States

Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX-II) (open access)

Li+ alumino-silicate ion source development for the Neutralized Drift Compression Experiment (NDCX-II)

To heat targets to electron-volt temperatures for the study of warm dense matter with intense ion beams, low mass ions, such as lithium, have an energy loss peak (dE/dx) at a suitable kinetic energy. The Heavy Ion Fusion Sciences (HIFS) program at Lawrence Berkeley National Laboratory will carry out warm dense matter experiments using Li{sup +} ion beam with energy 1.2-4 MeV in order to achieve uniform heating up to 0.1-1 eV. The accelerator physics design of Neutralized Drift Compression Experiment (NDCX-II) has a pulse length at the ion source of about 0.5 {micro}s. Thus for producing 50 nC of beam charge, the required beam current is about 100 mA. Focusability requires a normalized (edge) emittance {approx}2 {pi}-mm-mrad. Here, lithium aluminosilicate ion sources, of {beta}-eucryptite, are being studied within the scope of NDCX-II construction. Several small (0.64 cm diameter) lithium aluminosilicate ion sources, on 70%-80% porous tungsten substrate, were operated in a pulsed mode. The distance between the source surface and the mid-plane of the extraction electrode (1 cm diameter aperture) was 1.48 cm. The source surface temperature was at 1220 C to 1300 C. A 5-6 {micro}s long beam pulsed was recorded by a Faraday cup (+300 V on …
Date: April 20, 2011
Creator: LBNL; Roy, P. K.; Greenway, W.; Kwan, J. W.; Seidl, P. A. & Waldron, W.
Object Type: Article
System: The UNT Digital Library
Dielectric Wakefield Accelerator to drive the future FEL Light Source. (open access)

Dielectric Wakefield Accelerator to drive the future FEL Light Source.

X-ray free-electron lasers (FELs) are expensive instruments and a large part of the cost of the entire facility is driven by the accelerator. Using a high-energy gain dielectric wake-field accelerator (DWA) instead of the conventional accelerator may provide a significant cost saving and reduction of the facility size. In this article, we investigate using a collinear dielectric wakefield accelerator to provide a high repetition rate, high current, high energy beam to drive a future FEL x-ray light source. As an initial case study, a {approx}100 MV/m loaded gradient, 850 GHz quartz dielectric based 2-stage, wakefield accelerator is proposed to generate a main electron beam of 8 GeV, 50 pC/bunch, {approx}1.2 kA of peak current, 10 x 10 kHz (10 beamlines) in just 100 meters with the fill factor and beam loading considered. This scheme provides 10 parallel main beams with one 100 kHz drive beam. A drive-to-main beam efficiency {approx}38.5% can be achieved with an advanced transformer ratio enhancement technique. rf power dissipation in the structure is only 5 W/cm{sup 2} in the high repetition rate, high gradient operation mode, which is in the range of advanced water cooling capability. Details of study presented in the article include the overall …
Date: April 20, 2011
Creator: Jing, C.; Power, J. & Zholents, A.
Object Type: Report
System: The UNT Digital Library
NDCX-II, an Induction Linac for HEDP and IFE Research (open access)

NDCX-II, an Induction Linac for HEDP and IFE Research

The Heavy Ion Fusion Science Virtual National Laboratory in the USA is constructing a new Neutralized Drift Compression eXperiment (NDCX-II) at LBNL. This facility is being developed for high energy density physics and inertial fusion energy research. The 12 m long induction linac in NDCX-II will produce a Li{sup +} beam pulse, at energies of 1.2-3 MeV, to heat target material to the warm dense matter regime ({approx} 1 eV). By making use of special acceleration voltage waveforms, 2.5T solenoid focusing, and neutralized drift compression, 20 - 50 nC of beam charge from the ion source will be compressed longitudinally and radially to achieve a subnanosecond pulse length and mm-scale target spot size. The original Neutralized Drift Compression Experiment (NDCX-I) has successfully demonstrated simultaneous radial and longitudinal compression by imparting a velocity ramp to the ion beam, which then drifts in a neutralizing plasma to and through the final focussing solenoid and onto the target. At higher kinetic energy and current, NDCX-II will offer more than 100 times the peak energy fluence on target of NDCX-I. NDCX-II makes use of many parts from the decommissioned Advanced Test Accelerator (ATA) at LLNL. It includes 27 lattice periods between the injector and …
Date: April 20, 2011
Creator: Kwan, J. W.; Arbelaez, D.; Bieniosek, F. M.; Faltens, A.; Friedman, A.; Galvin, J. et al.
Object Type: Article
System: The UNT Digital Library
Final Corrective Action Study for the Former CCC/USDA Facility in Ramona, Kansas. (open access)

Final Corrective Action Study for the Former CCC/USDA Facility in Ramona, Kansas.

Past operations at a grain storage facility formerly leased and operated by the Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) in Ramona, Kansas, resulted in low concentrations of carbon tetrachloride in groundwater that slightly exceed the regulatory standard in only one location. As requested by the Kansas Department of Health and Environment, the CCC/USDA has prepared a Corrective Action Study (CAS) for the facility. The CAS examines corrective actions to address groundwater impacted by the former CCC/USDA facility but not releases caused by other potential groundwater contamination sources in Ramona. Four remedial alternatives were considered in the CAS. The recommended remedial alternative in the CAS consists of Environmental Use Control to prevent the inadvertent use of groundwater as a water supply source, coupled with groundwater monitoring to verify the continued natural improvement in groundwater quality. The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) has directed Argonne National Laboratory to prepare a Corrective Action Study (CAS), consistent with guidance from the Kansas Department of Health and Environment (KDHE 2001a), for the CCC/USDA grain storage facility formerly located in Ramona, Kansas. This effort is pursuant to a KDHE (2007a) request. Although carbon tetrachloride levels at the …
Date: April 20, 2011
Creator: LaFreniere, L. M.
Object Type: Report
System: The UNT Digital Library
TUNING OF SIZE AND SHAPE OF AU-PT NANOCATALYST FOR DIRECT METHANOL FUEL CELLS (open access)

TUNING OF SIZE AND SHAPE OF AU-PT NANOCATALYST FOR DIRECT METHANOL FUEL CELLS

In this paper, we report the precise control of the size, shape and surface morphology of Au-Pt nanocatalysts (cubes, blocks, octahedrons and dogbones) synthesized via a seed-mediated approach. Gold 'seeds' of different aspect ratios (1 to 4.2), grown by a silver-assisted approach, were used as templates for high-yield production of novel Au-Pt nanocatalysts at a low temperature (40 C). Characterization by electron microscopy (SEM, TEM, HRTEM), energy dispersive X-ray analysis (EDX), UV-Vis spectroscopy, zeta-potential (surface charge), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma mass spectrometry (ICP-MS) were used to better understand their physico-chemical properties, preferred reactivities and underlying nanoparticle growth mechanism. A rotating disk electrode was used to evaluate the Au-Pt nanocatalysts electrochemical performance in the oxygen reduction reaction (ORR) and the methanol oxidation reaction (MOR) of direct methanol fuel cells. The results indicate the Au-Pt dogbones are partially and in some cases completely unaffected by methanol poisoning during the evaluation of the ORR. The ORR performance of the octahedron particles in the absence of MeOH is superior to that of the Au-Pt dogbones and Pt-black, however its performance is affected by the presence of MeOH.
Date: April 20, 2011
Creator: Murph, S.
Object Type: Article
System: The UNT Digital Library
The DNA repair endonuclease XPG interacts directly and functionally with the WRN helicase defective in Werner syndrome (open access)

The DNA repair endonuclease XPG interacts directly and functionally with the WRN helicase defective in Werner syndrome

XPG is a structure-specific endonuclease required for nucleotide excision repair (NER). XPG incision defects result in the cancer-prone syndrome xeroderma pigmentosum, whereas truncating mutations of XPG cause the severe postnatal progeroid developmental disorder Cockayne syndrome. We show that XPG interacts directly with WRN protein, which is defective in the premature aging disorder Werner syndrome, and that the two proteins undergo similar sub-nuclear redistribution in S-phase and co-localize in nuclear foci. The co-localization was observed in mid- to late-S-phase, when WRN moves from nucleoli to nuclear foci that have been shown to contain protein markers of both stalled replication forks and telomeric proteins. We mapped the interaction between XPG and WRN to the C-terminal domains of each and show that interaction with the C-terminal domain of XPG strongly stimulates WRN helicase activity. WRN also possesses a competing DNA single-strand annealing activity that, combined with unwinding, has been shown to coordinate regression of model replication forks to form Holliday junction/chicken foot intermediate structures. We tested whether XPG stimulated WRN annealing activity and found that XPG itself has intrinsic strand annealing activity that requires the unstructured R- and C-terminal domains, but not the conserved catalytic core or endonuclease activity. Annealing by XPG is …
Date: April 20, 2011
Creator: Trego, Kelly S.; Chernikova, Sophia B.; Davalos, Albert R.; Perry, J. Jefferson P.; Finger, L. David; Ng, Cliff et al.
Object Type: Article
System: The UNT Digital Library
User's Manual for BEST-Dairy: Benchmarking and Energy/water-Saving Tool (BEST) for the Dairy Processing Industry (Version 1.2) (open access)

User's Manual for BEST-Dairy: Benchmarking and Energy/water-Saving Tool (BEST) for the Dairy Processing Industry (Version 1.2)

This User's Manual summarizes the background information of the Benchmarking and Energy/water-Saving Tool (BEST) for the Dairy Processing Industry (Version 1.2, 2011), including'Read Me' portion of the tool, the sections of Introduction, and Instructions for the BEST-Dairy tool that is developed and distributed by Lawrence Berkeley National Laboratory (LBNL).
Date: April 20, 2011
Creator: Xu, T.; Ke, J. & Sathaye, J.
Object Type: Report
System: The UNT Digital Library
Electrically Detected Magnetic Resonance of Neutral Donors Interacting with a Two-Dimensional Electron Gas (open access)

Electrically Detected Magnetic Resonance of Neutral Donors Interacting with a Two-Dimensional Electron Gas

We have measured the electrically detected magnetic resonance of donor-doped silicon field-effect transistors in resonant X- (9.7 GHz) and W-band (94 GHz) microwave cavities. The two-dimensional electron gas (2DEG) resonance signal increases by two orders of magnitude from X- to W-band, while the donor resonance signals are enhanced by over one order of magnitude. Bolometric effects and spin-dependent scattering are inconsistent with the observations. We propose that polarization transfer from the donor to the 2DEG is the main mechanism giving rise to the spin resonance signals.
Date: April 20, 2011
Creator: Lo, C. C.; Lang, V.; George, R. E.; Morton, J. J. L.; Tyryshkin, A. M.; Lyon, A. et al.
Object Type: Article
System: The UNT Digital Library
Reducing Turbulent Transport in Toroidal Configurations via Shaping (open access)

Reducing Turbulent Transport in Toroidal Configurations via Shaping

Recent progress in reducing turbulent transport in stellarators and tokamaks by 3D shaping using a stellarator optimization code in conjunction with a gyrokinetic code is presented. The original applications of the method focussed on ion temperature gradient transport in a quasi-axisymmetric stellarator design. Here, an examination of both other turbulence channels and other starting configurations is initiated. It is found that the designs evolved for transport from ion temperature gradient turbulence also display reduced transport from other transport channels whose modes are also stabilized by improved curvature, such as electron temperature gradient and ballooning modes. The optimizer is also applied to evolving from a tokamak, finding appreciable turbulence reduction for these devices as well. From these studies, improved understanding is obtained of why the deformations found by the optimizer are beneficial, and these deformations are related to earlier theoretical work in both stellarators and tokamaks.
Date: April 20, 2011
Creator: H.E. Mynick, N. Pomphrey and P. Xanthopoulos
Object Type: Report
System: The UNT Digital Library
Pacific Northwest National Laboratory National Environmental Policy Act Compliance Program -- FY 2010 Annual Report (open access)

Pacific Northwest National Laboratory National Environmental Policy Act Compliance Program -- FY 2010 Annual Report

During fiscal year (FY) 2010, Pacific Northwest National Laboratory (PNNL) Environmental Protection and Regulatory Programs Division (before March 1, 2011 known as the Environmental Management Services Department) staff performed a number of activities as part of PNNL’s National Environmental Policy Act (NEPA) compliance program. These activities helped to verify U.S. Department of Energy (DOE) Pacific Northwest Site Office (PNSO) and Richland Operations Office (RL) compliance with NEPA requirements and streamline the NEPA process for federal activities conducted at PNNL. Self-assessments were performed to address NEPA compliance and cultural and biological resource protection. The NEPA self-assessments focused on implementation within the PNNL Energy and Environment Directorate and routine maintenance activities conducted during the previous calendar year. The cultural and biological resource self-assessments were conducted in accordance with the PNSO Cultural and Biological Resources Management Plan, which specifies annual monitoring of important resources to assess and document the status of the resources and the associated protective mechanisms in place to protect sensitive resources.
Date: April 20, 2011
Creator: Weeks, Regan S.
Object Type: Report
System: The UNT Digital Library
Investigations of the Fundamental Surface Reactions Involved in the Sorption and Desorption of Radionuclides (open access)

Investigations of the Fundamental Surface Reactions Involved in the Sorption and Desorption of Radionuclides

Models for describing solution- and surface-phase reactions have been used for 30 years, but only recently applicable to complex surfaces. Duff et al., using micro-XANES, found that Pu was concentrated on Mn-oxide and smectite phases of zeolitic tuff, providing an evaluation of contaminant speciation on surfaces for modeling. Experiments at Los Alamos demonstrated that actinides display varying surface residence time distributions, probably reflective of mineral surface heterogeneity. We propose to investigate the sorption/desorption behavior of radionuclides from mineral surfaces, as effected by microorganisms, employing isolates from Nevada Test Site deep alluvium as a model system. Characterizations will include surface area, particle size distribution, x-ray diffraction (XRD), microprobe analysis, extractions, and microbiology. Surface interactions will be assessed by electron spectroscopy (XPS), x-ray absorption fine structure spectroscopy (XAFS), X-ray emission spectroscopy, transmission electron microscopy (TEM) and Scanning electron microscopy (SEM). Desert Research Institute (DRI), University of Nevada, Reno (UNR), and University of Nevada, Las Vegas (UNLV) researchers will collaborate to enhance scientific infrastructure and the understanding of contaminant behavior on surfaces, with broader implications for the management of DOE sites.
Date: April 20, 2011
Creator: Czerwinski, Ken; Heske, Clemens; Moser, Duane; Misra, Mnoranjan & McMillion, Glen
Object Type: Report
System: The UNT Digital Library
Exploring Quantum Degenerate Bose-Fermi Mixtures Toward Cooper Pairing of Fermionic Atoms (open access)

Exploring Quantum Degenerate Bose-Fermi Mixtures Toward Cooper Pairing of Fermionic Atoms

We have been exploring interaction dynamics in an ultracold, trapped gas of bosonic and fermionic atoms. Investigation of this new class of quantum degenerate gases concentrates on interaction dominated phenomena such as sympathetic cooling, phase separation, excitations, Feshbach resonances, and the effects of quantum degeneracy. In addition to exploring these new phenomena, we seek to understand and ultimately control the interactions in the gas. In particular, effective interactions between the fermionic atoms will be explored in the context of the longer term goal of realizing Cooper pairing of atoms.
Date: April 20, 2011
Creator: Jin, Deborah
Object Type: Report
System: The UNT Digital Library
The role of Life Cycle Assessment in identifying and reducing environmental impacts of CCS (open access)

The role of Life Cycle Assessment in identifying and reducing environmental impacts of CCS

Life Cycle Assessment (LCA) should be used to assist carbon capture and sequestration (CCS) planners to reduce greenhouse gas (GHG) emissions and avoid unintended environmental trade-offs. LCA is an analytical framework for determining environmental impacts resulting from processes, products, and services. All life cycle stages are evaluated including raw material sourcing, processing, operation, maintenance, and component end-of-life, as well as intermediate stages such as transportation. In recent years a growing number of LCA studies have analyzed CCS systems. We reviewed 50+ LCA studies, and selected 11 studies that compared the environmental performance of 23 electric power plants with and without CCS. Here we summarize and interpret the findings of these studies. Regarding overall climatemitigation effectiveness of CCS, we distinguish between the capture percentage of carbon in the fuels, the net carbon dioxide (CO2) emission reduction, and the net GHG emission reduction. We also identify trade-offs between the climate benefits and the potential increased non-climate impacts of CCS. Emissions of non-CO2 flue gases such as NOx may increase due to the greater throughput of fuel, and toxicity issues may arise due to the use of monoethanolamine (MEA) capture solvent, resulting in ecological and human health impacts. We discuss areas where improvements …
Date: April 20, 2011
Creator: Sathre, Roger; Masanet, Eric; Cain, Jennifer & Chester, Mikhail
Object Type: Article
System: The UNT Digital Library
Si Pillar Structured Thermal Neutron Detectors: Fabrication Challenges and Performance Expectations (open access)

Si Pillar Structured Thermal Neutron Detectors: Fabrication Challenges and Performance Expectations

None
Date: April 20, 2011
Creator: Nikolic, R. J.; Shao, Q.; Voss, L. F.; Conway, A. M.; Radev, R.; Wang, T. F. et al.
Object Type: Article
System: The UNT Digital Library
Mechanisms for Precipitation Variability of the Eastern Brazil/SACZ Convective Margin (open access)

Mechanisms for Precipitation Variability of the Eastern Brazil/SACZ Convective Margin

None
Date: April 20, 2011
Creator: Ma, H.; Ji, X.; Neelin, J. D. & Mechoso, C. R.
Object Type: Article
System: The UNT Digital Library
Design of Benchmark Imagery for Validating Facility Annotation Algorithms (open access)

Design of Benchmark Imagery for Validating Facility Annotation Algorithms

None
Date: April 20, 2011
Creator: Roberts, R S; Pope, P A; Vatsavai, R R; Jiang, M; Arrowood, L F; Trucano, T G et al.
Object Type: Article
System: The UNT Digital Library
Near Infrared Spectral Imaging of Explosives using a Tunable Optical Parametric Oscillator Laser Source (open access)

Near Infrared Spectral Imaging of Explosives using a Tunable Optical Parametric Oscillator Laser Source

None
Date: April 20, 2011
Creator: Klunder, G. L.; Margalith, E. & Nguyen, L.
Object Type: Article
System: The UNT Digital Library