High-throughput Accurate-wavelength Lens-based Visible Spectrometera (open access)

High-throughput Accurate-wavelength Lens-based Visible Spectrometera

A scanning visible spectrometer has been prototyped to complement fixed-wavelength transmission grating spectrometers for charge exchange recombination spectroscopy. Fast f/1.8 200 mm commercial lenses are used with a large 2160 mm-1 grating for high throughput. A stepping-motor controlled sine drive positions the grating, which is mounted on a precision rotary table. A high-resolution optical encoder on the grating stage allows the grating angle to be measured with an absolute accuracy of 0.075 arcsec, corresponding to a wavelength error ≤ 0.005 Å. At this precision, changes in grating groove density due to thermal expansion and variations in the refractive index of air are important. An automated calibration procedure determines all relevant spectrometer parameters to high accuracy. Changes in bulk grating temperature, atmospheric temperature and pressure are monitored between the time of calibration and the time of measurement to insure a persistent wavelength calibration
Date: June 4, 2010
Creator: Bell, Ronald E. & Scoti, Filippo
Object Type: Article
System: The UNT Digital Library
Evaluation of Reagent Emplacement Techniques for Phosphate-based Treatment of the Uranium Contamination Source in the 300 Area White Paper (open access)

Evaluation of Reagent Emplacement Techniques for Phosphate-based Treatment of the Uranium Contamination Source in the 300 Area White Paper

Persistent uranium contamination of groundwater under the 300 Area of the Hanford Site has been observed. The source of the uranium contamination resides in uranium deposits on sediments at the groundwater interface, and the contamination is mobilized when periodically wetted by fluctuations of Columbia River levels. Treatability work is ongoing to develop and apply phosphate-containing reagents to promote the formation of stable and insoluble uranium phosphate minerals (i.e., autunite) and other phosphate precipitates (di-calcium phosphate, apatite) to stabilize the uranium source. Technologies for applying phosphate-containing reagents by vertical percolation and lateral injection into sediments of the periodically wetted groundwater interface are being investigated. This report is a preliminary evaluation of technologies for lateral injection.
Date: June 4, 2010
Creator: Nimmons, Michael J.
Object Type: Report
System: The UNT Digital Library
Telescope Guiding with a HyViSI H2RG Used in Guide Mode (open access)

Telescope Guiding with a HyViSI H2RG Used in Guide Mode

We report on long exposure results obtained with a Teledyne HyViSI H2RG detector operating in guide mode. The sensor simultaneously obtained nearly seeing-limited data while also guiding the Kitt Peak 2.1 m telescope. Results from unguided and guided operation are presented and used to place lower limits on flux/fluence values for accurate centroid measurements. We also report on significant noise reduction obtained in recent laboratory measurements that should further improve guiding capability with higher magnitude stars.
Date: June 4, 2010
Creator: Simms, Lance M.; Figerb, Donald F.; Hanold, Brandon J.; Kahn, Steven M. & Gilmore, D.Kirk
Object Type: Article
System: The UNT Digital Library
The science case for 37Ar as a monitor for underground nuclear explosions (open access)

The science case for 37Ar as a monitor for underground nuclear explosions

A new calculation of the production of 37Ar from nuclear explosion neutron interactions on 40Ca in a suite of common sub-surface materials (rock, etc) is presented. Even in mineral structures that are relatively low in Ca, the resulting 37Ar signature is large enough for detection in cases of venting or gaseous diffusion driven by barometric pumping. Field and laboratory detection strategies and projected sensitivities are presented.
Date: June 4, 2010
Creator: Haas, Derek A.; Orrell, John L.; Bowyer, Ted W.; McIntyre, Justin I.; Miley, Harry S.; Aalseth, Craig E. et al.
Object Type: Report
System: The UNT Digital Library
Diagnostics for Ion Beam Driven High Energy Density Physics Experiments (open access)

Diagnostics for Ion Beam Driven High Energy Density Physics Experiments

Intense beams of heavy ions are capable of heating volumetric samples of matter to high energy density. Experiments are performed on the resulting warm dense matter (WDM) at the NDCX-I ion beam accelerator. The 0.3 MeV, 30-mA K{sup +} beam from NDCX-I heats foil targets by combined longitudinal and transverse neutralized drift compression of the ion beam. Both the compressed and uncompressed parts of the NDCX-I beam heat targets. The exotic state of matter (WDM) in these experiments requires specialized diagnostic techniques. We have developed a target chamber and fielded target diagnostics including a fast multi-channel optical pyrometer, optical streak camera, laser Doppler-shift interferometer (VISAR), beam transmission diagnostics, and high-speed gated cameras. We also present plans and opportunities for diagnostic development and a new target chamber for NDCX-II.
Date: January 4, 2010
Creator: Bieniosek, F. M.; Henestroza, E.; Lidia, S. & Ni, P. A.
Object Type: Article
System: The UNT Digital Library
Prediction of epigenetically regulated genes in breast cancer cell lines (open access)

Prediction of epigenetically regulated genes in breast cancer cell lines

Methylation of CpG islands within the DNA promoter regions is one mechanism that leads to aberrant gene expression in cancer. In particular, the abnormal methylation of CpG islands may silence associated genes. Therefore, using high-throughput microarrays to measure CpG island methylation will lead to better understanding of tumor pathobiology and progression, while revealing potentially new biomarkers. We have examined a recently developed high-throughput technology for measuring genome-wide methylation patterns called mTACL. Here, we propose a computational pipeline for integrating gene expression and CpG island methylation profles to identify epigenetically regulated genes for a panel of 45 breast cancer cell lines, which is widely used in the Integrative Cancer Biology Program (ICBP). The pipeline (i) reduces the dimensionality of the methylation data, (ii) associates the reduced methylation data with gene expression data, and (iii) ranks methylation-expression associations according to their epigenetic regulation. Dimensionality reduction is performed in two steps: (i) methylation sites are grouped across the genome to identify regions of interest, and (ii) methylation profles are clustered within each region. Associations between the clustered methylation and the gene expression data sets generate candidate matches within a fxed neighborhood around each gene. Finally, the methylation-expression associations are ranked through a logistic …
Date: May 4, 2010
Creator: Loss, Leandro A; Sadanandam, Anguraj; Durinck, Steffen; Nautiyal, Shivani; Flaucher, Diane; Carlton, Victoria EH et al.
Object Type: Article
System: The UNT Digital Library
Argonne National Laboratory Site Environmental Report for Calendar Year 2009. (open access)

Argonne National Laboratory Site Environmental Report for Calendar Year 2009.

This report discusses the status and the accomplishments of the environmental protection program at Argonne National Laboratory for calendar year 2009. The status of Argonne environmental protection activities with respect to compliance with the various laws and regulations is discussed, along with the progress of environmental corrective actions and restoration projects. To evaluate the effects of Argonne operations on the environment, samples of environmental media collected on the site, at the site boundary, and off the Argonne site were analyzed and compared with applicable guidelines and standards. A variety of radionuclides were measured in air, surface water, on-site groundwater, and bottom sediment samples. In addition, chemical constituents in surface water, groundwater, and Argonne effluent water were analyzed. External penetrating radiation doses were measured, and the potential for radiation exposure to off-site population groups was estimated. Results are interpreted in terms of the origin of the radioactive and chemical substances (i.e., natural, Argonne, and other) and are compared with applicable environmental quality standards. A U.S. Department of Energy (DOE) dose calculation methodology, based on International Commission on Radiological Protection recommendations and the U.S. Environmental Protection Agency's (EPA) CAP-88 Version 3 (Clean Air Act Assessment Package-1988) computer code, was used in preparing …
Date: August 4, 2010
Creator: Golchert, N. W.; Davis, T. M. & Moos, L. P.
Object Type: Report
System: The UNT Digital Library
Thermal Performance of Radioactive Material Packages in Transport Configuration (open access)

Thermal Performance of Radioactive Material Packages in Transport Configuration

Drum type packages are routinely used to transport radioactive material (RAM) in the U.S. Department of Energy (DOE) complex. These packages are designed to meet the federal regulations described in 10 CFR Part 71. The packages are transported in specially designed vehicles like Safe Secure Transport (SST) for safety and security. In the transport vehicles, the packages are placed close to each other to maximize the number of units in the vehicle. Since the RAM contents in the packagings produce decay heat, it is important that they are spaced sufficiently apart to prevent overheating of the containment vessel (CV) seals and the impact limiter to ensure the structural integrity of the package. This paper presents a simple methodology to assess thermal performance of a typical 9975 packaging in a transport configuration.
Date: March 4, 2010
Creator: Gupta, N.
Object Type: Article
System: The UNT Digital Library
Anion Analyses by Ion Chromatography for the Alternate Reductant Demonstration for the Defense Waste Processing Facility (open access)

Anion Analyses by Ion Chromatography for the Alternate Reductant Demonstration for the Defense Waste Processing Facility

The Process Science Analytical Laboratory (PSAL) at the Savannah River National Laboratory was requested by the Defense Waste Processing Facility (DWPF) to develop and demonstrate an Ion Chromatography (IC) method for the analysis of glycolate, in addition to eight other anions (fluoride, formate, chloride, nitrite, nitrate, sulfate, oxalate and phosphate) in Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) samples. The method will be used to analyze anions for samples generated from the Alternate Reductant Demonstrations to be performed for the DWPF at the Aiken County Technology Laboratory (ACTL). The method is specific to the characterization of anions in the simulant flowsheet work. Additional work will be needed for the analyses of anions in radiological samples by Analytical Development (AD) and DWPF. The documentation of the development and demonstration of the method fulfills the third requirement in the TTQAP, SRNL-RP-2010-00105, 'Task Technical and Quality Assurance Plan for Glycolic-Formic Acid Flowsheet Development, Definition and Demonstrations Tasks 1-3'.
Date: August 4, 2010
Creator: Best, D.
Object Type: Report
System: The UNT Digital Library
Analysis of Sludge Batch 4 (Macrobatch 5) for Canister S02902 and Sludge Batch 5 (Macrobatch 6) for Canister S03317 Dwpf Pour Stream Glass Samples (open access)

Analysis of Sludge Batch 4 (Macrobatch 5) for Canister S02902 and Sludge Batch 5 (Macrobatch 6) for Canister S03317 Dwpf Pour Stream Glass Samples

The Defense Waste Processing Facility (DWPF) began processing Sludge Batch 4 (SB4), Macrobatch 5 (MB5) on May 29, 2007. Sludge Batch 4 was a blend of the heel of Tank 40 from Sludge Batch 3 (SB3) and SB4 material qualified in Tank 51. On November 28, 2008, DWPF began processing Sludge Batch 5 (SB5) from Tank 40 which is a blend of the heel of Tank 40 from SB4, SB5 material qualified in Tank 51 and H-Canyon Pu and Np transfers. SB4 was processed using Frit 510 and SB5 used Frit 418. During processing of each sludge batch, the DWPF is required to take at least one glass sample to meet the objectives of the Glass Product Control Program and to complete the necessary Production Records so that the final glass product may be disposed of at a Federal Repository. During the processing of SB4 and SB5, glass samples were obtained during the pouring of canisters S02902 and S03317, respectively. The samples were transferred to the Savannah River National Laboratory (SRNL) where they were analyzed (durability, chemical and radionuclide composition). The following observations and conclusions are drawn from the analytical results provided in this report: (1) The sum of the …
Date: October 4, 2010
Creator: Reigel, M. & Bibler, N.
Object Type: Report
System: The UNT Digital Library
Overcharge Protection for 4 V Lithium Batteries at High Rates and Low Temperature (open access)

Overcharge Protection for 4 V Lithium Batteries at High Rates and Low Temperature

Overcharge protection for 4 V Li{sub 1.05}Mn{sub 1.95}O{sub 4}/lithium cells at charging rates in excess of 1 mA/cm{sup 2} (3C) and at temperatures as low as -20 C was achieved using a bilayer separator coated with two electroactive polymers. High rate and low temperature overcharge protection and discharge performance were improved by employing a design in which the polymer-coated portion of the separator is in parallel with the cell rather than between the electrodes. The effects of different membrane supports for the electroactive polymers are also examined.
Date: January 4, 2010
Creator: Chen, Guoying & Richardson, Thomas J.
Object Type: Article
System: The UNT Digital Library
Testing of 304l Stainless Steel in Nitric Acid Environments With Fluorides and Chlorides (open access)

Testing of 304l Stainless Steel in Nitric Acid Environments With Fluorides and Chlorides

Impure radioactive material processed in nitric acid solutions resulted in the presence of chlorides in a dissolver fabricated from 304L stainless steel. An experimental program was conducted to study the effects of chloride in nitric acid/fluoride solutions on the corrosion of 304L stainless steel. The test variables included temperature (80, 95, and 110 C) and the concentrations of nitric acid (6, 12, and 14 M), fluoride (0.01, 0.1, and 0.2 M) and chloride (100, 350, 1000, and 2000 ppm). The impact of welding was also investigated. Results showed that the chloride concentration alone was not a dominant variable affecting the corrosion, but rather the interaction of chloride with fluoride significantly affected corrosion.
Date: October 4, 2010
Creator: Mickalonis, J.
Object Type: Article
System: The UNT Digital Library
The Impact of Theoretical Uncertainties in the Halo Mass Function and Halo (open access)

The Impact of Theoretical Uncertainties in the Halo Mass Function and Halo

We study the impact of theoretical uncertainty in the dark matter halo mass function and halo bias on dark energy constraints from imminent galaxy cluster surveys. We find that for an optical cluster survey like the Dark Energy Survey, the accuracy required on the predicted halo mass function to make it an insignificant source of error on dark energy parameters is {approx}1%. The analogous requirement on the predicted halo bias is less stringent ({approx}5%), particularly if the observable-mass distribution can be well constrained by other means. These requirements depend upon survey area but are relatively insensitive to survey depth. The most stringent requirements are likely to come from a survey over a significant fraction of the sky that aims to observe clusters down to relatively low mass, M{sub th}{approx} 10{sup 13.7} h{sup -1} M{sub sun}; for such a survey, the mass function and halo bias must be predicted to accuracies of {approx}0.5% and {approx}1%, respectively. These accuracies represent a limit on the practical need to calibrate ever more accurate halo mass and bias functions. We find that improving predictions for the mass function in the low-redshift and low-mass regimes is the most effective way to improve dark energy constraints.
Date: June 4, 2010
Creator: Wu, Hao-Yi; Zentner, Andrew R. & Wechsler, Risa H.
Object Type: Article
System: The UNT Digital Library
Ceramicrete Stabilization of Radioactive-Salt-Containing Liquid Waste and Sludge Water. Final Crada Report. (open access)

Ceramicrete Stabilization of Radioactive-Salt-Containing Liquid Waste and Sludge Water. Final Crada Report.

It was found that the Ceramicrete Specimens incorporated the Streams 1 and 2 sludges with the adjusted loading about 41.6 and 31.6%, respectively, have a high solidity. The visible cracks in the matrix materials and around the anionite AV-17 granules included could not obtain. The granules mentioned above fixed by Ceramicrete matrix very strongly. Consequently, we can conclude that irradiation of Ceramecrete matrix, goes from the high radioactive elements, not result the structural degradation. Based on the chemical analysis of specimens No.462 and No.461 used it was shown that these matrix included the formation elements (P, K, Mg, O), but in the different samples their correlations are different. These ratios of the content of elements included are about {+-} 10%. This information shows a great homogeneity of matrix prepared. In the list of the elements founded, expect the matrix formation elements, we detected also Ca and Si (from the wollastonite - the necessary for Ceramicrete compound); Na, Al, S, O, Cl, Fe, Ni also have been detected in the Specimen No.642 from the waste forms: NaCl, Al(OH){sub 3}, Na{sub 2}SO{sub 4}. Fe(OH){sub 3}, nickel ferrocyanide and Ni(NO{sub 3})2. The unintelligible results also were found from analysis of an AV-17 granules, …
Date: August 4, 2010
Creator: Ehst, D. & Division, Nuclear Engineering
Object Type: Report
System: The UNT Digital Library
Construction Method Study for Installation of a Large Riser in a Single-Shell Tank (open access)

Construction Method Study for Installation of a Large Riser in a Single-Shell Tank

This study evaluates and identifies a construction method for cutting a hole in a single-shell tank dome. This study also identifies and evaluates vendors for performing the cut.
Date: August 4, 2010
Creator: Adkisson, D. A.
Object Type: Report
System: The UNT Digital Library
HEAVY ION FUSION SCIENCE VIRTUAL NATIONAL LABORATORY 1ST QUARTER 2010 MILESTONE REPORT:  Simulations of fast correction of chromatic aberrations to establish physics specifications for implementation on NDCX-1 and NDCX-2 (open access)

HEAVY ION FUSION SCIENCE VIRTUAL NATIONAL LABORATORY 1ST QUARTER 2010 MILESTONE REPORT: Simulations of fast correction of chromatic aberrations to establish physics specifications for implementation on NDCX-1 and NDCX-2

This milestone has been accomplished. The Heavy Ion Fusion Science Virtual National Laboratory has completed simulations of a fast correction scheme to compensate for chromatic and time-dependent defocusing effects in the transport of ion beams to the target plane in the NDCX-1 facility. Physics specifications for implementation in NDCX-1 and NDCX-2 have been established. This milestone has been accomplished. The Heavy Ion Fusion Science Virtual National Laboratory has completed simulations of a fast correction scheme to compensate for chromatic and time-dependent defocusing effects in the transport of ion beams to the target plane in the NDCX-1 facility. Physics specifications for implementation in NDCX-1 and NDCX-2 have been established. Focal spot differences at the target plane between the compressed and uncompressed regions of the beam pulse have been modeled and measured on NDCX-1. Time-dependent focusing and energy sweep from the induction bunching module are seen to increase the compressed pulse spot size at the target plane by factors of two or more, with corresponding scaled reduction in the peak intensity and fluence on target. A time-varying beam envelope correction lens has been suggested to remove the time-varying aberration. An Einzel (axisymmetric electric) lens system has been analyzed and optimized for general …
Date: January 4, 2010
Creator: LIDIA, S.M.; LUND, S.M. & SEIDL, P.A.
Object Type: Report
System: The UNT Digital Library
Benchmark Specifications and Data Requirements for Initial Modeling of the China Experimental Fast Reactor. (open access)

Benchmark Specifications and Data Requirements for Initial Modeling of the China Experimental Fast Reactor.

A specification is proposed for an initial transient benchmark analysis of the China Experimental Fast Reactor design based on the analysis capabilities of the SAS4A/SASSYS-1 code. For the initial benchmark, a single-channel protected transient overpower accident is defined. Reactivity feedback coefficients will not be required and simplified material properties are recommended. This report also describes the data required for developing the modeling input. This data includes assembly geometry, reactor power distributions, kinetics and decay heat data, and material properties. Comparisons of benchmark results will take place at a future SAS4A/SASSYS-1 training meeting planned to occur at Argonne National Laboratory. Future benchmark specifications will be planned to expand upon this initial model to include more complex reactivity feedback models, material properties, additional assembly geometry, and primary and intermediate coolant systems.
Date: June 4, 2010
Creator: Fanning, T. H. & Division, Nuclear Engineering
Object Type: Report
System: The UNT Digital Library
Universal versus Material-Dependent Two-Gap Behaviors in the High-Tc Cuprates: Angle-Resolved Photoemission Study of La_2-xSr_xCuO_4 (open access)

Universal versus Material-Dependent Two-Gap Behaviors in the High-Tc Cuprates: Angle-Resolved Photoemission Study of La_2-xSr_xCuO_4

We have investigated the doping and temperature dependences of the pseudogap/superconducting gap in the single-layer cuprate La{sub 2-x}Sr{sub x}CuO{sub 4} by angle-resolved photoemission spectroscopy. The results clearly exhibit two distinct energy and temperature scales, namely, the gap around ({pi}, 0) of magnitude {Delta}{asterisk} and the gap around the node characterized by the d-wave order parameter {delta}{sub 0}, like the double-layer cuprate Bi2212. In comparison with Bi2212 having higher T{sub c}'s, {delta}{sub 0} is smaller, while {delta}{asterisk} and T{ampersand} are similar. This result suggests that {delta}{asterisk} and T{asterisk} are approximately material-independent properties of a single Cu0{sub 2} plane, in contrast the material-dependent {delta}{sub 0}, representing the pairing strength.
Date: June 4, 2010
Creator: Yoshida, T.
Object Type: Article
System: The UNT Digital Library
Application for a Permit to Operate a Class III Solid Waste Disposal Site at the Nevada National Security Site Area 5 Asbestiform Low-Level Solid Waste Disposal Site (open access)

Application for a Permit to Operate a Class III Solid Waste Disposal Site at the Nevada National Security Site Area 5 Asbestiform Low-Level Solid Waste Disposal Site

The Nevada National Security Site (NNSS) is located approximately 105 km (65 mi) northwest of Las Vegas, Nevada. The U.S. Department of Energy National Nuclear Security Administration Nevada Site Office (NNSA/NSO) is the federal lands management authority for the NNSS and National Security Technologies, LLC (NSTec) is the Management and Operations contractor. Access on and off the NNSS is tightly controlled, restricted, and guarded on a 24-hour basis. The NNSS is posted with signs along its entire perimeter. NSTec is the operator of all solid waste disposal sites on the NNSS. The Area 5 Radioactive Waste Management Site (RWMS) is the location of the permitted facility for the Solid Waste Disposal Site (SWDS). The Area 5 RWMS is located near the eastern edge of the NNSS (Figure 1), approximately 26 km (16 mi) north of Mercury, Nevada. The Area 5 RWMS is used for the disposal of low-level waste (LLW) and mixed low-level waste. Many areas surrounding the RWMS have been used in conducting nuclear tests. The site will be used for the disposal of regulated Asbestiform Low-Level Waste (ALLW), small quantities of low-level radioactive hydrocarbon-burdened (LLHB) media and debris, LLW, LLW that contains Polychlorinated Biphenyl (PCB) Bulk Product Waste …
Date: October 4, 2010
Creator: Programs, NSTec Environmental
Object Type: Report
System: The UNT Digital Library
Authorizing the Dot Specification 6m Packaging for Continued Use at the Savannah River Site (open access)

Authorizing the Dot Specification 6m Packaging for Continued Use at the Savannah River Site

The U.S. Department of Transportation (DOT) Specification 6M packaging was in extensive use for more than 40 years for in-commerce shipments of Type B quantities of fissile and radioactive material (RAM) across the USA, among the Department of Energy (DOE) laboratories, and between facilities in the DOE production complex. In January 2004, the DOT Research and Special Programs Administration (RSPA) Agency issued a final rule in the Federal Register to ammend requirements in the Hazardous Materials Regulations (HMR) pertaining to the transportation of radioactive materials. The final rule became effective on October 1, 2004. One of those changes discontinued the use of the DOT specification 6M, along with other DOT specification packagings, on October 1, 2008. A main driver for the change was due to the fact that 6M specification packagings were not supported by a Safety Analysis Report for Packagings (SARP) that was compliant with Title 10 of the Code of Federal Regulations (CFR) Part 71 (10 CFR 71). The regulatory rules for the discontinued use have been edited in Title 49 of the CFR Parts 100-185, 2004 edition and thereafter. Prior to October 1, 2008, the use of the 6M within the boundaries of the Savannah River Site …
Date: March 4, 2010
Creator: Watkins, R.; Loftin, B. & Hoang, D.
Object Type: Article
System: The UNT Digital Library
Saltstone Processing Facility Transfer Sample (open access)

Saltstone Processing Facility Transfer Sample

On May 19, 2010, the Saltstone Production Facility inadvertently transferred 1800 gallons of untreated waste from the salt feed tank to Vault 4. During shut down, approximately 70 gallons of the material was left in the Saltstone hopper. A sample of the slurry in the hopper was sent to Savannah River National Laboratory (SRNL) to analyze the density, pH and the eight Resource Conservation and Recovery Act (RCRA) metals. The sample was hazardous for chromium, mercury and pH. The sample received from the Saltstone hopper was analyzed visually while obtaining sample aliquots and while the sample was allowed to settle. It was observed that the sample contains solids that settle in approximately 20 minutes (Figure 3-1). There is a floating layer on top of the supernate during settling and disperses when the sample is agitated (Figure 3-2). The untreated waste inadvertently transferred from the SFT to Vault 4 was toxic for chromium and mercury. In addition, the pH of the sample is at the regulatory limit. Visually inspecting the sample indicates solids present in the sample.
Date: August 4, 2010
Creator: Cozzi, A. & Reigel, M.
Object Type: Report
System: The UNT Digital Library
A Hybrid Monte Carlo-Deterministic Method for Global Binary Stochastic Medium Transport Problems (open access)

A Hybrid Monte Carlo-Deterministic Method for Global Binary Stochastic Medium Transport Problems

Global deep-penetration transport problems are difficult to solve using traditional Monte Carlo techniques. In these problems, the scalar flux distribution is desired at all points in the spatial domain (global nature), and the scalar flux typically drops by several orders of magnitude across the problem (deep-penetration nature). As a result, few particle histories may reach certain regions of the domain, producing a relatively large variance in tallies in those regions. Implicit capture (also known as survival biasing or absorption suppression) can be used to increase the efficiency of the Monte Carlo transport algorithm to some degree. A hybrid Monte Carlo-deterministic technique has previously been developed by Cooper and Larsen to reduce variance in global problems by distributing particles more evenly throughout the spatial domain. This hybrid method uses an approximate deterministic estimate of the forward scalar flux distribution to automatically generate weight windows for the Monte Carlo transport simulation, avoiding the necessity for the code user to specify the weight window parameters. In a binary stochastic medium, the material properties at a given spatial location are known only statistically. The most common approach to solving particle transport problems involving binary stochastic media is to use the atomic mix (AM) approximation …
Date: March 4, 2010
Creator: Keady, K P & Brantley, P
Object Type: Article
System: The UNT Digital Library
RESULTS FOR THE SECOND QUARTER 2010 TANK 50 WAC SLURRY SAMPLE: CHEMICAL AND RADIONUCLIDE CONTAMINANT RESULTS (open access)

RESULTS FOR THE SECOND QUARTER 2010 TANK 50 WAC SLURRY SAMPLE: CHEMICAL AND RADIONUCLIDE CONTAMINANT RESULTS

This report details the chemical and radionuclide contaminant results for the characterization of the 2010 Second Quarter sampling of Tank 50 for the Saltstone Waste Acceptance Criteria (WAC).1 Information from this characterization will be used by Liquid Waste Operations (LWO) to support the transfer of low-level aqueous waste from Tank 50 to the Salt Feed Tank in the Saltstone Facility in Z-Area, where the waste will be immobilized. This information is also used to update the Tank 50 Waste Characterization System. The following conclusions are drawn from the analytical results provided in this report: (1) The concentrations of the reported chemical and radioactive contaminants were less than their respective WAC targets or limits unless noted in this section. (2) The reported detection limits for {sup 94}Nb and {sup 144}Ce are above both the established and requested limits from References 4 and 6. (3) The reported detection limits for {sup 247}Cm and {sup 249}Cf are above the requested limits from Reference 4. However, they are below the limits established in Reference 6. (4) The reported detection limit for Isopar L is greater than the limit from Table 3 of the WAC. (5) A measurable concentration of Norpar 13 is present in …
Date: August 4, 2010
Creator: Reigel, M. & Bibler, N.
Object Type: Report
System: The UNT Digital Library
On The Origin of Light Dark Matter Species (open access)

On The Origin of Light Dark Matter Species

TeV-mass dark matter charged under a new GeV-scale gauge force can explain electronic cosmic-ray anomalies. We propose that the CoGeNT and DAMA direct detection experiments are observing scattering of light stable states 'GeV-Matter' that are charged under this force and constitute a small fraction of the dark matter halo. Dark higgsinos in a supersymmetric dark sector are natural candidates for GeV-Matter that scatter off protons with a universal cross-section of 5 x 10{sup -38} cm{sup 2} and can naturally be split by 10-30 keV so that their dominant interaction with protons is down-scattering. As an example, down-scattering of an O(5) GeV dark higgsino can simultaneously explain the spectra observed by both CoGeNT and DAMA. The event rates in these experiments correspond to a GeV-Matter abundance of 0.2-1% of the halo mass density. This abundance can arise directly from thermal freeze-out at weak coupling, or from the late decay of an unstable TeV-scale WIMP. Our proposal can be tested by searches for exotics in the BaBar and Belle datasets.
Date: June 4, 2010
Creator: Essig, Rouven.; Kaplan, Jared.; Schuster, Philip. & Toro, Natalia.
Object Type: Article
System: The UNT Digital Library