Addressing an Uncertain Future Using Scenario Analysis (open access)

Addressing an Uncertain Future Using Scenario Analysis

The Office of Energy Efficiency and Renewable Energy (EERE) has had a longstanding goal of introducing uncertainty into the analysis it routinely conducts in compliance with the Government Performance and Results Act (GPRA) and for strategic management purposes. The need to introduce some treatment of uncertainty arises both because it would be good general management practice, and because intuitively many of the technologies under development by EERE have a considerable advantage in an uncertain world. For example, an expected kWh output from a wind generator in a future year, which is not exposed to volatile and unpredictable fuel prices, should be truly worth more than an equivalent kWh from an alternative fossil fuel fired technology. Indeed, analysts have attempted to measure this value by comparing the prices observed in fixed-price natural gas contracts compared to ones in which buyers are exposed to market prices (see Bolinger, Wiser, and Golove and (2004)). In addition to the routine reasons for exploring uncertainty given above, the history of energy markets appears to have exhibited infrequent, but troubling, regime shifts, i.e., historic turning points at which the center of gravity or fundamental nature of the system appears to have abruptly shifted. Figure 1 below …
Date: December 15, 2006
Creator: Siddiqui, Afzal S. & Marnay, Chris
Object Type: Report
System: The UNT Digital Library
Analysis of Energy Saving Impacts of New Commercial Energy Codes for the Gulf Coast (open access)

Analysis of Energy Saving Impacts of New Commercial Energy Codes for the Gulf Coast

Report on an analysis of the energy savings and cost impacts associated with the use of newer and more efficiently commercial building energy codes in the states of Louisiana and Mississippi.
Date: December 15, 2006
Creator: Halverson, Mark A.; Gowri, Krishnan & Richman, Eric E.
Object Type: Report
System: The UNT Digital Library
Borehole Summary Report for Core Hole C4998 – Waste Treatment Plant Seismic Boreholes Project (open access)

Borehole Summary Report for Core Hole C4998 – Waste Treatment Plant Seismic Boreholes Project

Seismic borehole C4998 was cored through the upper portion of the Columbia River Basalt Group and Ellensburg Formation to provide detailed lithologic information and intact rock samples that represent the geology at the Waste Treatment Plant. This report describes the drilling of borehole C4998 and documents the geologic data collected during the drilling of the cored portion of the borehole.
Date: December 15, 2006
Creator: Barnett, D. BRENT & Garcia, Benjamin J.
Object Type: Report
System: The UNT Digital Library
Diffusion of Iodine and Rhenium in Category 3 Waste Encasement Concrete and Soil Fill Material (open access)

Diffusion of Iodine and Rhenium in Category 3 Waste Encasement Concrete and Soil Fill Material

Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e. sorption or precipitation). This understanding will enable accurate prediction of radionuclide fate when the waste forms come in contact with groundwater. A set of diffusion experiments using carbonated and non-carbonated concrete-soil half cells was conducted under unsaturated conditions (4% and 7% by wt moisture content). Spiked concrete half-cell specimens were prepared with and without colloidal metallic iron addition and were carbonated using supercritical carbon dioxide. Spikes of I and Re were added to achieve measurable diffusion profile in the soil part of the half-cell. In addition, properties of concrete materials likely to influence radionuclide migration such as carbonation were evaluated in an effort to correlate these properties with the release of iodine and rhenium.
Date: December 15, 2006
Creator: Wellman, Dawn M.; Mattigod, Shas V.; Whyatt, Greg A.; Powers, Laura; Parker, Kent E. & Wood, Marcus I.
Object Type: Report
System: The UNT Digital Library
Experimental Observation of Quantum Confinement in the Conduction Band of CdSe Quantum Dots (open access)

Experimental Observation of Quantum Confinement in the Conduction Band of CdSe Quantum Dots

Recent theoretical descriptions as to the magnitude of effect that quantum confinement has on he conduction band (CB) of CdSe quantum dots (QD) have been conflicting. In this manuscript, we experimentally identify quantum confinement effects in the CB of CdSe QDs for the first time. Using X-ray absorption spectroscopy, we have unambiguously witnessed the CB minimum shift to higher energy with decreasing particle size and have been able to compare these results to recent theories. Our experiments have been able to identify which theories correctly describe the CB states in CdSe QDs. In particular, our experiments suggest that multiple theories describe the shifts in the CB of CdSe QDs and are not mutually exclusive.
Date: December 15, 2006
Creator: Lee, J I; Meulenberg, R W; Hanif, K M; Mattoussi, H; Klepeis, J E; Terminello, L J et al.
Object Type: Article
System: The UNT Digital Library
Final Report DOE Contract No. DE-FG36-04G014294 ICEKAP 2004: A Collaborative Joint Geophysical Imaging Project at Krafla and IDDP P.E. Malin, S.A. Onacha, E. Shalev Division of Earth and Ocean Sciences Nicholas School of the Environment Duke University Durham, NC 27708 (open access)

Final Report DOE Contract No. DE-FG36-04G014294 ICEKAP 2004: A Collaborative Joint Geophysical Imaging Project at Krafla and IDDP P.E. Malin, S.A. Onacha, E. Shalev Division of Earth and Ocean Sciences Nicholas School of the Environment Duke University Durham, NC 27708

In this final report, we discuss both theoretical and applied research resulting from our DOE project, ICEKAP 2004: A Collaborative Joint Geophysical Imaging Project at Krafla and IDDP. The abstract below begins with a general discussion of the problem we addressed: the location and characterization of “blind” geothermal resources using microearthquake and magnetotelluric measurements. The abstract then describes the scientific results and their application to the Krafla geothermal area in Iceland. The text following this abstract presents the full discussion of this work, in the form of the PhD thesis of Stephen A. Onacha. The work presented here was awarded the “Best Geophysics Paper” at the 2005 Geothermal Resources Council meeting, Reno. This study presents the modeling of buried fault zones using microearthquake and electrical resistivity data based on the assumptions that fluid-filled fractures cause electrical and seismic anisotropy and polarization. In this study, joint imaging of electrical and seismic data is used to characterize the fracture porosity of the fracture zones. P-wave velocity models are generated from resistivity data and used in locating microearthquakes. Fracture porosity controls fluid circulation in the hydrothermal systems and the intersections of fracture zones close to the heat source form important upwelling zones for …
Date: December 15, 2006
Creator: Malin, Peter E.; Shalev, Eylon & Onacha, Stepthen A.
Object Type: Report
System: The UNT Digital Library
An In-situ method for the study of strain broadening usingsynchrotronx-ray diffraction (open access)

An In-situ method for the study of strain broadening usingsynchrotronx-ray diffraction

A tensonometer for stretching metal foils has beenconstructed for the study of strain broadening in x-ray diffraction lineprofiles. This device, which is designed for use on the powderdiffractometer in Station 2.3 at Daresbury Laboratory, allows in-situmeasurements to be performed on samples under stress. It can be used fordata collection in either transmission or reflection modes using eithersymmetric or asymmetric diffraction geometries. As a test case,measurements were carried out on a 18mum thick copper foil experiencingstrain levels of up to 5 percent using both symmetric reflection andsymmetric transmission diffraction. All the diffraction profilesdisplayed peak broadening and asymmetry which increased with strain. Themeasured profiles were analysed by the fundamental parameters approachusing the TOPAS peak fitting software. All the observed broadenedprofiles were modelled by convoluting a refineable diffraction profile,representing the dislocation and crystallite size broadening, with afixed instrumental profile pre-determined usinghigh quality LaB6reference powder. The de-convolution process yielded "pure" sampleintegral breadths and asymmetry results which displayed a strongdependence on applied strain and increased almost linearly with appliedstrain. Assuming crystallite size broadening in combination withdislocation broadening arising from fcc a/2<110>111 dislocations,we have extracted the variation of mechanic al property with strain. Theobservation of both peak asymmetry and broadening has been interpreted asa manifestation of …
Date: December 15, 2006
Creator: Tang, Chiu C.; Lynch, Peter A.; Cheary, Robert W. & Clark, Simon M.
Object Type: Article
System: The UNT Digital Library
Nanocrystal Solar Cells (open access)

Nanocrystal Solar Cells

This dissertation presents the results of a research agenda aimed at improving integration and stability in nanocrystal-based solar cells through advances in active materials and device architectures. The introduction of 3-dimensional nanocrystals illustrates the potential for improving transport and percolation in hybrid solar cells and enables novel fabrication methods for optimizing integration in these systems. Fabricating cells by sequential deposition allows for solution-based assembly of hybrid composites with controlled and well-characterized dispersion and electrode contact. Hyperbranched nanocrystals emerge as a nearly ideal building block for hybrid cells, allowing the controlled morphologies targeted by templated approaches to be achieved in an easily fabricated solution-cast device. In addition to offering practical benefits to device processing, these approaches offer fundamental insight into the operation of hybrid solar cells, shedding light on key phenomena such as the roles of electrode-contact and percolation behavior in these cells. Finally, all-inorganic nanocrystal solar cells are presented as a wholly new cell concept, illustrating that donor-acceptor charge transfer and directed carrier diffusion can be utilized in a system with no organic components, and that nanocrystals may act as building blocks for efficient, stable, and low-cost thin-film solar cells.
Date: December 15, 2006
Creator: Gur, Ilan
Object Type: Thesis or Dissertation
System: The UNT Digital Library
On the Mechanical Properties and Microstructure of Nitinol forBiomedical Stent Applications (open access)

On the Mechanical Properties and Microstructure of Nitinol forBiomedical Stent Applications

This dissertation was motivated by the alarming number of biomedical device failures reported in the literature, coupled with the growing trend towards the use of Nitinol for endovascular stents. The research is aimed at addressing two of the primary failure modes in Nitinol endovascular stents: fatigue-crack growth and overload fracture. The small dimensions of stents, coupled with their complex geometries and variability among manufacturers, make it virtually impossible to determine generic material constants associated with specific devices. Instead, the research utilizes a hybrid of standard test techniques (fracture mechanics and x-ray micro-diffraction) and custom-designed testing apparatus for the determination of the fracture properties of specimens that are suitable representations of self-expanding Nitinol stents. Specifically, the role of texture (crystallographic alignment of atoms) and the austenite-to-martensite phase transformation on the propagation of cracks in Nitinol was evaluated under simulated body conditions and over a multitude of stresses and strains. The results determined through this research were then used to create conservative safe operating and inspection criteria to be used by the biomedical community for the determination of specific device vulnerability to failure by fracture and/or fatigue.
Date: December 15, 2006
Creator: Robertson, Scott W.
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Preliminary Report on Operational Guidelines Developed for Use in Emergency Preparedness and Response to a Radiological Dispersal Device Incident. (open access)

Preliminary Report on Operational Guidelines Developed for Use in Emergency Preparedness and Response to a Radiological Dispersal Device Incident.

This report presents preliminary operational guidelines and supporting work products developed through the interagency Operational Guidelines Task Group (OGT). The report consolidates preliminary operational guidelines, all ancillary work products, and a companion software tool that facilitates their implementation into one reference source document. The report is intended for interim use and comment and provides the foundation for fostering future reviews of the operational guidelines and their implementation within emergency preparedness and response initiatives in the event of a radiological dispersal device (RDD) incident. The report principally focuses on the technical derivation and presentation of the operational guidelines. End-user guidance providing more details on how to apply these operational guidelines within planning and response settings is being considered and developed elsewhere. The preliminary operational guidelines are categorized into seven groups on the basis of their intended application within early, intermediate, and long-term recovery phases of emergency response. We anticipate that these operational guidelines will be updated and refined by interested government agencies in response to comments and lessons learned from their review, consideration, and trial application. This review, comment, and trial application process will facilitate the selection of a final set of operational guidelines that may be more or less inclusive …
Date: December 15, 2006
Creator: Yu, C.; Cheng, J. J.; Kamboj, S.; Domotor, S.; Wallo, A.; Division, Environmental Science et al.
Object Type: Report
System: The UNT Digital Library
Reactive Geochemical Transport Modeling of Concentrated Aqueous Solutions: Supplement to TOUGHREACT User's Guide for the PitzerIon-Interaction Model (open access)

Reactive Geochemical Transport Modeling of Concentrated Aqueous Solutions: Supplement to TOUGHREACT User's Guide for the PitzerIon-Interaction Model

In this report, we present: -- The Pitzer ion-interactiontheory and models -- Input file requirements for using the TOUGHREACTPitzer ion-interaction model and associated databases -- Run-time errormessages -- Verification test cases and application examples. For themain code structure, features, overall solution methods, description ofinput/output files for parameters other than those specific to theimplemented Pitzer model, and error messages, see the TOUGHREACT User'sGuide (Xu et al., 2005). The TOUGHREACT Pitzer version runs on aDEC-alpha architecture CPU, under OSF1 V5.1, with Compaq Digital FortranCompiler. The compiler run-time libraries are required for execution aswell as compilation. The code also runs on Intel Pentium IV andhigher-version CPU-based machines with Compaq Visual Fortran Compiler orIntel Fortran Compiler (integrated with the Microsoft DevelopmentEnvironment). The minimum hardware configuration should include 1 GB RAMand 1 GB (2 GB recommended) of available disk space.
Date: December 15, 2006
Creator: Zhang, Guoxiang; Spycher, Nicolas; Xu, Tianfu; Sonnenthal, Eric & Steefel , Carl
Object Type: Report
System: The UNT Digital Library
Accelerator-Driven Neutron Source for Cargo Screening (open access)

Accelerator-Driven Neutron Source for Cargo Screening

Advanced neutron interrogation systems for the screening ofsea-land cargo containers for shielded special nuclear materials (SNM)require a high-yield neutron source to achieve the desired detectionprobability, false alarm rate, and throughput. An accelerator-drivenneutron source is described that produces a forward directed beam ofhigh-energy (up to 8.5 MeV) neutrons utilizing the D(d,n)3He reaction atdeuteron beam energies of up to 6 MeV. The key components of the neutronsource are a high-current RFQ accelerator and an innovative neutronproduction target. A microwave-driven deuteron source is coupled to anelectrostatic LEBT that injects a 40 mA D+-beam into a 6 MeV, 5.1meter-long, 200 MHz RFQ. The RFQ is based on an unusual beam dynamicsdesign and is capable of operating at a duty factor that produces morethan 1.2 mA timeaverage beam current. The beam is transported to a2-atmosphere deuterium gas target with a specially-designed, thinentrance window. A high-frequency dipole magnet is used to spread thebeam over the long dimension of the 4 by 35 cm target window. The sourcewill be capable of delivering a neutron flux of ~;2 x 107 n/(cm2 x s) tothe center of a sea-land cargo container and is expected t o satisfy therequirements for full testing and demonstration of advanced neutroninterrogation techniques based on …
Date: November 15, 2006
Creator: Ludewigt, B. A.; Bleuel, D. L.; Hoff, M. D.; Kwan, J. W.; Li, D.; Ratti, A. et al.
Object Type: Article
System: The UNT Digital Library
A Barrel IFR Instrumented With Limited Streamer Tubes for BABAR Experiment (open access)

A Barrel IFR Instrumented With Limited Streamer Tubes for BABAR Experiment

The new barrel Instrumented Flux Return (IFR) of BABAR detector will be reported here. Limited Streamer Tubes (LSTs) have been chosen to replace the existing RPCs as active elements of the barrel IFR. The layout of the new detector will be discussed: in particular, a cell bigger than the standard one has been used to improve efficiency and reliability. The extruded profile is coated with a resistive layer of graphite having a typical surface resistivity between 0.2 and 0.4 MOhm/square. The tubes are assembled in modules and installed in 12 active layers of each sextant of the IFR detector. R&amp;D studies to choose the final design and Quality Control procedure adopted during the tube production will be briefly discussed. Finally the performances of installed LSTs into 2/3 of IFR after 8 months of operations will be reported.
Date: November 15, 2006
Creator: Andreotti, M.
Object Type: Article
System: The UNT Digital Library
Characterization of bubble core and cloudiness in Yb3+:Sr5(PO4)3F crystals using Micro-Raman spectroscopy (open access)

Characterization of bubble core and cloudiness in Yb3+:Sr5(PO4)3F crystals using Micro-Raman spectroscopy

Ytterbium doped strontium fluoroapatite Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F (Yb: S-FAP) crystals have been used in High Average Power Laser systems as gain medium. Growth induced defects associated with the crystal often affect their performance. In order to improve the crystal quality and its optical applications, it is imperative to understand the nature of these defects. In this study, we utilize Micro-Raman spectroscopy to characterize two common growth-induced defects: bubble core and cloudiness. We find the bubble core consist of voids and microcrystals of Yb: S-FAP. These microcrystals have very different orientation from that of the pure crystal outside the bubble core. In contrast to a previous report, neither Sr{sub 3}(PO{sub 4}){sub 2} nor Yb{sub 2}O{sub 3} are observed in the bubble core regions. On the other hand, the cloudy regions are made up of the host materials blended with a structural deformation along with impurities which include CaCO{sub 3}, YbPO{sub 4}, SrHPO{sub 4} and Sr{sub 2}P{sub 2}O{sub 7}. The impurities are randomly distributed in the cloudy regions. This analysis is necessary for understanding and eliminating these growth defects in Yb:S-FAP crystals.
Date: November 15, 2006
Creator: Cui, Yunlong; Roy, Utpal N.; Bai, Lihua; Burger, Arnold; Qiu, S. Roger & Schaffers, Kathleen
Object Type: Article
System: The UNT Digital Library
Complex Genetic Disorders and Intellectual Property Rights Final Report (open access)

Complex Genetic Disorders and Intellectual Property Rights Final Report

None
Date: November 15, 2006
Creator: Andrews, Lori, B.
Object Type: Report
System: The UNT Digital Library
CONTROL CHART DASHBOARDS MANAGING YOUR NUMBERS INSTEAD OF YOU NUMBER MANAGING YOU (open access)

CONTROL CHART DASHBOARDS MANAGING YOUR NUMBERS INSTEAD OF YOU NUMBER MANAGING YOU

This paper, which documents Fluor Hanford's application of Statistical Process Control (SPC) and Dashboards to support planning and decision making, is a sequel to ''Leading with Leading Indicators'' that was presented at WM 05. This year's paper provides more detail on management's use of SPC and control charts and discusses their integration into an executive summary using the popular color-cod3ed dashboard methodology. Fluor Hanford has applied SPC in a non-traditional (that is non-manufacturing) manner. Dr. Shewhart's 75-year-old control-chart methodologies have been updated to modern data processing, but are still founded on his sound, tried and true principles. These methods are playing a key role in safety and quality at what has been called the world's largest environmental cleanup project. The US Department of Energy's (DOE's) Hanford Site played a pivotal role in the nation's defense, beginning in the 1940s when it was established as part of the Manhattan Project. After more than 50 years of producing nuclear weapons, Hanford--which covers 586 square miles in southeastern Washington state--is now focused on three outcomes: (1) restoring the Columbia River corridor for multiple uses; (2) transitioning the central plateau to support long-term waste management; and (3) putting DOE assets to work for the …
Date: November 15, 2006
Creator: PREVETTE, S.S.
Object Type: Article
System: The UNT Digital Library
Coupled Biogeochemical Processes Governing the Stability of Bacteriogenic Uraninite and Release of U(VI) in Heterogeneous Media: Molecular to Meter Scales (open access)

Coupled Biogeochemical Processes Governing the Stability of Bacteriogenic Uraninite and Release of U(VI) in Heterogeneous Media: Molecular to Meter Scales

In-situ reductive biotransformation of subsurface U(VI) to U(IV) (as ?UO2?) has been proposed as a bioremediation method to immobilize uranium at contaminated DOE sites. The chemical stability of bacteriogenic ?UO2? is the seminal issue governing its success as an in-situ waste form in the subsurface. The structure and properties of chemically synthesized UO2+x have been investigated in great detail. It has been found to exhibit complex structural disorder, with nonstoichiometry being common, hence the designation ?UO2+x?, where 0 &lt; x &lt; 0.25. Little is known about the structures and properties of the important bacteriogenic analogs, which are believed to occur as nanoparticles in the environment. Chemically synthesized UO2+x exhibits an open fluorite structure and is known to accommodate significant doping of divalent cations. The extent to which bacteriogenic UO2+x incorporates common ground water cations (e.g., Ca2+) has not been investigated, and little is known about nonstoichiometry and structure defects in the bacteriogenic material. Particle size, nonstoichiometry, and doping may significantly alter the reactivity, and hence stability, of bacteriogenic UO2+x in the subsurface. The presence of associated sulfide minerals, and solid phase oxidants such as bacteriogenic Mn oxides may also affect the longevity of bacteriogenic UO2 in the subsurface.
Date: November 15, 2006
Creator: Bargar, John R.
Object Type: Report
System: The UNT Digital Library
Development of a Demagnetization Refrigerator for Solid State Research and Education (open access)

Development of a Demagnetization Refrigerator for Solid State Research and Education

The objective of this project is to develp an instrument to cool electrons in semiconductors to extremely low temperatures (lower than 1 millikelvin), a unique capability that would allow studies of new states of matter formed by low-dimensional electrons. At such low temperatures (and with an intense magnetic field), electronic behavior differs completely from ordinary ones observed at room temperatures. Studies of electrons at such low temperatures would open the door for fundamental discoveries in condensed matter physics. Understanding low-temperature electron transport in low-dimensional and nano-scale devices is the foundation for developing next generation quantum information and quantum computation technologies. The primary material systems for such investigations will be ultra-high quality GaAs/AlGaAs quantum structures grown by molecular beam epitaxy, materials that are widely used in lasers and telecommunications.
Date: November 15, 2006
Creator: Du, Rui-Rui
Object Type: Report
System: The UNT Digital Library
Environmental Remediation Sciences Program at the Stanford Synchrotron Radiation Laboratory (open access)

Environmental Remediation Sciences Program at the Stanford Synchrotron Radiation Laboratory

Synchrotron radiation (SR)-based techniques provide unique capabilities to address scientific issues underpinning environmental remediation science and have emerged as major research tools in this field. The high intensity of SR sources and x-ray photon-in/photon-out detection allow noninvasive in-situ analysis of dilute, hydrated, and chemically/structurally complex natural samples. SR x-rays can be focused to beams of micron and sub-micron dimension, which allows the study of microstructures, chemical microgradients, and microenvironments such as in biofilms, pore spaces, and around plant roots, that may control the transformation of contaminants in the environment. The utilization of SR techniques in environmental remediation sciences is often frustrated, however, by an ''activation energy barrier'', which is associated with the need to become familiar with an array of data acquisition and analysis techniques, a new technical vocabulary, beam lines, experimental instrumentation, and user facility administrative procedures. Many investigators find it challenging to become sufficiently expert in all of these areas or to maintain their training as techniques evolve. Another challenge is the dearth of facilities for hard x-ray micro-spectroscopy, particularly in the 15 to 23 KeV range, which includes x-ray absorption edges of the priority DOE contaminants Sr, U, Np, Pu, and Tc. Prior to the current program, …
Date: November 15, 2006
Creator: Bargar, John R.
Object Type: Report
System: The UNT Digital Library
Estimation Uncertainty in the Determinatin of the Master Curve Reference Temperature (open access)

Estimation Uncertainty in the Determinatin of the Master Curve Reference Temperature

The Master Curve Reference Temperature, T{sub 0}, characterizes the fracture performance of structural steels in the ductile-to-brittle transition region. For a given material, this reference temperature is estimated via fracture toughness testing. A methodology is presented to compute the standard error of an estimated T{sub 0} value from a finite sample of toughness data, in a unified manner for both constant temperature and multiple temperature test methods. Using the asymptotic properties of maximum likelihood estimators, closed-form expressions for the standard error of the estimate of T{sub 0} are presented for both test methods. This methodology includes statistically rigorous treatment of censored data, which represents an advance over the current ASTM E1921 methodology. Through Monte Carlo simulations of realistic constant temperature and multiple temperature test plans, the recommended likelihood-based procedure is shown to provide better statistical performance than the methods in the ASTM E1920 standards.
Date: November 15, 2006
Creator: Sham, TL & Eno, DR
Object Type: Article
System: The UNT Digital Library
Experience With the Resistive Plate Chamber in the BaBar Experiment (open access)

Experience With the Resistive Plate Chamber in the BaBar Experiment

The BABAR detector has operated nearly 200 Resistive Plate Chambers (RPCs), constructed as part of an upgrade of the forward endcap muon detector, for the past two years. The RPCs experience widely different background and luminosity-driven singles rates (0.01-10 Hz/cm{sup 2}) depending on position within the endcap. Some regions have integrated over 0.3 C/cm{sup 2}. RPC efficiency measured with cosmic rays and beam is high and stable. However, a few of the highest rate RPCs have suffered efficiency losses of 5-15%. Although constructed with improved techniques many of the RPCs, which are operated in streamer mode, have shown increased dark currents and noise rates that are correlated with the direction of the gas flow and the integrated current.
Date: November 15, 2006
Creator: Bellini, F.
Object Type: Article
System: The UNT Digital Library
Fission-Product Separation Based on Room-Temperature Ionic Liquids (open access)

Fission-Product Separation Based on Room-Temperature Ionic Liquids

The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions.
Date: November 15, 2006
Creator: Luo, Huimin
Object Type: Report
System: The UNT Digital Library
The Four-Loop Planar Amplitude and Cusp Anomalous Dimension in Maximally Supersymmetric Yang-Mills Theory (open access)

The Four-Loop Planar Amplitude and Cusp Anomalous Dimension in Maximally Supersymmetric Yang-Mills Theory

We present an expression for the leading-color (planar) four-loop four-point amplitude of N = 4 supersymmetric Yang-Mills theory in 4-2{epsilon} dimensions, in terms of eight separate integrals. The expression is based on consistency of unitarity cuts and infrared divergences. We expand the integrals around {epsilon} = 0, and obtain analytic expressions for the poles from 1/{epsilon}{sup 8} through 1/{epsilon}{sup 4}. We give numerical results for the coefficients of the 1/{epsilon}{sup 3} and 1/e{sup 2} poles. These results all match the known exponentiated structure of the infrared divergences, at four separate kinematic points. The value of the 1/{epsilon}{sup 2} coefficient allows us to test a conjecture of Eden and Staudacher for the four-loop cusp (soft) anomalous dimension. We find that the conjecture is incorrect, although our numerical results suggest that a simple modification of the expression, flipping the sign of the term containing {zeta}{sub 3}{sup 2}, may yield the correct answer. Our numerical value can be used, in a scheme proposed by Kotikov, Lipatov and Velizhanin, to estimate the two constants in the strong-coupling expansion of the cusp anomalous dimension that are known from string theory. The estimate works to 2.6% and 5% accuracy, providing non-trivial evidence in support of the …
Date: November 15, 2006
Creator: Bern, Zvi; Czakon, Michael; Dixon, Lance J.; Kosower, David A. & Smirnov, Vladimir A.
Object Type: Article
System: The UNT Digital Library
GLASS FABRICATION AND PRODUCT CONSISTENCY TESTING OF LANTHANIDE BOROSILICATE FRIT X COMPOSITION FOR PLUTONIUM DISPOSITION (open access)

GLASS FABRICATION AND PRODUCT CONSISTENCY TESTING OF LANTHANIDE BOROSILICATE FRIT X COMPOSITION FOR PLUTONIUM DISPOSITION

The Department of Energy Office of Environmental Management (DOE/EM) plans to conduct the Plutonium Disposition Project at the Savannah River Site (SRS) to disposition excess weapons-usable plutonium. A plutonium glass waste form is the preferred option for immobilization of the plutonium for subsequent disposition in a geologic repository. A reference glass composition (Lanthanide Borosilicate (LaBS) Frit B) was developed during the Plutonium Immobilization Program (PIP) to immobilize plutonium in the late 1990's. A limited amount of performance testing was performed on this baseline composition before efforts to further pursue Pu disposition via a glass waste form ceased. Recent FY05 studies have further investigated the LaBS Frit B formulation as well as development of a newer LaBS formulation denoted as LaBS Frit X. The objectives of this present task were to fabricate plutonium loaded LaBS Frit X glass and perform corrosion testing to provide near-term data that will increase confidence that LaBS glass product is suitable for disposal in the Yucca Mountain Repository. Specifically, testing was conducted in an effort to provide data to Yucca Mountain Project (YMP) personnel for use in performance assessment calculations. Plutonium containing LaBS glass with the Frit X composition with a 9.5 wt% PuO{sub 2} loading …
Date: November 15, 2006
Creator: Marra, J
Object Type: Report
System: The UNT Digital Library