High Resolution X-Ray Fluorescence Micro-Tomography on Single Sediment Particles (open access)

High Resolution X-Ray Fluorescence Micro-Tomography on Single Sediment Particles

This work focuses on the investigation of the distribution of contaminants in individual sediment particles from the New York/New Jersey Harbor. Knowledge of the spatial distribution of the contaminants within the particles is needed to enable (1) more sophisticated approaches to the understanding of the fate and transport of the contaminants in the environment and (2) more refined methods for cleaning the sediments. The size of the investigated particles ranges from 30-80 microns. Due to the low concentration of the elements of interest and the microscopic size of the environmental particles in these measurements, the small size and high intensity of the analyzing X-ray beam was critical. The high photon flux at the ESRF Microfocus beam line (ID13) was used as the basis for fluorescence tomography to investigate whether the inorganic compounds are taken upon the surface organic coating or whether they are distributed through the volume of the grains being analyzed. The experiments were done using a 13 keV monochromatic beam of approximately 2 {micro}m in size having an intensity of 10{sup 10} ph/s, allowing absolute detection limits on the 0.04-1 fg level for Ti, Cr, Mn, Fe, Ni, and Zn.
Date: July 29, 2002
Creator: Vincze, L.; Vekemans, B.; Szaloki, I.; Janssens, K.; Van Grieken, R.; Feng, H. et al.
Object Type: Article
System: The UNT Digital Library
Plant Physiological Aspects of Silicon (open access)

Plant Physiological Aspects of Silicon

The element silicon, Si, represents an anomaly in plant physiology (Epstein, 1994, 1999b). Plants contain the element in amounts comparable to those of such macronutrient elements as phosphorus, calcium, magnesium, viz. at tissue concentrations (dry weight basis) of about 0.1-10%, although both lower and higher values may be encountered. In some plants, such as rice and sugarcane, Si may be the mineral element present in largest amount. In much of plant physiological research, however, Si is considered a nonentity. Thus, not a single formulation of the widely used nutrient solutions includes Si. Experimental plants grown in these solutions are therefore abnormally low in their content of the element, being able to obtain only what Si is present as an unavoidable contaminant of the nutrient salts used, and from the experimental environment and their own seeds. The reason for the astonishing discrepancy between the prominence of Si in plants and its neglect in much of the enterprise of plant physiological research is that Si does not qualify as an ''essential'' element. Ever since the introduction of the solution culture method in the middle of the last century (Epstein, 1999a, b) it has been found that higher plants can grow in nutrient …
Date: July 10, 2002
Creator: Epstein, E.; Fan, T.W-M.; Higashi, R.M. & Silk, W.K.
Object Type: Report
System: The UNT Digital Library
Structural Studies of Archaealthermophilic Adenylate Kinase (open access)

Structural Studies of Archaealthermophilic Adenylate Kinase

Through this DOE-sponsored program Konisky has studied the evolution and molecular biology of microbes that live in extreme environments. The emphasis of this work has been the determination of the structural features of thermophilic enzymes that allow them to function optimally at near 100 C. The laboratory has focused on a comparative study of adenylate kinase (ADK), an enzyme that functions to interconvert adenine nucleotides. Because of the close phylogenetic relatedness of members of the Methanococci, differences in the structure of their ADKs will be dominated by structural features that reflect contributions to their optimal temperature for activity, rather than differences due to phylogenetic divergence. We have cloned, sequenced and modeled the secondary structure for several methanococcal ADKs. Using molecular modeling threading approaches that are based on the solved structure for the porcine ADK, we have also proposed a general low resolution three dimensional structure for each of the methanococcal enzymes. These analyses have allowed us to propose structural features that confer hyperthermoactivity to those enzymes functioning in the hyperthermophilic members of the Methanococci. Using protein engineering methodologies, we have tested our hypotheses by examining the effects of selective structural changes on thermoactivity. Despite possessing between 68-81% sequence identity, the …
Date: July 10, 2002
Creator: Konisky, J.
Object Type: Report
System: The UNT Digital Library
Nuclear Energy Research Initiative Cooperative Agreement DE-FC03-99SF21902 Technical Progress Report 1Q00 (open access)

Nuclear Energy Research Initiative Cooperative Agreement DE-FC03-99SF21902 Technical Progress Report 1Q00

OAK B188 Nuclear Energy Research Initiative Cooperative Agreement DE-FC03-99SF21902 Technical Progress Report 1Q00.
Date: July 16, 2002
Creator: unknown
Object Type: Report
System: The UNT Digital Library
OPTIMIZATION OF MUD HAMMER DRILLING PERFORMANCE - A PROGRAM TO BENCHMARK THE VIABILITY OF ADVANCED MUD HAMMER DRILLING (open access)

OPTIMIZATION OF MUD HAMMER DRILLING PERFORMANCE - A PROGRAM TO BENCHMARK THE VIABILITY OF ADVANCED MUD HAMMER DRILLING

This document details the progress to date on the OPTIMIZATION OF MUD HAMMER DRILLING PERFORMANCE -- A PROGRAM TO BENCHMARK THE VIABILITY OF ADVANCED MUD HAMMER DRILLING contract for the quarter starting April 2002 through June 2002. Even though we are awaiting the optimization portion of the testing program, accomplishments include the following: (1) Presentation material was provided to the DOE/NETL project manager (Dr. John Rogers) for the DOE exhibit at the 2002 Offshore Technology Conference. (2) Two meeting at Smith International and one at Andergauge in Houston were held to investigate their interest in joining the Mud Hammer Performance study. (3) SDS Digger Tools (Task 3 Benchmarking participant) apparently has not negotiated a commercial deal with Halliburton on the supply of fluid hammers to the oil and gas business. (4) TerraTek is awaiting progress by Novatek (a DOE contractor) on the redesign and development of their next hammer tool. Their delay will require an extension to TerraTek's contracted program. (5) Smith International has sufficient interest in the program to start engineering and chroming of collars for testing at TerraTek. (6) Shell's Brian Tarr has agreed to join the Industry Advisory Group for the DOE project. The addition of Brian …
Date: July 1, 2002
Creator: Tibbitts, Gordon & Judzis, Arnis
Object Type: Report
System: The UNT Digital Library
Very extended shapes in 108Cd: evidence for the occupation of 'hyper-intruder' orbitals (open access)

Very extended shapes in 108Cd: evidence for the occupation of 'hyper-intruder' orbitals

High-spin states in {sup 108}Cd were studied following the reaction {sup 64} Ni({sup 48}Ca,4n) at a beam energy of 207 MeV. Gamma rays were detected using the Gammasphere array. Two rotational bands have been observed at very high angular momentum. Measurements of fractional Doppler shifts yielded lower limits for the quadrupole moments and showed that the observed structures are at least as deformed as the superdeformed structures e.g. in the A {approx} 150 region, and possibly exceed a 2:1 axis ratio. The existence of very extended shapes has been predicted by cranked Strutinsky calculations, and recent projected shell model calculations suggest that the {pi}i{sub 13/2}hyper-intruder orbital is occupied in these newly observed bands.
Date: July 1, 2002
Creator: Gorgen, A.; Clark, R. M.; Fallon, P.; Cromaz, M.; Deleplanque, M. A.; Diamond, R. M. et al.
Object Type: Article
System: The UNT Digital Library
Physics of Off-Axis Electron Cyclotron Current Drive (open access)

Physics of Off-Axis Electron Cyclotron Current Drive

Electron cyclotron current drive is a key option for driving current off-axis in a tokamak, as needed for example for current profile control or for suppression of neoclassical tearing modes. Experiments in DIII-D at low beta have shown that the partial cancellation of the Fisch-Boozer co-current by the Ohkawa counter-current can cause strong deterioration of the current drive efficiency at larger minor radius. However, more recent experiments at higher power have shown that the loss in efficiency can be mostly recovered if the target plasma has higher electron beta, {beta}{sub e}. The improvement in efficiency with beta can be understood from a theoretical viewpoint by applying the Fokker-Planck code CQL3D, which shows excellent agreement with experiment over a wide range of parameters, thereby validating the code as an effective means of predicting the ECCD.
Date: July 1, 2002
Creator: Prater, R.; Petty, C. C.; Harvey, R.; Lin-Liu, Y. R.; Lohr, J. M. & Luce, T. C.
Object Type: Article
System: The UNT Digital Library
Heavy and Thermal Oil Recovery Production Mechanisms (open access)

Heavy and Thermal Oil Recovery Production Mechanisms

This technical progress report describes work performed from April 1 through June 30, 2002, for the project ''Heavy and Thermal Oil Recovery Production Mechanisms.'' We investigate a broad spectrum of topics related to thermal and heavy-oil recovery. Significant results were obtained in the areas of multiphase flow and rock properties, hot-fluid injection, improved primary heavy oil recovery, and reservoir definition. The research tools and techniques used are varied and span from pore-level imaging of multiphase fluid flow to definition of reservoir-scale features through streamline-based history-matching techniques. Briefly, experiments were conducted to image at the pore level matrix-to-fracture production of oil from a fractured porous medium. This project is ongoing. A simulation studied was completed in the area of recovery processes during steam injection into fractured porous media. We continued to study experimentally heavy-oil production mechanisms from relatively low permeability rocks under conditions of high pressure and high temperature. High temperature significantly increased oil recovery rate and decreased residual oil saturation. Also in the area of imaging production processes in laboratory-scale cores, we use CT to study the process of gas-phase formation during solution gas drive in viscous oils. Results from recent experiments are reported here. Finally, a project was completed …
Date: July 1, 2002
Creator: Kovscek, Anthony R.
Object Type: Report
System: The UNT Digital Library
Ecological and Cultural Importance of a Species at Risk of Extinction, Pacific Lamprey, 1964-2002 Technical Report. (open access)

Ecological and Cultural Importance of a Species at Risk of Extinction, Pacific Lamprey, 1964-2002 Technical Report.

The cultural and ecological values of Pacific lamprey (Lampetra tridentata) have not been understood by Euro-Americans and thus their great decline has almost gone unnoticed except by Native Americans, who elevated the issue and initiated research to restore its populations, at least in the Columbia Basin. They regard Pacific lamprey as a highly valued resource and as a result ksuyas (lamprey) has become one of their cultural icons. Ksuyas are harvested to this day as a subsistence food by various tribes along the Pacific coast and are highly regarded for their cultural value. Interestingly, our review suggests that the Pacific lamprey plays an important role in the food web, may have acted as a buffer for salmon from predators, and may have been an important source of marine nutrients to oligotrophic watersheds. This is very different from the Euro-American perception that lampreys are pests. We suggest that cultural biases affected management policies.
Date: July 1, 2002
Creator: Close, David A.
Object Type: Report
System: The UNT Digital Library
On leakage and seepage from geological carbon sequestration sites (open access)

On leakage and seepage from geological carbon sequestration sites

Geologic carbon sequestration is one strategy for reducing the rate of increase of global atmospheric carbon dioxide (CO{sub 2} ) concentrations (IEA, 1997; Reichle, 2000). As used here, the term geologic carbon sequestration refers to the direct injection of supercritical CO{sub 2} deep into subsurface target formations. These target formations will typically be either depleted oil and gas reservoirs, or brine-filled permeable formations referred to here as brine formations. Injected CO{sub 2} will tend to be trapped by one or more of the following mechanisms: (1) permeability trapping, for example when buoyant supercritical CO{sub 2} rises until trapped by a confining caprock; (2) solubility trapping, for example when CO{sub 2} dissolves into the aqueous phase in water-saturated formations, or (3) mineralogic trapping, such as occurs when CO{sub 2} reacts to produce stable carbonate minerals. When CO{sub 2} is trapped in the subsurface by any of these mechanisms, it is effectively sequestered away from the atmosphere where it would otherwise act as a greenhouse gas. The purpose of this report is to summarize our work aimed at quantifying potential CO{sub 2} seepage due to leakage from geologic carbon sequestration sites. The approach we take is to present first the relevant properties …
Date: July 18, 2002
Creator: Oldenburg, C. M.; Unger, A. J. A.; Hepple, R. P. & Jordan, P. D.
Object Type: Report
System: The UNT Digital Library
Alternative Fuels and Chemicals From Synthesis Gas Technical Progress Report: Number 31 (open access)

Alternative Fuels and Chemicals From Synthesis Gas Technical Progress Report: Number 31

The overall objectives of this program are to investigate potential technologies for the conversion of synthesis gas to oxygenated and hydrocarbon fuels and industrial chemicals, and to demonstrate the most promising technologies at DOE's LaPorte, Texas, Slurry Phase Alternative Fuels Development Unit (AFDU). The program will involve a continuation of the work performed under the Alternative Fuels from Coal-Derived Synthesis Gas Program and will draw upon information and technologies generated in parallel current and future DOE-funded contracts.
Date: July 1, 2002
Creator: unknown
Object Type: Report
System: The UNT Digital Library
A COMPUTATIONAL WORKBENCH ENVIRONMENT FOR VIRTUAL POWER PLANT SIMULATION (open access)

A COMPUTATIONAL WORKBENCH ENVIRONMENT FOR VIRTUAL POWER PLANT SIMULATION

This is the seventh Quarterly Technical Report for DOE Cooperative Agreement No.: DE-FC26-00NT41047. The goal of the project is to develop and demonstrate a computational workbench for simulating the performance of Vision 21 Power Plant Systems. Within the last quarter, good progress has been made on the development of the IGCC workbench. A series of parametric CFD simulations for single stage and two stage generic gasifier configurations have been performed. An advanced flowing slag model has been implemented into the CFD based gasifier model. A literature review has been performed on published gasification kinetics. Reactor models have been developed and implemented into the workbench for the majority of the heat exchangers, gas clean up system and power generation system for the Vision 21 reference configuration. Modifications to the software infrastructure of the workbench have been commenced to allow interfacing to the workbench reactor models that utilize the CAPE{_}Open software interface protocol.
Date: July 28, 2002
Creator: Bockelie, Mike; Swensen, Dave; Denison, Martin; Senior, Connie; Sarofim, Adel & Risio, Bene
Object Type: Report
System: The UNT Digital Library
Determining size-specific emission factors for environmental tobacco smoke particles (open access)

Determining size-specific emission factors for environmental tobacco smoke particles

Because size is a major controlling factor for indoor airborne particle behavior, human particle exposure assessments will benefit from improved knowledge of size-specific particle emissions. We report a method of inferring size-specific mass emission factors for indoor sources that makes use of an indoor aerosol dynamics model, measured particle concentration time series data, and an optimization routine. This approach provides--in addition to estimates of the emissions size distribution and integrated emission factors--estimates of deposition rate, an enhanced understanding of particle dynamics, and information about model performance. We applied the method to size-specific environmental tobacco smoke (ETS) particle concentrations measured every minute with an 8-channel optical particle counter (PMS-LASAIR; 0.1-2+ micrometer diameters) and every 10 or 30 min with a 34-channel differential mobility particle sizer (TSI-DMPS; 0.01-1+ micrometer diameters) after a single cigarette or cigar was machine-smoked inside a low air-exchange-rate 20 m{sup 3} chamber. The aerosol dynamics model provided good fits to observed concentrations when using optimized values of mass emission rate and deposition rate for each particle size range as input. Small discrepancies observed in the first 1-2 hours after smoking are likely due to the effect of particle evaporation, a process neglected by the model. Size-specific ETS particle …
Date: July 7, 2002
Creator: Klepeis, Neil E.; Apte, Michael G.; Gundel, Lara A.; Sextro, Richard G. & Nazaroff, William W.
Object Type: Article
System: The UNT Digital Library
Ferroelectric Cathodes in Transverse Magnetic Fields (open access)

Ferroelectric Cathodes in Transverse Magnetic Fields

Experimental investigations of a planar ferroelectric cathode in a transverse magnetic field up to 3 kGs are presented. It is shown that the transverse magnetic field affects differently the operation of ferroelectric plasma cathodes in ''bright'' and ''dark'' modes in vacuum. In the ''bright'' mode, when the surface plasma is formed, the application of the transverse magnetic field leads to an increase of the surface plasma density. In the ''dark'' mode, the magnetic field inhibits the development of electron avalanches along the surface, as it does similarly in other kinds of surface discharges in the pre-breakdown mode.
Date: July 29, 2002
Creator: Dunaevsky, Alexander; Raitses, Yevgeny & Fisch, Nathaniel J.
Object Type: Report
System: The UNT Digital Library
Beyond AEEI: Technical change in integrated assessment. Final report: DOE 43-400-54 ER62296 (open access)

Beyond AEEI: Technical change in integrated assessment. Final report: DOE 43-400-54 ER62296

In order to address the issue of technological progress, most integrated assessment models have incorporated methods to account for autonomous energy efficiency improvement, the natural tendency of an economy to find more efficient ways to produce energy services. Although the treatment of technical changes as an autonomous event is a reasonable modeling convenience, it is not a statement of actual cause and effect. The purpose of this research project is to examine the responsiveness of a particular technology, solar photovoltaic electricity generation, to research and development expenditures by the government and private industry. The goal is to be able to model how the technology can be expected to respond to future government expenditures. The first step was to develop a database of government expenditures on solar photovoltaic research and development. The next step was to develop an analytical dynamic optimization model that would allow the characterization of the important factors in the R&D process and the demonstration of generalizable principles of optimal investment in the R&D process. There is now a solid starting point for research into the relation between government spending on technology research and the response of the technology in terms of technical efficiency.
Date: July 1, 2002
Creator: Richards, Kenneth & Ashton, Brad
Object Type: Report
System: The UNT Digital Library
Damping in Yb nuclei (open access)

Damping in Yb nuclei

In a mixture of three Yb nuclei, we find the rotational damping widths vary from 180 keV at 1.1 MeV {gamma}-ray energy to 290 keV at 1.5 MeV, and the average compound damping widths (or spreading widths) vary from 40 keV at 1.1 MeV {gamma}-ray energy to 60 keV at 1.3 MeV. The simulations also suggest extensive motional narrowing.
Date: July 1, 2002
Creator: Stephens, F. S.; Deleplanque, M. A.; Lee, I. Y.; Ward, D.; Fallon, P.; Cromaz, M. et al.
Object Type: Article
System: The UNT Digital Library
Approximation Algorithms for Distance-2 Edge Coloring (open access)

Approximation Algorithms for Distance-2 Edge Coloring

The authors consider the link scheduling problem for packet radio networks which is assigning channels to the connecting links so that transmission may proceed on all links assigned the same channel simultaneously without collisions. This problem can be cast as the distance-2 edge coloring problem, a variant of proper edge coloring, on the graph with transceivers as vertices and links as edges. They present efficient approximation algorithms for the distance-2 edge coloring problem for various classes of graphs.
Date: July 17, 2002
Creator: Barrett, Christopher L.; Istrate, Gabriel; Vilikanti, Anil Kumar; Marathe, Madhav & Thite, Shripad V.
Object Type: Article
System: The UNT Digital Library
Defocus step size of the LBNL One Angstrom Microscope (open access)

Defocus step size of the LBNL One Angstrom Microscope

The change in focus of a high-resolution electron microscope is generally assumed to be linear with change in objective lens current. Thus the defocus step size should be constant for a constant step in lens current. Measurements on the LBNL One-Angstrom Microscope show that the step size increases with increasing underfocus (reduced lens current). Differentiation of the best-fit quadratic shows that the defocus step size varies linearly as defocus changes.
Date: July 2, 2002
Creator: O'Keefe, Michael A. & Nelson, E. Chris
Object Type: Report
System: The UNT Digital Library
Corrective Action Investigation Plan for Corrective Action Unit 410: Waste Disposal Trenches, Tonopah Test Range, Nevada, Revision 0 (includes ROTCs 1, 2, and 3) (open access)

Corrective Action Investigation Plan for Corrective Action Unit 410: Waste Disposal Trenches, Tonopah Test Range, Nevada, Revision 0 (includes ROTCs 1, 2, and 3)

This Corrective Action Investigation Plan contains the U.S. Department of Energy, National Nuclear Security Administration Nevada Operations Office's approach to collect the data necessary to evaluate corrective action alternatives appropriate for the closure of Corrective Action Unit (CAU) 410 under the Federal Facility Agreement and Consent Order. Corrective Action Unit 410 is located on the Tonopah Test Range (TTR), which is included in the Nevada Test and Training Range (formerly the Nellis Air Force Range) approximately 140 miles northwest of Las Vegas, Nevada. This CAU is comprised of five Corrective Action Sites (CASs): TA-19-002-TAB2, Debris Mound; TA-21-003-TANL, Disposal Trench; TA-21-002-TAAL, Disposal Trench; 09-21-001-TA09, Disposal Trenches; 03-19-001, Waste Disposal Site. This CAU is being investigated because contaminants may be present in concentrations that could potentially pose a threat to human health and/or the environment, and waste may have been disposed of with out appropriate controls. Four out of five of these CASs are the result of weapons testing and disposal activities at the TTR, and they are grouped together for site closure based on the similarity of the sites (waste disposal sites and trenches). The fifth CAS, CAS 03-19-001, is a hydrocarbon spill related to activities in the area. This site …
Date: July 16, 2002
Creator: United States. National Nuclear Security Administration. Nevada Operations Office.
Object Type: Report
System: The UNT Digital Library
Solenoid Magnets for the Front End of a Neutrino Factory. (open access)

Solenoid Magnets for the Front End of a Neutrino Factory.

This report describes the solenoid magnets in the front end (the section between the pion capture solenoid and the linear acceleration section) of the Level 2 study of a neutrino factory. The magnets described in the report start with the decay channel magnets that starts 18 meter downstream from the start of the pion production target. The magnet string ends with the transition solenoids that match the muon beam from the last cooling cell to the superconducting linear accelerator section. All of the magnets described in this report are solenoids. The field on axis in the solenoidal channel ranges from 1.25 T to just over 5.5 T. This report shows that the magnets in the front end of the neutrino factory are feasible.
Date: July 1, 2002
Creator: Green, M. A.; Yu, S. S.; Miller, J. R.; Prestemon, S. & Palmer, R. B.
Object Type: Article
System: The UNT Digital Library
Quantitative Tests of ELMs as Intermediate N Peeling-Ballooning Modes (open access)

Quantitative Tests of ELMs as Intermediate N Peeling-Ballooning Modes

OAK A271 QUANTITATIVE TESTS OF ELMS AS INTERMEDIATE N PEELING-BALLOONING MODES. Two of the major issues crucial for the design of the next generation tokamak burning plasma devices are the predictability of the edge pedestal height and control of the divertor heat load in H-mode configurations. Both of these are strongly impacted by edge localized modes (ELMs) and their size. A working model for ELMs is that they are intermediate toroidal mode number, n {approx} 5-30, peeling-ballooning modes driven by the large edge pedestal pressure gradient P{prime} and the associated large edge bootstrap current density J{sub BS}. the interplay between P{prime} and J{sub BS} as a discharge evolves can excite peeling-ballooning modes over a wide spectrum of n. The pedestal current density plays a dual role by stabilizing the high n ballooning modes via opening access to second stability but providing free energy to drive the intermediate n peeling modes. This makes a systematic evaluation of this model particularly challenging. This paper describes recent quantitative tests of this model using experimental data from the DIII-D and the JT-60U tokamaks. These tests are made possible by recent improvements to the ELITE MHD stability code, which allow an efficient evaluation of the …
Date: July 1, 2002
Creator: Lao, L. L.; Snyder, P. B.; Leonard, A. W.; Osborne, T. H.; Petrie, T. W.; Ferron, J. R. et al.
Object Type: Article
System: The UNT Digital Library
Oblique ion texturing of yttria-stabilized zirconia: The {l_brace}211{r_brace}<111> structure (open access)

Oblique ion texturing of yttria-stabilized zirconia: The {l_brace}211{r_brace}<111> structure

Amorphous (Zr,Y)O{sub x} films were synthesized by reactive magnetron sputtering and subsequently crystallized by oblique ion bombardment. Crystalline texture nucleated by the ion beam was replicated by solid-phase epitaxial growth throughout the formerly amorphous yttria-stabilized zirconia (YSZ) film. The resulting YSZ films have (211) orientation normal to the substrate with in-plane directions (111), parallel, and (110), transverse, to the azimuth of the ion beam. We hypothesize that the texture mechanism involves ion-induced film compression and shear. The results, taken together with prior work, show that oblique ion texturing of amorphous films is a general phenomenon that can be used to fabricate substrates with more than one type of crystallographic orientation.
Date: July 1, 2002
Creator: Berdahl, Paul; Reade, Ronald P.; Liu, Jinping; Russo, Richard E.; Fritzemeier, Les; Buczek, David et al.
Object Type: Article
System: The UNT Digital Library
Tank Waste Transport Stability: Summaries of Hanford Slurry and Salt-Solution Studies in FY 2000 (open access)

Tank Waste Transport Stability: Summaries of Hanford Slurry and Salt-Solution Studies in FY 2000

This report is a collection of summary articles on FY 2000 studies of slurry transport and salt-well pumping related to Hanford tank waste transfers. These studies are concerned with the stability (steady, uninterrupted flow) of tank waste transfers, a subset of the Department of Energy (DOE) Tanks Focus Area Tank (TFA) Waste Chemistry effort. This work is a collaborative effort of AEA Technology plc, the Diagnostic Instrumentation and Analysis Laboratory at Mississippi State University (DIAL-MSU), the Hemispheric Center for Environmental Technology at Florida International University (HCET-FIU), Numatec Hanford Corporation (NHC), and the Oak Ridge National Laboratory (ORNL). The purpose of this report is to provide, in a single document, an overview of these studies to help the reader identify contacts and resources for obtaining more detailed information and to help promote useful interchanges between researchers and users. Despite over 50 years of experience in transporting radioactive tank wastes to and from equipment and tanks at the Department of Energy's Hanford, Savannah River, and Oak Ridge sites, waste slurry transfer pipelines and process piping become plugged on occasion. At Hanford, several tank farm pipelines are no longer in service because of plugs. At Savannah River, solid deposits in the outlet line …
Date: July 8, 2002
Creator: Welch, T. D.
Object Type: Report
System: The UNT Digital Library
UNIVERSAL BEHAVIOR OF CHARGED PARTICLE PRODUCTION IN HEAVY ION COLLISIONS AT RHIC ENERGIES. (open access)

UNIVERSAL BEHAVIOR OF CHARGED PARTICLE PRODUCTION IN HEAVY ION COLLISIONS AT RHIC ENERGIES.

The PHOBOS experiment at RHIC has measured the multiplicity of primary charged particles as a function of centrality and pseudorapidity in Au+Au collisions at {radical}(s{sub NN}) = 19.6, 130 and 200 GeV. Two observations indicate universal behavior of charged particle production in heavy ion collisions. The first is that forward particle production, over a range of energies, follows a universal limiting curve with a non-trivial centrality dependence. The second arises from comparisons with pp/{bar p}p and e{sup +}e{sup -} data. &lt;N{sub ch}&gt;/&lt;N{sub part}/2&gt; in nuclear collisions at high energy scales with {radical}s in a similar way as N{sub ch} in e{sup +}e{sup -} collisions and has a very weak centrality dependence. These features may be related to a reduction in the leading particle effect due to the multiple collisions suffered per participant in heavy ion collisions.
Date: July 24, 2002
Creator: Steinberg, P. A. & COLLABORATION, FOR THE PHOBOS
Object Type: Article
System: The UNT Digital Library