detect neutrons by neutron capture in the {sup 3}He detector subsequent to moderation. The process of detection requires from 30 to 60 {micro}s. As will be explained in Section 3.3 the rate of detecting correlated neutrons (signal) from the same fission are independent of this time but the rate of accidental correlations (noise) are proportional to this time. The well counters are at a distinct disadvantage when there is a large source of uncorrelated neutrons present from ({alpha}, n) reactions for example. Plastic scintillating detectors, as were used in FMD, require only about 20 ns to detect neutrons from fission. One thousandth as many accidental coincidences are therefore accumulated. The major problem with the use of fast-plastic scintillation detectors, however, is that both neutrons and gamma rays are detected. The pulses from the two are indistinguishable in these detectors. For this thesis, a new technique was developed to use higher-order time correlation …
Date: November 12, 2002
Creator: Oberer, R.B.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Plasma Performance Improvements with Liquid Lithium Limiters in CDX-U (open access)

Plasma Performance Improvements with Liquid Lithium Limiters in CDX-U

The use of flowing liquid lithium as a first wall for a reactor has potentially attractive physics and engineering features. The Current Drive experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory has begun experiments with a fully toroidal liquid lithium limiter. CDX-U is a compact [R = 34 cm, a = 22 cm, Btoroidal = 2 kG, IP =100 kA, T(subscript)e(0) {approx} 100 eV, n(subscript)e(0) {approx} 5 x 10{sup 19} m-3] short-pulse (<25 msec) spherical tokamak with extensive diagnostics. The limiter, which consists of a shallow circular stainless steel tray of radius 34 cm and width 10 cm, can be filled with lithium to a depth of a few millimeters, and forms the lower limiting surface for the discharge. Heating elements beneath the tray are used to liquefy the lithium prior to the experiment. The total area of the tray is approximately 2000 cm{sup 2}. The tokamak edge plasma, when operated in contact with the lithium-filled tray, shows evidence of reduced impurities and recycling. The reduction in re cycling and impurities is largest when the lithium is liquefied by heating to 250 degrees Celsius. Discharges which are limited by the liquid lithium tray show evidence of performance enhancement. Radiated power …
Date: July 12, 2002
Creator: Majeski, R.; Boaz, M.; Hoffman, D.; Jones, B.; Kaita, R.; Kugel, H. et al.
Object Type: Report
System: The UNT Digital Library
Durability of SRP Waste Glass - Effects of Waste Loading, Part III (open access)

Durability of SRP Waste Glass - Effects of Waste Loading, Part III

The objective of this study was to develop further understanding of the effects of waste loading on glass leaching. Specifically, waste loadings up to 60 wt per cent oxides were investigated by leaching glasses in buffered and unbuffered solutions.
Date: September 12, 2002
Creator: Wicks, G. G.
Object Type: Report
System: The UNT Digital Library
Acceleration schedules for a recirculating heavy-ion accelerator (open access)

Acceleration schedules for a recirculating heavy-ion accelerator

None
Date: August 12, 2002
Creator: Sharp, W. M. & Grote, D. P.
Object Type: Article
System: The UNT Digital Library
Enabling cleanup technology transfer. (open access)

Enabling cleanup technology transfer.

Technology transfer in the environmental restoration, or cleanup, area has been challenging. While there is little doubt that innovative technologies are needed to reduce the times, risks, and costs associated with the cleanup of federal sites, particularly those of the Departments of Energy (DOE) and Defense, the use of such technologies in actual cleanups has been relatively limited. There are, of course, many reasons why technologies do not reach the implementation phase or do not get transferred from developing entities to the user community. For example, many past cleanup contracts provided few incentives for performance that would compel a contractor to seek improvement via technology applications. While performance-based contracts are becoming more common, they alone will not drive increased technology applications. This paper focuses on some applications of cleanup methodologies and technologies that have been successful and are illustrative of a more general principle. The principle is at once obvious and not widely practiced. It is that, with few exceptions, innovative cleanup technologies are rarely implemented successfully alone but rather are implemented in the context of enabling processes and methodologies. And, since cleanup is conducted in a regulatory environment, the stage is better set for technology transfer when the context …
Date: August 12, 2002
Creator: Ditmars, J. D.
Object Type: Article
System: The UNT Digital Library
Advanced pulse-shape analysis and implementation of gamma-ray tracking in a position-sensitive coaxial HPGe detector (open access)

Advanced pulse-shape analysis and implementation of gamma-ray tracking in a position-sensitive coaxial HPGe detector

None
Date: November 12, 2002
Creator: Kuhn, Austin L.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Environmental Implications of Tc-99 DWPF Operation and Saltcrete (open access)

Environmental Implications of Tc-99 DWPF Operation and Saltcrete

This paper presents the radiological effect on the offsite population from technetium-99 (Tc-99) releases associated with the disposal of the Savannah River Plant high-level waste.
Date: September 12, 2002
Creator: Turcotte, M-D.S.
Object Type: Report
System: The UNT Digital Library
Microstructure and pinning properties of hexagonal-disc shaped single crystalline MgB2 (open access)

Microstructure and pinning properties of hexagonal-disc shaped single crystalline MgB2

We synthesized hexagonal-disc-shaped MgB2 single crystals under high-pressure conditions and analyzed the microstructure and pinning properties. The lattice constants and the Laue pattern of the crystals from x-ray micro-diffraction showed the crystal symmetry of MgB2. A thorough crystallographic mapping within a single crystal showed that the edge and c axis of hexagonal-disc shape exactly matched the [10-10] and the [0001] directions of the MgB2 phase. Thus, these well-shaped single crystals may be the best candidates for studying the direction dependences of the physical properties. The magnetization curve and the magnetic hysteresis curve for these single crystals showed the existence of a wide reversible region and weak pinning properties, which supported our single crystals being very clean.
Date: December 12, 2002
Creator: Jung, C. U.; Kim, J. Y.; Chowdhury, P.; Kim, Kijoon H. P.; Lee, Sung-Ik; Koh, D. S. et al.
Object Type: Article
System: The UNT Digital Library
Seismic methods for resource exploration in enhanced geothermal systems (open access)

Seismic methods for resource exploration in enhanced geothermal systems

A finite-difference modeling study of seismic wave propagation was conducted to determine how to best investigate subsurface faults and fracture zones in geothermal areas. The numerical model was created based on results from a previous seismic reflection experiment. A suite of fault models was investigated including blind faults and faults with surface expressions. The seismic data suggest that blind faults can be detected by a sudden attenuation of seismic wave amplitudes, as long the fault is located below the receiver array. Additionally, a conversion from P- to S-waves indicates the reflection and refraction of the P-waves while propagating across the fault. The drop in amplitudes and the excitation of S-waves can be used to estimate the location of the fault at depth. The accuracy of the numerical modeling depends on the availability of a priori in situ information (velocity and density) from borehole experiments in the geothermal area.
Date: June 12, 2002
Creator: Gritto, Roland & Majer, Ernest L.
Object Type: Article
System: The UNT Digital Library
Performance Data of a Pulsed Power Photo Injector (open access)

Performance Data of a Pulsed Power Photo Injector

There has been a lot of interest in compact sources of high brightness, relativistic electron beams. One approach for developing such a source is to apply a high gradient that remains constant during the generation and acceleration of the electron beam. In this paper, we describe high voltage pulse generators that deliver up to 5 MV with 1 ns pulse duration. These devices are synchronizable to an external trigger with jitter of {approx}0.5 ns and can establish gradients in excess of 1 GV/m between two electrodes without breakdown. In the presence of field gradients up to 0.5 GV/m, electron beams of bunch lengths ranging from 1 ns to 0.3 ps and diameter < 300 {micro}m have been generated by irradiating the cathode with UV lasers. Characteristics of these electron beams as well as those produced via field emission at gradients up to 1 GV/m will be discussed.
Date: November 12, 2002
Creator: Smedley, J.; Srinivasan - Rao, T.; Tsang, T.; Farrell, J. P. & Batchelor, K.
Object Type: Article
System: The UNT Digital Library
Origin and recharge rates of alluvial ground waters, Eastern Desert, Egypt. (open access)

Origin and recharge rates of alluvial ground waters, Eastern Desert, Egypt.

Stable isotope and tritium analyses of shallow ground waters in the Eastern Desert of Egypt showed that the waters were derived largely by evaporation of regional precipitation and at least partly from precipitation in the past 45 y. To estimate the ground water recharge rate, we developed an integrated hydrologic model based on satellite data, geologic maps, infiltration parameters, and spatial rainfall distribution. Modeling indicated that during a severe 1994 storm, recharge through transmission loss in Wadi El-Tarfa was 21% of the precipitation volume. From archival precipitation data, we estimate that the annual recharge rate for the El-Tarfa alluvial aquifer is 4.7 x 10{sup 6} m{sup 3}. Implications for the use of renewable ground waters in arid areas of Egypt and in neighboring countries are clear.
Date: April 12, 2002
Creator: Sultan, M.; Gheith, H.; Sturchio, N. C.; El Alfy, Z. & Danishwar, S.
Object Type: Article
System: The UNT Digital Library
Texas Register, Volume 27, Number 15, Pages 2901-3276, April 12, 2002 (open access)

Texas Register, Volume 27, Number 15, Pages 2901-3276, April 12, 2002

A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code.
Date: April 12, 2002
Creator: Texas. Secretary of State.
Object Type: Journal/Magazine/Newsletter
System: The Portal to Texas History
Texas Register, Volume 27, Number 28, Pages 6149-6472, July 12, 2002 (open access)

Texas Register, Volume 27, Number 28, Pages 6149-6472, July 12, 2002

A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code.
Date: July 12, 2002
Creator: Texas. Secretary of State.
Object Type: Journal/Magazine/Newsletter
System: The Portal to Texas History
Unemployment Insurance: Increased Focus on Program Integrity Could Reduce Billions in Overpayments (open access)

Unemployment Insurance: Increased Focus on Program Integrity Could Reduce Billions in Overpayments

A letter report issued by the General Accounting Office with an abstract that begins "The Unemployment Insurance (UI) program is a federal-state partnership to help replace the lost earnings of unemployed persons and to stabilize the economy during a recession. The Department of Labor estimates that $2.4 billion in overpayments were made in 2001, including $577 million attributed to fraud or abuse. Overpayments in the UI program result from management and operational practices at the state and federal level. At the state level, many states do not sufficiently balance the need to quickly process and pay UI claims with the need to control program payments. Moreover, states rely heavily on self-reported information from claimants for other important data, such as a claimant's receipt of other federal or state program benefits and whether they are citizens of the United States. At the federal level, policies and directives from the Department of Labor affect states' priorities and procedures in a manner that makes overpayments more likely."
Date: July 12, 2002
Creator: United States. General Accounting Office.
Object Type: Report
System: The UNT Digital Library
Dynamic heat and moisture transport and baroclinic adjustment (open access)

Dynamic heat and moisture transport and baroclinic adjustment

In connection with the authors work on the apparent Iris Effect, they have acquired 2 years of additional data, and are redoing their analysis with the larger amount of data. So far, the results duplicate earlier results with greater statistical significance. They have also responded (successfully) to a number of criticisms of the initial publication. In particular, while differing estimates of cloudy and clear emissivity may be correct, they have shown that they reduce feedback factors by no more than 20%. The resulting feedback factors remain negative and large. Moreover, current data analyses suggest that the earlier estimates may be low for other reasons. They have also shown that all cloudy regions in the region covered by the GMS satellite are convective in origin. They are, however, continuing their work on an improved measure of cumulus activity. In particular, they are using TRMM data to determine thresholds in the T11 channel of GMS that are functions of time, position and SST. They have confirmed that the previous results had a very high statistical significance. However, they expect that the use of the improved measure of cumulus will improve this still further. They have completed their study of the possible reconciliation …
Date: April 12, 2002
Creator: Lindzen, Richard S.
Object Type: Report
System: The UNT Digital Library
Internet Banking: Changing Expectations and Regulations (open access)

Internet Banking: Changing Expectations and Regulations

This report provides an overview of the changing expectations and regulations of internet banking.
Date: March 12, 2002
Creator: Eubanks, Walter W.
Object Type: Report
System: The UNT Digital Library
MEASUREMENT OF LINEAR COUPLING RESONANCE IN RHIC. (open access)

MEASUREMENT OF LINEAR COUPLING RESONANCE IN RHIC.

Linear coupling is one of the factors that determine beam lifetime in RHIC. The traditional method of measuring the minimum tune separation requires a tune scan and can't be done parasitically or during the acceleration ramp. A new technique of using ac dipoles to measure linear coupling resonance has been developed at RHIC. This method measures the degree of coupling by comparing the amplitude of the horizontal coherent excitation with the amplitude of the vertical coherent excitation if the beam is excited by the vertical AC dipole and vice versa. One advantage of this method is that it can be done without changing tunes from the normal machine working points. In principle, this method can also localize the coupling source by mapping out the coupling driving terms throughout the ring. This is very useful for local decoupling the interaction regions in RHIC. A beam experiment of measuring linear coupling has been performed in RHIC during its 2003 run, and the analysis of the experimental data is discussed in this paper.
Date: May 12, 2002
Creator: BAI,M. PILAT,F. SATOGATA,T. TOMAS,R.
Object Type: Article
System: The UNT Digital Library
Tax Returns of Individuals: Statistical Charts for the Five Most Recent Years (open access)

Tax Returns of Individuals: Statistical Charts for the Five Most Recent Years

This report provides answers to some of the most frequently asked questions concerning the federal individual income tax, including the number of returns filed, average tax per return, and income tax as percentage of adjusted gross income. This report will be updated as the Internal Revenue Service (IRS) releases new or revised statistics.
Date: December 12, 2002
Creator: Solomon, Arnold D.
Object Type: Report
System: The UNT Digital Library
Barrier Foil Heating Simulations Using LASNEX (open access)

Barrier Foil Heating Simulations Using LASNEX

It is necessary to place a barrier foil in front of the X-ray converter target to prevent the backstreaming ions. This research note presents the simulations of foil heating using the latest EOS tables. LASNEX simulations are carried out using both DARHT-II and ETA-II beam parameters. Results for all the foils studied here, using the DARHT-II beam parameters, show that the integrated line density along the axis at the end of the 4th pulse remains essentially unchanged even if the foils are heated by beams with relatively small beam spot sizes. The temperature can reach up to 3000 C on graphite foil but can only reach several hundred degree Celsius on Mylar foil. Simulations also show that ETA-II beam can create a ''burn-through'' hole on all the foils except graphite and diamond foils, which may require pre-heat. The threshold beam spot size required for hole formation will be compared with LASNEX simulation for the purpose of code verification.
Date: March 12, 2002
Creator: Ho, D. D.-M.
Object Type: Report
System: The UNT Digital Library
Retirement Savings and Household Wealth in 2000: Analysis of Census Bureau Data (open access)

Retirement Savings and Household Wealth in 2000: Analysis of Census Bureau Data

This report examines recent trends in retirement saving and the policy implications. The aging of the American population and the impending retirement of the "baby boom" will place significant strains over the next several decades on both Social Security and on retirees' own financial resources. With continued increases in average life expectancies, retirees in the 21st century will have to stretch their savings and other assets over longer periods of retirement than were experienced by their parents and grandparents.
Date: December 12, 2002
Creator: Purcell, Patrick J.
Object Type: Report
System: The UNT Digital Library
Achieving High Dopant Concentrations in Si: First Principles Simulations (open access)

Achieving High Dopant Concentrations in Si: First Principles Simulations

In this paper we discuss methods to obtain high dopant concentrations during processing of Si devices. The possibility of increasing the solubility of B in Si by misfit stress is investigated. The enthalpy of B atoms is calculated, with and without stress, using density functional theory. A second approach, the trapping of excess dopant atoms during deposition of Si, is also considered. For this purpose, the enthalpies of several dopant species in sites near the surface are calculated.
Date: August 12, 2002
Creator: Centoni, S A; Sadigh, B; Caturla, M J; Gilmer, G H & Diaz de la Rubia, T
Object Type: Article
System: The UNT Digital Library