Absolute Determination of Charge-Coupled Device Quantum Detection Efficiency Using Si K-Edge X-Ray Absorption Fine Structure (open access)

Absolute Determination of Charge-Coupled Device Quantum Detection Efficiency Using Si K-Edge X-Ray Absorption Fine Structure

We report a method to determine the quantum detection efficiency and the absorbing layers on a front-illuminated charge-coupled device (CCD). The CCD under study, as part of a crystal spectrometer, measures intense continuum x-ray emission from a picosecond laser-produced plasma and spectrally resolves the Si K-edge x-ray absorption fine structure features due to the electrode gate structure of the device. The CCD response across the Si K-edge shows a large discontinuity as well as a number of oscillations that are identified individually and uniquely from Si, SiO{sub 2}, and Si{sub 3}N{sub 4} layers. From the spectral analysis of the structure and K-edge discontinuity, the active layer thickness and the different absorbing layers thickness can be determined precisely. A precise CCD detection model from 0.2-10 keV can be deduced from this highly sensitive technique.
Date: May 6, 2012
Creator: Dunn, J. & Steel, A. B.
System: The UNT Digital Library
Accurately measuring MPI broadcasts in a computational grid (open access)

Accurately measuring MPI broadcasts in a computational grid

An MPI library's implementation of broadcast communication can significantly affect the performance of applications built with that library. In order to choose between similar implementations or to evaluate available libraries, accurate measurements of broadcast performance are required. As we demonstrate, existing methods for measuring broadcast performance are either inaccurate or inadequate. Fortunately, we have designed an accurate method for measuring broadcast performance, even in a challenging grid environment. Measuring broadcast performance is not easy. Simply sending one broadcast after another allows them to proceed through the network concurrently, thus resulting in inaccurate per broadcast timings. Existing methods either fail to eliminate this pipelining effect or eliminate it by introducing overheads that are as difficult to measure as the performance of the broadcast itself. This problem becomes even more challenging in grid environments. Latencies a long different links can vary significantly. Thus, an algorithm's performance is difficult to predict from it's communication pattern. Even when accurate pre-diction is possible, the pattern is often unknown. Our method introduces a measurable overhead to eliminate the pipelining effect, regardless of variations in link latencies. choose between different available implementations. Also, accurate and complete measurements could guide use of a given implementation to improve application …
Date: May 6, 1999
Creator: T, Karonis N & de Supinski, B R
System: The UNT Digital Library
Activities of ZGS people in the 1980`s and 1990`s (open access)

Activities of ZGS people in the 1980`s and 1990`s

The ZGS people went off in every direction: to universities, to other laboratories, to universities and laboratories in other countries, and to other occupations in the private sector or federal agencies. Some people even cycled around through one or more of the above and eventually would up back to Argonne. As a good pupil of the David Manson school of weasel words. I recognize the need to insert a {open_quotes}to the best of my knowledge{close_quotes} disclaimer statement here. It became clear to me that I couldn`t vouch for the accuracy of all of the information shown below when, to my surprise and delight, I found on the official registration list for this conference the names of people I really, really, never expected to see again!
Date: May 6, 1994
Creator: Day, J.
System: The UNT Digital Library
Addendum to: Applications of evaluated nuclear data in the LAHET code (open access)

Addendum to: Applications of evaluated nuclear data in the LAHET code

This document is intended to provide additional information supplementing a prior publication. The discussion describes the details of the implementation of the proton nonelastic cross section parameterization for LAHET usage. It also documents extensions of the method to stable nuclei with 2 {le} Z {le} 5.
Date: May 6, 1997
Creator: Prael, R.E. & Chadwick, M.B.
System: The UNT Digital Library
Advanced array techniques for unattended ground sensor applications (open access)

Advanced array techniques for unattended ground sensor applications

Sensor arrays offer opportunities to beam form, and time-frequency analyses offer additional insights to the wavefield data. Data collected while monitoring three different sources with unattended ground sensors in a 16-element, small-aperture (approximately 5 meters) geophone array are used as examples of model-based seismic signal processing on actual geophone array data. The three sources monitored were: (Source 01). A frequency-modulated chirp of an electromechanical shaker mounted on the floor of an underground bunker. Three 60-second time-windows corresponding to (a) 50 Hz to 55 Hz sweep, (b) 60 Hz to 70 Hz sweep, and (c) 80 Hz to 90 Hz sweep. (Source 02). A single transient impact of a hammer striking the floor of the bunker. Twenty seconds of data (with the transient event approximately mid-point in the time window.(Source 11)). The transient event of a diesel generator turning on, including a few seconds before the turn-on time and a few seconds after the generator reaches steady-state conditions. The high-frequency seismic array was positioned at the surface of the ground at a distance of 150 meters (North) of the underground bunker. Four Y-shaped subarrays (each with 2-meter apertures) in a Y-shaped pattern (with a 6-meter aperture) using a total of 16 …
Date: May 6, 1997
Creator: Followill, Fred E.; Wolford, James K. & Candy, James V.
System: The UNT Digital Library
Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames (open access)

Analyzing and Tracking Burning Structures in Lean Premixed Hydrogen Flames

None
Date: May 6, 2009
Creator: Bremer, P; Weber, G; Pascucci, V; Day, M & Bell, J
System: The UNT Digital Library
BayesLoc: A robust location program for multiple seismic events given an imperfect earth model and error-corrupted seismic data (open access)

BayesLoc: A robust location program for multiple seismic events given an imperfect earth model and error-corrupted seismic data

None
Date: May 6, 2011
Creator: Myers, S C; Johannesson, G & Mellors, R J
System: The UNT Digital Library
BBU design of linear induction accelerator cells for radiography application (open access)

BBU design of linear induction accelerator cells for radiography application

There is an ongoing effort to develop accelerating modules for high-current electron accelerators for advanced radiography application. Accelerating modules with low beam-cavity coupling impedances along with gap designs with acceptable field stresses comprise a set of fundamental design criteria. We examine improved cell designs which have been developed for accelerator application in several radiographic operating regimes. We evaluate interaction impedances, analyze the effects of beam structure coupling on beam dynamics (beam break-up instability and corkscrew motion). We also provide estimates of coupling through interesting new high-gradient insulators and evaluate their potential future application in induction cells.
Date: May 6, 1997
Creator: Shang, C. C.; Chen, Y. J.; Gaporaso, G. J.; Houck, T. L.; Molau, N. E.; Focklen, J. et al.
System: The UNT Digital Library
Beam-storage studies in the Fermilab main ring (open access)

Beam-storage studies in the Fermilab main ring

Bunched beams of 100 and 150 GeV have been stored in the Fermilab Main Ring for periods of up to one hour. The observations of beam current and beam profiles are analyzed for the effects of gas scattering, chromaticity and non-linear magnetic field.
Date: May 6, 1982
Creator: MacLachlan, J.A.
System: The UNT Digital Library
Beam tests of the 12 MHz RFQ RIB injector for ATLAS. (open access)

Beam tests of the 12 MHz RFQ RIB injector for ATLAS.

Beam tests of the ANL 12 MHz Radio-Frequency Quadruple (RFQ), designed for use as the initial element of an injector system for radioactive beams into the existing ATLAS accelerators, are in progress. Recent high-voltage tests of the RFQ without beam achieved the design intervane voltage of 100 kV CW, enabling beam tests with A/q as large as 132 using beams from the ANL Physics Division 4 MV Dynamitron accelerator facility. Although the RFQ was designed for bunched beams, initial tests have been performed with unbunched beams. Experiments with stable, unbunched beams of singly-charged {sup 132}Xe and {sup 84}Kr measured the output beam energy distribution as a function of the RFQ operating voltage. The observed energies are in excellent agreement with numerical beam simulations.
Date: May 6, 1999
Creator: Clifft, B. E.; Kaye, R. A.; Kedzie, M. & Shepard, K. W.
System: The UNT Digital Library
Bpm System for the Sns Ring and Transfer Lines. (open access)

Bpm System for the Sns Ring and Transfer Lines.

The Spallation Neutron Source Ring accumulates about 1060 pulses of 38mA peak current IGeV H-minus particles from the Linac thru the HEBT line, then delivers this accumulated beam in a single pulse to the mercury target via the RTBT line. Bunching frequency of beam in the HEBT line is 402.5MHz, and about 1MHz in the Ring and RTBT. Position monitor electrodes in HEBT are of the shorted stripline type, with apertures of 12cm except in the dispersive bend, where the aperture is 21cm. Ring and RTBT electrodes are open striplines, with apertures of 21, 26, 30, and 36cm. All pickups are dual plane. The electronics will be PC-based with the Analog/Digital Front End passing data and receiving control and timing thru a custom PC1 interface developed by LANL[l]. LabVIEW will be used to direct the acquisition, process the data, and transfer results via Ethernet to the EPICS control system. To handle the dynamic range required with well over 60dB variation in signal size, the Ring and RTBT electronics will employ a fast gain switching technique that will take advantage of the 300ns tail-to-head gap to provide position measurement during the entire accumulation cycle. Beam-based alignment will be utilized as part …
Date: May 6, 2002
Creator: Dawson, W. C.; Cameron, P.; Cerniglia, P.; Cupolo, J.; Degen, C.; Dellapenna, A. et al.
System: The UNT Digital Library
Comparison of the corrosion behaviors of the glass-bonded sodalite ceramic waste form and reference HLW glasses. (open access)

Comparison of the corrosion behaviors of the glass-bonded sodalite ceramic waste form and reference HLW glasses.

A glass-bonded sodalite ceramic waste form is being developed for the long-term immobilization of salt wastes that are generated during spent nuclear fuel conditioning activities. A durable waste form is prepared by hot isostatic pressing (HIP) a mixture of salt-loaded zeolite powders and glass frit. A mechanistic description of the corrosion processes is being developed to support qualification of the CWF for disposal. The initial set of characterization tests included two standard tests that have been used extensively to study the corrosion behavior of high level waste (HLW) glasses: the Material Characterization Center-1 (MCC-1) Test and the Product Consistency Test (PCT). Direct comparison of the results of tests with the reference CWF and HLW glasses indicate that the corrosion behaviors of the CWF and HLW glasses are very similar.
Date: May 6, 1999
Creator: Ebert, W. L. & Lewis, M. A.
System: The UNT Digital Library
Correlation Wave-Front Sensing Algorithms for Shack-Hartmann-Based Adaptive Optics using a Point Source (open access)

Correlation Wave-Front Sensing Algorithms for Shack-Hartmann-Based Adaptive Optics using a Point Source

Shack-Hartmann based Adaptive Optics system with a point-source reference normally use a wave-front sensing algorithm that estimates the centroid (center of mass) of the point-source image 'spot' to determine the wave-front slope. The centroiding algorithm suffers for several weaknesses. For a small number of pixels, the algorithm gain is dependent on spot size. The use of many pixels on the detector leads to significant propagation of read noise. Finally, background light or spot halo aberrations can skew results. In this paper an alternative algorithm that suffers from none of these problems is proposed: correlation of the spot with a ideal reference spot. The correlation method is derived and a theoretical analysis evaluates its performance in comparison with centroiding. Both simulation and data from real AO systems are used to illustrate the results. The correlation algorithm is more robust than centroiding, but requires more computation.
Date: May 6, 2003
Creator: Poynee, L A
System: The UNT Digital Library
Cosmos++: Relativistic Magnetohydrodynamics on Unstructured Grids with Local Adaptive Refinement (open access)

Cosmos++: Relativistic Magnetohydrodynamics on Unstructured Grids with Local Adaptive Refinement

A new code and methodology are introduced for solving the fully general relativistic magnetohydrodynamic (GRMHD) equations using time-explicit, finite-volume discretization. The code has options for solving the GRMHD equations using traditional artificial-viscosity (AV) or non-oscillatory central difference (NOCD) methods, or a new extended AV (eAV) scheme using artificial-viscosity together with a dual energy-flux-conserving formulation. The dual energy approach allows for accurate modeling of highly relativistic flows at boost factors well beyond what has been achieved to date by standard artificial viscosity methods. it provides the benefit of Godunov methods in capturing high Lorentz boosted flows but without complicated Riemann solvers, and the advantages of traditional artificial viscosity methods in their speed and flexibility. Additionally, the GRMHD equations are solved on an unstructured grid that supports local adaptive mesh refinement using a fully threated oct-tree (in three dimensions) network to traverse the grid hierarchy across levels and immediate neighbors. A number of tests are presented to demonstrate robustness of the numerical algorithms and adaptive mesh framework over a wide spectrum of problems, boosts, and astrophysical applications, including relativistic shock tubes, shock collisions, magnetosonic shocks, Alfven wave propagation, blast waves, magnetized Bondi flow, and the magneto-rotational instability in Kerr black hole spacetimes.
Date: May 6, 2005
Creator: Anninos, P; Fragile, P C & Salmonson, J D
System: The UNT Digital Library
Coupling various methods for convection-diffusion problems with applications to flows in porous media (open access)

Coupling various methods for convection-diffusion problems with applications to flows in porous media

None
Date: May 6, 1999
Creator: Lazrov, R D; Pasciak, J E & Vassilevski, P S
System: The UNT Digital Library
Criticality safety evaluation - an endusers's perspective (open access)

Criticality safety evaluation - an endusers's perspective

This paper presents criticality safety evaluations from an enduser's perspective. Overall issues related to a criticality safety evaluation in an operations support setting are discussed. A work flow process is presented which shows the key steps in conducting an effective criticality evaluation. Finally, a few suggestions are given to assist newcomers to this field.
Date: May 6, 1999
Creator: Huang, S T
System: The UNT Digital Library
DARHT-II Energy Analyzer (open access)

DARHT-II Energy Analyzer

An energy analyzer system is being built for the DARHT-II accelerator similar to the energy analyzer used on the Astron accelerator. This system consists of a scattering wire, magnetic bend, and null signal detector. The wire thickness of 40 mil carbon and the scattering angle of 11 degrees is chosen for good signal to noise ratio. The dipole bend angle is 60 degrees, with a 30 cm radius of curvature. The image-plane focal distance is chosen for the required energy resolution. The energy resolution and acceptance are 0.1% and {+-}5% with a time response of 10 nsec. The wire must survive the 2{micro}sec 2kA, 18.4 MeV DARHT-II beam. The MCNP code was used to study the wire scattered properties. The scattered beam fills the available 1x2 cm dipole aperture. The dispersion normal to the beam direction is 0.43 cm%. The detector is a PIN diode array which determines the beam position on the chip. This array consists of 40 2.5x0.1x0.25 mm bins with a gain in excess of 10000. The system will be installed in the space between the debris blocker and the cruncher solenoid up-stream from the shuttle dump.
Date: May 6, 2003
Creator: Paul, A C; Hawkins, S; McCarrick, J; Sullivan, J; Watson, J; Westenskow, G et al.
System: The UNT Digital Library
Decreased expression of RNA interference machinery, Dicer and Drosha, is associated with poor outcome in ovarian cancer patients (open access)

Decreased expression of RNA interference machinery, Dicer and Drosha, is associated with poor outcome in ovarian cancer patients

The clinical and functional significance of RNA interference (RNAi) machinery, Dicer and Drosha, in ovarian cancer is not known and was examined. Dicer and Drosha expression was measured in ovarian cancer cell lines (n=8) and invasive epithelial ovarian cancer specimens (n=111) and correlated with clinical outcome. Validation was performed with previously published cohorts of ovarian, breast, and lung cancer patients. Anti-Galectin-3 siRNA and shRNA transfections were used for in vitro functional studies. Dicer and Drosha mRNA and protein levels were decreased in 37% to 63% of ovarian cancer cell lines and in 60% and 51% of human ovarian cancer specimens, respectively. Low Dicer was significantly associated with advanced tumor stage (p=0.007), and low Drosha with suboptimal surgical cytoreduction (p=0.02). Tumors with both high Dicer and Drosha were associated with increased median patient survival (>11 years vs. 2.66 years for other groups; p<0.001). In multivariate analysis, high Dicer (HR=0.48; p=0.02), high-grade histology (HR=2.46; p=0.03), and poor chemoresponse (HR=3.95; p<0.001) were identified as independent predictors of disease-specific survival. Findings of poor clinical outcome with low Dicer expression were validated in separate cohorts of cancer patients. Galectin-3 silencing with siRNA transfection was superior to shRNA in cell lines with low Dicer (78-95% vs. …
Date: May 6, 2008
Creator: Merritt, William M.; Lin, Yvonne G.; Han, Liz Y.; Kamat, Aparna A.; Spannuth, Whitney A.; Schmandt, Rosemarie et al.
System: The UNT Digital Library
DESIGN OF AN IMPROVED ION CHAMBER FOR THE SNS. (open access)

DESIGN OF AN IMPROVED ION CHAMBER FOR THE SNS.

Ion chambers are in common use as beam loss monitors at many accelerators. A unit designed and used at FNAL and later at BNL was proposed for the SNS. Concerns about the ion collection times and low collection efficiency at high loss rates led to improvements to this unit and the design of an alternate chamber with better characteristics. Prototypes have been tested with pulsed beams. The design and test results for both detectors will be presented.
Date: May 6, 2002
Creator: Witkover, R. L. & Gassner, D.
System: The UNT Digital Library
Diagnostics for Fast Ignition Science (open access)

Diagnostics for Fast Ignition Science

The concept for Electron Fast Ignition Inertial Confinement Fusion demands sufficient laser energy be transferred from the ignitor pulse to the assembled fuel core via {approx}MeV electrons. We have assembled a suite of diagnostics to characterize such transfer. Recent experiments have simultaneously fielded absolutely calibrated extreme ultraviolet multilayer imagers at 68 and 256eV; spherically bent crystal imagers at 4 and 8keV; multi-keV crystal spectrometers; MeV x-ray bremmstrahlung and electron and proton spectrometers (along the same line of sight); nuclear activation samples and a picosecond optical probe based interferometer. These diagnostics allow careful measurement of energy transport and deposition during and following laser-plasma interactions at extremely high intensities in both planar and conical targets. Augmented with accurate on-shot laser focal spot and pre-pulse characterization, these measurements are yielding new insight into energy coupling and are providing critical data for validating numerical PIC and hybrid PIC simulation codes in an area that is crucial for many applications, particularly fast ignition. Novel aspects of these diagnostics and how they are combined to extract quantitative data on ultra high intensity laser plasma interactions are discussed, together with implications for full-scale fast ignition experiments.
Date: May 6, 2008
Creator: MacPhee, A.; Akli, K.; Beg, F.; Chen, C.; Chen, H.; Clarke, R. et al.
System: The UNT Digital Library
Dijet event shapes as diagnostic tools (open access)

Dijet event shapes as diagnostic tools

Event shapes have long been used to extract information about hadronic final states and the properties of QCD, such as particle spin and the running coupling. Recently, a family of event shapes, the angularities, has been introduced that depends on a continuous parameter. This additional parameter-dependence further extends the versatility of event shapes. It provides a handle on nonperturbative power corrections, on non-global logarithms, and on the flow of color in the final state.
Date: May 6, 2005
Creator: Berger, Carola F.
System: The UNT Digital Library
Diode Pumped Alkali Vapor Lasers - A New Pathway to High Beam Quality at High Average Power (open access)

Diode Pumped Alkali Vapor Lasers - A New Pathway to High Beam Quality at High Average Power

Resonance-transition alkali-vapor lasers have only recently been demonstrated [1] but are already attracting considerable attention. Alkali-atom-vapor gain media are among the simplest possible systems known, so there is much laboratory data upon which to base performance predictions. Therefore, accurate modeling is possible, as shown by the zero- free-parameter fits [2] to experimental data on alkali-vapor lasers pumped with Ti:sapphire lasers. The practical advantages of two of the alkali systems--Rb and Cs--are enormous, since they are amenable to diode-pumping [3,4]. Even without circulating the gas mixture, these lasers can have adequate cooling built-in owing to the presence of He in their vapor cells. The high predicted (up to 70%) optical-to-optical efficiency of the alkali laser, the superb (potentially 70% or better) wall-plug efficiency of the diode pumps, and the ability to exhaust heat at high temperature (100 C) combine to give a power-scalable architecture that is lightweight. A recent design exercise [5] at LLNL estimated that the system ''weight-to-power ratio'' figure of merit could be on the order of 7 kg/kW, an unprecedented value for a laser of the 100 kW class. Beam quality is expected to be excellent, owing to the small dn/dT value of the gain medium. There is …
Date: May 6, 2005
Creator: Page, R H; Boley, C D; Rubenchik, A M & Beach, R J
System: The UNT Digital Library
Direct Conversion of Neutron Energy and Other Advantages of a Large Yield Per Pulse, Inertial-Confinement Fusion Reactor (open access)

Direct Conversion of Neutron Energy and Other Advantages of a Large Yield Per Pulse, Inertial-Confinement Fusion Reactor

Aspects of an inertial-confinement, fusion reactor that uses an energy release {approx gt}10{sup 11} joules are discussed. The large energy release makes possible direct conversion of the fusion neutrons' energy after nuclear heating of an evaporated blanket to the plasma state. Surface damage by charged particles is avoided and structural damage by neutrons is alleviated. Complex fuel assemblies and other expandable parts may be used as a result of the high monetary value of the energy release.
Date: May 6, 1974
Creator: Burke, R. J. & Cutting, J. C.
System: The UNT Digital Library
Discovering New Events Beyond the Catalog - Application of Matched Field Processing to Salton Sea Geothermal Field Seismicity (open access)

Discovering New Events Beyond the Catalog - Application of Matched Field Processing to Salton Sea Geothermal Field Seismicity

None
Date: May 6, 2011
Creator: Wang, J; Templeton, D C & Harris, D B
System: The UNT Digital Library