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THE FUTURE OF SPIN PHYSICS AT BNL. (open access)

THE FUTURE OF SPIN PHYSICS AT BNL.

The Relativistic Heavy Ion Collider (RHIC) at BNL is the world's only polarized proton-proton collider. Collisions at center-of-mass energies up to 500 GeV and beam polarizations approaching 70% (longitudinal or transverse) are provided to two experiments, STAR and PHENIX, at luminosities {ge} 10{sup 32}/cm{sup 2}/sec. Transverse polarized beam has also been provided to the BRAHMS experiment. Measurements that bear on the important question of the spin content of the nucleon are beginning to appear. Over the next 10 years, as the performance of polarized proton running at RHIC is further developed, the Spin Physics program at RHIC will provide definitive measurements of the contributions to the proton's spin of the gluon, the sea quarks and the orbital motion of the partons in the proton's wave function. We plan to extend the reach of our study of the role of spin in QCD with the development of ''eRHIC'', which will provide polarized e-p collisions to a new detector.
Date: October 2, 2006
Creator: ARONSON, S. & DESHPANDE, A.
System: The UNT Digital Library
ACCELERATING POLARIZED PROTONS TO HIGH ENERGY. (open access)

ACCELERATING POLARIZED PROTONS TO HIGH ENERGY.

The Relativistic Heavy Ion Collider (RHIC) is designed to provide collisions of high energy polarized protons for the quest of understanding the proton spin structure. Polarized proton collisions at a beam energy of 100 GeV have been achieved in RHIC since 2001. Recently, polarized proton beam was accelerated to 250 GeV in RHIC for the first time. Unlike accelerating unpolarized protons, the challenge for achieving high energy polarized protons is to fight the various mechanisms in an accelerator that can lead to partial or total polarization loss due to the interaction of the spin vector with the magnetic fields. We report on the progress of the RHIC polarized proton program. We also present the strategies of how to preserve the polarization through the entire acceleration chain, i.e. a 200 MeV linear accelerator, the Booster, the AGS and RHIC.
Date: October 2, 2006
Creator: Bai, M.; Ahrens, L.; Alekseev, I. G.; Alessi, J.; Beebe-Wang, J.; Blaskiewicz, M. et al.
System: The UNT Digital Library
Multilayer Defects Nucleated by Substrate Pits: A Comparison of Actinic Inspection and Non-Actinic Inspection Techniques (open access)

Multilayer Defects Nucleated by Substrate Pits: A Comparison of Actinic Inspection and Non-Actinic Inspection Techniques

The production of defect-free mask blanks remains a key challenge for EUV lithography. Mask-blank inspection tools must be able to accurately detect all critical defects while simultaneously having the minimum possible false-positive detection rate. We have recently observed and here report the identification of bump-type buried substrate defects, that were below the detection limit of a non-actinic (i.e. non-EUV) in inspection tool. Presently, the occurrence inspection of pit-type defects, their printability, and their detectability with actinic techniques and non-actinic commercial tools, has become a significant concern. We believe that the most successful strategy for the development of effective non-actinic mask inspection tools will involve the careful cross-correlation with actinic inspection and lithographic printing. In this way, the true efficacy of prototype inspection tools now under development can be studied quantitatively against relevant benchmarks. To this end we have developed a dual-mode actinic mask inspection system capable of scanning mask blanks for defects (with simultaneous EUV bright-field and dark-field detection) and imaging those same defects with a zoneplate microscope that matches or exceeds the resolution of EUV steppers.
Date: October 2, 2006
Creator: Barty, A.; Goldberg, K.; Kearney, P.; Rekawa, S.; LaFontaine, B.; Wood, O. et al.
System: The UNT Digital Library
A Historical and Current Perspective on Predicting Thermal Cookoff Behavior (open access)

A Historical and Current Perspective on Predicting Thermal Cookoff Behavior

Prediction of thermal explosions using chemical kinetic models dates back nearly a century. However, it has only been within the past 25 years that kinetic models and digital computers made reliable predictions possible. Two basic approaches have been used to derive chemical kinetic models for high explosives: [1] measurement of the reaction rate of small samples by mass loss (thermogravimetric analysis, TGA), heat release (differential scanning calorimetry, DSC), or evolved gas analysis (mass spectrometry, infrared spectrometry, etc.) or [2] inference from larger-scale experiments measuring the critical temperature (T{sub m}, lowest T for self-initiation), the time to explosion as a function of temperature, and sometimes a few other results, such as temperature profiles. Some of the basic principles of chemical kinetics involved are outlined, and major advances in these two approaches through the years are reviewed.
Date: June 2, 2006
Creator: Burnham, A K; Weese, R K; Wemhoff, A P & Maienschein, J L
System: The UNT Digital Library
SO YOU WANT TO BE A LATTICE THEORIST? (open access)

SO YOU WANT TO BE A LATTICE THEORIST?

For this after dinner talk I intersperse images of real lattices with a discussion of the motivations for lattice gauge theory and some current unresolved issues.
Date: September 2, 2006
Creator: CREUTZ, M.
System: The UNT Digital Library
ENDF/B-VII.0: Next Generation Evaluated Nuclear Data Library for Nuclear Science and Technology (open access)

ENDF/B-VII.0: Next Generation Evaluated Nuclear Data Library for Nuclear Science and Technology

We describe the next generation general purpose Evaluated Nuclear Data File, ENDF/B-VII.0, of recommended nuclear data for advanced nuclear science and technology applications. The library, released by the U.S. Cross Section Evaluation Working Group (CSEWG) in December 2006, contains data primarily for reactions with incident neutrons, protons, and photons on almost 400 isotopes. The new evaluations are based on both experimental data and nuclear reaction theory predictions. The principal advances over the previous ENDF/B-VI library are the following: (1) New cross sections for U, Pu, Th, Np and Am actinide isotopes, with improved performance in integral validation criticality and neutron transmission benchmark tests; (2) More precise standard cross sections for neutron reactions on H, {sup 6}Li, {sup 10}B, Au and for {sup 235,238}U fission, developed by a collaboration with the IAEA and the OECD/NEA Working Party on Evaluation Cooperation (WPEC); (3) Improved thermal neutron scattering; (4) An extensive set of neutron cross sections on fission products developed through a WPEC collaboration; (5) A large suite of photonuclear reactions; (6) Extension of many neutron- and proton-induced reactions up to an energy of 150 MeV; (7) Many new light nucleus neutron and proton reactions; (8) Post-fission beta-delayed photon decay spectra; (9) New …
Date: October 2, 2006
Creator: Chadwick, M. B.; Oblozinsky, P.; Herman, M.; Greene, N. M.; McKnight, R. D.; Smith, D. L. et al.
System: The UNT Digital Library
Defense Waste Processing Facility (DWPF), Modular CSSX Unit (CSSX), and Waste Transfer Line System of Salt Processing Program (U) (open access)

Defense Waste Processing Facility (DWPF), Modular CSSX Unit (CSSX), and Waste Transfer Line System of Salt Processing Program (U)

All of the waste streams from ARP, MCU, and SWPF processes will be sent to DWPF for vitrification. The impact these new waste streams will have on DWPF's ability to meet its canister production goal and its ability to support the Salt Processing Program (ARP, MCU, and SWPF) throughput needed to be evaluated. DWPF Engineering and Operations requested OBU Systems Engineering to evaluate DWPF operations and determine how the process could be optimized. The ultimate goal will be to evaluate all of the Liquid Radioactive Waste (LRW) System by developing process modules to cover all facilities/projects which are relevant to the LRW Program and to link the modules together to: (1) study the interfaces issues, (2) identify bottlenecks, and (3) determine the most cost effective way to eliminate them. The results from the evaluation can be used to assist DWPF in identifying improvement opportunities, to assist CBU in LRW strategic planning/tank space management, and to determine the project completion date for the Salt Processing Program.
Date: February 2, 2006
Creator: Chang, Robert
System: The UNT Digital Library
Metastable Solid Solution Phases in the LiFePO4/FePO4 System (open access)

Metastable Solid Solution Phases in the LiFePO4/FePO4 System

None
Date: January 2, 2006
Creator: Chen, Guoying Chen; Song, Xiangyun & Richardson, Thomas J.
System: The UNT Digital Library
2006 Vibrational Spectroscopy Gordon Conference (open access)

2006 Vibrational Spectroscopy Gordon Conference

This Report is Description of Vibrational Spectroscopy at Gordon Conference
Date: July 2, 2006
Creator: Crim, Forrest Fleming
System: The UNT Digital Library
Transitive closure and metric inequality of weighted graphs:detecting protein interaction modules using cliques (open access)

Transitive closure and metric inequality of weighted graphs:detecting protein interaction modules using cliques

We study transitivity properties of edge weights in complex networks. We show that enforcing transitivity leads to a transitivity inequality which is equivalent to ultra-metric inequality. This can be used to define transitive closure on weighted undirected graphs, which can be computed using a modified Floyd-Warshall algorithm. We outline several applications and present results of detecting protein functional modules in a protein interaction network.
Date: June 2, 2006
Creator: Ding, Chris; He, Xiaofeng; Xiong, Hui; Peng, Hanchuan & Holbrook,Stephen R.
System: The UNT Digital Library
Hydrodynamic Simulations and Soft X-ray Laser Interferometric Studies of Energy Transport in Tightly Focused Laser-Heated Aluminum Plasmas (open access)

Hydrodynamic Simulations and Soft X-ray Laser Interferometric Studies of Energy Transport in Tightly Focused Laser-Heated Aluminum Plasmas

Contains the benefits of short wavelength ps probes for measuring plasmas.
Date: August 2, 2006
Creator: Dunn, J.; Moon, S.; Smith, R.; Keenan, R.; Nilsen, J.; Hunter, J. et al.
System: The UNT Digital Library
Building Science-Relevant Literacy with Technical Writing in High School (open access)

Building Science-Relevant Literacy with Technical Writing in High School

By drawing on the in-class work of an on-going literacy outreach project, this paper explains how well-chosen technical writing activities can earn time in high-school science courses by enabling underperforming students (including ESL students) to learn science more effectively. We adapted basic research-based text-design and usability techniques into age-appropriate exercises and cases using the cognitive apprenticeship approach. This enabled high-school students, aided by explicit guidelines, to build their cognitive maturity, learn how to craft good instructions and descriptions, and apply those skills to better note taking and technical talks in their science classes.
Date: June 2, 2006
Creator: Girill, T R
System: The UNT Digital Library
Phenomenology of the left-right twin Higgs model (open access)

Phenomenology of the left-right twin Higgs model

The twin Higgs mechanism was proposed recently to solve the little hierarchy problem. We study the implementation of the twin Higgs mechanism in left-right models. At the TeV scale, heavy quark and gauge bosonsappear, with rich collider phenomenology. In addition, there are extra Higgs bosons, some of which couple to both the standard model fermion sector and the gauge sector, while others couple to the gauge bosons only. We present the particle spectrum and study the general features of the collider phenomenology of this class of model at the Large Hadron Collider.
Date: November 2, 2006
Creator: Goh, Hock-Seng; Goh, Hock-Seng & Su, Shufang
System: The UNT Digital Library
Distinguishing between Dirac and Majorana neutrinos withtwo-particle interferometry (open access)

Distinguishing between Dirac and Majorana neutrinos withtwo-particle interferometry

Two-particle interferometry, a second-order interferenceeffect, is explored as another possible tool to distinguish betweenmassive Dirac and Majorana neutrinos. A simple theoretical framework isdiscussed in the context of several gedanken experiments. The method canin principle provide both the mass scale and the quantum nature of theneutrino for a certain class of incoherent left-handed sourcecurrents.
Date: March 2, 2006
Creator: Gutierrez, Thomas D.
System: The UNT Digital Library
Gridded Electron Guns and Modulation of Intense Beams (open access)

Gridded Electron Guns and Modulation of Intense Beams

Gridded guns are useful for producing modulated electron beams. This modulation is generally limited to simple gating of the beam, but may be used to apply structure to the beam pulse shape. In intense beams, this structure spawns space charge waves whose dynamics depend in part on the relative strengths of the velocity and density variations which comprise the initial current modulation. In this paper, we calculate the strengths of beam current and velocity modulation produced in a gridded electron gun, and show that under normal conditions the initial modulation is dominated by density variation rather than velocity variation.
Date: May 2, 2006
Creator: Harris, J R & O'Shea, P G
System: The UNT Digital Library
Sub-nanometer-scale measurements of the interaction of ultrafast soft x-ray free-electron-laser pulses with matter (open access)

Sub-nanometer-scale measurements of the interaction of ultrafast soft x-ray free-electron-laser pulses with matter

Femtosecond pulses from soft-x-ray free-electron lasers (FELs) [1] are ideal for directly probing matter at atomic length scales and timescales of atomic motion. An important component of understanding ultrafast phenomena of light-matter interactions is concerned with the onset of atomic motion which is impeded by the atoms inertia. This delay of structural changes will enable atomic-resolution flash-imaging [2-3] to be performed at upcoming x-ray FELs [4-5] with pulses intense enough to record the x-ray scattering from single molecules [6]. We explored this ultrafast high-intensity regime with the FLASH soft-x-ray FEL [7-8] by measuring the reflectance of nanostructured multilayer mirrors using pulses with fluences far in excess of the mirrors damage threshold. Even though the nanostructures were ultimately completely destroyed, we found that they maintained their integrity and reflectance characteristics during the 25-fs-long pulse, with no evidence for any structural changes during that time over lengths greater than 3 {angstrom}. In the recently built FLASH FEL [7], x-rays are produced from short electron pulses oscillating in a periodic magnet array, called an undulator, by the principle of self-amplification of spontaneous emission [9-10]. The laser quality of the x-ray pulses can be quantified by the peak spectral brilliance of the source, which …
Date: August 2, 2006
Creator: Hau-Riege, S.; Chapman, H.; Krzywinski, J.; Sobierajski, R.; London, R.; Bionta, R. et al.
System: The UNT Digital Library
Type B Package Radioactive Material Contents Compliance (open access)

Type B Package Radioactive Material Contents Compliance

None
Date: March 2, 2006
Creator: Hensel, Steve J.; Watkins, R. W. & Smith, A. C.
System: The UNT Digital Library
Strains in Thermally Growing Alumina Films Measured in-situ usingSynchrotron X-rays (open access)

Strains in Thermally Growing Alumina Films Measured in-situ usingSynchrotron X-rays

Strains in thermally grown oxides have been measured in-situ, as the oxides develop and evolve. Extensive data have been acquired from oxides grown in air at elevated temperatures on different model alloys that form Al{sub 2}O{sub 3}. Using synchrotron x-rays at the Advanced Photon Source (Beamline 12BM, Argonne National Laboratory), Debye-Scherrer diffraction patterns from the oxidizing specimen were recorded every 5 minutes during oxidation and subsequent cooling. The diffraction patterns were analyzed to determine strains in the oxides, as well as phase changes and the degree of texture. To study a specimen's response to stress perturbation, the oxidizing temperature was quickly cooled from 1100 to 950 C to impose a compressive thermal stress in the scale. This paper describes this new experimental approach and gives examples from oxidized {beta}-NiAl, Fe-20Cr-10Al, Fe-28Al-5Cr and H{sub 2}-annealed Fe-28Al-5Cr (all at. %) alloys to illustrate some current understanding of the development and relaxation of growth stresses in Al{sub 2}O{sub 3}.
Date: January 2, 2006
Creator: Hou, P.Y.; Paulikas, A.P. & Veal, B.W.
System: The UNT Digital Library
Applications of Ultrafast Terahertz Pulses for Intra-ExcitonicSpectroscopy of Quasi-2D Electron-Hole Gases (open access)

Applications of Ultrafast Terahertz Pulses for Intra-ExcitonicSpectroscopy of Quasi-2D Electron-Hole Gases

Excitons are of fundamental interest and of importance foropto-electronic applications of bulk and nano-structured semiconductors.This paper discusses the utilization of ultrafast terahertz (THz) pulsesfor the study of characteristic low-energy excitations of photoexcitedquasi 2D electron-hole (e-h) gases. Optical-pump THz-probe spectroscopyat 250-kHz repetition rate is employed to detect characteristic THzsignatures of excitons and unbound e-h pairs in GaAs quantum wells.Exciton and free-carrier densities are extracted from the data using atwo-component model. We report the detailed THz response and pairdensities for different photoexcitation energies resonant to heavy-holeexcitons, light-hole excitons, or the continuum of unbound pairs. Suchexperiments can provide quantitative insights into wavelength, time, andtemperature dependence of the low-energy response and composition ofoptically excited e-h gases in low-dimensionalsemiconductors.
Date: September 2, 2006
Creator: Kaindl, Robert A.; Carnahan, Marc A.; Hagele, Daniel & Chemla, D.S.
System: The UNT Digital Library
Simulation of Turbulent Combustion Fields of Shock-Dispersed Aluminum Using the AMR Code (open access)

Simulation of Turbulent Combustion Fields of Shock-Dispersed Aluminum Using the AMR Code

We present a Model for simulating experiments of combustion in Shock-Dispersed-Fuel (SDF) explosions. The SDF charge consisted of a 0.5-g spherical PETN booster, surrounded by 1-g of fuel powder (flake Aluminum). Detonation of the booster charge creates a high-temperature, high-pressure source (PETN detonation products gases) that both disperses the fuel and heats it. Combustion ensues when the fuel mixes with air. The gas phase is governed by the gas-dynamic conservation laws, while the particle phase obeys the continuum mechanics laws for heterogeneous media. The two phases exchange mass, momentum and energy according to inter-phase interaction terms. The kinetics model used an empirical particle burn relation. The thermodynamic model considers the air, fuel and booster products to be of frozen composition, while the Al combustion products are assumed to be in equilibrium. The thermodynamic states were calculated by the Cheetah code; resulting state points were fit with analytic functions suitable for numerical simulations. Numerical simulations of combustion of an Aluminum SDF charge in a 6.4-liter chamber were performed. Computed pressure histories agree with measurements.
Date: November 2, 2006
Creator: Kuhl, A L; Bell, J B; Beckner, V E & Khasainov, B
System: The UNT Digital Library
OPERATIONAL LIMITATIONS FOR DEMOLITION OF A HIGHLY ALPHA CONTAMINATED BUILDING MODLES VERSUS MEASURED AIR & SURFACE ACTIVITY CONCENTRATIONS (open access)

OPERATIONAL LIMITATIONS FOR DEMOLITION OF A HIGHLY ALPHA CONTAMINATED BUILDING MODLES VERSUS MEASURED AIR & SURFACE ACTIVITY CONCENTRATIONS

The demolition of a facility historically used for processing and handling transuranic materials is considered. Residual alpha emitting radionuclide contamination poses an exposure hazard if released to the local environment during the demolition. The process of planning for the demolition of this highly alpha contaminated building, 232-Z, included a predemolition modeling analysis of potential exposures. Estimated emission rates were used as input to an air dispersion model to estimate frequencies of occurrence of peak air and surface exposures. Postdemolition modeling was also conducted, based on the actual demolition schedule and conditions. The modeling results indicated that downwind deposition is the main operational limitation for demolition of a highly alpha-contaminated building. During the demolition of 232-Z, airborne radiation and surface contamination were monitored. The resultant non-detect monitoring results indicate a significant level of conservatism in the modeled results. This comparison supports the use of more realistic assumption in the estimating emission rates. The resultant reduction in modeled levels of potential exposures has significant implications in terms of the projected costs of demolition of such structures.
Date: November 2, 2006
Creator: LLOYD, E.R.
System: The UNT Digital Library
Laboratory Measurements of the Line Emission from Mid-Z L-Shell Ions in the EUV (open access)

Laboratory Measurements of the Line Emission from Mid-Z L-Shell Ions in the EUV

We are continuing EBIT measurements of line lists in the EUV region for use as astrophysical diagnostics and have recently measured the same transitions in much denser plasma of the NSTX tokamak. This allows us to calibrate density-sensitive line ratios at their upper limits. We compare our observations at low and high density with calculations from the Flexible Atomic Code.
Date: May 2, 2006
Creator: Lepson, J K; Beiersdorfer, P; Chen, H; Gu, M F & Kahn, S M
System: The UNT Digital Library
Nucleon Structure in Lattice Qcd With Dynamical Domain--Wall Fermions Quarks. (open access)

Nucleon Structure in Lattice Qcd With Dynamical Domain--Wall Fermions Quarks.

We report RBC and RBC/UKQCD lattice QCD numerical calculations of nucleon electroweak matrix elements with dynamical domain-wall fermions (DWF) quarks. The first, RBC, set of dynamical DWF ensembles employs two degenerate flavors of DWF quarks and the DBW2 gauge action. Three sea quark mass values of 0.04, 0.03 and 0.02 in lattice units are used with 220 gauge configurations each. The lattice cutoff is a{sup -1} {approx} 1.7GeV and the spatial volume is about (1.9fm){sup 3}. Despite the small volume, the ratio of the isovector vector and axial charges g{sub A}/g{sub V} and that of structure function moments <x>{sub u-d}/<x>{sub {Delta}u-{Delta}d} are in agreement with experiment, and show only very mild quark mass dependence. The second, RBC/UK, set of ensembles employs one strange and two degenerate (up and down) dynamical DWF quarks and Iwasaki gauge action. The strange quark mass is set at 0.04, and three up/down mass values of 0.03, 0.02 and 0.01 in lattice units are used. The lattice cutoff is a{sup -1} {approx} 1.6GeV and the spatial volume is about (3.0fm){sup 3}. Even with preliminary statistics of 25-30 gauge configurations, the ratios g{sub A}/g{sub V} and <x>{sub u-d}/<x>{sub {Delta}u-{Delta}d} are consistent with experiment and show only very …
Date: October 2, 2006
Creator: Lin, H. W. & Ohta, S.
System: The UNT Digital Library
Global crop yield losses from recent warming (open access)

Global crop yield losses from recent warming

Global yields of the world-s six most widely grown crops--wheat, rice, maize, soybeans, barley, sorghum--have increased since 1961. Year-to-year variations in growing season minimum temperature, maximum temperature, and precipitation explain 30% or more of the variations in yield. Since 1991, climate trends have significantly decreased yield trends in all crops but rice, leading to foregone production since 1981 of about 12 million tons per year of wheat or maize, representing an annual economic loss of $1.2 to $1.7 billion. At the global scale, negative impacts of climate trends on crop yields are already apparent. Annual global temperatures have increased by {approx}0.4 C since 1980, with even larger changes observed in several regions (1). While many studies have considered the impacts of future climate changes on food production (2-5), the effects of these past changes on agriculture remain unclear. It is likely that warming has improved yields in some areas, reduced them in others, and had negligible impacts in still others; the relative balance of these effects at the global scale is unknown. An understanding of this balance would help to anticipate impacts of future climate changes, as well as to more accurately assess recent (and thereby project future) technologically driven …
Date: June 2, 2006
Creator: Lobell, D & Field, C
System: The UNT Digital Library