A superconducting detector endstation for high-resolution energy-dispersive SR-XRF (open access)

A superconducting detector endstation for high-resolution energy-dispersive SR-XRF

We have built a two-stage adiabatic demagnetization refrigerator (ADR) to operate cryogenic high-resolution x-ray detectors in synchrotron-based fluorescence applications. The detector is held at the end of a 40 cm cold finger that extends into a UHV sample chamber. The ADR attains a base temperature below 100 mK with about 24 hours hold time below 400 mK, and does not require pumping on the liquid He bath. We will discuss cryostat design and performance.
Date: September 15, 2000
Creator: Friedrich, S; Drury, O; Niedermayr, T; Cunningham, M F; van den Berg, M L; Ullom, J N et al.
System: The UNT Digital Library
Computational Science at Brookhaven National Laboratory: Three Selected Topics. (open access)

Computational Science at Brookhaven National Laboratory: Three Selected Topics.

We present an overview of computational science at Brookhaven National Laboratory (BNL), with selections from three areas: fluids, nanoscience, and biology. The work at BNL in each of these areas is itself very broad, and we select a few topics for presentation within each of them.
Date: September 15, 2003
Creator: Davenport, J. W.; Deng, Y.; Glimm, J. & Samulyak, R.
System: The UNT Digital Library
The discovery of six Lyα emitters near a radio galaxy at z~5.2 (open access)

The discovery of six Lyα emitters near a radio galaxy at z~5.2

The authors present the results of narrow-band and broad-band imaging with the Very Large Telescope of the field surrounding the radio galaxy TN J0924-2201 at z = 5.2. 14 candidate Ly{alpha} emitters with an observed equivalent width of at least 124 {angstrom} were detected. Spectroscopy of 8 of these objects revealed 6 having redshifts similar to that of the radio galaxy. The density of emitters near the radio galaxy is a factor 3-4 higher than in the field, and comparable to the density of Ly{alpha} emitters in the protocluster 1338-1942 at z = 4.1. The Ly{alpha} emitters near TN J0924-2201 could therefore be part of a structure that will evolve into a 10{sup 15} M{sub {circle_dot}} cluster. These observations confirm that substantial clustering of Ly{alpha} emitters occur at z > 5 and strengthen the idea that radio galaxies in the early Universe pinpoint regions of high density.
Date: September 15, 2004
Creator: Venemans, B. P.; Rottgering, H. A.; Overzier, R. A.; Miley, G. K.; De Breuck, C.; Kurk, J. D. et al.
System: The UNT Digital Library
Experiments on Laser and E-Beam Transport and Interaction in a Plasma Channel. (open access)

Experiments on Laser and E-Beam Transport and Interaction in a Plasma Channel.

An ablative capillary discharge is installed into a linac beamline and serves as a plasma source for generating and characterizing wakefields. Simultaneously, the electron beam is used as a tool for plasma diagnostics. A high-energy picosecond CO{sub 2} laser channeled within the same capillary strongly affects a counterpropagating electron beam. These observations, supported with simulations, suggest the possibility of manipulating relativistic electron beams by steep plasma channels ponderomotively produced by a laser.
Date: September 15, 2004
Creator: Pogorelsky, I. V.; Pavlishin, I. V.; Ben-Zvi, Ilan & Al., Et
System: The UNT Digital Library
Measurement of high energy ions. [Time-of-flight spectrometer] (open access)

Measurement of high energy ions. [Time-of-flight spectrometer]

The current interest in fast ions has prompted the design of a new time-of-flight ion spectrometer which measures the high energy ions from a laser produced plasma. A magnet was used to separate the ions from the intense background of electrons, x-rays and scattered light. The design of the instrument is wide band so that ions with energies 0.03 to 3000 keV/amu can be measured. Results from target experiments on the LLL ARGUS laser facility will be presented. The fast ion spectrum is dovetailed with the spectrum of the slower ions collected by Faraday cups and thus provides a measurement for the total energy carried by ions. The charge to mass ratio of the ions can be calculated from the spectrometer output.
Date: September 15, 1976
Creator: Glaros, S. S.; Tirsell, K. G.; Rupert, V. C.; Catron, H. C. & Slivinsky, V. W.
System: The UNT Digital Library
Structural analysis of a superconducting central solenoid for the Tokamak Physics Experiment (open access)

Structural analysis of a superconducting central solenoid for the Tokamak Physics Experiment

The Tokamak Physics Experiment (TPX) concept design uses superconducting coils to accomplish magnetic confinement. The central solenoid (CS) magnet is divided vertically into 8 equal segments which are powered independently. The eddy current heating from the pulsed operation is too high for a case type construction; therefore, a {open_quotes}no case{close_quotes} design has been chosen. This {open_quotes}no case{close_quotes} design uses the conductor conduit as the primary structure and the electrical insulation as a structural adhesive. This electrical insulation is the {open_quotes}weak link{close_quotes} in the coil winding pack structure and needs to be modeled in detail. A global finite element model with smeared winding pack properties was used to study the CS magnet structural behavior. The structural analysis results and peak stresses will be presented.
Date: September 15, 1993
Creator: O`Connor, T. G. & Heim, J. R.
System: The UNT Digital Library
Testing of ITER prototype cable-in-conduit conductors in the FENIX facility (open access)

Testing of ITER prototype cable-in-conduit conductors in the FENIX facility

The Fusion Engineering International experiment (FENIX) Test Facility has been operational since 1991 at the Lawrence Livermore National Laboratory for testing the International Thermonuclear Experimental Reactor (ITER) prototype conductors. These conductors are designed to operate stably with transport current of more than 40 kA at a magnetic field of 13 T. The FENIX facility consists of four magnet sets that are configured to allow easy access to the 40-cm high-field region with a test cross-section area of 10 * 15 cm{sup 2}. FENIX provides test conditions that closely simulate the ITER magnet operation mode. Performed experiments Include measurements of critical current, current-sharing temperature, forced-flow properties, stability, joint performance and cyclic fatigue effects. This paper describes the design and performance of these experiments.
Date: September 15, 1993
Creator: Shen, S. S.; Chaplin, M. R.; Felker, B.; Hassenzahl, W. V.; Kishiyama, K. I. & Parker, J. M.
System: The UNT Digital Library
Physics of YbBiPt (open access)

Physics of YbBiPt

YbBiPt has a low temperature linear specific heat coefficient of 8J/mole-Yb K{sup 2} and a small specific-heat anomaly at 0.4K. We discuss new experiments on specific-heat of diluted YbBiPt, and magnetic field dependent effects and electrical resistivity in pure YbBiPt. We argue that in this material the Kondo and crystal-field energy scales are small and of comparable magnitude, placing YbBiPt in the same class as many Uranium heavy-electron compounds.
Date: September 15, 1992
Creator: Thompson, J. D.; Canfield, P. C.; Lacerda, A.; Hundley, M. F.; Fisk, Z. (Los Alamos National Lab., NM (United States)); Ott, H. R. et al.
System: The UNT Digital Library
15-foot bubble chamber characteristics (open access)

15-foot bubble chamber characteristics

Specifications, operation, characteristics, cost, and experience with the NAL 15-ft bubble chamber are described. Beam availability and some experimental proposals are discussed. (WHK)
Date: September 15, 1975
Creator: Huson, F. R.
System: The UNT Digital Library
Development of uranium reference particles to support nuclear safeguards (open access)

Development of uranium reference particles to support nuclear safeguards

None
Date: September 15, 2010
Creator: Stefaniak, E.; Kips, R.; Truyens, J.; Aregbe, Y.; Kraiem, M.; Richter, S. et al.
System: The UNT Digital Library
Droplet Evolution in Warm Dense Matter Expanding Flow (open access)

Droplet Evolution in Warm Dense Matter Expanding Flow

None
Date: September 15, 2010
Creator: Armijo, J & Barnard, J J
System: The UNT Digital Library
Advanced instrumentation for nuclear monitoring (open access)

Advanced instrumentation for nuclear monitoring

None
Date: September 15, 1975
Creator: Armantrout, G.; McGibbon, A.; Swierkowski, S.; Sherohman, J. & Yee, J.
System: The UNT Digital Library
Probing small x parton densities in ultraperipheral AA and pAcollisions at the LHC (open access)

Probing small x parton densities in ultraperipheral AA and pAcollisions at the LHC

We calculate photoproduction rates for several hard processes in ultraperipheral proton-lead and lead-lead collisions at the LHC with {radical}s{sub NN} = 8.8 and 5.5 TeV respectively which could be triggered in the large LHC detectors. We use ATLAS as an example. The lead ion is treated as a source of (coherently produced) photons with energies and intensities greater than those of equivalent ep collisions at HERA.We find very large rates for both inclusive and diffractive production which will extend the HERA x range by nearly an order of magnitude for similar virtualities. We demonstrate that it is possible to reach the kinematic regime where nonlinear effects are larger than at HERA.
Date: September 15, 2005
Creator: Strikman, Mark; Vogt, Ramona & White, Sebastian
System: The UNT Digital Library
Dose as a function of radial distance from a 930 MeV $sup 4$He ion beam (open access)

Dose as a function of radial distance from a 930 MeV $sup 4$He ion beam

None
Date: September 15, 1975
Creator: Varma, M.N.; Paretzke, H.; Baum, J.W.; Lyman, J.T. & Howard, J.
System: The UNT Digital Library
Physical Property Modeling of Concentrated Cesium Eluate Solutions, Part I - Derivation of Models (open access)

Physical Property Modeling of Concentrated Cesium Eluate Solutions, Part I - Derivation of Models

Major analytes projected to be present in the Hanford Waste Treatment Plant cesium ion-exchange eluate solutions were identified from the available analytical data collected during radioactive bench-scale runs, and a test matrix of cesium eluate solutions was designed within the bounding concentrations of those analytes. A computer model simulating the semi-batch evaporation of cesium eluate solutions was run in conjunction with a multi-electrolyte aqueous system database to calculate the physical properties of each test matrix solution concentrated to the target endpoints of 80% and 100% saturation. The calculated physical properties were analyzed statistically and fitted into mathematical expressions for the bulk solubility, density, viscosity, heat capacity and volume reduction factor as a function of temperature and concentration of each major analyte in the eluate feed. The R{sup 2} of the resulting physical property models ranged from 0.89 to 0.99.
Date: September 15, 2005
Creator: Choi, A.S.; Pierce, R. A.; Edwards, T. B. & Calloway, T. B.
System: The UNT Digital Library
A Cone Jet-Finding Algorithm for Heavy Ion Collisions at LHC Energies (open access)

A Cone Jet-Finding Algorithm for Heavy Ion Collisions at LHC Energies

Standard jet finding techniques used in elementary particle collisions have not been successful in the high track density of heavy-ion collisions. This paper describes a modified cone-type jet finding algorithm developed for the complex environment of heavy-ion collisions. The primary modification to the algorithm is the evaluation and subtraction of the large background energy, arising from uncorrelated soft hadrons, in each collision. A detailed analysis of the background energy and its event-by-event fluctuations has been performed on simulated data, and a method developed to estimate the background energy inside the jet cone from the measured energy outside the cone on an event-by-event basis. The algorithm has been tested using Monte-Carlo simulations of Pb+Pb collisions at {radical}s = 5.5 TeV for the ALICE detector at the LHC. The algorithm can reconstruct jets with a transverse energy of 50 GeV and above with an energy resolution of {approx} 30%.
Date: September 15, 2006
Creator: Blyth, S; Horner, M J; Awes, T; Cormier, T; Gray, H; Klay, J L et al.
System: The UNT Digital Library
Structure, Stability and Elm Dynamics of the H-Mode Pedestal in DIII-D (open access)

Structure, Stability and Elm Dynamics of the H-Mode Pedestal in DIII-D

None
Date: September 15, 2005
Creator: Fenstermacher, M. E.; Osborne, T. H.; Leonard, A. W.; Snyder, P. B.; Thomas, D. M.; Boedo, J. A. et al.
System: The UNT Digital Library
First Operation of a Free-Electron Laser Generating GW Power Radiation at 32-Nm Wavelength (open access)

First Operation of a Free-Electron Laser Generating GW Power Radiation at 32-Nm Wavelength

Many scientific disciplines ranging from physics, chemistry and biology to material sciences, geophysics and medical diagnostics need a powerful X-ray source with pulse lengths in the femtosecond range. This would allow, for example, time-resolved observation of chemical reactions with atomic resolution. Such radiation of extreme intensity, and tunable over a wide range of wavelengths, can be accomplished using high-gain free-electron lasers (FEL). Here we present results of the first successful operation of an FEL at a wavelength of 32 nm, with ultra-short pulses (25 fs FWHM), a peak power at the Gigawatt level, and a high degree of transverse and longitudinal coherence. The experimental data are in full agreement with theory. This is the shortest wavelength achieved with an FEL to date and an important milestone towards a user facility designed for wavelengths down to 6 nm. With a peak brilliance exceeding the state-of-the-art of synchrotron radiation sources by seven orders of magnitude, this device opens a new field of experiments, and it paves the way towards sources with even shorter wavelengths, such as the Linac Coherent Light Source at Stanford, USA, and the European X-ray Free Electron Laser Facility in Hamburg, Germany.
Date: September 15, 2006
Creator: Ayvazian, V.; Baboi, N.; Bahr, J.; Balandin, V.; Beutner, B.; Brandt, A. et al.
System: The UNT Digital Library
3D highly oriented nanoparticulate and microparticulate array ofmetal oxide materials (open access)

3D highly oriented nanoparticulate and microparticulate array ofmetal oxide materials

Advanced nano and micro particulate thin films of 3d transition and post-transition metal oxides consisting of nanorods and microrods with parallel and perpendicular orientation with respect to the substrate normal, have been successfully grown onto various substrates by heteronucleation, without template and/or surfactant, from the aqueous condensation of solution of metal salts or metal complexes (aqueous chemical growth). Three-dimensional arrays of iron oxide nanorods and zinc oxide nanorods with parallel and perpendicular orientation are presented as well as the oxygen K-edge polarization dependent x-ray absorption spectroscopy (XAS) study of anisotropic perpendicularly oriented microrod array of ZnO performed at synchrotron radiation source facility.
Date: September 15, 2006
Creator: Vayssieres, Lionel; Guo, Jinghua & Nordgren, Joseph
System: The UNT Digital Library
Ultra Low Density and Highly Crosslinked Biocompatible Shape Memory Polyurethane Foams (open access)

Ultra Low Density and Highly Crosslinked Biocompatible Shape Memory Polyurethane Foams

None
Date: September 15, 2011
Creator: Singhal, P.; Rodriguez, J. N.; Small, W., IV; Eagleaston, S.; De Water, J. V.; Maitland, D. J. et al.
System: The UNT Digital Library
LLNL Tandem Mirror Experiment (TMX) upgrade vacuum system (open access)

LLNL Tandem Mirror Experiment (TMX) upgrade vacuum system

TMX Upgrade is a large, tandem, magnetic-mirror fusion experiment with stringent requirements on base pressure (10/sup -8/ torr), low H reflux from the first walls, and peak gas pressure (5 x 10/sup -7/ torr) due to neutral beam gas during plasma operation. The 225 m/sup 3/ vacuum vessel is initially evacuated by turbopumps. Cryopumps provide a continuous sink for gases other than helium, deuterium, and hydrogen. The neutral beam system introduces up to 480 l/s of H or D. The hydrogen isotopes are pumped at very high speed by titanium sublimed onto two cylindrical radially separated stainless steel quilted liners with a total surface area of 540 m/sup 2/. These surfaces (when cooled to about 80/sup 0/K) provide a pumping speed of 6 x 10/sup 7/ l/s for hydrogen. The titanium getter system is programmable and is used for heating as well as gettering. The inner plasma liner can be operated at elevated temperatures to enhance migration of gases away from the surfaces close to the plasma. Glow discharge cleaning is part of the pumpdown procedure. The design features are discussed in conjunction with the operating procedures developed to manage the dynamic vacuum conditions.
Date: September 15, 1981
Creator: Pickles, W. L.; Chargin, A. K. & Drake, R. P.
System: The UNT Digital Library
Nonlinear Rayleigh-Taylor and Richtmyer-Meshkov Mixing Experiments at Nova (open access)

Nonlinear Rayleigh-Taylor and Richtmyer-Meshkov Mixing Experiments at Nova

The evolution of the Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities in the nonlinear regime of growth was investigated in indirect-drive experiments on the Nova laser. The RT experiments investigated the evolution of both single- and multimode perturbations at an embedded interface, isolated from the effects of ablation. This ``classical`` geometry allows short wavelength ({lambda} {approximately} 10-20 {micro}m) perturbations to grow strongly, in marked contrast to prior results at an ablation front. The RM experiments studied singly- and doubly-shocked perturbed interfaces in both face-on and side-on geometries. (U)
Date: September 15, 1997
Creator: Budil, K. S.; Remington, B. A.; Weber, S. V.; Farley, D.R.; Murray, S. & Peyser, T.A.
System: The UNT Digital Library
A Generalized Portable SHMEM Library for High Performance Computing (open access)

A Generalized Portable SHMEM Library for High Performance Computing

This paper describes a portable one-sided communication library GPSHMEM that follows the interfaces of the successful SHMEM library introduced by Cray Research Inc. for their distributed memory systems: the Cray T3D and T3E. The portability is achieved by relying on ARMCI, a low-level communication library developed to support one-sided communication in distributed array libraries and compiler run-time systems, and the MPI message passing interface. The paper discusses implementation, requirements, and initial experience with GPSHMEM.
Date: September 15, 2000
Creator: Parzyszek, Krzysztof; Nieplocha, Jarek & Kendall, Ricky A.
System: The UNT Digital Library
High rate PLD of diamond-like-carbon utilizing high repetition rate visible lasers (open access)

High rate PLD of diamond-like-carbon utilizing high repetition rate visible lasers

Pulsed Laser Deposition (PLD) has been shown to be an effective method for producing a wide variety of thin films of high-value-added materials. The high average powers and high pulse repetition frequencies of lasers under development at LLNL make it possible to scale-up PLD processes that have been demonstrated in small systems in a number of university, government, and private laboratories to industrially meaningful, economically feasible technologies. A copper vapor laser system at LLNL has been utilized to demonstrate high rate PLD of high quality diamond-like-carbon (DLC) from graphite targets. The deposition rates for PLD obtained with a 100 W laser were {approx} 2000 {mu}m{center_dot}cm{sup 2}/h, or roughly 100 times larger than those reported by chemical vapor deposition (CVD) or physical vapor deposition (PVD) methods. Good adhesion of thin (up to 2 pm) films has been achieved on a small number of substrates that include SiO{sub 2} and single crystal Si. Present results indicate that the best quality DLC films can be produced at optimum rates at power levels and wavelengths compatible with fiber optic delivery systems. If this is also true of other desirable coating systems, this PLD technology could become an extremely attractive industrial tool for high value …
Date: September 15, 1994
Creator: McLean, William, II; Fehring, Edward J.; Dragon, Ernest P. & Warner, Bruce E.
System: The UNT Digital Library