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Searching for Gamma-Ray Blazar Candidates Among the Unidentified INTEGRAL Sources (open access)

Searching for Gamma-Ray Blazar Candidates Among the Unidentified INTEGRAL Sources

The identification of low-energy counterparts for {gamma}-ray sources is one of the biggest challenge in modern {gamma}-ray astronomy. Recently, we developed and successfully applied a new association method to recognize {gamma}-ray blazar candidates that could be possible counterparts for the unidentified {gamma}-ray sources above 100 MeV in the second Fermi Large Area Telescope (LAT) catalog (2FGL). This method is based on the Infrared (IR) colors of the recent Wide-Field Infrared Survey Explorer (WISE) all-sky survey. In this letter we applied our new association method to the case of unidentified INTEGRAL sources (UISs) listed in the fourth soft gamma-ray source catalog (4IC). Only 86 UISs out of the 113 can be analyzed, due to the sky coverage of the WISE Preliminary data release. Among these 86 UISs, we found that 18 appear to have a {gamma}-ray blazar candidate within their positional error region. Finally, we analyzed the Swift archival data available for 10 out these 18 {gamma}-ray blazar candidates, and we found that 7 out of 10 are clearly detected in soft X-rays and/or in the optical-ultraviolet band. We cannot confirm the associations between the UISs and the selected {gamma}-ray blazar candidates due to the discrepancies between the INTEGRAL and the …
Date: April 2, 2012
Creator: Massaro, F.; Paggi, A.; D'Abrusco, R. & Tosti, G.
Object Type: Article
System: The UNT Digital Library
Electro-optic Phase Grating Streak Spectrometer (open access)

Electro-optic Phase Grating Streak Spectrometer

The electro-optic phase grating streak spectrometer (EOPGSS) generates a time-resolved spectra equivalent to that obtained with a conventional spectrometer/streak camera combination, but without using a streak camera (by far the more expensive and problematic component of the conventional system). The EOPGSS is based on a phase, rather than an amplitude grating. Further, this grating is fabricated of electro-optic material such as, for example, KD*P, by either etching grooves into an E-O slab, or by depositing lines of the E-O material onto an optical flat. An electric field normal to the grating alters the material’s index of refraction and thus affects a shift (in angle) of the output spectrum. Ramping the voltage streaks the spectrum correspondingly. The streak and dispersion directions are the same, so a second (static, conventional) grating disperses the spectrum in the orthogonal direction to prevent different wavelengths from “overwriting” each other. Because the streaking is done by the grating, the streaked output spectrum is recorded with a time-integrating device, such as a CCD. System model, typical design, and performance expectations will be presented.
Date: August 2, 2012
Creator: Goldin, F. J.
Object Type: Article
System: The UNT Digital Library
Use Of Stream Analyzer For Solubility Predictions Of Selected Hanford Tank Waste (open access)

Use Of Stream Analyzer For Solubility Predictions Of Selected Hanford Tank Waste

The Hanford Tank Waste Operations Simulator (HTWOS) models the mission to manage, retrieve, treat and vitrify Hanford waste for long-term storage and disposal. HTWOS is a dynamic, flowsheet, mass balance model of waste retrieval and treatment activities. It is used to evaluate the impact of changes on long-term mission planning. The project is to create and evaluate the integrated solubility model (ISM). The ISM is a first step in improving the chemistry basis in HTWOS. On principal the ISM is better than the current HTWOS solubility. ISM solids predictions match the experimental data well, with a few exceptions. ISM predictions are consistent with Stream Analyzer predictions except for chromium. HTWOS is producing more realistic results with the ISM.
Date: November 2, 2012
Creator: Pierson, Kayla; Belsher, Jeremy & Ho, Quynh-dao
Object Type: Article
System: The UNT Digital Library
DOE 2012 Occupational Radiation Exposure October 2013 (open access)

DOE 2012 Occupational Radiation Exposure October 2013

The U.S. Department of Energy (DOE) Office of Analysis within the Office of Health, Safety and Security (HSS) publishes the annual DOE Occupational Radiation Exposure Report to provide an overview of the status of radiation protection practices at DOE (including the National Nuclear Security Administration [NNSA]). The DOE 2012 Occupational Radiation Exposure Report provides an evaluation of DOE-wide performance regarding compliance with Title 10, Code of Federal Regulations (C.F.R.), Part 835, Occupational Radiation Protection dose limits and as low as reasonably achievable (ALARA) process requirements. In addition, the report provides data to DOE organizations responsible for developing policies for protection of individuals from the adverse health effects of radiation. The report provides a summary and an analysis of occupational radiation exposure information from the monitoring of individuals involved in DOE activities. Over the past 5-year period, the occupational radiation exposure information is analyzed in terms of aggregate data, dose to individuals, and dose by site. As an indicator of the overall amount of radiation dose received during the conduct of operations at DOE, the report includes information on collective total effective dose (TED). The TED is comprised of the effective dose (ED) from external sources, which includes neutron and photon …
Date: February 2, 2012
Creator: unknown
Object Type: Report
System: The UNT Digital Library
Time-Resolved Soft X-Ray Spectra From Laser-Produced Cu Plasma (open access)

Time-Resolved Soft X-Ray Spectra From Laser-Produced Cu Plasma

The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated from a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800-1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in 2-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target.
Date: May 2, 2012
Creator: Cone, K. V.; Dunn, J.; Baldis, H. A.; May, M. J.; Purvis, M. A.; Scott, H. A. et al.
Object Type: Article
System: The UNT Digital Library
Texas Register, Volume 37, Number 9, Pages 1431-1560, March 2, 2012 (open access)

Texas Register, Volume 37, Number 9, Pages 1431-1560, March 2, 2012

A weekly publication, the Texas Register serves as the journal of state agency rulemaking for Texas. Information published in the Texas Register includes proposed, adopted, withdrawn and emergency rule actions, notices of state agency review of agency rules, governor's appointments, attorney general opinions, and miscellaneous documents such as requests for proposals. After adoption, these rulemaking actions are codified into the Texas Administrative Code.
Date: March 2, 2012
Creator: Texas. Secretary of State.
Object Type: Journal/Magazine/Newsletter
System: The Portal to Texas History
Improving the J/psi Production Baseline at RHIC and the LHC (open access)

Improving the J/psi Production Baseline at RHIC and the LHC

None
Date: July 2, 2012
Creator: Vogt, R; Nelson, R E & Frawley, A D
Object Type: Article
System: The UNT Digital Library
Design and Modeling of a Non-blocking Checkpointing System (open access)

Design and Modeling of a Non-blocking Checkpointing System

None
Date: May 2, 2012
Creator: Sato, K; Moody, A; Mohror, K; Maruyama, N; Gamblin, T; de Supinski, B R et al.
Object Type: Article
System: The UNT Digital Library

Theoretical Predictions of the thermodynamic Properties of Solid Sorbents Capture CO2 Applications

We are establishing a theoretical procedure to identify most potential candidates of CO{sub 2} solid sorbents from a large solid material databank to meet the DOE programmatic goal for energy conversion; and to explore the optimal working conditions for the promising CO{sub 2} solid sorbents, especially from room to warm T ranges with optimal energy usage, used for both pre- and post-combustion capture technologies.
Date: May 2, 2012
Creator: Duan, Yuhua; Sorescu, Dan; David, Luebke & Pennline, Henry
Object Type: Presentation
System: The UNT Digital Library
TECHNICAL BASIS FOR DOE STANDARD 3013 EQUIVALENCY SUPPORTING REDUCED TEMPERATURE STABILIZATION OF OXALATE-DERIVED PLUTONIUM OXIDE PRODUCED BY THE HB-LINE FACILITY AT SAVANNAH RIVER SITE (open access)

TECHNICAL BASIS FOR DOE STANDARD 3013 EQUIVALENCY SUPPORTING REDUCED TEMPERATURE STABILIZATION OF OXALATE-DERIVED PLUTONIUM OXIDE PRODUCED BY THE HB-LINE FACILITY AT SAVANNAH RIVER SITE

The HB-Line (HBL) facility at the Savannah River Site (SRS) is designed to produce high-purity plutonium dioxide (PuO{sub 2}) which is suitable for future use in production of Mixed Oxide (MOX) fuel. The MOX Fuel Fabrication Facility (MFFF) requires PuO{sub 2} feed to be packaged per the U.S. Department of Energy (DOE) Standard 3013 (DOE-STD-3013) to comply with the facility's safety basis. The stabilization conditions imposed by DOE-STD-3013 for PuO{sub 2} (i.e., 950 C for 2 hours) preclude use of the HBL PuO{sub 2} in direct fuel fabrication and reduce the value of the HBL product as MFFF feedstock. Consequently, HBL initiated a technical evaluation to define acceptable operating conditions for production of high-purity PuO{sub 2} that fulfills the DOE-STD-3013 criteria for safe storage. The purpose of this document is to demonstrate that within the defined operating conditions, the HBL process will be equivalent for meeting the requirements of the DOE-STD-3013 stabilization process for plutonium-bearing materials from the DOE complex. The proposed 3013 equivalency reduces the prescribed stabilization temperature for high-purity PuO{sub 2} from oxalate precipitation processes from 950 C to 640 C and places a limit of 60% on the relative humidity (RH) at the lowest material temperature. The …
Date: July 2, 2012
Creator: Duffey, J.; Livingston, R.; Berg, J. & Veirs, D.
Object Type: Report
System: The UNT Digital Library
An Undulator Based Polarized Positron Source for CLIC (open access)

An Undulator Based Polarized Positron Source for CLIC

A viable positron source scheme is proposed that uses circularly polarized gamma rays generated from the main 250 GeV electron beam. The beam passes through a helical superconducting undulator with a magnetic field of {approx} 1 Tesla and a period of 1.15 cm. The gamma-rays produced in the undulator in the energy range between {approx} 3 MeV - 100 MeV will be directed to a titanium target and produce polarized positrons. The positrons are then captured, accelerated and transported to a Pre-Damping Ring (PDR). Detailed parameter studies of this scheme including positron yield, and undulator parameter dependence are presented. Effects on the 250 GeV CLIC main beam, including emittance growth and energy loss from the beam passing through the undulator are also discussed.
Date: July 2, 2012
Creator: Liu, Wanming; Gai, Wei; Rinolfi, Louis & Sheppard, John
Object Type: Article
System: The UNT Digital Library
The 60-month all-sky BAT Survey of AGN and the Anisotropy of Nearby AGN (open access)

The 60-month all-sky BAT Survey of AGN and the Anisotropy of Nearby AGN

Surveys above 10 keV represent one of the the best resources to provide an unbiased census of the population of Active Galactic Nuclei (AGN). We present the results of 60 months of observation of the hard X-ray sky with Swift/BAT. In this timeframe, BAT detected (in the 15-55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGN, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of {approx}2 larger over similarly complete sets of AGN. Our sample contains (at least) 15 bona-fide Compton-thick AGN and 3 likely candidates. Compton-thick AGN represent a {approx}5% of AGN samples detected above 15 keV. We use the BAT dataset to refine the determination of the LogN-LogS of AGN which is extremely important, now that NuSTAR prepares for launch, towards assessing the AGN contribution to the cosmic X-ray background. We show that the LogN-LogS of AGN selected above 10 keV is now established to a {approx}10% precision. We derive the luminosity function of Compton-thick AGN and measure a space density of 7.9{sub -2.9}{sup +4.1} x 10{sup -5} Mpc{sup -3} for objects with a de-absorbed luminosity larger than 2 x 10{sup 42} erg s{sup -1}. …
Date: April 2, 2012
Creator: Ajello, M.; /KIPAC, Menlo Park; Alexander, D.M.; U., /Durham; Greiner, J.; /Garching, Max Planck Inst., MPE et al.
Object Type: Article
System: The UNT Digital Library
SDU 6 MODELING STUDY TO SUPPORT DESIGN DEVELOPMENT (open access)

SDU 6 MODELING STUDY TO SUPPORT DESIGN DEVELOPMENT

In response to Technical Task Request (TTR) HLW-SSF-TTR-2012-0017 (1), SRNL performed modeling studies to evaluate alternative design features for the 32 million gallon Saltstone Disposal Unit (SDU) referred to as SDU 6. This initial modeling study was intended to assess the performance of major components of the structure that are most significant to the PA. Information provided by the modeling will support the development of a SDU 6 Preliminary Design Model and Recommendation Report to be written by SRR Closure and Waste Disposal Authority. Key inputs and assumptions for the modeling were provided to SRNL in SRR-SPT-2011-00113 (2). A table reiterates the base case and four sensitivity case studies requested in this reference. In general, as shown in Table 4, when compared to Vault 2 Case A, the Base Case SDU 6 design produced higher peak fluxes to the water table during the 10,000 year period of analysis but lower peak fluxes within a 15,000 to 20,000 time frame. SDU 6 will contain approximately ten times the inventory of a single Vault 2 and the SDU 6 footprint is comparable to that of a group of four Vault 2 disposal units. Therefore, the radionuclide flux from SDU 6 and that …
Date: May 2, 2012
Creator: Smith, F.
Object Type: Report
System: The UNT Digital Library
Reliable High Performance Peta- and Exa-Scale Computing (open access)

Reliable High Performance Peta- and Exa-Scale Computing

As supercomputers become larger and more powerful, they are growing increasingly complex. This is reflected both in the exponentially increasing numbers of components in HPC systems (LLNL is currently installing the 1.6 million core Sequoia system) as well as the wide variety of software and hardware components that a typical system includes. At this scale it becomes infeasible to make each component sufficiently reliable to prevent regular faults somewhere in the system or to account for all possible cross-component interactions. The resulting faults and instability cause HPC applications to crash, perform sub-optimally or even produce erroneous results. As supercomputers continue to approach Exascale performance and full system reliability becomes prohibitively expensive, we will require novel techniques to bridge the gap between the lower reliability provided by hardware systems and users unchanging need for consistent performance and reliable results. Previous research on HPC system reliability has developed various techniques for tolerating and detecting various types of faults. However, these techniques have seen very limited real applicability because of our poor understanding of how real systems are affected by complex faults such as soft fault-induced bit flips or performance degradations. Prior work on such techniques has had very limited practical utility because …
Date: April 2, 2012
Creator: Bronevetsky, G
Object Type: Report
System: The UNT Digital Library
Linear Collider Test Facility: Twiss Parameter Analysis at the IP/Post-IP Location of the ATF2 Beam Line (open access)

Linear Collider Test Facility: Twiss Parameter Analysis at the IP/Post-IP Location of the ATF2 Beam Line

At the first stage of the ATF2 beam tuning, vertical beam size is usually bigger than 3 {micro}m at the IP. Beam waist measurements using wire scanners and a laser wire are usually performed to check the initial matching of the beam through to the IP. These measurements are described in this paper for the optics currently used ({beta}{sub x} = 4cm and {beta}{sub y} = 1mm). Software implemented in the control room to automate these measurements with integrated analysis is also described. Measurements showed that {beta} functions and emittances were within errors of measurements when no rematching and coupling corrections were done. However, it was observed that the waist in the horizontal (X) and vertical (Y) plane was abnormally shifted and simulations were performed to try to understand these shifts. They also showed that multiknobs are needed in the current optics to correct simultaneously {alpha}{sub x}, {alpha}{sub y} and the horizontal dispersion (D{sub x}). Such multiknobs were found and their linearity and orthogonality were successfully checked using MAD optics code. The software for these multiknobs was implemented in the control room and waist scan measurements using the {alpha}{sub y} knob were successfully performed.
Date: July 2, 2012
Creator: Bolzon, Benoit; Jeremie, Andrea; Bai, Sha; Bambade, Philip & White, Glen
Object Type: Article
System: The UNT Digital Library
Simultaneous Multiwavelength Observation of Mkn 501 in a Low State in 2006 (open access)

Simultaneous Multiwavelength Observation of Mkn 501 in a Low State in 2006

None
Date: April 2, 2012
Creator: Anderhub, H.; Antonelli, L. A.; Antoranz, P.; Backes, M.; Baixeras, C.; Balestra, S. et al.
Object Type: Article
System: The UNT Digital Library
ANALYSES OF HTF-48-12-20/24 (FEBRUARY, 2012) AND ARCHIVED HTF-E-05-021 TANK 48H SLURRY SAMPLES (open access)

ANALYSES OF HTF-48-12-20/24 (FEBRUARY, 2012) AND ARCHIVED HTF-E-05-021 TANK 48H SLURRY SAMPLES

Personnel characterized a Savannah River National Laboratory (SRNL) archived sample of Tank 48H slurry (HTF-E-05-021) in addition to the composite of samples HTF-48-12-20 and HTF-48-12-24, which were both retrieved in February 2012. The combined February 2012 sample is referred to as HTF-48-12-20/24 in this report. The results from these analyses are compared with Tank 48H samples analyzed in 2003, 2004, and 2005. This work supports the effort to demonstrate copper-catalyzed peroxide oxidation (CCPO) of organic content in this material. The principal findings with respect to the chemical and physical characteristics of the most recent sample are: (1) The measured potassium tetraphenylborate (KTPB) solid concentration is 1.76 wt %; (2) Titanium was in line with 2004 and 2005 slurry measurements at 897 mg/L, it represents 0.1535 {+-} 0.0012 wt % monosodium titanate (MST); (3) The measured insoluble solids content was 1.467 wt %; (4) The free hydroxide concentration in the Tank 48H filtrate sample (1.02 {+-} 0.02 M) is close to the Tank 48H limit (1.0 M); (5) Carbonate reported by total inorganic carbon (TIC, 1.39 {+-} 0.03 M) is more than double the concentrations measured in past (2003-2005) samples; (6) The soluble potassium content (measured at 286 {+-} 23 mg/L) …
Date: August 2, 2012
Creator: Nash, C. & Peters, T.
Object Type: Report
System: The UNT Digital Library
Fermi LAT Observations of LS I +61 303: First Detection of an Orbital Modulation in GeV Gamma Rays (open access)

Fermi LAT Observations of LS I +61 303: First Detection of an Orbital Modulation in GeV Gamma Rays

This Letter presents the first results from the observations of LS I +61{sup o}303 using Large Area Telescope data from the Fermi Gamma-Ray Space Telescope between 2008 August and 2009 March. Our results indicate variability that is consistent with the binary period, with the emission being modulated at 26.6 {+-} 0.5 days. This constitutes the first detection of orbital periodicity in high-energy gamma rays (20 MeV-100 GeV, HE). The light curve is characterized by a broad peak after periastron, as well as a smaller peak just before apastron. The spectrum is best represented by a power law with an exponential cutoff, yielding an overall flux above 100 MeV of 0.82 {+-} 0.03(stat) {+-} 0.07(syst) 10{sup -6} ph cm{sup -2} s{sup -1}, with a cutoff at 6.3 {+-} 1.1(stat) {+-} 0.4(syst) GeV and photon index {Gamma} = 2.21 {+-} 0.04(stat) {+-} 0.06(syst). There is no significant spectral change with orbital phase. The phase of maximum emission, close to periastron, hints at inverse Compton scattering as the main radiation mechanism. However, previous very high-energy gamma ray (>100 GeV, VHE) observations by MAGIC and VERITAS show peak emission close to apastron. This and the energy cutoff seen with Fermi suggest that the link …
Date: April 2, 2012
Creator: Abdo, A. A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Axelsson, M.; Baldini, L. et al.
Object Type: Article
System: The UNT Digital Library
Computational fluid dynamic modeling of fluidized-bed polymerization reactors (open access)

Computational fluid dynamic modeling of fluidized-bed polymerization reactors

Polyethylene is one of the most widely used plastics, and over 60 million tons are produced worldwide every year. Polyethylene is obtained by the catalytic polymerization of ethylene in gas and liquid phase reactors. The gas phase processes are more advantageous, and use fluidized-bed reactors for production of polyethylene. Since they operate so close to the melting point of the polymer, agglomeration is an operational concern in all slurry and gas polymerization processes. Electrostatics and hot spot formation are the main factors that contribute to agglomeration in gas-phase processes. Electrostatic charges in gas phase polymerization fluidized bed reactors are known to influence the bed hydrodynamics, particle elutriation, bubble size, bubble shape etc. Accumulation of electrostatic charges in the fluidized-bed can lead to operational issues. In this work a first-principles electrostatic model is developed and coupled with a multi-fluid computational fluid dynamic (CFD) model to understand the effect of electrostatics on the dynamics of a fluidized-bed. The multi-fluid CFD model for gas-particle flow is based on the kinetic theory of granular flows closures. The electrostatic model is developed based on a fixed, size-dependent charge for each type of particle (catalyst, polymer, polymer fines) phase. The combined CFD model is first verified …
Date: November 2, 2012
Creator: Rokkam, Ram
Object Type: Thesis or Dissertation
System: The UNT Digital Library
WaterTransport in PEM Fuel Cells: Advanced Modeling, Material Selection, Testing and Design Optimization (open access)

WaterTransport in PEM Fuel Cells: Advanced Modeling, Material Selection, Testing and Design Optimization

Water management in Proton Exchange Membrane, PEM, Fuel Cells is challenging because of the inherent conflicts between the requirements for efficient low and high power operation. Particularly at low powers, adequate water must be supplied to sufficiently humidify the membrane or protons will not move through it adequately and resistance losses will decrease the cell efficiency. At high power density operation, more water is produced at the cathode than is necessary for membrane hydration. This excess water must be removed effectively or it will accumulate in the Gas Diffusion Layers, GDLs, between the gas channels and catalysts, blocking diffusion paths for reactants to reach the catalysts and potentially flooding the electrode. As power density of the cells is increased, the challenges arising from water management are expected to become more difficult to overcome simply due to the increased rate of liquid water generation relative to fuel cell volume. Thus, effectively addressing water management based issues is a key challenge in successful application of PEMFC systems. In this project, CFDRC and our partners used a combination of experimental characterization, controlled experimental studies of important processes governing how water moves through the fuel cell materials, and detailed models and simulations to improve …
Date: October 2, 2012
Creator: Cole, J. Vernon; Roy, Abhra; Damle, Ashok; Dahr, Hari; Kumar, Sanjiv; Jain, Kunal et al.
Object Type: Report
System: The UNT Digital Library
Unidentified Gamma-Ray Sources: Hunting Gamma-Ray Blazars (open access)

Unidentified Gamma-Ray Sources: Hunting Gamma-Ray Blazars

One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of the unidentified {gamma}-ray sources (UGSs). Despite the large improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one third of the Fermi-detected objects are still not associated to low energy counterparts. Recently, using the Wide-field Infrared Survey Explorer (WISE) survey, we discovered that blazars, the rarest class of Active Galactic Nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Based on this result, we designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated to the UGS sample of the second Fermi {gamma}-ray catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated to {gamma}-ray sources in the 2FGL catalog.
Date: April 2, 2012
Creator: Massaro, F.; D'Abrusco, R.; Tosti, G.; Ajello, M. & Gasparrini, A.Paggi.D.
Object Type: Article
System: The UNT Digital Library
X-ray Streak Camera Cathode Development and Timing Accuracy of the 4w UV Fiducial System at the National Ignition Facility (open access)

X-ray Streak Camera Cathode Development and Timing Accuracy of the 4w UV Fiducial System at the National Ignition Facility

The convergent ablator experiments at the National Ignition Facility (NIF) are designed to measure the peak velocity and remaining ablator mass of an indirectly driven imploding capsule. Such a measurement can be performed using an x-ray source to backlight the capsule and an x-ray streak camera to record the capsule as it implodes. The ultimate goal of this experiment is to achieve an accuracy of 2% in the velocity measurement, which translates to a {+-}2 ps temporal accuracy over any 300 ps interval for the streak camera. In order to achieve this, a 4-{omega} (263nm) temporal fiducial system has been implemented for the x-ray streak camera at NIF. Aluminum, Titanium, Gold and Silver photocathode materials have been tested. Aluminum showed the highest quantum efficiency, with five times more peak signal counts per fiducial pulse when compared to Gold. The fiducial pulse data was analyzed to determine the centroiding a statistical accuracy for incident laser pulse energies of 1 and 10 nJ, showing an accuracy of {+-}1.6 ps and {+-}0.7 ps respectively.
Date: May 2, 2012
Creator: Opachich, Y P; Palmer, N; Homoelle, D; Hatch, B W; Bell, P; Bradley, D et al.
Object Type: Article
System: The UNT Digital Library
United abominations: Density functional studies of heavy metal chemistry (open access)

United abominations: Density functional studies of heavy metal chemistry

Carbonyl and nitrile addition to uranyl (UO{sup 2}{sup 2+}) are studied. The competition between nitrile and water ligands in the formation of uranyl complexes is investigated. The possibility of hypercoordinated uranyl with acetone ligands is examined. Uranyl is studied with diactone alcohol ligands as a means to explain the apparent hypercoordinated uranyl. A discussion of the formation of mesityl oxide ligands is also included. A joint theory/experimental study of reactions of zwitterionic boratoiridium(I) complexes with oxazoline-based scorpionate ligands is reported. A computational study was done of the catalytic hydroamination/cyclization of aminoalkenes with zirconium-based catalysts. Techniques are surveyed for programming for graphical processing units (GPUs) using Fortran.
Date: April 2, 2012
Creator: Schoendorff, George
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Distinguishing Pu metal from Pu oxide using fast neutron counting (open access)

Distinguishing Pu metal from Pu oxide using fast neutron counting

None
Date: February 2, 2012
Creator: Chapline, G & Verbeke, J
Object Type: Article
System: The UNT Digital Library