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Accelerator Challenges and Opportunities for Future Neutrino Experiments (open access)

Accelerator Challenges and Opportunities for Future Neutrino Experiments

There are three types of future neutrino facilities currently under study, one based on decays of stored beta-unstable ion beams (?Beta Beams?), one based on decays of stored muon beams (?Neutrino Factory?), and one based on the decays of an intense pion beam (?Superbeam?). In this paper we discuss the challenges each design team must face and the R&D being carried out to turn those challenges into technical opportunities. A new program, the Muon Accelerator Program, has begun in the U.S. to carry out the R&D for muon-based facilities, including both the Neutrino Factory and, as its ultimate goal, a Muon Collider. The goals of this program will be briefly described.
Date: December 24, 2010
Creator: Zisman, Michael S
System: The UNT Digital Library
Progress on a Be Cavity Design (open access)

Progress on a Be Cavity Design

Previous RF experiments with normal-conducting cavities have demonstrated that there is a significant degradation in maximum gradient when the cavity is subjected to a strong axial magnetic field. We have developed a model suggesting that a cavity with beryllium walls may perform better than copper cavities. In this paper we outline the issues that led us to propose fabricating a Be-wall cavity. We also discuss a concept for fabricating such a cavity and mention some of the manufacturing issues we expect to face.
Date: December 24, 2010
Creator: Li, D.; Palmer, R.; Stratakis, D.; Virostek, S. & Zisman, Michael S.
System: The UNT Digital Library
Direct Comparison of the X-Ray Emission and Absorption of Cerium Oxide (open access)

Direct Comparison of the X-Ray Emission and Absorption of Cerium Oxide

Bremstrahlung Isochromat Spectroscopy (BIS). The XES spectra were collected using a Specs electron gun for the excitation and the XES 350 grating monochromator and channel plate system from Scienta as the photon detection. Spectra were collected in 'normal mode,' where the electron gun kinetic energy (KE) and the energy position of the center of the channel plate were both fixed and the energy distribution in the photon (hv) spectrum was derived from the intensities distributed across the channel plate detector in the energy dispersal direction. The polycrystalline Ce sample was oxidized by exposure to air at ambient pressures. After introduction to the ultra-high vacuum system, the oxidized sample was bombarded with Ar, to clean the topmost surface region and stabilize the surface and near surface regions. Although CeO{sub 2} would be the thermodynamically preferred composition in an oxygen rich environment, the combination of a vacuum environment and ion etching may have driven the near surface region into a Ce{sub 2}O{sub 3} stoichiometry. XES data collection occurred with the sample at or near room temperature. The base pressure of the system was 3 x 10{sup -10} torr, but the pressure changed depending the energy and current of the electron gun. For …
Date: November 24, 2010
Creator: Tobin, J G; Yu, S W; Chung, B W; Waddill, G D & Denlinger, J D
System: The UNT Digital Library
Energy Efficiency Design Options for Residential Water Heaters: Economic Impacts on Consumers (open access)

Energy Efficiency Design Options for Residential Water Heaters: Economic Impacts on Consumers

The U.S. Department of Energy (DOE) recently completed a rulemaking process in which it amended the existing energy efficiency standards for residential water heaters. A key factor in DOE?s consideration of new standards is the economic impacts on consumers. Determining such impacts requires a comparison of the additional first cost of energy efficiency design options with the savings in operating costs. This paper describes the method used to conduct the life-cycle cost (LCC) and payback period analysis for gas and electric storage water heaters. It presents the estimated change in LCC associated with more energy-efficient equipment, including heat pump electric water heaters and condensing gas water heaters, for a representative sample of U.S. homes. The study included a detailed accounting of installation costs for the considered design options, with a focus on approaches for accommodating the larger dimensions of more efficient water heaters. For heat pump water heaters, the study also considered airflow requirements, venting issues, and the impact of these products on the indoor environment. The results indicate that efficiency improvement relative to the baseline design reduces the LCC in the majority of homes for both gas and electric storage water heaters, and heat pump electric water heaters and …
Date: November 24, 2010
Creator: Lekov, Alex; Franco, Victor; Meyers, Steve; Thompson, Lisa & Letschert, Virginie
System: The UNT Digital Library
Soft X-ray Spectroscopy Study of the Electronic Structure of Oxidized and Partially Oxidized Magnetite Nanoparticles (open access)

Soft X-ray Spectroscopy Study of the Electronic Structure of Oxidized and Partially Oxidized Magnetite Nanoparticles

The crystal structure of magnetite nanoparticles may be transformed to maghemite by complete oxidation, but under many relevant conditions the oxidation is partial, creating a mixed-valence material with structural and electronic properties that are poorly characterized. We used X-ray diffraction, Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy, and soft X-ray absorption and emission spectroscopy to characterize the products of oxidizing uncoated and oleic acid-coated magnetite nanoparticles in air. The oxidization of uncoated magnetite nanoparticles creates a material that is structurally and electronically indistinguishable from maghemite. By contrast, while oxidized oleic acid-coated nanoparticles are also structurally indistinguishable from maghemite, Fe L-edge spectroscopy revealed the presence of interior reduced iron sites even after a 2-year period. We used X-ray emission spectroscopy at the O K-edge to study the valence bands (VB) of the iron oxide nanoparticles, using resonant excitation to remove the contributions from oxygen atoms in the ligands and from low-energy excitations that obscured the VB edge. The bonding in all nanoparticles was typical of maghemite, with no detectable VB states introduced by the long-lived, reduced-iron sites in the oleic acid-coated sample. However, O K-edge absorption spectroscopy observed a 0.2 eV shift in the position of the lowest unoccupied …
Date: October 24, 2010
Creator: Gilbert, Benjamin; Katz, Jordan E.; Denlinger, Jonathan D.; Yin, Yadong; Falcone, Roger & Waychunas, Glenn A.
System: The UNT Digital Library
Development of the ITER Advanced Steady State and Hybrid Scenarios (open access)

Development of the ITER Advanced Steady State and Hybrid Scenarios

Full discharge simulations are performed to examine the plasma current rampup, flattop and rampdown phases self-consistently with the poloidal field (PF) coils and their limitations, plasma transport evolution, and heating/current drive (H/CD) sources. Steady state scenarios are found that obtain 100% non-inductive current with Ip = 7.3-10.0 MA, βN ~ 2.5 for H98 = 1.6, Q’s range from 3 to 6, n/nGr = 0.75-1.0, and NB, IC, EC, and LH source have been examined. The scenarios remain within CS/PF coil limits by advancing the pre-magnetization by 40 Wb. Hybrid scenarios have been identified with 35-40% non-inductive current for Ip = 12.5 MA, H98 ~ 1.25, with q(0) reaching 1 at or after the end of rampup. The equilibrium operating space for the hybrid shows a large range of scenarios can be accommodated, and access 925-1300 s flattop burn durations.
Date: September 24, 2010
Creator: Kessel, C. E.; Campbell, D.; Casper, T.; Gribov, Y. & Snipes, J.
System: The UNT Digital Library
Enhanced Constraints on theta13 from A Three-Flavor Oscillation Analysis of Reactor Antineutrinos at KamLAND (open access)

Enhanced Constraints on theta13 from A Three-Flavor Oscillation Analysis of Reactor Antineutrinos at KamLAND

We present new constraints on the neutrino oscillation parameters {Delta}m{sub 21}{sup 2}, {theta}{sub 12}, and {theta}{sub 13} from a three-flavor analysis of solar and KamLAND data. The KamLAND data set includes data acquired following a radiopurity upgrade and amounts to a total exposure of 3.49 x 10{sup 32} target-proton-year. Under the assumption of CPT invariance, a two-flavor analysis ({theta}{sub 13} = 0) of the KamLAND and solar data yields the best-fit values tan{sup 2} {theta}{sub 12} = 0.444{sub -0.030}{sup +0.036} and {Delta}m{sub 21}{sup 2} = 7.50{sub -0.20}{sup +0.19} x 10{sup -5} eV{sup 2}; a three-flavor analysis with {theta}{sub 13} as a free parameter yields the best-fit values tan{sup 2} {theta}{sub 12} = 0.452{sub -0.033}{sup +0.035}, {Delta}m{sub 21}{sup 2} = 7.50{sub -0.20}{sup +0.19} x 10{sup -5}eV{sup 2}, and sin{sup 2} {theta}{sub 13} = 0.020{sub -0.016}{sup +0.016}. This {theta}{sub 13} interval is consistent with other recent work combining the CHOOZ, atmospheric and long-baseline accelerator experiments. We also present a new global {theta}{sub 13} analysis, incorporating the CHOOZ, atmospheric and accelerator data, which indicates sin{sup 2} {theta}{sub 13} = 0.017{sub -0.009}{sup +0.010}, a nonzero value at the 93% C.L. This finding will be further tested by upcoming accelerator and reactor experiments.
Date: September 24, 2010
Creator: Collaboration, The KamLAND; Gando, A.; Gando, Y.; Ichimura, K.; Ikeda, H.; Inoue, K. et al.
System: The UNT Digital Library
Experiments and Simulations of ITER-like Plasmas in Alcator C-Mod (open access)

Experiments and Simulations of ITER-like Plasmas in Alcator C-Mod

Alcator C-Mod is performing ITER-like experiments to benchmark and verify projections to 15 MA ELMy H-mode Inductive ITER discharges. The main focus has been on the transient ramp phases. The plasma current in C-Mod is 1.3 MA and toroidal field is 5.4 T. Both Ohmic and ion cyclotron (ICRF) heated discharges are examined. Plasma current rampup experiments have demonstrated that (ICRF and LH) heating in the rise phase can save voltseconds (V-s), as was predicted for ITER by simulations, but showed that the ICRF had no effect on the current profile versus Ohmic discharges. Rampdown experiments show an overcurrent in the Ohmic coil (OH) at the H to L transition, which can be mitigated by remaining in H-mode into the rampdown. Experiments have shown that when the EDA H-mode is preserved well into the rampdown phase, the density and temperature pedestal heights decrease during the plasma current rampdown. Simulations of the full C-Mod discharges have been done with the Tokamak Simulation Code (TSC) and the Coppi-Tang energy transport model is used with modified settings to provide the best fit to the experimental electron temperature profile. Other transport models have been examined also. __________________________________________________
Date: September 24, 2010
Creator: Wilson, J. R.; Kessel, C. E.; Wolfe, S.; Hutchinson, I. H.; Bonoli, P.; Fiore, C. et al.
System: The UNT Digital Library
H5hut: A High-Performance I/O Library for Particle-based Simulations (open access)

H5hut: A High-Performance I/O Library for Particle-based Simulations

Particle-based simulations running on large high-performance computing systems over many time steps can generate an enormous amount of particle- and field-based data for post-processing and analysis. Achieving high-performance I/O for this data, effectively managing it on disk, and interfacing it with analysis and visualization tools can be challenging, especially for domain scientists who do not have I/O and data management expertise. We present the H5hut library, an implementation of several data models for particle-based simulations that encapsulates the complexity of HDF5 and is simple to use, yet does not compromise performance.
Date: September 24, 2010
Creator: Howison, Mark; Adelmann, Andreas; Bethel, E. Wes; Gsell, Achim; Oswald, Benedikt & Prabhat,
System: The UNT Digital Library
Through-Bond Interactions in the Diradical Intermediates Formed in the Rearrangements of Bicyclo[n.m.0]alkatetraenes (open access)

Through-Bond Interactions in the Diradical Intermediates Formed in the Rearrangements of Bicyclo[n.m.0]alkatetraenes

Article on through-bond interactions in the diradical intermediates formed in the rearrangements of bicyclo[n.m.0]alkatetraenes.
Date: September 24, 2010
Creator: Lovitt, Charity Flener; Dong, Hao; Hrovat, David A.; Gleiter, Rolf & Borden, Weston T.
System: The UNT Digital Library
Tuning HDF5 for Lustre File Systems (open access)

Tuning HDF5 for Lustre File Systems

HDF5 is a cross-platform parallel I/O library that is used by a wide variety of HPC applications for the flexibility of its hierarchical object-database representation of scientific data. We describe our recent work to optimize the performance of the HDF5 and MPI-IO libraries for the Lustre parallel file system. We selected three different HPC applications to represent the diverse range of I/O requirements, and measured their performance on three different systems to demonstrate the robustness of our optimizations across different file system configurations and to validate our optimization strategy. We demonstrate that the combined optimizations improve HDF5 parallel I/O performance by up to 33 times in some cases running close to the achievable peak performance of the underlying file system and demonstrate scalable performance up to 40,960-way concurrency.
Date: September 24, 2010
Creator: Howison, Mark; Koziol, Quincey; Knaak, David; Mainzer, John & Shalf, John
System: The UNT Digital Library
"Applications and future trends in polymer materials for green energy systems: from energy generation and storage, to CO2 capture and transportaion" (open access)

"Applications and future trends in polymer materials for green energy systems: from energy generation and storage, to CO2 capture and transportaion"

Presentation describes United Technologies Research Center's recent work in green energy systems, including APRA-E project content to create a synthetic analogue of the carbonic anhydrase enzyme and incorporate it into a membrane for CO2 separation from the flue gas of a coal power plant.
Date: August 24, 2010
Creator: Zafiris, George
System: The UNT Digital Library
Calibration of a High Resolution Grating Soft X-ray Spectrometer (open access)

Calibration of a High Resolution Grating Soft X-ray Spectrometer

None
Date: August 24, 2010
Creator: Magee, E. W.; Dunn, J.; Brown, G. V.; Cone, K. V.; Park, J.; Porter, F. S. et al.
System: The UNT Digital Library
An experimental and kinetic modeling study of n-octane and 2-methylheptane in an opposed-flow diffusion flame (open access)

An experimental and kinetic modeling study of n-octane and 2-methylheptane in an opposed-flow diffusion flame

None
Date: August 24, 2010
Creator: Sarathy, S M; Yeung, C; Westbrook, C K; Pitz, W J; Mehl, M & Thomson, M J
System: The UNT Digital Library
U.S. – Mexican War Veterans and the Congressional Pension Fight (open access)

U.S. – Mexican War Veterans and the Congressional Pension Fight

A draft of an article published in the journal Military History of the West about the challenges U.S. - Mexican War veterans faced receiving their pensions after the Civil War.
Date: August 24, 2010
Creator: Van Wagenen, Michael Scott
System: The UNT Digital Library
Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums (open access)

Demonstration of ignition radiation temperatures in indirect-drive inertial confinement fusion hohlraums

None
Date: July 24, 2010
Creator: Glenzer, S H; MacGowan, B J & Meezan, N B
System: The UNT Digital Library
Flavin-Catalyzed Insertion of Oxygen into Rhenium-Methyl Bonds (open access)

Flavin-Catalyzed Insertion of Oxygen into Rhenium-Methyl Bonds

Article discussing flavin-catalyzed insertion of oxygen into rhenium-methyl bonds.
Date: July 24, 2010
Creator: Pouy, Mark J.; Milczek, Erika M.; Figg, Travis M.; Otten, Brooke M.; Prince, Bruce M.; Gunnoe, T. Brent et al.
System: The UNT Digital Library
Assembling the Marine Metagenome, One Cell at a Time (open access)

Assembling the Marine Metagenome, One Cell at a Time

The difficulty associated with the cultivation of most microorganisms and the complexity of natural microbial assemblages, such as marine plankton or human microbiome, hinder genome reconstruction of representative taxa using cultivation or metagenomic approaches. Here we used an alternative, single cell sequencing approach to obtain high-quality genome assemblies of two uncultured, numerically significant marine microorganisms. We employed fluorescence-activated cell sorting and multiple displacement amplification to obtain hundreds of micrograms of genomic DNA from individual, uncultured cells of two marine flavobacteria from the Gulf of Maine that were phylogenetically distant from existing cultured strains. Shotgun sequencing and genome finishing yielded 1.9 Mbp in 17 contigs and 1.5 Mbp in 21 contigs for the two flavobacteria, with estimated genome recoveries of about 91percent and 78percent, respectively. Only 0.24percent of the assembling sequences were contaminants and were removed from further analysis using rigorous quality control. In contrast to all cultured strains of marine flavobacteria, the two single cell genomes were excellent Global Ocean Sampling (GOS) metagenome fragment recruiters, demonstrating their numerical significance in the ocean. The geographic distribution of GOS recruits along the Northwest Atlantic coast coincided with ocean surface currents. Metabolic reconstruction indicated diverse potential energy sources, including biopolymer degradation, proteorhodopsin photometabolism, …
Date: June 24, 2010
Creator: Woyke, Tanja; Xie, Gary; Copeland, Alex; Gonzalez, Jose M.; Han, Cliff; Kiss, Hajnalka et al.
System: The UNT Digital Library
Numerical Simulation of Phase Space Advection in Gyrokinetic Models of Fusion Plasmas (open access)

Numerical Simulation of Phase Space Advection in Gyrokinetic Models of Fusion Plasmas

None
Date: June 24, 2010
Creator: Dorr, M R; Cohen, R H; Colella, P; Hittinger, J A & Martin, D F
System: The UNT Digital Library
A Seemingly Simple Task: Filling a Solenoid Volume in Vacuum with Dense Plasma (open access)

A Seemingly Simple Task: Filling a Solenoid Volume in Vacuum with Dense Plasma

Space-charge neutralization of a pulsed, high-current ion beam is required to compress and focus the beam on a target for warm dense matter physics or heavy ion fusion experiments. We described attempts to produce dense plasma in and near the final focusing solenoid through which the ion beam travels, thereby providing an opportunity for the beam to acquire the necessary charge-compensating electrons. Among the options are plasma injection from four pulsed vacuum arc sources located outside the solenoid, and using a high current (> 4 kA) pulsed vacuum arc plasma from a ring cathode near the edge of the solenoid. The plasma distribution is characterized by photographic means and by an array of movable Langmuir probes. The plasma is produced at several cathode spots distributed azimuthally on the ring cathode. Beam neutralization and compression are accomplished, though issues of density, uniformity, and pulse-to-pulse reproducibly remain to be solved.
Date: June 24, 2010
Creator: Anders, Andre; Kauffeldt, Marina; Roy, Prabir & Oks, Efim
System: The UNT Digital Library
Steering the Self-Assembly of Octadecylamine Monolayers on Mica by Controlled Mechanical Energy Transfer from the AFM Tip (open access)

Steering the Self-Assembly of Octadecylamine Monolayers on Mica by Controlled Mechanical Energy Transfer from the AFM Tip

We have studied the effect of mechanical energy transfer from the tip of an Atomic Force Microscope on the dynamics of self-assembly of monolayer films of octadecylamine on mica. The formation of the self-assembled film proceeds in two successive stages, the first being a fast adsorption from solution that follows a Langmuir isotherm. The second is a slower process of island growth by aggregation of the molecules dispersed on the surface. We found that the dynamics of aggregation can be altered substantially by the addition of mechanical energy into the system through controlled tip-surface interactions. This leads to either the creation of pinholes in existing islands as a consequence of vacancy concentration, and to the assembly of residual molecules into more compact islands.
Date: June 24, 2010
Creator: Benitez, J.J.; Heredia-Guerrero, J.A. & Salmeron, M.
System: The UNT Digital Library
Distribution of Te inclusions in a CdZnTe wafer and their effects on the electrical properties of fabricated devices (open access)

Distribution of Te inclusions in a CdZnTe wafer and their effects on the electrical properties of fabricated devices

We quantified the size and concentration of Te-inclusions along the lateral- and the growth-directions of a {approx}6 mm thick wafer cut axially along the center of a CdZnTe ingot. We fabricated devices, selecting samples from the center slice outward in both directions, and then tested their response to incident x-rays. We employed, in concert, an automated IR transmission microscopic system and a highly collimated synchrotron X-ray source that allowed us to acquire and correlate comprehensive information on Te inclusions and other defects to assess the material factors limiting the performance of CdZnTe detectors.
Date: May 24, 2010
Creator: Hossain , A.; Xu, L.; Bolotnikov, A. E.; Camarda, G. S.; Cui, Y.; Yang, G. et al.
System: The UNT Digital Library
Local Magnitude Tomography in California (open access)

Local Magnitude Tomography in California

None
Date: May 24, 2010
Creator: Ford, S R; Uhrhammer, R A & Hellweg, M
System: The UNT Digital Library
Long Range Active Detection of HEU Based on Thermal Neutron Multiplication (open access)

Long Range Active Detection of HEU Based on Thermal Neutron Multiplication

We report on the results of measurements of proton irradiation on a series of targets at Brookhaven National Laboratory’s (BNL) Alternate Gradient Synchrotron Facility (AGS), in collaboration with LANL and SNL. We examined the prompt radiation environment in the tunnel for the DTRA-sponsored series (E 972), which investigated the penetration of air and subsequent target interaction of 4 GeV proton pulses. Measurements were made by means of an organic scintillator with a 500 MHz bandwidth system. We found that irradiation of a depleted uranium (DU) target resulted in a large gamma-ray signal in the 100-500 µsec time region after the proton flash when the DU was surrounded by polyethylene, but little signal was generated if it was surrounded by boron-loaded polyethylene. Subsequent Monte Carlo (MCNPX) calculations indicated that the source of the signal was consistent with thermal neutron capture in DU. The MCNPX calculations also indicated that if one were to perform the same experiment with a highly enriched uranium (HEU) target there would be a distinctive fast neutron yield in this 100-500 µsec time region from thermal neutron-induced fission. The fast neutrons can be recorded by the same direct current system and differentiated from gamma ray pulses in organic …
Date: May 24, 2010
Creator: L., Forman; I., Dioszegi; Salwen, C. & and Vanier, P.E.
System: The UNT Digital Library