Optical Properties in Non-equilibrium Phase Transitions (open access)

Optical Properties in Non-equilibrium Phase Transitions

An open question about the dynamical behavior of materials is how phase transition occurs in highly non-equilibrium systems. One important class of study is the excitation of a solid by an ultrafast, intense laser. The preferential heating of electrons by the laser field gives rise to initial states dominated by hot electrons in a cold lattice. Using a femtosecond laser pump-probe approach, we have followed the temporal evolution of the optical properties of such a system. The results show interesting correlation to non-thermal melting and lattice disordering processes. They also reveal a liquid-plasma transition when the lattice energy density reaches a critical value.
Date: January 5, 2006
Creator: Ao, T; Ping, Y; Widmann, K; Price, D F; Lee, E; Tam, H et al.
Object Type: Article
System: The UNT Digital Library
The International Linear Collider Beam Dumps (open access)

The International Linear Collider Beam Dumps

The ILC beam dumps are a key part of the accelerator design. At Snowmass 2005, the current status of the beam dump designs was reviewed, and the options for the overall dump layout considered. This paper describes the available dump options for the baseline and the alternatives and considers issues for the dumps that require resolution.
Date: January 30, 2006
Creator: Appleby, R.; Keller, L.; Markiewicz, T.; Seryi, A.; Walz, D. & Sugahara, R.
Object Type: Article
System: The UNT Digital Library
Tethered Lubricants for Small Systems (open access)

Tethered Lubricants for Small Systems

The objective of this research project is two-fold. First, to fundamentally understand friction and relaxation dynamics of polymer chains near surfaces; and second, to develop novel self-lubricated substrates suitable for MEMS devices. During the three-year performance period of this study the PI and his students have shown using theory and experiments that systematic introduction of disorder into tethered lubricant coatings (e.g. by using self-assembled monolayer (SAM) mixtures or SAMs with nonlinear, branched architectures) can be used to significantly reduce the friction coefficient of a surface. They have also developed a simple procedure based on dielectric spectroscopy for quantifying the effect of surface disorder on molecular relaxation in lubricant coatings. Details of research accomplishments in each area of the project are described in the body of the report.
Date: January 9, 2006
Creator: Archer, Lynden A.
Object Type: Report
System: The UNT Digital Library
U.S.-EU Cooperation Against Terrorism (open access)

U.S.-EU Cooperation Against Terrorism

This report examines the evolution of counterterrorism cooperation between the United States and the European Union (EU), particularly since the September 11, 2001 terrorist attacks. It includes a discussion of U.S.-EU cooperation progress and ongoing challenges, as well as perspectives and issues for Congress.
Date: January 24, 2006
Creator: Archick, Kristin
Object Type: Report
System: The UNT Digital Library
The United States and Europe: Possible Options for U.S. Policy (open access)

The United States and Europe: Possible Options for U.S. Policy

None
Date: January 23, 2006
Creator: Archick, Kristin
Object Type: Report
System: The UNT Digital Library
NATO and the European Union (open access)

NATO and the European Union

Report which discusses issues related to the North Atlantic Trade Organization (NATO) and the European Union (EU) including the level of involvement of the entities in using political and military actions to defend against terrorism and proliferation, the types of military forces necessary, the role of the EU in crisis management, the appropriateness of decision-making procedures to respond to emerging threats, and the role of other international institutions.
Date: January 3, 2006
Creator: Archick, Kristin & Gallis, Paul E.
Object Type: Report
System: The UNT Digital Library
European Union’s Arms Embargo on China: Implications and Options for U.S. Policy (open access)

European Union’s Arms Embargo on China: Implications and Options for U.S. Policy

None
Date: January 26, 2006
Creator: Archick, Kristin; Grimmett, Richard F. & Kan, Shirley A.
Object Type: Report
System: The UNT Digital Library
Islamist Extremism in Europe (open access)

Islamist Extremism in Europe

This report provides an overview of Islamist extremism in Europe, possible terrorist links, European responses, and implications for the United States. Although the vast majority of Muslims in Europe are not involved in radical activities, Islamist extremists and vocal fringe communities that advocate terrorism exist and reportedly have provided cover for terrorist cells.
Date: January 6, 2006
Creator: Archick, Kristin; Rollins, John & Woehrel, Steven
Object Type: Report
System: The UNT Digital Library
Magnetization reversal of uncompensated Fe moments in exchangebiased Ni/FeF2 bilayers (open access)

Magnetization reversal of uncompensated Fe moments in exchangebiased Ni/FeF2 bilayers

The magnetization reversal of uncompensated Fe moments in exchange biased Ni/FeF{sub 2} bilayers was determined using soft x-ray magnetic circular and linear dichroism. The hysteresis loops resulting from the Fe moments are almost identical to those of the ferromagnetic Ni layer. However, a vertical loop shift indicates that some Fe moments are pinned in the antiferromagnetically ordered FeF{sub 2}. The pinned moments are oriented antiparallel to small cooling fields leading to negative exchange bias, but parallel to large cooling fields resulting in positive exchange bias. No indication for the formation of a parallel antiferromagnetic domain wall in the FeF{sub 2} layer upon magnetization reversal in the Ni layer was found.
Date: January 1, 2006
Creator: Arenholz, Elke; Liu, Kai; Li, Zhipan & Schuller, Ivan K.
Object Type: Article
System: The UNT Digital Library
Development of an Acoustic Sensor for On-Line Gas Temperature Measurement in Gasifiers (open access)

Development of an Acoustic Sensor for On-Line Gas Temperature Measurement in Gasifiers

This project was awarded under U.S. Department of Energy (DOE) National Energy Technology Laboratory (NETL) Program Solicitation DE-PS26-02NT41422 and specifically addresses Technical Topical Area 2-Gasification Technologies. The project team includes Enertechnix, Inc. as the main contractor and ConocoPhillips Company as a technical partner, who also provides access to the SG Solutions Gasification Facility (formerly Wabash River Energy Limited), host for the field-testing portion of the research. Since 1989 the U.S. Department of Energy has supported development of advanced coal gasification technology. The Wabash River and TECO IGCC demonstration projects supported by the DOE have demonstrated the ability of these plants to achieve high levels of energy efficiency and extremely low emissions of hazardous pollutants. However, a continuing challenge for this technology is the tradeoff between high carbon conversion which requires operation with high internal gas temperatures, and limited refractory life which is exacerbated by those high operating temperatures. Attempts to control internal gas temperature so as to operate these gasifiers at the optimum temperature have been hampered by the lack of a reliable technology for measuring internal gas temperatures. Thermocouples have serious survival problems and provide useful temperature information for only a few days or weeks after startup before burning …
Date: January 15, 2006
Creator: Ariessohn, Peter & Hornung, Hans
Object Type: Report
System: The UNT Digital Library
Obligate autotrophy in the ammonia oxidizing bacterium Nitrosomonas europaea. (open access)

Obligate autotrophy in the ammonia oxidizing bacterium Nitrosomonas europaea.

Closing report for project DOE-FG02-03ER15436. The project studied obligate autotrophy in the ammonia oxidizing bacterium Nitrosomonas europaea. Nitrosomonas europaea can obtain all of its energy and reductant for growth from the oxidation of ammonia to nitrite and is, therefore, classified as a chemolithotroph. This bacterium is also an autotroph, which can derive all cellular carbon from carbon dioxide. N. europaea seems incapable of growth with other carbon or energy sources. This restricted capability is surprising given that ammonia is a poor energy source. The main goal of the project was to examine the basis of autotrophy in N. europaea or, thought of another way, to determine the barriers to heterotrophy. The approach was enabled by the N. europaea genome sequence, stimulating new ways of thinking about this physiological paradox—an insistence on a single, albeit poor, energy source. Objective 1 was to examine the expression and regulation of the genes coding for alpha-ketoglutarate dehydrogenase, determine if the enzyme’s activity is present, and determine whether alteration of the expression levels influences autotrophic growth. Although Nitrosomonas europaea lacks measurable alpha-ketoglutarate dehydrogenase activity, the genome sequence revealed the presence of the genes encoding the enzyme. A knockout mutation was created in the sucA gene …
Date: January 1, 2006
Creator: Arp, Daniel James & Sayavedra-Soto, Luis Alberto
Object Type: Text
System: The UNT Digital Library
Cost-Effective Method for Producing Self Supported Palladium Alloy Membranes for Use in Efficient Production of Coal Derived Hydrogen Quarterly Technical Progress Report: September 2003-January 2006 (open access)

Cost-Effective Method for Producing Self Supported Palladium Alloy Membranes for Use in Efficient Production of Coal Derived Hydrogen Quarterly Technical Progress Report: September 2003-January 2006

In the past quarter, significant progress has been made in optimize the deposition and release characteristics of ultrathin (less than 4 micron) membranes from rigid silicon substrates. Specifically, we have conducted a series of statistically designed experiments to examine the effects of plasma cleaning and compliant layer deposition conditions on the stress, release and pinhole density of membranes deposited on 4 inch and 6 inch round substrates. With this information we have progressed to the deposition and release of ultra-thin membranes from 12-inch diameter (113 sq. in.) rigid substrates, achieving a key milestone for large-area membrane fabrication. Idatech received and is beginning preparations to test the Pd alloy membranes fabricated at SwRI the previous quarter. They are currently evaluating alternate gasketing methods and support materials that will allow for effective sealing and mounting of such thin membranes. David Edlund has also recently left Idatech and Bill Pledger (Chief Engineer) has replaced him as the primary technical point of contact. At Idetech's request a small number of additional 16 sq. in, samples were provided in a 2 in. by 8 in. geometry for use in a new module design currently under development. Recent work at the Colorado School of Mines has …
Date: January 1, 2006
Creator: Arps, J.
Object Type: Report
System: The UNT Digital Library
Surface structure of CdSe Nanorods revealed by combined X-rayabsorption fine structure measurements and ab-initio calculations (open access)

Surface structure of CdSe Nanorods revealed by combined X-rayabsorption fine structure measurements and ab-initio calculations

We report orientation-specific, surface-sensitive structural characterization of colloidal CdSe nanorods with extended X-ray absorption fine structure spectroscopy and ab-initio density functional theory calculations. Our measurements of crystallographically-aligned CdSe nanorods show that they have reconstructed Cd-rich surfaces. They exhibit orientation-dependent changes in interatomic distances which are qualitatively reproduced by our calculations. These calculations reveal that the measured interatomic distance anisotropy originates from the nanorod surface.
Date: January 27, 2006
Creator: Aruguete, Deborah A.; Marcus, Matthew A.; Li, Liang-shi; Williamson, Andrew; Fakra, Sirine; Gygi, Francois et al.
Object Type: Article
System: The UNT Digital Library
Towards the NNLL Precision in the Decay $\bar B \rightarrow X_s \gamma$ (open access)

Towards the NNLL Precision in the Decay $\bar B \rightarrow X_s \gamma$

The present NLL prediction for the decay rate of the rare inclusive process {bar B} {yields} X{sub s}{gamma} has a large uncertainty due to the charm mass renormalization scheme ambiguity. We estimate that this uncertainty will be reduced by a factor of 2 at the NNLL level. This is a strong motivation for the on-going NNLL calculation, which will thus significantly increase the sensitivity of the observable {bar B} {yields} X{sub s}{gamma} to possible new degrees of freedom beyond the SM. We also give a brief status report of the NNLL calculation.
Date: January 5, 2006
Creator: Asatrian, Hrachia M.; Hovhannisyan, Artyom; Poghosyan, Vahagn; Inst., /Yerevan Phys.; Greub, Christoph; U., /Bern et al.
Object Type: Article
System: The UNT Digital Library
Measurements of $\Lambda^+_c$ Branching Fractions of Cabibbo-Suppressed Decay Modes involving $\Lambda$ and $\Sigma^{0}$ (open access)

Measurements of $\Lambda^+_c$ Branching Fractions of Cabibbo-Suppressed Decay Modes involving $\Lambda$ and $\Sigma^{0}$

None
Date: January 11, 2006
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Object Type: Report
System: The UNT Digital Library
Measurements of the Branching Fractions and CP Asymmetries of B -> D0_CP K Decays (open access)

Measurements of the Branching Fractions and CP Asymmetries of B -> D0_CP K Decays

We present a study of the decay B{sup -} {yields} D{sub (CP)}{sup 0} K{sup -} and its charge conjugate, where D{sub (CP)}{sup 0} is reconstructed in CP-even, CP-odd, and non-CP flavor eigenstates, based on a sample of 232 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II e{sup +}e{sup -} storage ring. We measure the partial-rate charge asymmetries AC{sub CP{+-}} and the ratios R{sub CP{+-}} of the B {yields} D{sup 0} K decay branching fractions as measured in CP{+-} and non-CP D{sup 0} decays: A{sub CP+} = 0.35 {+-} 0.13(stat) {+-} 0.04(syst), A{sub CP-} = -0.06 {+-} 0.13(stat) {+-} 0.04(syst), R{sub CP+} = 0.90 {+-} 0.12(stat) {+-} 0.04(syst), R{sub CP-} = 0.86 {+-} 0.10(stat) {+-} 0.05(syst).
Date: January 5, 2006
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Object Type: Article
System: The UNT Digital Library
Search for the Rare Decays $B^0\to D_s^{(*)+} a_{0(2)}^-$ (open access)

Search for the Rare Decays $B^0\to D_s^{(*)+} a_{0(2)}^-$

The authors have searched for the decays B{sup 0} {yields} D{sub s}{sup +}a{sub 0}{sup -}, B{sup 0} {yields} D*{sub s}{sup +} a{sub 0}{sup -}, B{sup 0} {yields} D{sub s}{sup +}a{sub 2}{sup -} and B{sup 0} {yields} D*{sub s}{sup +} a{sub 2}{sup -} in a sample of about 230 million {Upsilon}(4S) {yields} B{bar B} decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. They find no evidence for these decays and set upper limits at 90% C.L. on the branching fractions: {Beta}(B{sup 0} {yields} D{sub s}{sup +} a{sub 0}{sup -}) < 1.9 x 10{sup -5}, {Beta}(B{sup 0} {yields} D*{sub s}{sup +} a{sub 0}{sup -}) < 3.6 x 10{sup -5}, {Beta}(B{sup 0} {yields} D{sub s}{sup +} a{sub 2}{sup -}) < 1.9 x 10{sup -4}, and {Beta}(B{sup 0} {yields} D*{sub s}{sup +} a{sub 2}{sup -}) < 2.0 x 10{sup -4}.
Date: January 9, 2006
Creator: Aubert, B.; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Object Type: Report
System: The UNT Digital Library
Science and Technology Review March 2006 (open access)

Science and Technology Review March 2006

This month's issue has the following articles: (1) Without Fanfare, Technicians Safely Keep the Laboratory Humming--Commentary by Bruce T. Goodwin; (2) These People Make Things Happen--Technicians at Lawrence Livermore, comprising more than 20 percent of the workforce, are essential to research efforts. March 2006; (3) The Shocking Truth about Detonations and Metals--The multichannel x-ray system Hydra records the changes in metals undergoing a high-explosives shock, revealing phenomena not predicted by material models; (4) Floating into Thin Air--High-flying balloon gathers images from x-ray sources that are out of this world; and (5) Carbon Goes Full Cycle in the Amazon--Recent measurements indicate that the Amazon River basin returns carbon to the atmosphere in only 5 years.
Date: January 18, 2006
Creator: Aufderheide, M B
Object Type: Report
System: The UNT Digital Library
More with Less (open access)

More with Less

None
Date: January 17, 2006
Creator: Austin, C. R.; Goldston, W. T. & Milner, T. N.
Object Type: Article
System: The UNT Digital Library
Tecnetium-99 Behavior in Savannah River Site High Level Waste Sludges During Waste Processing (open access)

Tecnetium-99 Behavior in Savannah River Site High Level Waste Sludges During Waste Processing

This paper presents results of a study of the behavior of technetium-99 (Tc-99) during high level waste (HLW) processing operations at Savannah River Site (SRS). Its behavior during HLW processing is important to understand because Tc-99 can fractionate in the waste and appear in both the sludge and the salt tanks at SRS. It can also be soluble in groundwaters and thus is an important radionuclide that may dictate how much waste has to be removed from a tank to prepare it for permanent closure. The HLW processing steps considered in this study are: (1) The initial caustic neutralization of the acidic waste streams generated in the SRS canyons to prepare the waste for storage in the mild steel tanks in the SRS Tank Farm. Waste that is insoluble in caustic precipitates while soluble elements remain in the supernates. At SRS insoluble components are segregated into sludge tanks and soluble components into the salt tanks. (2) The operations in the SRS Tank Farm that wash the sludge in preparation for immobilization for permanent disposal. (3) The sludge immobilization process in the Defense Waste Processing Facility (DWPF) that solidifies the solids into a stable borosilicate glass. The data in this study …
Date: January 3, 2006
Creator: BIBLER, N. E.; Fellinger, T. L. & Hobbs, D. T.
Object Type: Article
System: The UNT Digital Library
Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants (open access)

Fiber Optical Micro-detectors for Oxygen Sensing in Power Plants

A reflection mode fiber optic oxygen sensor that can operate at high temperatures for power plant applications is being developed. The sensor is based on the {sup 3}O{sub 2} quenching of the red emission from hexanuclear molybdenum chloride clusters. Previously we described a particle-in-binder approach to immobilizing the potassium salt of a molybdenum cluster, K{sub 2}Mo{sub 6}Cl{sub 14}, at the tips of optical fibers. Compared to previous methods, the particle-in-binder approach affords fibers with greatly improved mechanical properties. We have extensively characterized two fiber sensors at high temperature. We obtain quenching ratios between pure nitrogen and 21% oxygen as high as 3.9 x at 70 C. For the first sensor at 60 C we obtained a {+-} 1% variation in the quenching ratio over 6 cycles of measurement, and monitored the device performance over 23 days. We were able to operate the second sensor continuously for 14 hours at 70 C, and the sensor quenching ratio was stable to 5% over that time period. These are promising results for a high temperature fiber optical oxygen sensor based on molybdenum chloride clusters.
Date: January 1, 2006
Creator: Baker, Gregory L.; Ghosh, Ruby N.; III, D.J. Osborn & Zhang, Po
Object Type: Report
System: The UNT Digital Library
Idaho National Laboratory Vadose Zone Research Park Geohydrological Monitoring Results (open access)

Idaho National Laboratory Vadose Zone Research Park Geohydrological Monitoring Results

Vadose zone lithology, hydrological characterization of interbed sediments, and hydrological data from subsurface monitoring of Idaho Nuclear Technology and Engineering Center wastewater infiltration are presented. Three-dimensional subsurface lithology of the vadose zone beneath the Vadose Zone Research Park is represented in a 2 dimensional (2 D) diagram showing interpolated lithology between monitoring wells. Laboratory-measured values for saturated hydraulic conductivity and porosity are given for three major interbeds, denoted as the B BC interbed (20 to 35 m bls), the C D interbed (40 to 45 m bls), and the DE 1 2 interbed (55 to 65 m bls), along with an overall physical description of the sediments and geologic depositional environments. Pre-operational pore water pressure conditions are presented to show the presence and location of perched water zones before pond discharge at the New Percolation Ponds. Subsurface infiltration conditions during initial high-volume discharge are presented to show water arrival times and arrival sequences. Steady-state conditions are then presented to show formation and locations of perched water zones and recharge sources after several months of discharge to the New Percolation Ponds.
Date: January 1, 2006
Creator: Baker, Kristine
Object Type: Report
System: The UNT Digital Library
Efficient Data Management for Knowledge Discovery in Large-Scale Geospatial Imagery Collections (open access)

Efficient Data Management for Knowledge Discovery in Large-Scale Geospatial Imagery Collections

We describe the results of our investigation on supporting ad-hoc and continuous queries over data streams. The major problem we address here is how to identify and utilize metadata for smart caching and to support queries over streaming and archived or historical data.
Date: January 24, 2006
Creator: Baldwin, Chuck & Abdulla, Ghaleb
Object Type: Report
System: The UNT Digital Library
Arctic National Wildlife Refuge (ANWR): Controversies for the 109th Congress (open access)

Arctic National Wildlife Refuge (ANWR): Controversies for the 109th Congress

This is a report by the Arctic National Wildlife Refuge, specifically about the controversies for the 109th Congress.
Date: January 31, 2006
Creator: Baldwin, Pamela; Gelb, Bernard A. & Corn, M. Lynne
Object Type: Report
System: The UNT Digital Library