Study of the $\tau^- to 3h^- 2h^+ \nu_\tau$ Decay (open access)

Study of the $\tau^- to 3h^- 2h^+ \nu_\tau$ Decay

The branching fraction of the {tau}{sup -} {yields} 3h{sup -} 2h{sup +} {nu}{sub {tau}} decay (h = {pi}, K) is measured with the BABAR detector to be (8.56 {+-} 0.05 {+-} 0.42) x 10{sup -4}, where the first error is statistical and the second systematic. The observed structure of this decay is significantly different from the phase space prediction, with the {rho} resonance playing a strong role. The decay {tau}{sup -} {yields} f{sub 1}(1285){pi}{sup -}{nu}{sub {tau}}, with the f{sub 1}(1285) meson decaying to four charged pions, is observed and the branching fraction is measured to be (3.9 {+-} 0.7 {+-} 0.5) x 10{sup -4}.
Date: May 4, 2005
Creator: Aubert, Bernard; Barate, R.; Boutigny, D.; Couderc, F.; Karyotakis, Y.; Lees, J. P. et al.
Object Type: Article
System: The UNT Digital Library
Design and performance of soft gamma-ray detector for NeXT mission (open access)

Design and performance of soft gamma-ray detector for NeXT mission

The Soft Gamma-ray Detector (SGD) on board NeXT (Japanese future high energy astrophysics mission) is a Compton telescope with narrow field of view, which utilizes Compton kinematics to enhance its background rejection capabilities. It is realized as a hybrid semiconductor gamma-ray detector which consists of silicon and Cadmium Telluride (CdTe) detectors. It can detect photons in an energy band 0.05-1 MeV at a background level of 5 x 10{sup -7} counts/s/cm{sup 2}/keV; the silicon layers are required to improve the performance at a lower energy band (<0.3 MeV). Excellent energy resolution is the key feature of the SGD to achieve both high angular resolution and good background rejection capability. Its ability to measure gamma-ray polarization opens up a new window to study gamma-ray emission in the universe. We will present the development of key technologies to realize the SGD; high quality CdTe, low noise front-end VLSI and bump bonding technology. Energy resolutions of 1.7 keV (FWHM) for CdTe pixel detectors and 1.1 keV for silicon strip detectors have been measured. We also present the validation of Monte Carlo simulation used to evaluate the performance of the SGD.
Date: May 4, 2005
Creator: Tajima, H.; Kamae, T.; Madejski, G.; Takahashi, T.; Nakazawa, K.; Watanabe, S. et al.
Object Type: Article
System: The UNT Digital Library
Dynamic apeerture in damping rings with realistic wigglers (open access)

Dynamic apeerture in damping rings with realistic wigglers

The International Linear Collider based on superconducting RF cavities requires the damping rings to have extremely small equilibrium emittance, huge circumference, fast damping time, and large acceptance. To achieve all of these requirements is a very challenging task. In this paper, we will present a systematic approach to designing the damping rings using simple cells and non-interlaced sextupoles. The designs of the damping rings with various circumferences and shapes, including dogbone, are presented. To model realistic wigglers, we have developed a new hybrid symplectic integrator for faster and accurate evaluation of dynamic aperture of the lattices.
Date: May 4, 2005
Creator: Cai, Yunhai
Object Type: Article
System: The UNT Digital Library
Chemical states and electronic structure of a HfO(-2) / Ge(001) interface (open access)

Chemical states and electronic structure of a HfO(-2) / Ge(001) interface

We report the chemical bonding structure and valence band alignment at the HfO{sub 2}/Ge (001) interface by systematically probing various core level spectra as well as valence band spectra using soft x-rays at the Stanford Synchrotron Radiation Laboratory. We investigated the chemical bonding changes as a function of depth through the dielectric stack by taking a series of synchrotron photoemission spectra as we etched through the HfO{sub 2} film using a dilute HF-solution. We found that a very non-stoichiometric GeO{sub x} layer exists at the HfO{sub 2}/Ge interface. The valence band spectra near the Fermi level in each different film structure were carefully analyzed, and as a result, the valence band offset between Ge and GeO{sub x} was determined to be {Delta}E{sub v} (Ge-GeO{sub x}) = 2.2 {+-} 0.15 eV, and that between Ge and HfO{sub 2}, {Delta}E{sub v} (Ge-HfO{sub 2}) = 2.7 {+-} 0.15 eV.
Date: May 4, 2005
Creator: Seo, Kang-ill; McIntyre, Paul C.; /Stanford U., Materials Sci. Dept.; Sun, Shiyu; Lee, Dong-Ick; Pianetta, Piero et al.
Object Type: Report
System: The UNT Digital Library
Technical Analysis of the Hydrogen Energy Station Concept, Phase I and Phase II (open access)

Technical Analysis of the Hydrogen Energy Station Concept, Phase I and Phase II

Phase I Due to the growing interest in establishing a domestic hydrogen infrastructure, several hydrogen fueling stations already have been established around the country as demonstration units. While these stations help build familiarity with hydrogen fuel in their respective communities, hydrogen vehicles are still several years from mass production. This limited number of hydrogen vehicles translates to a limited demand for hydrogen fuel, a significant hurdle for the near-term establishment of commercially viable hydrogen fueling stations. By incorporating a fuel cell and cogeneration system with a hydrogen fueling station, the resulting energy station can compensate for low hydrogen demand by providing both hydrogen dispensing and combined heat and power (CHP) generation. The electrical power generated by the energy station can be fed back into the power grid or a nearby facility, which in turn helps offset station costs. Hydrogen production capacity not used by vehicles can be used to support building heat and power loads. In this way, an energy station can experience greater station utility while more rapidly recovering capital costs, providing an increased market potential relative to a hydrogen fueling station. At an energy station, hydrogen is generated on-site. Part of the hydrogen is used for vehicle refueling …
Date: May 4, 2005
Creator: TIAX, LLC
Object Type: Report
System: The UNT Digital Library
Final Report DOE Grant No. DE-FG02-03ER83817 Integrated Reactor Design for Hydrogen Production from Biomass-Sourced Reactants Streams Using the Aqueous-Phase Carbohydrate Reforming (ACR) Process (open access)

Final Report DOE Grant No. DE-FG02-03ER83817 Integrated Reactor Design for Hydrogen Production from Biomass-Sourced Reactants Streams Using the Aqueous-Phase Carbohydrate Reforming (ACR) Process

In this Phase I Small Business Innovation research project Virent Energy Systems (Virent) attempted to demonstrate the feasibility of generating high yields of hydrogen by developing the appropriate reactor system for the novel liquid-phase reforming of aqueous-phase carbohydrate streams derived from biomass. In this project platinum-based catalysts were initially utilized to establish the technical feasibility of reactor design for reforming carbohydrates found in biomass to hydrogen.
Date: May 4, 2005
Creator: Cortright, Randy D.
Object Type: Report
System: The UNT Digital Library
White Paper on Ion Beam Transport for ICF: Issues, R&D Need,and Tri-Lab Plans (open access)

White Paper on Ion Beam Transport for ICF: Issues, R&D Need,and Tri-Lab Plans

To date, most resources for ion beam fusion have been devoted to development of accelerators and target physics; relatively few resources have gone into ion beam transport development. Because of theoretical studies and substantial experience with electron beam transport, the ion beam transport community is now poised to develop and optimize ion beam transport for ICF. Because of this Tri-Lab effort, a path for coordinated development of ion beam transport has been established. The rate of progress along this path will now be determined largely by the availability of resources.
Date: May 4, 2005
Creator: Olson, C.; Lee, E. & Langdon, B.
Object Type: Report
System: The UNT Digital Library
Reduction in Energy Consumption & Variability in Steel Foundry Operations (open access)

Reduction in Energy Consumption & Variability in Steel Foundry Operations

This project worked to improve the efficiency of the steel casting industry by reducing the variability that occurs because of process and product variation. The project focused on the post shakeout operations since roughly half of the production costs are in this area. These improvements will reduce the amount of variability, making it easier to manage the operation and improve the competitiveness. The reduction in variability will also reduce the need for many rework operations, which will result in a direct reduction of energy usage, particularly by the reduction of repeated heat treatment operations. Further energy savings will be realized from the reduction of scrap and reduced handling. Field studies were conducted at ten steel foundries that represented the U.S. steel casting industry, for a total of over 100 weeks of production observation. These studies quantified the amount of variability, and looked toward determining the source. A focus of the data collected was the grinding operations since this is a major effort in the cleaning room, and it represents the overall casting quality. The grinding was divided into two categories, expected and unexpected. Expected grinding is that in which the location of the effort is known prior to making the …
Date: May 4, 2005
Creator: Peters, Frank
Object Type: Report
System: The UNT Digital Library
Precision measurement of the weak mixing angle in Moller scattering (open access)

Precision measurement of the weak mixing angle in Moller scattering

We report on a precision measurement of the parity-violating asymmetry in fixed target electron-electron (Moeller) scattering: A{sub PV} = (-131 {+-} 14 (stat.) {+-} 10 (syst.)) x 10{sup -9}, leading to the determination of the weak mixing angle sin{sup 2} {theta}{sub W}{sup eff} = 0.2397 {+-} 0.0010 (stat.) {+-} 0.0008 (syst.), evaluated at Q{sup 2} = 0.026 GeV{sup 2}. Combining this result with the measurements of sin{sup 2} {theta}{sub W}{sup eff} at the Z{sup 0} pole, the running of the weak mixing angle is observed with over 6{sigma} significance. The measurement sets constraints on new physics effects at the TeV scale.
Date: May 4, 2005
Creator: Anthony, P. L.; Arnold, R. G.; Arroyo, C.; Bega, K.; Biesiada, J.; Bosted, P. E. et al.
Object Type: Article
System: The UNT Digital Library
Forensic Medicine: Age Written in Teeth by Nuclear Bomb Tests (open access)

Forensic Medicine: Age Written in Teeth by Nuclear Bomb Tests

Establishing the age of individuals is an important step in identification and a frequent challenge in forensic medicine. This can be done with high precision up to adolescence by analysis of dentition, but establishing the age of adults has remained difficult. Here we show that measuring {sup 14}C from nuclear bomb tests in tooth enamel provides a sensitive way to establish when a person was born.
Date: May 4, 2005
Creator: Lawrence Livermore National Laboratory
Object Type: Article
System: The UNT Digital Library
Prediction and Measurement of Phase Transformations, Phase-Dependent Properties and Residual Stresses in Steels (open access)

Prediction and Measurement of Phase Transformations, Phase-Dependent Properties and Residual Stresses in Steels

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Date: May 4, 2005
Creator: Becker, M.; Jordan, C.; Lachhander, S. K.; Mengel, A. & Renauld, M.
Object Type: Article
System: The UNT Digital Library