Directional Stand-off Detection of Fast Neutrons and Gammas Using Angular Scattering Distributions (open access)

Directional Stand-off Detection of Fast Neutrons and Gammas Using Angular Scattering Distributions

We have investigated the response of a DoubleScatter Neutron Spectrometer (DSNS) for sources at long distances (gr than 200 meters). We find that an alternative method for analyzing double scatter data avoids some uncertainties introduced by amplitude measurements in plastic scintillators.Time of flight is used to discriminate between gamma and neutron events, and the kinematic distributions of scattering angles are assumed to apply. Non-relativistic neutrons are most likely to scatter at 45°, while gammas with energies greater than 2 MeV are most likely to be forward scattered. The distribution of scattering angles of fission neutrons arriving from a distant point source generates a 45° cone, which can be back-projected to give the source direction. At the same time, the distribution of Compton-scattered gammas has a maximum in the forward direction, and can be made narrower by selecting events that deposit minimal energy in the first scattering event. We have further determined that the shape of spontaneous fission neutron spectra at ranges gr than 110 m is still significantly different from thecosmic ray background.
Date: October 25, 2009
Creator: Vanier, Peter E.; Dioszegi, Istvan; Salwen, Ccynthia & Forman, Leon
Object Type: Article
System: The UNT Digital Library
Technosocial Modeling for Determining the Status and Nature of a State’s Nuclear Activities (open access)

Technosocial Modeling for Determining the Status and Nature of a State’s Nuclear Activities

The International Atomic Energy Agency State Evaluation Process: The Role of Information Analysis in Reaching Safeguards Conclusions (Mathews et al. 2008), several examples of nonproliferation models using analytical software were developed that may assist the IAEA with collecting, visualizing, analyzing, and reporting information in support of the State Evaluation Process. This paper focuses on one of the examples a set of models developed in the Proactive Scenario Production, Evidence Collection, and Testing (ProSPECT) software that evaluates the status and nature of a state’s nuclear activities. The models use three distinct subject areas to perform this assessment: the presence of nuclear activities, the consistency of those nuclear activities with national nuclear energy goals, and the geopolitical context in which those nuclear activities are taking place. As a proof-of-concept for the models, a crude case study was performed. The study, which attempted to evaluate the nuclear activities taking place in Syria prior to September 2007, yielded illustrative, yet inconclusive, results. Due to the inconclusive nature of the case study results, changes that may improve the model’s efficiency and accuracy are proposed.
Date: September 25, 2009
Creator: Gastelum, Zoe N. & Harvey, Julia B.
Object Type: Report
System: The UNT Digital Library
Electron Liquids in Semiconductor Quantum Structures (open access)

Electron Liquids in Semiconductor Quantum Structures

The groups led by Stormer and Pinczuk have focused this project on goals that seek the elucidation of novel many-particle effects that emerge in two-dimensional electron systems (2DES) as the result from fundamental quantum interactions. This experimental research is conducted under extreme conditions of temperature and magnetic field. From the materials point of view, the ultra-high mobility systems in GaAs/AlGaAs quantum structures continue to be at the forefront of this research. The newcomer materials are based on graphene, a single atomic layer of graphite. The graphene research is attracting enormous attention from many communities involved in condensed matter research. The investigated many-particle phenomena include the integer and fractional quantum Hall effect, composite fermions, and Dirac fermions, and a diverse group of electron solid and liquid crystal phases. The Stormer group performed magneto-transport experiments and far-infrared spectroscopy, while the Pinczuk group explores manifestations of such phases in optical spectra.
Date: May 25, 2009
Creator: Pinczuk, Aron
Object Type: Report
System: The UNT Digital Library
Upscaling of Long-Term U9VI) Desorption from Pore Scale Kinetics to Field-Scale Reactive Transport Models (open access)

Upscaling of Long-Term U9VI) Desorption from Pore Scale Kinetics to Field-Scale Reactive Transport Models

Environmental systems exhibit a range of complexities which exist at a range of length and mass scales. Within the realm of radionuclide fate and transport, much work has been focused on understanding pore scale processes where complexity can be reduced to a simplified system. In describing larger scale behavior, the results from these simplified systems must be combined to create a theory of the whole. This process can be quite complex, and lead to models which lack transparency. The underlying assumption of this approach is that complex systems will exhibit complex behavior, requiring a complex system of equations to describe behavior. This assumption has never been tested. The goal of the experiments presented is to ask the question: Do increasingly complex systems show increasingly complex behavior? Three experimental tanks at the intermediate scale (Tank 1: 2.4m x 1.2m x 7.6cm, Tank 2: 2.4m x 0.61m x 7.6cm, Tank 3: 2.4m x 0.61m x 0.61m (LxHxW)) have been completed. These tanks were packed with various physical orientations of different particle sizes of a uranium contaminated sediment from a former uranium mill near Naturita, Colorado. Steady state water flow was induced across the tanks using constant head boundaries. Pore water was removed …
Date: January 25, 2009
Creator: Miller, Andy
Object Type: Report
System: The UNT Digital Library
Photodiode-Based X-Ray Beam-Position Monitor With High Spatial-Resolution for the NSLS-II Beamlines (open access)

Photodiode-Based X-Ray Beam-Position Monitor With High Spatial-Resolution for the NSLS-II Beamlines

We developed a photodiode-based monochromatic X-ray beam-position monitor (X-BPM) with high spatial resolution for the project beamlines of the NSLS-II. A ring array of 32 Si PIN-junction photodiodes were designed for use as a position sensor, and a low-noise HERMES4 ASIC chip was integrated into the electronic readout system. A series of precision measurements to characterize electrically the Si-photodiode sensor and the ASIC chip demonstrated that the inherent noise is sufficiently below tolerance levels. Following up modeling of detector's performance, including geometrical optimization using a Gaussian beam, we fabricated and assembled a first prototype. In this paper, we describe the development of this new state-of-the-art X-ray BPM along the beamline, in particular, downstream from the monochromator.
Date: May 25, 2009
Creator: Yoon, P.S. & Siddons, D. P.
Object Type: Article
System: The UNT Digital Library
Te Inclusions in CZT Detectors: New Method for Correcting Their Adverse Effects (open access)

Te Inclusions in CZT Detectors: New Method for Correcting Their Adverse Effects

Both Te inclusions and point defects can trap the charge carriers generated by ionizing particles in CdZnTe (CZT) detectors. The amount of charge trapped by point defects is proportional to the carriers’ drift time and can be corrected electronically. In the case of Te inclusions, the charge loss depends upon their random locations with respect to the electron cloud. Consequently, inclusions introduce fluctuations in the charge signals, which cannot be easily corrected. In this paper, we describe direct measurements of the cumulative effect of Te inclusions and its influence on the response of CZT detectors of different thicknesses and different sizes and concentrations of Te inclusions. We also discuss a means of partially correcting their adverse effects.
Date: October 25, 2009
Creator: Bolotnikov, A. E.; Babalola, S.; Camarda, G. S.; Cui, Y.; Egarievwe, S. U.; Hawrami, R. et al.
Object Type: Article
System: The UNT Digital Library
Influence of ammonium availability on expression of nifD and amtB genes during biostimulation of a U(VI) contaminated aquifer: implications for U(VI) removal and monitoring the metabolic state of Geobacteraceae (open access)

Influence of ammonium availability on expression of nifD and amtB genes during biostimulation of a U(VI) contaminated aquifer: implications for U(VI) removal and monitoring the metabolic state of Geobacteraceae

The influence of ammonium availability on bacterial community structure and the physiological status of Geobacter species during in situ bioremediation of uranium-contaminated groundwater was evaluated. Ammonium concentrations varied by 2 orders of magnitude (<4 to 400 ?M) across the study site. Analysis of 16S rRNA sequences suggested that ammonium may have been one factor influencing the community composition prior to acetate amendment with Rhodoferax species predominating over Geobacter species with higher ammonium and Dechloromonas species dominating at the site with lowest ammonium. However, once acetate was added and dissimilatory metal reduction was stimulated, Geobacter species became the predominant organisms at all locations. Rates of U(VI) reduction appeared to be more related to acetate concentrations rather than ammonium levels. In situ mRNA transcript abundance of the nitrogen fixation gene, nifD, and the ammonium transporter gene, amtB, in Geobacter species indicated that ammonium was the primary source of nitrogen during uranium reduction. The abundance of amtB was inversely correlated to ammonium levels, whereas nifD transcript levels were similar across all sites examined. These results suggest that nifD and amtB expression are closely regulated in response to ammonium availability to ensure an adequate supply of nitrogen while conserving cell resources. Thus, quantifying nifD …
Date: March 25, 2009
Creator: Mouser, Paula J.; N'Guessan, A. Lucie; Elifantz, Hila; Holmes, Dawn E.; Williams, Kenneth H; Wilkins, Michael J. et al.
Object Type: Article
System: The UNT Digital Library
Cost-Effectiveness and Impact Analysis of Adoption of Standard 90.1-2007 for New York State (open access)

Cost-Effectiveness and Impact Analysis of Adoption of Standard 90.1-2007 for New York State

This report is a subset of the commercial nationwide building energy code analysis. New York has cost criteria that must also be met, and this report includes those details. This report will be finalized when the nationwide analysis report is finalized in September.
Date: June 25, 2009
Creator: Halverson, Mark A.; Gowri, Krishnan & Bartlett, Rosemarie
Object Type: Report
System: The UNT Digital Library
Measurement and Analysis Plan for Investigation of Spent-Fuel Assay Using Lead Slowing-Down Spectroscopy (open access)

Measurement and Analysis Plan for Investigation of Spent-Fuel Assay Using Lead Slowing-Down Spectroscopy

Under funding from the Department of Energy Office of Nuclear Energy’s Materials, Protection, Accounting, and Control for Transmutation (MPACT) program (formerly the Advanced Fuel Cycle Initiative Safeguards Campaign), Pacific Northwest National Laboratory (PNNL) and Los Alamos National Laboratory (LANL) are collaborating to study the viability of lead slowing-down spectroscopy (LSDS) for spent-fuel assay. Based on the results of previous simulation studies conducted by PNNL and LANL to estimate potential LSDS performance, a more comprehensive study of LSDS viability has been defined. That study includes benchmarking measurements, development and testing of key enabling instrumentation, and continued study of time-spectra analysis methods. This report satisfies the requirements for a PNNL/LANL deliverable that describes the objectives, plans and contributing organizations for a comprehensive three-year study of LSDS for spent-fuel assay. This deliverable was generated largely during the LSDS workshop held on August 25-26, 2009 at Rensselaer Polytechnic Institute (RPI). The workshop itself was a prominent milestone in the FY09 MPACT project and is also described within this report.
Date: September 25, 2009
Creator: Smith, Leon E.; Haas, Derek A.; Gavron, Victor A.; Imel, G. R.; Ressler, Jennifer J.; Bowyer, Sonya M. et al.
Object Type: Report
System: The UNT Digital Library
The (3He,tf) as a surrogate reaction to determine (n,f) cross sections in the 10 to 20 MeV energy range (open access)

The (3He,tf) as a surrogate reaction to determine (n,f) cross sections in the 10 to 20 MeV energy range

The surrogate reaction 238U(3He,tf) is used to determine the 237Np(n,f) cross section indirectly over an equivalent neutron energy range from 10 to 20 MeV. A self-supporting ~;;761 mu g/cm2 metallic 238U foil was bombarded with a 42 MeV 3He2+ beam from the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory (LBNL). Outgoing charged particles and fission fragments were identified using the Silicon Telescope Array for Reaction Studies (STARS), consists of two 140 mu m and one 1000 mu m Micron S2 type silicon detectors. The 237Np(n,f) cross sections, determined indirectly, were compared with the 237Np(n,f) cross section data from direct measurements, the Evaluated Nuclear Data File (ENDF/B-VII.0), and the Japanese Evaluated Nuclear Data Library (JENDL 3.3) and found to closely follow those datasets. Use of the (3He,tf) reaction as a surrogate to extract (n,f) cross section in the 10 to 20 MeV equivalent neutron energy is found to be suitable.
Date: February 25, 2009
Creator: Basunia, M. S.; Clark, R. M.; Goldblum, B. L.; Bernstein, L. A.; Phair, L.; Burke, J. T. et al.
Object Type: Article
System: The UNT Digital Library
Axial-Torsion Testing Plastic-Bonded Explosives to Failure (open access)

Axial-Torsion Testing Plastic-Bonded Explosives to Failure

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Date: March 25, 2009
Creator: Gagliardi, F J & Cunningham, B J
Object Type: Article
System: The UNT Digital Library
Initial Component Testing for a Germanium Array Cryostat (open access)

Initial Component Testing for a Germanium Array Cryostat

This report describes progress on the construction of two ultra-low-background cryostats that are part of the NA-22 funded “Radionuclide Laboratories” (RN Labs) project. Each cryostat will house seven high-purity germanium crystals (HPGe). These cryostats are being built from a limited set of materials that are known to have very low levels of radioactive impurities. The RN Labs instrument is designed to take advantage of low background performance, high detection efficiency, and - coincidence signatures to provide unprecedented gamma spectroscopy sensitivity. The project is focused on improving gamma analysis capabilities for nuclear detonation detection (NDD) applications. The instrument also has the potential for basic nuclear physics research. Section 1 provides the background for the project. Section 2 discusses germanium crystal acceptance testing. Design problems were found after the first delivery of new detectors from the vendor, Canberra Semiconductors. The first four crystals were returned for repair, resulting in a delay in crystal procurement. Section 3 provides an update on copper electroforming. In general, electroforming parts for RN Labs has proceeded smoothly, but there have been recent problems in electroforming three large copper parts necessary for the project. Section 4 describes the first round of testing for the instrument: anti-cosmic scintillator testing, …
Date: July 25, 2009
Creator: Keillor, Martin E.; Aalseth, Craig E.; Day, Anthony R.; Fast, James E.; Hoppe, Eric W.; Hyronimus, Brian J. et al.
Object Type: Report
System: The UNT Digital Library
Results of Compact Stellarator Eengineering Trade Studies (open access)

Results of Compact Stellarator Eengineering Trade Studies

A number of technical requirements and performance criteria can drive stellarator costs, e.g., tight tolerances, accurate coil positioning, low aspect ratio (compactness), choice of assembly strategy, metrology, and complexity of the stellarator coil geometry. With the completion of a seven-year design and construction effort of the National Compact Stellarator Experiment (NCSX) it is useful to interject the NCSX experience along with the collective experiences of the NCSX stellarator community to improving the stellarator configuration. Can improvements in maintenance be achieved by altering the stellarator magnet configuration with changes in the coil shape or with the combination of trim coils? Can a mechanical configuration be identified that incorporates a partial set of shaped fixed stellarator coils along with some removable coil set to enhance the overall machine maintenance? Are there other approaches that will simplify the concepts, improve access for maintenance, reduce overall cost and improve the reliability of a stellarator based power plant? Using ARIES-CS and NCSX as reference cases, alternative approaches have been studied and developed to show how these modifications would favorably impact the stellarator power plant and experimental projects. The current status of the alternate stellarator configurations being developed will be described and a comparison made to …
Date: September 25, 2009
Creator: T. Brown, L. Bromberg, and M. Cole
Object Type: Article
System: The UNT Digital Library
A Supernodal Approach to Incomplete LU Factorization with Partial Pivoting (open access)

A Supernodal Approach to Incomplete LU Factorization with Partial Pivoting

We present a new supernode-based incomplete LU factorization method to construct a preconditioner for solving sparse linear systems with iterative methods. The new algorithm is primarily based on the ILUTP approach by Saad, and we incorporate a number of techniques to improve the robustness and performance of the traditional ILUTP method. These include the new dropping strategies that accommodate the use of supernodal structures in the factored matrix. We present numerical experiments to demonstrate that our new method is competitive with the other ILU approaches and is well suited for today's high performance architectures.
Date: June 25, 2009
Creator: Li, Xiaoye Sherry & Shao, Meiyue
Object Type: Article
System: The UNT Digital Library
Alternate VHTR/HTE INterface for mitigating tritum. (open access)

Alternate VHTR/HTE INterface for mitigating tritum.

High temperature creep in structures at the interface between the nuclear plant and the hydrogen plant and the migration of tritium from the core through structures in the interface are two key challenges for the Very High Temperature Reactor (VHTR) coupled to the High Temperature Electrolysis (HTE) process. The severity of these challenges, however, can be reduced by lowering the temperature at which the interface operates. Preferably this should be accomplished in a way that does not reduce combined plant efficiency and other performance measures. A means for doing so is described in this report. A heat pump is used to raise the temperature of near-waste heat from the PCU to the temperature at which nine-tenths of the HTE process heat is needed. In addition to mitigating tritium transport and creep of structures, structural material commodity costs are reduced and plant efficiency is increased by a couple of percent.
Date: February 25, 2009
Creator: Vilim, R.
Object Type: Report
System: The UNT Digital Library
Parameterizing Size Distribution in Ice Clouds (open access)

Parameterizing Size Distribution in Ice Clouds

PARAMETERIZING SIZE DISTRIBUTIONS IN ICE CLOUDS David L. Mitchell and Daniel H. DeSlover ABSTRACT An outstanding problem that contributes considerable uncertainty to Global Climate Model (GCM) predictions of future climate is the characterization of ice particle sizes in cirrus clouds. Recent parameterizations of ice cloud effective diameter differ by a factor of three, which, for overcast conditions, often translate to changes in outgoing longwave radiation (OLR) of 55 W m-2 or more. Much of this uncertainty in cirrus particle sizes is related to the problem of ice particle shattering during in situ sampling of the ice particle size distribution (PSD). Ice particles often shatter into many smaller ice fragments upon collision with the rim of the probe inlet tube. These small ice artifacts are counted as real ice crystals, resulting in anomalously high concentrations of small ice crystals (D < 100 µm) and underestimates of the mean and effective size of the PSD. Half of the cirrus cloud optical depth calculated from these in situ measurements can be due to this shattering phenomenon. Another challenge is the determination of ice and liquid water amounts in mixed phase clouds. Mixed phase clouds in the Arctic contain mostly liquid water, and the …
Date: September 25, 2009
Creator: DeSlover, Daniel & Mitchell, David L.
Object Type: Report
System: The UNT Digital Library
Correlation method for the measure of mask-induced line-edge roughness in extreme ultraviolet lithography (open access)

Correlation method for the measure of mask-induced line-edge roughness in extreme ultraviolet lithography

As critical dimensions for leading-edge semiconductor devices shrink, line-edge roughness (LER) requirements are pushing well into the single digit nanometer regime. At these scales many new sources of LER must be considered. In the case of extreme ultraviolet (EUV) lithography, modeling has shown the lithographic mask to be a source of significant concern. Here we present a correlation-based methodology for experimentally measuring the magnitude of mask contributors to printed LER. The method is applied to recent printing results from a 0.3 numerical aperture EUV microfield exposure tool. The measurements demonstrate that such effects are indeed present and of significant magnitude. The method is also used to explore the effects of illumination coherence and defocus and has been used to verify model-based predictions of mask-induced LER.
Date: May 25, 2009
Creator: Naulleau, Patrick
Object Type: Article
System: The UNT Digital Library
Design of 10 GeV laser wakefield accelerator stages with shaped laser modes (open access)

Design of 10 GeV laser wakefield accelerator stages with shaped laser modes

We present particle-in-cell simulations, using the VORPAL framework, of 10 GeV laser plasma wakefield accelerator stages. Scaling of the physical parameters with the plasma density allows us to perform these simulations at reasonable cost and to design high performance stages. In particular we show that, by choosing to operate in the quasi-linear regime, we can use higher order laser modes to tailor the focusing forces. This makes it possible to increase the matched electron beam radius and hence the total charge in the bunch while preserving the low bunch emittance required for applications.
Date: September 25, 2009
Creator: Cormier-Michel, Estelle; Esarey, E.; Geddes, C. G. R.; Geddes, C. G. R.; Leemans, W. P.; Bruhwiler, D. L. et al.
Object Type: Article
System: The UNT Digital Library
IMG ER: A System for Microbial Genome Annotation Expert Review and Curation (open access)

IMG ER: A System for Microbial Genome Annotation Expert Review and Curation

A rapidly increasing number of microbial genomes are sequenced by organizations worldwide and are eventually included into various public genome data resources. The quality of the annotations depends largely on the original dataset providers, with erroneous or incomplete annotations often carried over into the public resources and difficult to correct. We have developed an Expert Review (ER) version of the Integrated Microbial Genomes (IMG) system, with the goal of supporting systematic and efficient revision of microbial genome annotations. IMG ER provides tools for the review and curation of annotations of both new and publicly available microbial genomes within IMG's rich integrated genome framework. New genome datasets are included into IMG ER prior to their public release either with their native annotations or with annotations generated by IMG ER's annotation pipeline. IMG ER tools allow addressing annotation problems detected with IMG's comparative analysis tools, such as genes missed by gene prediction pipelines or genes without an associated function. Over the past year, IMG ER was used for improving the annotations of about 150 microbial genomes.
Date: May 25, 2009
Creator: Markowitz, Victor M.; Mavromatis, Konstantinos; Ivanova, Natalia N.; Chen, I-Min A.; Chu, Ken & Kyrpides, Nikos C.
Object Type: Report
System: The UNT Digital Library
Pressure Systems Stored-Energy Threshold Risk Analysis (open access)

Pressure Systems Stored-Energy Threshold Risk Analysis

Federal Regulation 10 CFR 851, which became effective February 2007, brought to light potential weaknesses regarding the Pressure Safety Program at the Pacific Northwest National Laboratory (PNNL). The definition of a pressure system in 10 CFR 851 does not contain a limit based upon pressure or any other criteria. Therefore, the need for a method to determine an appropriate risk-based hazard level for pressure safety was identified. The Laboratory has historically used a stored energy of 1000 lbf-ft to define a pressure hazard; however, an analytical basis for this value had not been documented. This document establishes the technical basis by evaluating the use of stored energy as an appropriate criterion to establish a pressure hazard, exploring a suitable risk threshold for pressure hazards, and reviewing the methods used to determine stored energy. The literature review and technical analysis concludes the use of stored energy as a method for determining a potential risk, the 1000 lbf-ft threshold, and the methods used by PNNL to calculate stored energy are all appropriate. Recommendations for further program improvements are also discussed
Date: August 25, 2009
Creator: Paulsen, Samuel S.
Object Type: Report
System: The UNT Digital Library
Identification and Characterization of Hydrogeologic Units at the Nevada Test Site Using Geophysical Logs: Examples from the Underground Test Area Project (open access)

Identification and Characterization of Hydrogeologic Units at the Nevada Test Site Using Geophysical Logs: Examples from the Underground Test Area Project

The diverse and complex geology of the Nevada Test Site region makes for a challenging environment for identifying and characterizing hydrogeologic units penetrated by wells drilled for the U.S. Department of Energy, National Nuclear Security Administration, Underground Test Area (UGTA) Environmental Restoration Sub-Project. Fortunately, UGTA geoscientists have access to large and robust sets of subsurface geologic data, as well as a large historical knowledge base of subsurface geological analyses acquired mainly during the underground nuclear weapons testing program. Of particular importance to the accurate identification and characterization of hydrogeologic units in UGTA boreholes are the data and interpretation principles associated with geophysical well logs. Although most UGTA participants and stakeholders are probably familiar with drill hole data such as drill core and cuttings, they may be less familiar with the use of geophysical logs; this document is meant to serve as a primer on the use of geophysical logs in the UGTA project. Standard geophysical logging tools used in the UGTA project to identify and characterize hydrogeologic units are described, and basic interpretation principles and techniques are explained. Numerous examples of geophysical log data from a variety of hydrogeologic units encountered in UGTA wells are presented to highlight the use …
Date: March 25, 2009
Creator: Lance Prothro, Sigmund Drellack, Margaret Townsend
Object Type: Report
System: The UNT Digital Library
Thorough characterization of a EUV mask (open access)

Thorough characterization of a EUV mask

We reported that we were successful in our 45nm technology node device demonstration in February 2008 and 22nm node technology node device patterning in February 2009 using ASML's Alpha Demo Tool (ADT). In order to insert extreme ultraviolet (EUV) lithography at the 15nm technology node and beyond, we have thoroughly characterized one EUV mask, a so-called NOVACD mask. In this paper, we report on three topics, The first topic is an analysis of line edge roughness (LER) using a mask Scanning Electron Microscope (SEM), an Atomic Force Microscope (AFM) and the Actinic Inspection Tool (AIT) to compare resist images printed with the ASML ADT. The results of the analysis show a good correlation between the mask AFM and the mask SEM measurements, However, the resist printing results for the isolated space patterns are slightly different. The cause ofthis discrepancy may be resist blur, image log slope and SEM image quality and so on. The second topic is an analysis of mask topography using an AFM and relative reflectivity of mirror and absorber surface using the AIT, The AFM data show 6 and 7 angstrom rms roughness for mirror and absorber, respectively. The reflectivity measurements show that the mirror reflects EUV …
Date: June 25, 2009
Creator: Mizuno, H.; McIntyre, G.; Koay, C.-W.; Burkhardt, M.; He, L.; Hartley, J. et al.
Object Type: Article
System: The UNT Digital Library
PEP Support Laboratory Leaching and Permeate Stability Tests (open access)

PEP Support Laboratory Leaching and Permeate Stability Tests

Pacific Northwest National Laboratory (PNNL) has been tasked by Bechtel National Inc. (BNI) on the River Protection Project-Hanford Tank Waste Treatment and Immobilization Plant (RPP-WTP) project to perform research and development activities to resolve technical issues identified for the Pretreatment Facility (PTF). The Pretreatment Engineering Platform (PEP) was designed, constructed, and operated as part of a plan to respond to issue M12, "Undemonstrated Leaching Processes," of the External Flowsheet Review Team (EFRT) issue response plan.( ) The PEP is a 1/4.5-scale test platform designed to simulate the WTP pretreatment caustic leaching, oxidative leaching, ultrafiltration solids concentration, and slurry washing processes. The PEP replicates the WTP leaching processes using prototypic equipment and control strategies. A simplified flow diagram of the PEP system is shown in Figure 1.1. Two operating scenarios are currently being evaluated for the ultrafiltration process (UFP) and leaching operations. The first scenario has caustic leaching performed in the UFP-2 ultrafiltration feed vessels (i.e., vessel UFP-VSL-T02A in the PEP and vessels UFP-VSL-00002A and B in the WTP PTF). The second scenario has caustic leaching conducted in the UFP-1 ultrafiltration feed preparation vessels (i.e., vessels UFP-VSL-T01A and B in the PEP and vessels UFP-VSL-00001A and B in the WTP PTF). …
Date: September 25, 2009
Creator: Russell, Renee L.; Peterson, Reid A.; Rinehart, Donald E. & Buchmiller, William C.
Object Type: Report
System: The UNT Digital Library
The Use of Weighting in Periodicity Searches in All-Sky Monitor Data: Applications to the GLAST LAT (open access)

The Use of Weighting in Periodicity Searches in All-Sky Monitor Data: Applications to the GLAST LAT

The light curves produced by all-sky monitors, such as the Rossi X-ray Timing Explorer All-Sky Monitor and the Swift Burst Alert Telescope (BAT), generally have non-uniform error bars. In searching for periodic modulation in this type of data using power spectra it can be important to use appropriate weighting of data points to achieve the best sensitivity. It was recently demonstrated that for Swift BAT data a simple weighting scheme can actually sometimes reduce the sensitivity of the power spectrum depending on source brightness. Instead, a modified weighting scheme, based on the Cochran semi-weighted mean, gives improved results independent of source brightness. We investigate the benefits of weighting power spectra in period searches using simulated GLAST LAT observations of {gamma}-ray binaries.
Date: June 25, 2009
Creator: Corbet, Robin & Dubois, Richard
Object Type: Article
System: The UNT Digital Library