Effects of Light Scalar Mesons in eta -> 3pi decay (open access)

Effects of Light Scalar Mesons in eta -> 3pi decay

We study the role of a possible nonet of light scalar mesons in the still interesting [eta] -> 3[p]i decay process, with the primary motivation of learning more about the scalars themselves. The framework is a conventional non-linear chiral Lagrangian of pseudoscalars and vectors extended to include the scalars. The parameters involving the scalars were previously obtained to fit the s-wave [pi][pi] and [pi] K scatterings in the region up to about 1 GeV as well as the strong decay [eta]' --> [eta][pi][pi]. At first, one might expect a large enhancement from diagrams including a light [sigma] (560). However there is an amusing cancellation mechanism which prevents this from occurring. In the simplest model there is an enhancement of about 13 per cent in the [eta] -> 3[pi] decay rate due to the scalars. In a more complicated model which includes derivative type symmetry breakers, the cancellation is modified and the scalars contribute about 30 percent of the total decay rate (although the total is not significantly changed). The vectors do not contribute much. Our model produces a reasonable estimate for the related a{sub 0}(980) - f{sub 0}(980) mixing strength, which has been a topic of current debate. Promising directions …
Date: October 1, 2002
Creator: Abdel-Rehim, Abdou; Black, Deirdre; Fariborz, Amir H. & Schechter, Joseph
System: The UNT Digital Library
Disappearance of back-to-back high p {sub T} hadron correlations in central Au+Au collisions at {radical}s{sub NN} = 200 GeV (open access)

Disappearance of back-to-back high p {sub T} hadron correlations in central Au+Au collisions at {radical}s{sub NN} = 200 GeV

Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudo-rapidity range and full azimuth in Au+Au and p+p collisions at = {radical}s{sub NN} = 200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes already observed in elementary collisions. A strong back-to-back correlation exists for p+p and peripheral Au + Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium.
Date: October 25, 2002
Creator: Adler, C.; Ahammed, Z.; Allgower, C.; Amonett, J.; Anderson, B. D.; Anderson, M. et al.
System: The UNT Digital Library
DESIGN, FABRICATION, INSTALLATION AND TESTING OF IN-VESSEL CONTROL COILS FOR DIII-D (open access)

DESIGN, FABRICATION, INSTALLATION AND TESTING OF IN-VESSEL CONTROL COILS FOR DIII-D

OAK A271 DESIGN, FABRICATION, INSTALLATION AND TESTING OF IN-VESSEL CONTROL COILS FOR DIII-D. Since 1995, DIII-D has performed correction of magnetic field imperfections using a set of six external picture frame coils located on the vessel mid-plane. Recently, these coils have also demonstrated significant benefits when used for feedback of the resistive wall mode, an instability that limits the plasma performance at high beta. Modeling has shown that substantial performance improvements can be achieved by installing new coils inside the vessel and expanding the poloidal coverage above and below the mid-plane. Two prototype internal coils were installed in 2001 and have been tested successfully. installation of a set of twelve internal coils and magnetic sensors in the DIII-D tokamak is to be completed in December 2002. The design requirement for the new coil system was to maximize the magnetic field at the plasma edge, operate with a frequency range of dc to 1000 Hz, and fit behind the existing graphite wall tiles. The coil design adopted and installed is a water-cooled hollow copper conductor insulated with polyamide and housed inside a stainless steel tube that forms a vacuum boundary. The coil is rigidly mounted to the inside of the vacuum …
Date: October 1, 2002
Creator: Anderson, P. M.; Baxi, C. B.; Kellman, A. G.; Reis, E. E. & Robinson, J. I.
System: The UNT Digital Library
A Dynamically Adaptive Arbitrary Lagrangian-Eulerian Method for Hydrodynamics (open access)

A Dynamically Adaptive Arbitrary Lagrangian-Eulerian Method for Hydrodynamics

A new method that combines staggered grid Arbitrary Lagrangian-Eulerian (ALE) techniques with structured local adaptive mesh refinement (AMR) has been developed for solution of the Euler equations. The novel components of the combined ALE-AMR method hinge upon the integration of traditional AMR techniques with both staggered grid Lagrangian operators as well as elliptic relaxation operators on moving, deforming mesh hierarchies. Numerical examples demonstrate the utility of the method in performing detailed three-dimensional shock-driven instability calculations.
Date: October 19, 2002
Creator: Anderson, R W; Pember, R B & Elliott, N S
System: The UNT Digital Library
Multiphase Advection and Radiation Diffusion with Material Interfaces on Unstructured Meshes (open access)

Multiphase Advection and Radiation Diffusion with Material Interfaces on Unstructured Meshes

A collection of numerical methods are presented for the advection or remapping of material properties on unstructured and staggered polyhedral meshes in arbitrary Lagrange-Eulerian calculations. The methods include several new procedures to track and capture sharp interface boundaries, and to partition radiation energy into multi-material thermal states. The latter is useful for extending and applying consistently single material radiation diffusion solvers to multi-material problems.
Date: October 3, 2002
Creator: Anninos, P
System: The UNT Digital Library
The effect of specific chloride adsorption on the electrochemical behavior of ultrathin Pd films deposited on Pt(111) in acid solution (open access)

The effect of specific chloride adsorption on the electrochemical behavior of ultrathin Pd films deposited on Pt(111) in acid solution

The electrochemical behavior of thin Pd films supported on a Pt(111) electrode is investigated by cyclic voltammetry (CV) and in-situ Fourier transform infrared (FTIR) spectroscopy. It is demonstrated that in perchloric acid solution underpotential deposition of hydrogen (H{sub upd}) and hydroxyl adsorption (OH{sub ad}) is in strong competition with the adsorption of Cl- anions, the latter being present as a trace impurity in HClO{sub 4}. The interaction of Cl- with Pd is rather strong, controlling the adsorption of H{sub upd} and OH{sub ad} as well as the kinetic rate of CO oxidation. The microscopic insight (the binding sites) of the adsorbed CO (CO{sub ad}) and the rate of CO oxidation (established from CO2 production) on Pt(111) modified with a (sub)monolayer of Pd is elucidated by means of Fourier infrared (FTIR) spectroscopy. The appearance of both the characteristic Pt(111)-CO{sub ad} and Pt(111)1 ML Pd-CO{sub ad} stretching bands on a Pt(111) surface covered by 0.5 ML Pd confirms previous findings that the Pd atoms agglomerate into islands and that the bare Pt areas and the Pd islands behave according to their own surface chemistry. The systematic increase of the Pd surface coverage results in a gradual change in the catalytic properties of …
Date: October 1, 2002
Creator: Arenz, M.; Stamenkovic, V.; Schmidt, T. J.; Wandelt, K.; Ross, P. N. & Markovic, N. M.
System: The UNT Digital Library
Positron Annihilation in Insulating Materials (open access)

Positron Annihilation in Insulating Materials

We describe positron results from a wide range of insulating materials. We have completed positron experiments on a range of zeolite-y samples, KDP crystals, alkali halides and laser damaged SiO{sub 2}. Present theoretical understanding of positron behavior in insulators is incomplete and our combined theoretical and experimental approach is aimed at developing a predictive understanding of positrons and positronium annihilation characteristics in insulators. Results from alkali halides and alkaline-earth halides show that positrons annihilate with only the halide ions, with no apparent contribution from the alkali or alkaline-earth cations. This contradicts the results of our existing theory for metals, which predicts roughly equal annihilation contributions from cation and anion. We also present result obtained using Munich positron microprobe on laser damaged SiO{sub 2} samples.
Date: October 18, 2002
Creator: Asoka-Kumar, P & Sterne, PA
System: The UNT Digital Library
Hydration and mobility of HO-(aq) (open access)

Hydration and mobility of HO-(aq)

The hydroxide anion plays an essential role in many chemical and biochemical reactions. But questions of its hydration state and transport in water are currently controversial. Here we address this situation using the quasi-chemical theory of solutions. The simplest such approach suggests that HO [H20]3- is the most probable species at infinite dilution in aqueous solution under standard conditions, followed by the HO . [H20]2- and HO . [HzO]- forms which are close together in stablity. HO . [H20]4- is less stable, in contrast to recent proposals that the latter structure is the most stable hydration species in solution. Ab initio molecular dynamics results presented here support the dominance of the tri-hydrated form, but that the population distribution is broad and sensitive to solution conditions. On the basis of these results, the mobility of hydroxide can be simply that of a proton hole. This contrasts with recent proposals invoking the interconversion of a stable 'trap' structure HO . [H20]4- to HO . [H20]3- as the rate determining step in the transport process.
Date: October 31, 2002
Creator: Asthagiri, D. (Dilipkumar); Pratt, Lawrence Riley; Kress, J. D. (Joel D.) & Gomez, M. A. (Maria A.)
System: The UNT Digital Library
Large Scale Atmospheric Chemistry Simulations for 2001: An Analysis of Ozone and Other Species in Central Arizona (open access)

Large Scale Atmospheric Chemistry Simulations for 2001: An Analysis of Ozone and Other Species in Central Arizona

A key atmospheric gas is ozone. Ozone in the stratosphere is beneficial to the biosphere because it absorbs a significant fraction of the sun's shorter wavelength ultraviolet radiation. Ozone in the troposphere is a pollutant (respiratory irritant in humans and acts to damage crops, vegetation, and many materials). It affects the Earths energy balance by absorbing both incoming solar radiation and outgoing long wave radiation. An important part of the oxidizing capacity of the atmosphere involves ozone, through a photolysis pathway that leads to the hydroxyl radical (OH). Since reaction with OH is a major sink of many atmospheric species, its concentration controls the distributions of many radiatively important species. Ozone in the troposphere arises from both in-situ photochemical production and transport from the stratosphere. Within the troposphere, ozone is formed in-situ when carbon monoxide (CO), methane (CH4), and non-methane hydrocarbons (NMHCs) react in the presence of nitrogen oxides (NO, = NO + NO2) and sunlight. The photochemistry of the stratosphere differs significantly from that in the troposphere. Within the stratosphere, ozone formation is initiated by the photolysis of 02. Stratospheric ozone may be destroyed via catalytic reactions with NO, H (hydrogen), OH, CI (chlorine) and Br (bromine), or photolysis. …
Date: October 8, 2002
Creator: Atherton, C; Bergmann, D; Cameron-Smith, P; Connell, P; Molenkamp, C; Rotman, D et al.
System: The UNT Digital Library
Preparation and characterization of aerogels derived from Al(OH){sub 3} and CrO{sub 3} (open access)

Preparation and characterization of aerogels derived from Al(OH){sub 3} and CrO{sub 3}

None
Date: October 1, 2002
Creator: Ayers, Michael R.; White, Ashley A.; Song, Xanyoun & Hunt, Arlon J.
System: The UNT Digital Library
The D0 Detector for Run II (open access)

The D0 Detector for Run II

The general purpose D0 collider detector at the Fermilab Tevatron has undergone major upgrades for Run II. We describe the current status and performance of the D0 detector.
Date: October 18, 2002
Creator: Babukhadia, Levan
System: The UNT Digital Library
Multi-keV X-Ray Conversion Efficiency in Laser-Produced Plasmas (open access)

Multi-keV X-Ray Conversion Efficiency in Laser-Produced Plasmas

X-ray sources are created at the Nova and Omega laser by irradiating a confined volume of Ar, Xe, or Kr gas. The gas is heated by forty 0.35 {micro}m wavelength, 1-ns square laser beams to produce He-like ions that radiate K-shell emission over mm-sized dimensions. The targets are designed to be ''underdense'', meaning that the initial gas density is lower than the critical density of the laser, n{sub c} {approx} 10{sup 21} cm{sup -3}. The laser energy is primarily absorbed by inverse bremsstrahlung and a supersonic heat wave efficiently ionizes the gas. Results from time-resolved and time-integrated diagnostics over a range of experimental parameters are compared. This work represents an important, new method for development of efficient, large-area, tailored multi-keV x-ray sources.
Date: October 31, 2002
Creator: Back, C. A.; Landen, O. L.; Hammer, J. H.; Suter, L. J.; Miller, M. C.; Davis, J. et al.
System: The UNT Digital Library
Aerial Image Microscopes for the Inspection of Defects in EUV Masks (open access)

Aerial Image Microscopes for the Inspection of Defects in EUV Masks

The high volume inspection equipment currently available to support development of EUV blanks is non-actinic. The same is anticipated for patterned EUV mask inspection. Once potential defects are identified and located by such non-actinic inspection techniques, it is essential to have instrumentation to perform detailed characterization, and if repairs are performed, re-evaluation. The ultimate metric for the acceptance or rejection of a mask due to a defect, is the wafer level impact. Thus measuring the aerial image for the site under question is required. An EUV Aerial Image Microscope (''AIM'') similar to the current AIM tools for 248nm and 193nm exposure wavelength is the natural solution for this task. Due to the complicated manufacturing process of EUV blanks, AIM measurements might also be beneficial to accurately assessing the severity of a blank defect. This is an additional application for an EUV AIM as compared to today's use In recognition of the critical role of an EUV AIM for the successful implementation of EUV blank and mask supply, International SEMATECH initiated this design study with the purpose to define the technical requirements for accurately simulating EUV scanner performance, demonstrating the feasibility to meet these requirements and to explore various technical approaches …
Date: October 22, 2002
Creator: Barty, A.; Taylor, J. S.; Hudyma, R.; Spiller, E.; Sweeney, D. W.; Shelden, G. et al.
System: The UNT Digital Library
Kinetics of phase growth in Nb3Sn formation for heat treatment optimization (open access)

Kinetics of phase growth in Nb3Sn formation for heat treatment optimization

The kinetics of growth and superconducting properties of Nb{sub 3}Sn are investigated as a function of the heat treatment (HT) duration and temperature for Internal Tin and Powder-in-Tube strands at 650, 700 and 750 C. For all times and temperatures, the Nb{sub 3}Sn layer thickness is measured, the critical current at 4.2 K is tested as a function of magnetic field, and the upper critical field is evaluated. Results of the layer critical current density are also shown as a function of HT duration and temperature.
Date: October 25, 2002
Creator: Barzi, Emanuela & Mattafirri, Sara
System: The UNT Digital Library
First Run II results with the CDF detector (open access)

First Run II results with the CDF detector

We report the first results obtained by the CDF collaboration from the analysis of the Tevatron Run II data collected until June 2002. All components of the CDF detector are operating at or near the design specifications. Typical physics signals are observed and used both to characterize the CDF detector performance, and to make several physics measurements. In spite of the still limited accumulated luminosity some measurements are already competitive with the best currently available.
Date: October 18, 2002
Creator: Bedeschi, F.
System: The UNT Digital Library
Development of the low return loss 340-size ceramic window for the APS linac. (open access)

Development of the low return loss 340-size ceramic window for the APS linac.

The Advanced Photon Source (APS) linac high-power switching system makes use of 340-size waveguide components. These components include vacuum-grade furnace-brazed transitions, pressurized-grade aluminum 340-size switches, and more recently 340-size ceramic windows. The fabrication of these 340-size windows proceeded with brazing of ceramic membrane to thin-walled copper sleeves and real-time network analyzer testing performed by the ASD (Accelerator Systems Division) RF (Radio Frequency) Group. Initially it was thought that this real-time testing of prototype hardware would be necessary in the investigative stage to establish the required dimensions and physical geometry to satisfy the 40-dB return-loss criteria. However, producing four windows now installed involved real-time network analyzer testing during production of each window conducted in parallel with adjustments of tuners designed into each 340-size ceramic window.
Date: October 10, 2002
Creator: Berg, S.; Bromberek, D.; Goeppner, G.; Haase, A.; Hoyt, J.; Michalek, W. et al.
System: The UNT Digital Library
Inhibition of K+ currents of outer hair cells in guinea pig cochlea by fluoxetine (open access)

Inhibition of K+ currents of outer hair cells in guinea pig cochlea by fluoxetine

Article discussing the inhibition of K+ currents of outer hair cells in guinea pig cochlea by fluoxetine.
Date: October 25, 2002
Creator: Bian, Jing-Tan; Yeh, Jay Z.; Aistrup, Gary L.; Narahashi, Toshio & Moore, Ernest J.
System: The UNT Digital Library
W boson cross section and decay properties at the Tevatron (open access)

W boson cross section and decay properties at the Tevatron

The authors present the first measurements of {sigma}(p{bar p} {yields} W {yields} {ell}{nu}) and {sigma}(p{bar p} {yields} Z {yields} {ell}{ell}) at {radical}s = 1.96 TeV, along with new measurements of W angular-decay distributions in p{bar p} collisions at {radical}s = 1.8 TeV.
Date: October 16, 2002
Creator: Bloom, K.
System: The UNT Digital Library
Anomalous momentum dependence of the quasiparticle scattering ratein overdoped Bi2Sr2CaCu2O8 (open access)

Anomalous momentum dependence of the quasiparticle scattering ratein overdoped Bi2Sr2CaCu2O8

The question of the anisotropy of the electron scattering in high temperature superconductors is investigated using high resolution angle-resolved photoemission data from Pb-doped Bi2Sr2CaCu2O8(Bi2212) with suppressed superstructure. The scattering rate of low energy electrons along two bilayer split pieces of the Fermi surface is measured (via the quasiparticle peak width), and no increase of scattering towards the antinode (Pi,0) region is observed, contradicting the expectation from Q=(Pi, Pi) scattering. The results put a limit on the effects of Q=(Pi, Pi) scattering on the electronic structure of this overdoped superconductor with still very high Tc.
Date: October 14, 2002
Creator: Bogdanov, P. V.; Lanzara, A.; Zhou, X. J.; Yang, W. L.; Eisaki, H.; Hussain, Z. et al.
System: The UNT Digital Library
NNSA/NV Consequence Management Capabilities for Radiological Emergency Response (open access)

NNSA/NV Consequence Management Capabilities for Radiological Emergency Response

The U.S. Department of Energy's National Nuclear Security Administration Nevada Operations Office (NNSA/NV) provides an integrated Consequence Management (CM) response capability for the (NNSA) in the event of a radiological emergency. This encompasses planning, technical operations, and home team support. As the lead organization for CM planning and operations, NNSA/NV coordinates the response of the following assets during the planning and operational phases of a radiological accident or incident: (1) Predictive dispersion modeling through the Atmospheric Release Advisory Capability (ARAC) at Lawrence Livermore National Laboratory (LLNL) and the High Consequence Assessment Group at Sandia National Laboratories (SNL); (2) Regional radiological emergency assistance through the eight Radiological Assistance Program (RAP) regional response centers; (3) Medical advice and assistance through the Radiation Emergency Assistance Center/Training Site (REAC/TS) in Oak Ridge, Tennessee; (4) Aerial radiological mapping using the fixed-wing and rotor-wing aircraft of the Aerial Measuring System (AMS); (5) Consequence Management Planning Teams (CMPT) and Consequence Management Response Teams (CMRT) to provide CM field operations and command and control. Descriptions of the technical capabilities employed during planning and operations are given below for each of the elements comprising the integrated CM capability.
Date: October 1, 2002
Creator: Bowman, D. R.
System: The UNT Digital Library
Capillary rise in nesting cylinders (open access)

Capillary rise in nesting cylinders

None
Date: October 15, 2002
Creator: Brady, Victor; Concus, Paul & Finn, Robert
System: The UNT Digital Library
The International Criticality Safety Benchmark Evaluation Project (open access)

The International Criticality Safety Benchmark Evaluation Project

Most safety concerns associated with operations at nuclear facilities are very similar to the safety concerns associated with operations at non-nuclear facilities. The potential for a nuclear criticality accident is one concern that is unique to the nuclear industry. However, if managed properly, the risk of a criticality accident can be reduced to an acceptable level. In fact, the risk of a criticality accident can generally be reduced to a level that is much lower than the risk associated with non-nuclear activities that have similar consequences.
Date: October 1, 2002
Creator: Briggs, Joseph Blair; Dean, V. F. & Presic, M.
System: The UNT Digital Library
Electron Beam Production and Characterization for the PLEIADES Thomson X-ray Source (open access)

Electron Beam Production and Characterization for the PLEIADES Thomson X-ray Source

We report on the performance of an S-band RF photocathode electron gun and accelerator for operation with the PLEIADES Thomson x-ray source at LLNL. Simulations of beam production, transport, and focus are presented. It is shown that a 1 ps, 500 pC electron bunch with a normalized emittance of less than 5 {pi}mm-mrad can be delivered to the interaction point. Initial electron measurements are presented. Calculations of expected x-ray flux are also performed, demonstrating an expected peak spectral brightness of 10{sup 20} photons/s/mm{sup 2}/mrad{sup 2}/0.1% bandwidth. Effects of RF phase jitter are also presented, and planned phase measurements and control methods are discussed.
Date: October 14, 2002
Creator: Brown, W J; Hartemann, F V; Tremaine, A M; Springer, P T; Le Sage, G P; Barty, C P J et al.
System: The UNT Digital Library
RF Phase Stability and Electron Beam Characterization for the PLEIADES Thomson X-Ray Source (open access)

RF Phase Stability and Electron Beam Characterization for the PLEIADES Thomson X-Ray Source

We report on the performance of an S-band RF photocathode electron gun and accelerator for operation with the PLEIADES Thomson x-ray source at LLNL. To produce picosecond, high brightness x-ray pulses, picosecond timing, terahertz bandwidth diagnostics, and RF phase control are required. Planned optical, RF, x-ray and electron beam measurements to characterize the dependence of electron beam parameters and synchronization on RF phase stability are presented.
Date: October 16, 2002
Creator: Brown, W J; Hartemann, F V; Tremaine, A M; Springer, P T; Le Sage, G P; Barty, C P J et al.
System: The UNT Digital Library