Application of Imaging Plate to X-Ray Imaging and Spectroscopy in Laser Plasma Experiments (open access)

Application of Imaging Plate to X-Ray Imaging and Spectroscopy in Laser Plasma Experiments

We report recent progress of x-ray diagnostic techniques in laser plasma experiment with using imaging plates. Imaging plate is a photo-stimulable phosphor screen (BaF(Br0.85,10.15):Eu{sup 2+}) deposited on flexible metal or plastic substrate. We applied the imaging plate to x-ray microscopy in laser fusion experiment experiments. Self-emission x-ray images of imploded core were obtained successfully with using imaging plate and high magnification target mounted pinhole arrays. The imaging plates were applied also in ultra-intense laser experiment at the Rutherford Appleton Laboratory. Small samarium foil was irradiated by high intensity laser pulse from the Vulcan laser system. The k shell x-rays from the foil ({approx}40keV) was used as a line x-ray source for microscopic radiography. Performance of imaging plate on high-energy x-ray backlit radiography was demonstrated by imaging sinusoidal grooves of 6um amplitude on a Au foil. Detailed spectrum of k shell x-ray from Cu embedded foil target was successfully observed by fully coupling imaging plate with a highly ordered pyrolytic graphite crystal spectrometer. The performances of the imaging plates evaluated in actual laser plasma experiments will be presented.
Date: April 25, 2006
Creator: Izumi, N.; Snavely, R.; Gregori, G.; Koch, J. A.; Park, H. & Remington, B. A.
Object Type: Article
System: The UNT Digital Library
Bootstrapping One-Loop QCD Amplitudeswith General Helicities (open access)

Bootstrapping One-Loop QCD Amplitudeswith General Helicities

The recently developed on-shell bootstrap for computing one-loop amplitudes in non-supersymmetric theories such as QCD combines the unitarity method with loop-level on-shell recursion. For generic helicity configurations, the recursion relations may involve undetermined contributions from non-standard complex singularities or from large values of the shift parameter. Here we develop a strategy for sidestepping difficulties through use of pairs of recursion relations. To illustrate the strategy, we present sets of recursion relations needed for obtaining n-gluon amplitudes in QCD. We give a recursive solution for the one-loop n-gluon QCD amplitudes with three or four color-adjacent gluons of negative helicity and the remaining ones of positive helicity. We provide an explicit analytic formula for the QCD amplitude A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}), as well as numerical results for A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), A{sub 8;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}, 8{sup +}), and A{sub 8;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup -}, 5{sup +}, 6{sup +}, 7{sup +}, 8{sup +}). We expect the on-shell bootstrap approach to have widespread applications to phenomenological studies at colliders.
Date: April 25, 2006
Creator: Berger, Carola F.; Bern, Zvi; Dixon, Lance J.; Forde, Darren & Kosower, David A.
Object Type: Report
System: The UNT Digital Library
Broadband dielectric function of non-equilibrium warm dense gold (open access)

Broadband dielectric function of non-equilibrium warm dense gold

We report on the first single-state measurement of the broadband (450-800 nm) dielectric function of gold isochorically heated by a femtosecond laser pulse to energy densities of 10{sup 6}-10{sup 7} J/kg. A Drude and an inter-band component are clearly seen in the imaginary part of the dielectric function. The Drude component increases with energy density while the inter-band component shows both enhancement and red shift. This is in strong disagreement with predictions of a recent calculation of dielectric function based on limited k-point sampling.
Date: April 25, 2006
Creator: Ping, Y.; Hanson, D.; Koslow, I.; Ogitsu, T.; Prendergast, D.; Schwegler, E. et al.
Object Type: Article
System: The UNT Digital Library
CH Packaging Program Guidance (open access)

CH Packaging Program Guidance

The purpose of this document is to provide the technical requirements for preparation for use, operation, inspection, and maintenance of a Transuranic Package TransporterModel II (TRUPACT-II), a HalfPACT shipping package, and directly related components. This document complies with the minimum requirements as specified in the TRUPACT-II Safety Analysis Report for Packaging (SARP), HalfPACT SARP, and U.S. Nuclear Regulatory Commission (NRC) Certificates of Compliance (C of C) 9218 and 9279, respectively. In the event of a conflict between this document and the SARP or C of C, the C of C shall govern. The C of Cs state: "each package must be prepared for shipment and operated in accordance with the procedures described in Chapter 7.0, Operating Procedures, of the application." They further state: "each package must be tested and maintained in accordance with the procedures described in Chapter 8.0, Acceptance Tests and Maintenance Program of the Application." Chapter 9.0 of the SARP charges the U.S. Department of Energy (DOE) or the Waste Isolation Pilot Plant| (WIPP) management and operating (M&O) contractor with assuring packaging is used in accordance with the requirements of the C of C. Because the packaging is NRC-approved, users need to be familiar with Title 10 Code …
Date: April 25, 2006
Creator: None, None
Object Type: Report
System: The UNT Digital Library
Final Report: X-ray Studies of Materials Dynamics at MHATT-CAT Sector 7, Advanced Photon Source (open access)

Final Report: X-ray Studies of Materials Dynamics at MHATT-CAT Sector 7, Advanced Photon Source

This Final Report describes the scientific accomplishments that have been achieved with support from grant DE-FG02-03ER46023 during the period 12/01/02 ? 11/30/05. The funding supported a vigorous scientific program allowing the PI to achieve leadership in a number of important areas. In particular, research carried out during this period has opened way to ultrafast dynamics studies of materials by combining the capabilities of synchrotron radiation with those of ultrafast lasers. This enables the initiation of laser-induced excitations and studies of their subsequent dynamics using laser-pump/x-ray probe techniques. Examples of such excitations include phonons, shock waves, excitons, spin-waves, and polaritons. The breadth of phenomena that can now be studied in the time-domain is very broad, revealing new phenomena and mechanisms that are critical to many applications of materials.
Date: April 25, 2006
Creator: Clarke, Roy
Object Type: Report
System: The UNT Digital Library
First-principles thermoelasticity of transition metals at high pressure I. Tantalum prototype in the quasi-harmonic limit (open access)

First-principles thermoelasticity of transition metals at high pressure I. Tantalum prototype in the quasi-harmonic limit

The thermoelastic properties of bcc tantalum have been investigated over a broad range of pressures (up to 10 Mbar) and temperatures (up to 26,000 K) using a new first-principles approach that accurately accounts for cold, electron-thermal, and ion-thermal contributions in materials where anharmonic effects are small. Specifically, we have combined ab initio full-potential linear-muffin-tin-orbital (FP-LMTO) electronic-structure calculations for the cold and electron-thermal contributions to the elastic moduli with phonon contributions for the ion-thermal part calculated using model generalized pseudopotential theory (MGPT). For the latter, a summation of terms over the Brillouin zone is performed within the quasi-harmonic approximation, where each term is composed of a strain derivative of the phonon frequency at a particular k point. At ambient pressure, the resulting temperature dependence of the Ta elastic moduli is in excellent agreement with ultrasonic measurements. The experimentally observed anomalous behavior of C{sub 44} at low temperatures is shown to originate from the electron-thermal contribution. At higher temperatures, the main contribution to the temperature dependence of the elastic moduli comes from thermal expansion, but inclusion of the electron- and ion-thermal contributions is essential to obtain quantitative agreement with experiment. In addition, the pressure dependence of the moduli at ambient temperature compares …
Date: April 25, 2006
Creator: Orlikowski, D.; Soderlind, P. & Moriarty, J. A.
Object Type: Article
System: The UNT Digital Library
Hard X-ray Imaging for Measuring Laser Absorption Spatial Profiles on the National Ignition Facility (open access)

Hard X-ray Imaging for Measuring Laser Absorption Spatial Profiles on the National Ignition Facility

Hard x-ray (''Thin wall'') imaging will be employed on the National Ignition Facility (NIF) to spatially locate laser beam energy deposition regions on the hohlraum walls in indirect drive Inertial Confinement Fusion (ICF) experiments, relevant for ICF symmetry tuning. Based on time resolved imaging of the hard x-ray emission of the laser spots, this method will be used to infer hohlraum wall motion due to x-ray and laser ablation and any beam refraction caused by plasma density gradients. In optimizing this measurement, issues that have to be addressed are hard x-ray visibility during the entire ignition laser pulse with intensities ranging from 10{sup 13} to 10{sup 15} W/cm{sup 2}, as well as simultaneous visibility of the inner and the outer laser drive cones. In this work we will compare the hard x-ray emission calculated by LASNEX and analytical modeling with thin wall imaging data recorded previously on Omega and during the first hohlraum experiments on NIF. Based on these calculations and comparisons the thin wall imaging will be optimized for ICF/NIF experiments.
Date: April 25, 2006
Creator: Dewald, E L; Jones, O S; Landen, O L; Suter, L; Amendt, P; Turner, R E et al.
Object Type: Article
System: The UNT Digital Library
Heat Loss by Helicity Injection II (open access)

Heat Loss by Helicity Injection II

Arguments are reviewed showing that helicity transport always flattens the temperature profile, yielding unit current amplification in SSPX and flat temperature profiles in RFP's whenever the dynamo is active. The argument is based on transport theory yielding a hyper-resistivity {Lambda} {approx} (c{sup 2}/{omega}{sub pc}{sup 2}){chi}{sub c} with electron thermal diffusivity {chi}{sub c}, valid for any process producing a random-walk in electron constants of motion in the unperturbed field. The theory could be tested by deriving {Lambda} from helicity transport in SSPX, by analogy with recent analysis yielding {chi}{sub c} from heat transport. If the predicted ratio {Lambda}/{chi}{sub c} is confirmed, efforts to increase current amplification in SSPX must be based on scenario scenarios consistent with slow helicity transport compared to heat s transport (pulsed reactor, multipulse, neutral beam injection).
Date: April 25, 2006
Creator: Fowler, T K
Object Type: Report
System: The UNT Digital Library
High Energy Neutrino Flash From Far-UV/X-Ray Flares of Gamma-Ray Bursts (open access)

High Energy Neutrino Flash From Far-UV/X-Ray Flares of Gamma-Ray Bursts

The recent observations of bright optical and X-ray flares by the Swift satellite suggest these are produced by the late activities of the central engine. We study the neutrino emission from far-UV/X-ray flares under the late internal shock model. Since the efficiency of pion production in the highest energy is higher than that of the prompt bursts, such neutrino flashes from flares can give comparable or larger contributions to a diffuse very high energy neutrino background if the total energy input into flares is comparable to the radiated energy of the prompt bursts. These signals are very important because they have possibility to probe the nature of flares (baryonic or magnetic, the photon field, the magnetic field, and so on).
Date: April 25, 2006
Creator: Murase, Kohta; /Kyoto U., Yukawa Inst., Kyoto; Nagataki, Shigehiro & /Kyoto U., Yukawa Inst., Kyoto /KIPAC, Menlo Park
Object Type: Report
System: The UNT Digital Library
An Introduction to Algebraic Multigrid (open access)

An Introduction to Algebraic Multigrid

Algebraic multigrid (AMG) solves linear systems based on multigrid principles, but in a way that only depends on the coefficients in the underlying matrix. The author begins with a basic introduction to AMG methods, and then describes some more recent advances and theoretical developments
Date: April 25, 2006
Creator: Falgout, R D
Object Type: Article
System: The UNT Digital Library
Killing Two Birds with One Stone: Can Real-Time Pricing SupportRetail Competition and Demand Response? (open access)

Killing Two Birds with One Stone: Can Real-Time Pricing SupportRetail Competition and Demand Response?

As retail choice states reach the end of their transitional, rate-cap periods, state regulators must decide what type of default supply service to provide to customers that have not switched to a competitive retail supplier. In a growing number of states, regulators have adopted real-time pricing (RTP) as the default service for large commercial and industrial (C&I) customers. Although this trend is driven chiefly by policy objectives related to retail competition, default service RTP may have the added benefit of stimulating demand response. To evaluate the potential role of RTP as a means to both ends--retail market development and demand response--we conducted a comprehensive review of experience with default RTP in the U.S. and examined the emergence of RTP as a product offering by competitive retail suppliers. Across the ten utilities with default RTP in place in 2005, between 5% and 35% of the applicable load remained on the rate. Based on interviews with competitive retailers, we find evidence to suggest that a comparable amount of load in these states has switched to hourly pricing arrangements with competitive retailers. Many customers on default or competitive hourly pricing are paying prices indexed to the real-time spot market, and thus have no …
Date: April 25, 2006
Creator: Barbose, Galen; Bharvirkar, Ranjit; Goldman, Charles; Hopper,Nicole & Neenan, Bernie
Object Type: Article
System: The UNT Digital Library
Method for high temperature mercury capture from gas streams (open access)

Method for high temperature mercury capture from gas streams

A process to facilitate mercury extraction from high temperature flue/fuel gas via the use of metal sorbents which capture mercury at ambient and high temperatures. The spent sorbents can be regenerated after exposure to mercury. The metal sorbents can be used as pure metals (or combinations of metals) or dispersed on an inert support to increase surface area per gram of metal sorbent. Iridium and ruthenium are effective for mercury removal from flue and smelter gases. Palladium and platinum are effective for mercury removal from fuel gas (syngas). An iridium-platinum alloy is suitable for metal capture in many industrial effluent gas streams including highly corrosive gas streams.
Date: April 25, 2006
Creator: Granite, E. J. & Pennline, H. W.
Object Type: Patent
System: The UNT Digital Library
Numerical Simulation of Groundwater Withdrawal from Proposed Pumping Near the Southeastern Nevada Test Site (open access)

Numerical Simulation of Groundwater Withdrawal from Proposed Pumping Near the Southeastern Nevada Test Site

Current modeling of the southeastern portion of the Nevada Test Site (NTS) with a refined U.S. Geological Survey Death Valley regional groundwater flow system model shows that impacts from pumping by proposed Southern Nevada Water Authority (SNWA) and Vidler Water Company (VWC) wells can be substantial over 75 years of operation. Results suggest that significant drawdown at proposed well sites will occur with depths of drawdown ranging from 8 m to nearly 1,600 m. The areal extent of 0.5 m of drawdown is also significant, impacting Mercury Valley, Amargosa, Indian Springs, Three Lakes, and Frenchman Flat basins. Drawdown will impact Army No.1 Water Well in Mercury Valley by lowering water levels 2.1 m but will not impact other NTS production wells. It is also predicted that flowpaths from detonation sites within the NTS will be altered with the potential to move material out of the NTS. Impacts to both springs and regions of groundwater evapotranspiration (modeled as MODFLOW drain cells) appear very minimal, with an estimated 0.2-percent reduction in flow to these regions. This amounts to a loss of more that 55,000 m3/year (45 acre-ft/year), or more than 4,000,000 m3 (3,400 acre-ft) during 75 years of groundwater withdrawal by pumping …
Date: April 25, 2006
Creator: Carroll, R.W.H.; R.L.Hershey & Pohll, G.M.
Object Type: Report
System: The UNT Digital Library
Reconfigurable Hybrid Interconnection for Static and DynamicScientific Applications (open access)

Reconfigurable Hybrid Interconnection for Static and DynamicScientific Applications

As we enter the era of petascale computing, system architects must plan for machines composed of tens of thousands or even hundreds of thousands of processors. Although fully connected networks such as fat-tree interconnects currently dominate HPC network designs, such approaches are inadequate for thousands of processors due to the superlinear growth of component costs. Traditional low-degree interconnect topologies, such as the 3D torus, have reemerged as a competitive solution because the number of switch components scales linearly with the node count, but such networks are poorly suited for the requirements of many scientific applications. We present our latest work on a hybrid switch architecture called HFAST that uses circuit switches to dynamically reconfigure a lower-degree interconnect to suit the topological requirements of each scientific application. This paper expands upon our prior work on the requirements of non-adaptive applications by analyzing the communication characteristics of dynamically adapting AMR code and presents a methodology that captures the evolving communication requirements. We also present a new optimization that computes the under-utilization of fat-tree interconnects for a given communication topology, showing the potential of constructing a ''fit-tree'' for the application by using the HFAST circuit switches to provision an optimal interconnect topology for …
Date: April 25, 2006
Creator: Kamil, Shoaib; Pinar, Ali; Gunter, Daniel; Lijewski, Michael; Oliker, Leonid; Shalf, John et al.
Object Type: Article
System: The UNT Digital Library
Recovery of a CVD diamond detection system from strong pulses of laser produced x-rays (open access)

Recovery of a CVD diamond detection system from strong pulses of laser produced x-rays

We are studying the response of a CVD diamond detector to a strong x-ray pulse followed by a second weaker pulse arriving 50 to 300 ns later, with a contrast in amplitude of about 1000. These tests, performed at the LLNL Jupiter laser facility, are intended to produce charge carrier densities similar to those expected during a DT implosion at NIF, where a large 14.1 MeV neutron pulse is followed by a weak downscattered neutron signal produced by slower 6-10 MeV neutrons. The number of downscattered neutrons must be carefully measured in order to obtain an accurate value for the areal density, which is proportional to the ratio of downscattered to primary neutrons. The effects of the first strong pulse may include saturation of the diamond wafer, saturation of the oscilloscope, or saturation of the associated power and data acquisition electronics. We are presenting a double pulse experiment that will use a system of several polycrystalline CVD diamond detectors irradiated by 8.6 keV x-rays emitted from a zinc target. We will discuss implication for a NIF areal density measurement.
Date: April 25, 2006
Creator: Dauffy, L S; Koch, J A; Izumi, N; Tommasini, R & Lerche, R A
Object Type: Article
System: The UNT Digital Library
Soft x-ray spectrometer operation at the National Ignition Facility (open access)

Soft x-ray spectrometer operation at the National Ignition Facility

Radiation drive diagnostics during the NIF early light campaign was supported by an 18 channel soft x-ray spectrometer (Dante). In order to achieve a measurement accuracy of 2% in radiation temperature absolute calibration of the individual channels was necessary and signal distortion through long transmission lines had to be compensated for as well. For fast signals the signal attenuation due to the long (50m) cables amounted to {approx} 20% {at} 100MHz, which was corrected by a cable compensation in the frequency domain. The varying effects of cable distortion for a variety of signals between 1ns and 9ns in length were evaluated and corrections were applied. Results of the thus calculated temperatures of the NEL campaign will be presented compared to LASNEX predictions, showing agreement in peak radiation temperature within less than 2%.
Date: April 25, 2006
Creator: Schein, J.; Dewald, E.; Campbell, K.; Turner, R.; Weber, F.; Rhodes, M. et al.
Object Type: Article
System: The UNT Digital Library
Solid-Density Plasma characterization with X-ray scattering on the 200-J Janus Laser (open access)

Solid-Density Plasma characterization with X-ray scattering on the 200-J Janus Laser

We present collective x-ray scattering (CXS) measurements using a Chlorine He-{alpha} x-ray source pumped with less than 200 J of laser energy. The experimental scattering spectra show plasmon resonances from shocked samples. These experiments use only 10{sup 12} x-ray photons at the sample of which 10{sup -5} have been scattered and detected with a highly efficient curved crystal spectrometer. Our results demonstrate that x-ray scattering is a viable technique on smaller laser facilities making CXS measurements accessible to a broad scientific community.
Date: April 25, 2006
Creator: Neumayer, P B; Gregori, G; Ravasio, A; Price, D; Bastea, M; Landen, O L et al.
Object Type: Article
System: The UNT Digital Library
A STRUCTURAL INTEGRITY ASSESSMENT OF UNDERGROUND PIPING ASSOCIATED WITH THE TRANSFER OF RADIOACTIVE WASTE (open access)

A STRUCTURAL INTEGRITY ASSESSMENT OF UNDERGROUND PIPING ASSOCIATED WITH THE TRANSFER OF RADIOACTIVE WASTE

Radioactive wastes are confined in 49 underground storage tanks at the Savannah River Site. The waste is transported between tanks via underground transfer piping. An assessment of the structural integrity of the transfer piping was performed to ensure that the present condition of the piping was sound and to provide life expectancy estimates for the piping based on anticipated service. The assessment reviewed the original design of the piping, the potential and observed degradation mechanisms, the results from past inspections of the piping, and a Fitness-For-Service evaluation for a section of piping that experienced pitting in a locally thinned area. The assessment concluded that the piping was structurally sound. Assuming that service conditions remain the same, the piping will remain functional for its intended service life.
Date: April 25, 2006
Creator: Wiersma, B
Object Type: Article
System: The UNT Digital Library

Testing the Concept of Drift Shadow With X-Ray Absorption Imaging Experiments

None
Date: April 25, 2006
Creator: Altman, S.J.
Object Type: Presentation
System: The UNT Digital Library