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ALS user meeting features 10th anniversary celebration (open access)

ALS user meeting features 10th anniversary celebration

The Advanced Light Source (ALS) saw first light on October 5, 1993, not quite to the day but close to 10 years before the 2003 ALS Users Association meeting, held October 6-8. Fittingly, the proceedings included retrospectives from two of the key players in the early history of the ALS, David Attwood and Jay Marx, and a display of photographs chronicling its construction and commissioning. Science highlights, highlights from young researchers, and posters constituted the meat of the program on Monday and Tuesday morning, while workshops took over Tuesday afternoon and all day Wednesday.
Date: December 5, 2003
Creator: Robinson, Art
System: The UNT Digital Library
Compressible Multiphase Flows in an ALE Framework (open access)

Compressible Multiphase Flows in an ALE Framework

None
Date: December 5, 2003
Creator: Stevens, David; Nelson, B.; Fogarty, P.; Eberle, C. & Ulrickson, M.
System: The UNT Digital Library
Hyperspectral Imaging of Functional Patterns for Disease Assessment and Treatment Monitoring (open access)

Hyperspectral Imaging of Functional Patterns for Disease Assessment and Treatment Monitoring

We have designed and built a six-band multi-spectral NIR imaging system used in clinical testing on cancer patients. From our layered tissue model, we create blood volume and blood oxygenation images for patient treatment monitoring.
Date: December 5, 2003
Creator: Hassan, Moinuddin; Hattery, David; Vogel, Abby; Chernomorkik, Victor; Demos, Stavros; Aleman, Karen et al.
System: The UNT Digital Library
Impaired fertility in T-stock female mice after superovulation (open access)

Impaired fertility in T-stock female mice after superovulation

Superovulation of female mice with exogenous gonadotrophins is routinely used for increasing the number of eggs ovulated by each female in reproductive and developmental studies. We report an unusual effect of superovulation on fertilization in mice. In vivo matings of superovulated T-stock females with B6C3F1 males resulted in a 2-fold reduction (P<0.001) in the frequencies of fertilized eggs compared to control B6C3F1 matings. In addition, {approx}22 hr after mating only 15% of fertilized eggs recovered in T-stock females had reached the metaphase stage of the first cleavage division versus 87% in B6C3F1 females (P < 0.0001). Matings with T-stock males did not improve the reproductive performance of T-stock females. To investigate the possible cause(s) for the impaired fertilization and zygotic development, the experiments were repeated using in vitro fertilization. Under these conditions, the frequencies of fertilized eggs were not different in superovulated T-stock and B6C3F1 females (51.7% {+-} 6.0 and 64.5% {+-}3.8, P=0.10). There was a 7-fold increase in the frequencies of fertilized T-stock eggs that completed the first cell cycle of development after in vitro versus in vivo fertilization. These results rule out an intrinsic deficiency of the T-stock oocyte as the main reason for the impaired fertility after …
Date: December 5, 2003
Creator: Wyrobek, A J; Bishop, J B; Marchetti, F & Zudova, D
System: The UNT Digital Library
Studies of the N=90 region: The decay of 154Eu to 154Gd (open access)

Studies of the N=90 region: The decay of 154Eu to 154Gd

The decay of {sup 154}Eu {yields} {sup 154}Gd has been studied by {gamma}-ray singles and {gamma}-{gamma} coincidence spectroscopy using an array of 20 Compton-suppressed Ge detectors. The primary goal of the work was to confirm or refute a large number of questionable features in the decay scheme: the outcome is the removal of 8 levels from the previously adopted scheme, with the result that a new type of collective band is revealed. Many weak decay branches for the decay are clarified. These results are critical for understanding the structure of {sup 154}Gd and the N = 90 isotones; and the improved completeness of the decay scheme contributes to the use of {sup 154}Eu as a metrological standard.
Date: December 5, 2003
Creator: Kulp, W. D.; Wood, J. L.; Krane, K. S.; Loats, J.; Schmelzenbach, P.; Stapels, C. J. et al.
System: The UNT Digital Library
The CDF data handling system (open access)

The CDF data handling system

The Collider Detector at Fermilab (CDF) records proton-antiproton collisions at center of mass energy of 2.0 TeV at the Tevatron collider. A new collider run, Run II, of the Tevatron started in April 2001. Increased luminosity will result in about 1 PB of data recorded on tapes in the next two years. Currently the CDF experiment has about 260 TB of data stored on tapes. This amount includes raw and reconstructed data and their derivatives. The data storage and retrieval are managed by the CDF Data Handling (DH) system. This system has been designed to accommodate the increased demands of the Run II environment and has proven robust and reliable in providing reliable flow of data from the detector to the end user. This paper gives an overview of the CDF Run II Data Handling system which has evolved significantly over the course of this year. An outline of the future direction of the system is given.
Date: November 5, 2003
Creator: Litvintsev, Dmitry O.
System: The UNT Digital Library
Electronic and magnetic properties of zincblende half-metal superlattices (open access)

Electronic and magnetic properties of zincblende half-metal superlattices

Zincblende half-metallic compounds such as CrAs, with large magnetic moments and high Curie temperatures, are promising materials for spintronic applications. They explore layered materials, consisting of alternating layers of zincblende half-metals, by first principles calculations, and find that superlattices of (CrAs){sub 1}(MnAs){sub 1} and (CrAs){sub 2}(MnAs){sub 2} are half-metallic with magnetic moments of 7.0{mu}{sub B} and 14.0{mu}{sub B} per unit cell, respectively. They discuss the nature of the bonding and half-metallicity in these materials and, based on the understanding acquired, develop a simple expression for the magnetic moment in such materials. They explore the range of lattice constants over which half-metallicity is manifested, and suggest corresponding substrates for growth in thin film form.
Date: November 5, 2003
Creator: Fong, C Y; Qian, M C; Pask, J; Yang, L H & Dag, S
System: The UNT Digital Library
Hash sorter - firmware implementation and an application for the Fermilab BTeV level 1 trigger system (open access)

Hash sorter - firmware implementation and an application for the Fermilab BTeV level 1 trigger system

A hardware hash sorter for the Fermilab BTeV Level 1 trigger system will be presented. The has sorter examines track-segment data before the data are sent to a system comprised of 2500 Level 1 processors, and rearranges the data into bins based on the slope of track segments. They have found that by using the rearranged data, processing time is significantly reduced allowing the total number of processors required for the Level 1 trigger system to be reduced. The hash sorter can be implemented in an FPGA that is already included as part of the design of the trigger system. Hash sorting has potential applications in a broad area in trigger and DAQ systems. It is a simple O(n) process and is suitable for FPGA implementation. Several implementation strategies will also be discussed in this document.
Date: November 5, 2003
Creator: al., Jinyuan Wu et
System: The UNT Digital Library
Heavy quarks and lattice QCD (open access)

Heavy quarks and lattice QCD

This paper is a review of heavy quarks in lattice gauge theory, focusing on methodology. It includes a status report on some of the calculations that are relevant to heavy-quark spectroscopy and to flavor physics.
Date: November 5, 2003
Creator: Kronfeld, Andreas S.
System: The UNT Digital Library
A New Lifshitz Transition and the Equation of State of Osmium (open access)

A New Lifshitz Transition and the Equation of State of Osmium

We have measured the equation of state (EoS) of osmium to 75 GPa under hydrostatic conditions at room temperature using angle dispersive x-ray diffraction. A least-squares fit of the data using a third order Birch-Murnaghan EoS yields K{sub 0} = 411 {+-} 6 GPa and K'{sub 0} = 4.0 {+-} 0.2, showing osmium is in fact more compressible than diamond. Most importantly, we have documented an anomaly in the compressibility at 20.3 GPa associated with a large discontinuity in the first pressure derivative of the c/a ratio. This discontinuity likely arises from the collapse of the small hole-ellipsoid in the Fermi surface near the L point. There has been much interest in the possibility of a Lifshitz [1] or electronic topological transition (ETT) in zinc at high-pressure near 10 GPa. Interestingly, while the experimental data remain somewhat ambiguous [2-5], most simulations suggest the ETT exists in this pressure range [6-8]. Recently, Steinle-Neumann et al. [8] have shown that the transition arises from changes in the band structure near the high-symmetry point K where three bands cross the Fermi surface upon compression. Thus one might expect that other hcp metals should exhibit similar phenomena. The hcp 4d and 5d transition elements …
Date: November 5, 2003
Creator: Occelli, F.; Aracne, C. M.; Teter, D. M.; Hanfland, M.; Canny, B.; Couzinet, B. et al.
System: The UNT Digital Library
Pixel multichip module design for a high energy physics experiment (open access)

Pixel multichip module design for a high energy physics experiment

At Fermilab, a pixel detector multichip module is being developed for the BTeV experiment. The module is composed of three layers. The lowest layer is formed by the readout integrated circuits (ICs). The back of the ICs is in thermal contact with the supporting structure, while the top is flip-chip bump-bonded to the pixel sensor. A low mass flex-circuit interconnect is glued on the top of this assembly, and the readout IC pads are wire-bounded to the circuit. This paper presents recent results on the development of a multichip module prototype and summarizes its performance characteristics.
Date: November 5, 2003
Creator: al., Guilherme Cardoso et
System: The UNT Digital Library
A Quantitative Comparison of Numerical Methods for the Compressible Euler Equations: Fifth-order WENO and Piecewise-Linear Godunov (open access)

A Quantitative Comparison of Numerical Methods for the Compressible Euler Equations: Fifth-order WENO and Piecewise-Linear Godunov

A numerical study is undertaken comparing a fifth-order version of the weighted essentially non-oscillatory numerical (WENO5) method to a modern piecewise-linear, second-order, version of Godunov's (PLMDE) method for the compressible Euler Equations. A series of one-dimensional test problems are examined beginning with classical linear problems and ending with complex shock interactions. The problems considered are: (1) linear advection of a Gaussian pulse in density, (2) Sod's shock tube problem, (3) the ''peak'' shock tube problem, (4) a version of the Shu and Osher shock entropy wave interaction and (5) the Woodward and Colella interacting shock wave problem. For each problem and method, run times, density error norms and convergence rates are reported for each method as produced from a common code test-bed. The linear problem exhibits the advertised convergence rate for both methods as well as the expected large disparity in overall error levels; WENO5 has the smaller errors and an enormous advantage in overall efficiency (in accuracy per unit CPU time). For the nonlinear problems with discontinuities, however, we generally see both first-order self-convergence of error as compared to an exact solution, or when an analytic solution is not available, a converged solution generated on an extremely fine grid. …
Date: November 5, 2003
Creator: Greenough, J A & Rider, W J
System: The UNT Digital Library
Study of indium and solder bumps for the BTeV Pixel Detector (open access)

Study of indium and solder bumps for the BTeV Pixel Detector

The pixel detector proposed for the BTeV experiment at the Fermilab Tevatron will use bump-bonding technology based on either Indium or Pb/Sn solder to connect the front-end readout chips to the silicon pixel sensors. We have studied the strength of the bumps by visual inspection of the bumps bonding silicon sensor modules to dummy chips made out of glass. The studies were done before and after thermal cycles, exposed to intense irradiation, and with the assemblies glued to a graphite substrate. We have also carried out studies on effects of temperature changes on both types of bump bonds by observing the responses of single-chip pixel detectors to an Sr{sup 90} source. We report the results from these studies and our plan to measure the effect of cryogenic temperatures on the bumps.
Date: November 5, 2003
Creator: al., Simon W Kwan et
System: The UNT Digital Library
Testing a Low-Influence Spindle Drive Motor (open access)

Testing a Low-Influence Spindle Drive Motor

Precision spindles used for diamond turning and other applications requiring low error motion generally require a drive system that ideally applies a pure torque to the rotating spindle. Frequently a frameless motor, that is, one without its own bearings, is directly coupled to the spindle to make a compact and simple system having high resonant frequencies. Although in addition to delivering drive torque, asymmetries in the motor cause it to generate disturbance loads (forces and moments) which influence the spindle error motion of the directly coupled system. This paper describes the tests and results for a particular frameless, brushless DC motor that was originally developed for military and space applications requiring very low torque ripple. Because the construction of the motor should also lead to very low disturbance loads, it was selected for use on a new diamond turning and grinding machine under developed at Lawrence Livermore National Laboratory. The level of influence for this motor-spindle combination is expected to be of order one nanometer for radial and axial error motion.
Date: November 5, 2003
Creator: Hale, L; Wulff, T & Sedgewick, J
System: The UNT Digital Library
Time-Reversal Analysis for Scatterer Characterization (open access)

Time-Reversal Analysis for Scatterer Characterization

Only the simplest monopole scattering behavior has usually been treated in previous time-reversal analyses. A new application of time-reversal processing of wave scattering data permits characterization of scatterers by analyzing the number and nature of the singular functions (or eigenfunctions) associated with individual scatterers when they have multiple contributions from monopole, dipole and/or quadrupole scattering terms. We discuss acoustic, elastic, and electromagnetic scattering problems for low frequencies (ka < 1, k being the wavenumber and a the radius of the scatterer). Specific examples for electromagnetic scattering from one of a number of small conducting spheres show that each sphere can have up to six distinct time-reversal eigenfunctions associated with it.
Date: November 5, 2003
Creator: Chambers, D H & Berryman, J G
System: The UNT Digital Library
2w Laser Propagation and Raman Backscatter in Underdense Gas Bag Plasmas (open access)

2w Laser Propagation and Raman Backscatter in Underdense Gas Bag Plasmas

Recent 2{omega} gasbag experiments on the Helen laser studied single-beam propagation and backscatter as a function of gas density. We present a comprehensive analysis of these experiments using simulations in HYDRA. Post-processed results agree well with experimental fast x-ray images (FXI) showing stable laser propagation across the bag. The measured total stimulated Raman backscatter (SRS) increases with initial gas density up to n{sub e} {approx} 0.08 n{sub c}, then decreases. Near-backscatter images (NBI) show that the decrease in total SRS with increasing density is not due to scatter outside of the collection optics. SRS gain spectra calculated from the HYDRA results agree well with experimental streak spectra. The tilt and spread in wavelength of the spectra appear to be explained by gasbag hydrodynamics only, with no need to invoke filamentation. Axial density gradients and laser pump absorption may combine to detune and limit SRS gain at high density.
Date: September 5, 2003
Creator: Meezan, N.; Divol, L.; Suter, L.; Miller, M.; Stevenson, R. M.; Slark, G. et al.
System: The UNT Digital Library
All Fiber Technology for High-Energy Petawatt Front End Laser Systems (open access)

All Fiber Technology for High-Energy Petawatt Front End Laser Systems

We are developing an all fiber front end for the next generation high-energy petawatt (HEPW) laser at Lawrence Livermore National Laboratory (LLNL). The ultimate goal of the LLNL HEPW effort is to generate 5-kJ pulses capable of compression to 5ps at 1053nm, enabling advanced x-ray backlighters and possible demonstration of fast ignition. We discuss the front-end of the laser design from the fiber master oscillator, which generates the mode-locked 20nm bandwidth initial pulses through the 10mJ output of the large flattened mode (LFM) fiber amplifier. Development of an all fiber front end requires technological breakthroughs in the key areas of the master oscillator and fiber amplification. Chirped pulse amplification in optical fibers has been demonstrated to 1mJ. Further increase is limited by the onset of stimulated Raman scattering (SRS). We have recently demonstrated a new flattened mode fiber technology, which reduces peak power for a given energy and thus the onset of SRS. Controlled experiments with 1st generation fibers yielded 0.5mJ of energy while significantly increasing the point at which nonlinear optical effects degrade the amplified pulse. In this paper we will discuss our efforts to extend this work to greater than 20mJ using our large flattened mode fiber amplifier.
Date: September 5, 2003
Creator: Dawson, J W; Liao, Z M; Jovanovic, I; Wattellier, B; Beach, R; Payne, S A et al.
System: The UNT Digital Library
Design and Test of Advanced Multi-Layer Dielectric Gratings for High Energy Petawatt (open access)

Design and Test of Advanced Multi-Layer Dielectric Gratings for High Energy Petawatt

In this paper we discuss recent work on the development of high damage threshold, high efficiency MLD (multilayer dielectric) diffraction gratings for use in high energy, petawatt laser systems. This effort involves a close integration between modeling, fabrication, and testing. The modeling work is used to identify grating designs that satisfy the constraints of high efficiency (>94%) and low field enhancement which is a necessary condition for high damage threshold. Subscale MLD gratings for test are being fabricated in an advanced ion-etch machine we have recently built. The testing effort is being conducted in a dedicated laboratory. The laser beam used to test the samples is based on an OPCPA (optical parametric chirped-pulse amplifier) and a compressor that can provide pulse energies up to 50mJ with pulse lengths variable from 0.3-20 ps. This test station is equipped with diagnostics to fully characterize both the spatial and temporal characteristics of the test beam at the plane of the sample. Initial results have demonstrated a dependence of damage threshold on incident angle that is in good agreement with the field enhancement calculations. We have demonstrated a grating design with a damage threshold of 3J/cm{sup 2} and are investigating manufacturability and reproducibility issues …
Date: September 5, 2003
Creator: Molander, W.; Komashko, A.; Britten, J.; Jones, L.; Brown, C.; Caird, J. et al.
System: The UNT Digital Library
Local Structure of amorphous (PbO){sub x}[(B{sub 2}O{sub 3}){sub 1-z}(Al{sub 2}O{sub 3}){sub z}]{sub y} (SiO{sub 2}){sub y} Dielectric Materials by Multinuclear Solid State NMR (open access)

Local Structure of amorphous (PbO){sub x}[(B{sub 2}O{sub 3}){sub 1-z}(Al{sub 2}O{sub 3}){sub z}]{sub y} (SiO{sub 2}){sub y} Dielectric Materials by Multinuclear Solid State NMR

Structural speciation of glasses in the systems PbO-B{sub 2}O{sub 3}-SiO{sub 2}, PbO-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-SiO{sub 2}, and PbO-Al{sub 2}O{sub 3}-SiO{sub 2} were studied using solid-state {sup 29}Si, {sup 27}Al, {sup 11}B, and {sup 207}Pb nuclear magnetic resonance (NMR) and Raman spectroscopy. Application of these methods provided insight into the role of Al{sub 2}O{sub 3} incorporation in the lead-borosilicate glass networks. The general composition range studied was (PbO){sub x} [(B{sub 2}O{sub 3}){sub 1-z} (Al{sub 2}O{sub 3})z]{sub y}(SiO{sub 2}){sub y} where x = 0.35, 0.5, and 0.65, y = (1-x)/2 and z = 0.0, 0.5 and 1.0. Additional insight was obtained via {sup 27}Al 2D-3QMAS experiments. The {sup 207}Pb spin echo mapping spectra showed a transition from ionic (Pb{sup 2+}) to covalently bound lead species with increased PbO contents in the borosilicate glasses. The addition of aluminum to the glass network further enhanced the lead species transition resulting in a higher relative amount of covalent lead bonding in the high PbO content alumino-borosilicate glass. The number of BO{sub 4} units present in the {sup 11}B MAS NMR decreased with increasing PbO contents for both the borosilicate and the alumino-borosilicate glass systems, with the addition of aluminum further promoting the BO{sub 3} …
Date: September 5, 2003
Creator: Sawvel, A.; Chinn, S.; Bourcier, W. & Maxwell, R.
System: The UNT Digital Library
Parametric Techniques for Extreme-Contracts, High-Energy Petawatt Pulses (open access)

Parametric Techniques for Extreme-Contracts, High-Energy Petawatt Pulses

Prepulses are of great concern in high-power lasers: if their intensity is sufficiently high, they can heat and/or destroy a target before the arrival of the main pulse. For ultrahigh peak power lasers, for which focused intensity can exceed 10{sup 21} W/cm{sup 2}, a contrast of at least 10{sup 8} is the minimum requirement to avoid preionization of solid targets. Conventional preamplification stages do not meet this requirement, primarily due to prepulse originating from regenerative amplification. Optical parametric amplification (OPA) is well-known to generate pulses with a prepulse contrast equal to the gain of the amplifier, but it does not remove pre-existing prepulses. In this paper we describe a novel technique for contrast enhancement in cascaded optical parametric amplifiers (COPA). Based on cascaded idler utilization, COPA represents a versatile technique with a potentially infinite prepulse contrast enhancement. We have experimentally demonstrated COPA, producing a prepulse contrast of 10{sup 8}, limited by the sensitivity of measurement. A simple modification of the front end of a petawatt-type laser that utilizes optical parametric chirped pulse amplification (OPCPA) can yield unprecedented levels of prepulse contrast.
Date: September 5, 2003
Creator: Jovanovic, I; Wattellier, B & Barty, C P J
System: The UNT Digital Library
Study of Neutron Scattering in the NIF Chamber and Use of Neutron Activation as a Yield Diagnostic(Tu011.5) (open access)

Study of Neutron Scattering in the NIF Chamber and Use of Neutron Activation as a Yield Diagnostic(Tu011.5)

One of the planned core neutron diagnostics for NIF will use material activation to aid in determining information about target neutron yields. While this technique was routinely used on Nova and is in use today on Omega, the substantially larger chamber size and neutron yields for NIF raise several new issues for this technique. The effect of neutron scattering, due to the larger amount of entrant equipment inside the chamber, and more importantly, scattering inside the NIF target itself, is shown to be a significant effect. The appropriate location of the counting room to analyze activated samples that is sufficiently protected from neutron fluences is discussed. There are no significant safety issues related to sample handling when using In and Cu for short durations (minutes). We recommend placement and thickness of Cu samples based on neutron yield.
Date: September 5, 2003
Creator: Tobin, M. & Song, P.
System: The UNT Digital Library
Influence of Composition, Helium Generation Rate and Dpa Rate on Neutron-Induced Swelling of Fe-15Cr-16Ni-0.25Ti Alloys in FFTF at {approx} 400 Degrees C (open access)

Influence of Composition, Helium Generation Rate and Dpa Rate on Neutron-Induced Swelling of Fe-15Cr-16Ni-0.25Ti Alloys in FFTF at {approx} 400 Degrees C

Contrary to the behavior of swelling of f.c.c. Fe-15Cr-16Ni and Fe-15Cr-16Ni-0.25Ti alloys irradiated together in the same FFTF-MOTA experiment, Fe-15Cr-16Ti-0.25Ti-0.05C does not exhibit a dependence of swelling on dpa rate at {approx}400 C. The transient regime of swelling is prolonged by carbon addition, however. Addition of boron to the carbon-doped alloy decreases the swelling somewhat but does not restore the sensitivity to dpa rate. It appears that the primary influence of boron is chemical in nature, probably associated with boron's impact on the behavior of carbon. Boron's role as a source of helium is thought to be secondary.
Date: August 5, 2003
Creator: Okita, T; Wolfer, W G; Sato, T; Sekimura, N & Garner, F A
System: The UNT Digital Library
Atomic resolution of lithium ions in LiCoO{sub 2} (open access)

Atomic resolution of lithium ions in LiCoO{sub 2}

LiCoO{sub 2} is the most common lithium storage material used as positive electrode in lithium rechargeable batteries. Ordering of lithium and vacancies has a profound effect on the physical properties of Li{sub x}CoO{sub 2} and the electrochemical performances of lithium batteries. An exit surface wave (ESW) phase image reconstructed from experimental images obtained on the LBNL One-Angstrom Microscope (OAM) shows all three types of atoms in LiCoO{sub 2}.
Date: June 5, 2003
Creator: Shao-Horn, Yang; Croguennec, Laurence; Delmas, Claude; Nelson, E. Chris & O'Keefe, Michael A.
System: The UNT Digital Library
Instrumentation optimization for positron emission mammography (open access)

Instrumentation optimization for positron emission mammography

The past several years have seen designs for PET cameras optimized to image the breast, commonly known as Positron Emission Mammography or PEM cameras. The guiding principal behind PEM instrumentation is that a camera whose field of view is restricted to a single breast has higher performance and lower cost than a conventional PET camera. The most common geometry is a pair of parallel planes of detector modules, although geometries that encircle the breast have also been proposed. The ability of the detector modules to measure the depth of interaction (DOI) is also a relevant feature. This paper finds that while both the additional solid angle coverage afforded by encircling the breast and the decreased blurring afforded by the DOI measurement improve performance, the ability to measure DOI is more important than the ability to encircle the breast.
Date: June 5, 2003
Creator: Moses, William W. & Qi, Jinyi
System: The UNT Digital Library