Core-Collapse Supernovae and Host Galaxy Stellar Populations (open access)

Core-Collapse Supernovae and Host Galaxy Stellar Populations

We have used images and spectra of the Sloan Digital Sky Survey to examine the host galaxies of 519 nearby supernovae. The colors at the sites of the explosions, as well as chemical abundances, and specific star formation rates of the host galaxies provide circumstantial evidence on the origin of each supernova type. We examine separately SN II, SN IIn, SN IIb, SN Ib, SN Ic, and SN Ic with broad lines (SN Ic-BL). For host galaxies that have multiple spectroscopic fibers, we select the fiber with host radial offset most similar to that of the SN. Type Ic SN explode at small host offsets, and their hosts have exceptionally strongly star-forming, metal-rich, and dusty stellar populations near their centers. The SN Ic-BL and SN IIb explode in exceptionally blue locations, and, in our sample, we find that the host spectra for SN Ic-BL show lower average oxygen abundances than those for SN Ic. SN IIb host fiber spectra are also more metal-poor than those for SN Ib, although a significant difference exists for only one of two strong-line diagnostics. SN Ic-BL host galaxy emission lines show strong central specific star formation rates. In contrast, we find no strong evidence …
Date: April 5, 2013
Creator: Kelly, Patrick L.; /KIPAC, Menlo Park /SLAC; Kirshner, Robert P. & Astrophys., /Harvard-Smithsonian Ctr.
Object Type: Article
System: The UNT Digital Library
Engine Materials Compatability with Alternative Fuels (open access)

Engine Materials Compatability with Alternative Fuels

The compatibility of aluminum and aluminum alloys with synthetic fuel blends comprised of ethanol and reference fuel C (a 50/50 mix of toluene and iso-octane) was examined as a function of water content and temperature. Commercially pure wrought aluminum and several cast aluminum alloys were observed to be similarly susceptible to substantial corrosion in dry (< 50 ppm water) ethanol. Corrosion rates of all the aluminum materials examined were accelerated by increased temperature and ethanol content in the fuel mixture, but inhibited by increased water content. Pretreatments designed to stabilize passive films on aluminum increased the incubation time for onset of corrosion, suggesting film stability is a significant factor in the mechanism of corrosion.
Date: April 5, 2013
Creator: Pawel, Steve & Moore, D.
Object Type: Report
System: The UNT Digital Library
Experimental Study of Turbulent Mixing in the Richtmyer-Meshkov Instability (open access)

Experimental Study of Turbulent Mixing in the Richtmyer-Meshkov Instability

None
Date: April 5, 2013
Creator: Weber, C R; Haehn, N S; Oakley, J; Rothamer, D & Bonazza, R
Object Type: Article
System: The UNT Digital Library
Gamma Lines without a Continuum: Thermal Models for the Fermi-LAT 130 GeV Gamma Line (open access)

Gamma Lines without a Continuum: Thermal Models for the Fermi-LAT 130 GeV Gamma Line

None
Date: April 5, 2013
Creator: Bai, Yang; /SLAC /Wisconsin U., Madison; Shelton, Jessie & U., /Yale
Object Type: Article
System: The UNT Digital Library
The generation of efficient supported (Heterogeneous) olefin metathesis catalysts (open access)

The generation of efficient supported (Heterogeneous) olefin metathesis catalysts

Over the past decade, a new family of homogeneous metathesis catalysts has been developed that will tolerate most organic functionalities as well as water and air. These homogeneous catalysts are finding numerous applications in the pharmaceutical industry as well as in the production of functional polymers. In addition the catalysts are being used to convert seed oils into products that can substitute for those that are now made from petroleum products. Seed oils are unsaturated, contain double bonds, and are a ready source of linear hydrocarbon fragments that are specifically functionalized. To increase the number of applications in the area of biomaterial conversion to petrol chemicals, the activity and efficiency of the catalysts need to be as high as possible. The higher the efficiency of the catalysts, the lower the cost of the conversion and a larger number of practical applications become available. Active supported catalysts were prepared and tested in the conversion of seed oils and other important starting materials. The outcome of the work was successful and the technology has been transferred to a commercial operation to develop viable applications of the discovered systems. A biorefinery that converts seed oils is under construction in Indonesia. The catalysts developed …
Date: April 5, 2013
Creator: Grubbs, Robert H.
Object Type: Report
System: The UNT Digital Library
Nuclear Fabrication Consortium (open access)

Nuclear Fabrication Consortium

This report summarizes the activities undertaken by EWI while under contract from the Department of Energy (DOE) – Office of Nuclear Energy (NE) for the management and operation of the Nuclear Fabrication Consortium (NFC). The NFC was established by EWI to independently develop, evaluate, and deploy fabrication approaches and data that support the re-establishment of the U.S. nuclear industry: ensuring that the supply chain will be competitive on a global stage, enabling more cost-effective and reliable nuclear power in a carbon constrained environment. The NFC provided a forum for member original equipment manufactures (OEM), fabricators, manufacturers, and materials suppliers to effectively engage with each other and rebuild the capacity of this supply chain by : • Identifying and removing impediments to the implementation of new construction and fabrication techniques and approaches for nuclear equipment, including system components and nuclear plants. • Providing and facilitating detailed scientific-based studies on new approaches and technologies that will have positive impacts on the cost of building of nuclear plants. • Analyzing and disseminating information about future nuclear fabrication technologies and how they could impact the North American and the International Nuclear Marketplace. • Facilitating dialog and initiate alignment among fabricators, owners, trade associations, and …
Date: April 5, 2013
Creator: Levesque, Stephen
Object Type: Report
System: The UNT Digital Library
Regulation of Electrochemically Generated Ferrous Ions from an Iron Cathode for Pd-Catalytic Transformation of MTBE in Groundwater (open access)

Regulation of Electrochemically Generated Ferrous Ions from an Iron Cathode for Pd-Catalytic Transformation of MTBE in Groundwater

None
Date: April 5, 2013
Creator: Liao, P; Yuan, S; Chen, M; Tong, M; Xie, W & Zhang, P
Object Type: Article
System: The UNT Digital Library
A Test for Emergent Dynamics (open access)

A Test for Emergent Dynamics

None
Date: April 5, 2013
Creator: Hook, Anson
Object Type: Article
System: The UNT Digital Library
US LHCNet: Transatlantic Networking for the LHC and the U.S. HEP Community (open access)

US LHCNet: Transatlantic Networking for the LHC and the U.S. HEP Community

US LHCNet provides the transatlantic connectivity between the Tier1 computing facilities at the Fermilab and Brookhaven National Labs and the Tier0 and Tier1 facilities at CERN, as well as Tier1s elsewhere in Europe and Asia. Together with ESnet, Internet2, and other R&E Networks participating in the LHCONE initiative, US LHCNet also supports transatlantic connections between the Tier2 centers (where most of the data analysis is taking place) and the Tier1s as needed. Given the key roles of the US and European Tier1 centers as well as Tier2 centers on both continents, the largest data flows are across the Atlantic, where US LHCNet has the major role. US LHCNet manages and operates the transatlantic network infrastructure including four Points of Presence (PoPs) and currently six transatlantic OC-192 (10Gbps) leased links. Operating at the optical layer, the network provides a highly resilient fabric for data movement, with a target service availability level in excess of 99.95%. This level of resilience and seamless operation is achieved through careful design including path diversity on both submarine and terrestrial segments, use of carrier-grade equipment with built-in high-availability and redundancy features, deployment of robust failover mechanisms based on SONET protection schemes, as well as the design …
Date: April 5, 2013
Creator: Newman, Harvey B. & Barczyk, Artur J.
Object Type: Report
System: The UNT Digital Library
Conceptual Design - Polar Drive Ignition Campaign (open access)

Conceptual Design - Polar Drive Ignition Campaign

The Laboratory for Laser Energetics (LLE) at the University of Rochester is proposing a collaborative effort with Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratories (LANL), the Naval Research Laboratory (NRL), and General Atomics (GA) with the goal of developing a cryogenic polar drive (PD) ignition platform on the National Ignition Facility (NIF). The scope of this proposed project requires close discourse among theorists, experimentalists, and laser and system engineers. This document describes how this proposed project can be broken into a series of parallel independent activities that, if implemented, could deliver this goal in the 2017 timeframe. This Conceptual Design document is arranged into two sections: mission need and design requirements. Design requirements are divided into four subsystems: (1) A point design that details the necessary target specifications and laser pulse requirements; (2) The beam smoothing subsystem that describes the MultiFM 1D smoothing by spectral dispersion (SSD); (3) New optical elements that include continuous phase plates (CPP's) and distributed polarization rotators (DPR's); and (4) The cryogenic target handling and insertion subsystem, which includes the design, fabrication, testing, and deployment of a dedicated PD ignition target insertion cryostat (PD-ITIC). This document includes appendices covering: the primary criteria and functional …
Date: April 5, 2012
Creator: Hansen, R
Object Type: Report
System: The UNT Digital Library
Discovery of Very High Energy Gamma Rays from PKS 1424+240 and Multiwavelength Constraints on its Redshift (open access)

Discovery of Very High Energy Gamma Rays from PKS 1424+240 and Multiwavelength Constraints on its Redshift

We report the first detection of very-high-energy (VHE) gamma-ray emission above 140GeV from PKS 1424+240, a BL Lac object with an unknown redshift. The photon spectrum above 140GeV measured by VERITAS is well described by a power law with a photon index of 3.8 {+-}0.5{sub stat} {+-} 0.3{sub syst} and a flux normalization at 200 GeV of (5.1 {+-} 0.9{sub stat} {+-} 0.5{sub syst}) x 10{sup -11} TeV{sup -1} cm{sup -2} s{sup -1}, where stat and syst denote the statistical and systematical uncertainty, respectively. The VHE flux is steady over the observation period between MJD 54881 and 55003 (2009 February 19 to June 21). Flux variability is also not observed in contemporaneous high energy observations with the Fermi Large Area Telescope (LAT). Contemporaneous X-ray and optical data were also obtained from the Swift XRT and MDM observatory, respectively. The broadband spectral energy distribution (SED) is well described by a one-zone synchrotron self-Compton (SSC) model favoring a redshift of less than 0.1. Using the photon index measured with Fermi in combination with recent extragalactic background light (EBL) absorption models it can be concluded from the VERITAS data that the redshift of PKS 1424+240 is less than 0.66.
Date: April 5, 2012
Creator: Acciari, V. A.; Aliu, E.; Arlen, T.; Aune, T.; Bautista, M.; Beilicke, M. et al.
Object Type: Report
System: The UNT Digital Library
Dynamic structure factor in warm dense beryllium (open access)

Dynamic structure factor in warm dense beryllium

None
Date: April 5, 2012
Creator: Glenzer, S H; Fortmann, C; Doeppner, T; Plagemann, K U; Sperling, P; Thiele, R et al.
Object Type: Article
System: The UNT Digital Library
Expert Unreviewed Safety Question Determinations (USQD) (open access)

Expert Unreviewed Safety Question Determinations (USQD)

None
Date: April 5, 2012
Creator: Mitchell, M A & Montgomery, P
Object Type: Article
System: The UNT Digital Library
Final Report (open access)

Final Report

The purpose of this project was to better understand the 'Multiscale Dynamics of Relaxor Ferroelectrics'. The output of the project is summarized in the narrative. The results of the work were presented at a number of different conferences and four papers were written, the references to which are also indicated in the report and which have also been uploaded on e-link. The multiscale dynamics of relaxors was clearly identified in the three characteristic temperatures that were identified. In particular, we were the first group to identify an intermediate temperature, T*, at which the correlations between off-center ions in relaxor cross-over from being dynamic to being static and giving rise to the characteristic relaxor behavior in the dielectric constant. Other groups have now confirmed the existence of such an intermediate temperature. We also made and reported two other observations: (1) a coherent interference phenomena (EIT-like effect) near the transition of several relaxors, which provides information on the nature and mechanism of the transition; and (2) in a similar way, inelastic neutron scattering results were interpreted as resonant scattering of acoustic phonons by localized modes in polar nanodomains. In parallel with the neutron scattering work, we also developed a theory of the …
Date: April 5, 2012
Creator: Toulouse, J.
Object Type: Report
System: The UNT Digital Library
Layout And Results From The Initial Opeeration Of The High-resolution X-ray Imaging Crystal Spectrometer On The Large Helical Device (open access)

Layout And Results From The Initial Opeeration Of The High-resolution X-ray Imaging Crystal Spectrometer On The Large Helical Device

First results of ion and electron temperature pro le measurements from the x-ray imaging crystal spectrometer (XICS) diagnostic on the Large Helical Device (LHD) are presented. This diagnostic system has been operational since the beginning of the 2011 LHD experimental campaign and is the rst application of the XICS diagnostic technique to helical plasma geometry. The XICS diagnostic provides measurements of ion and electron temperature pro les in LHD with a spatial resolution of 2cm and a time resolution of ≥#21; 10ms. Ion temperature pro les from the XICS diagnostic are possible under conditions where charge exchange recombination spectroscopy (CXRS) is not possible (high density) or is perturbative to the plasma (low density or radio frequency heated plasmas). Measurements are made by using a spherically bent crystal to provide a spectrally resolved 1D image of the plasma from line integrated emission of helium-like Ar16+. The nal hardware design and con guration are detailed along with the calibration procedures. Line-integrated ion and electron temperature measurements are presented, and the measurement accuracy is discussed. Finally central temperature measurements from the XICS system are compared to measurements from the Thomson scattering and CXRS systems, showing excellent agreement.
Date: April 5, 2012
Creator: Pablant, N A; Delgado-Apricio, L; Goto, M; Hill, K W; Lzerson, S; Morita, S et al.
Object Type: Report
System: The UNT Digital Library
Muon Muon Collider: Feasibility Study (open access)

Muon Muon Collider: Feasibility Study

A feasibility study is presented of a 2 + 2 TeV muon collider with a luminosity of L = 10{sup 35} cm{sup -2}s{sup -1}. The resulting design is not optimized for performance, and certainly not for cost; however, it does suffice - we believe - to allow us to make a credible case, that a muon collider is a serious possibility for particle physics and, therefore, worthy of R and D support so that the reality of, and interest in, a muon collider can be better assayed. The goal of this support would be to completely assess the physics potential and to evaluate the cost and development of the necessary technology. The muon collider complex consists of components which first produce copious pions, then capture the pions and the resulting muons from their decay; this is followed by an ionization cooling channel to reduce the longitudinal and transverse emittance of the muon beam. The next stage is to accelerate the muons and, finally, inject them into a collider ring wich has a small beta function at the colliding point. This is the first attempt at a point design and it will require further study and optimization. Experimental work will be …
Date: April 5, 2012
Creator: Gallardo, J. C.; Palmer, R. B.; Tollestrup, A. V.; Sessler, A. M.; Skrinsky, A. N.; Geer, S. et al.
Object Type: Article
System: The UNT Digital Library
Observation of Laser Induced Magnetization Dynamics in Co/Pd Multilayers with Coherent X-ray Scattering (open access)

Observation of Laser Induced Magnetization Dynamics in Co/Pd Multilayers with Coherent X-ray Scattering

We report on time-resolved coherent x-ray scattering experiments of laser induced magnetization dynamics in Co/Pd multilayers with a high repetition rate optical pump x-ray probe setup. Starting from a multi-domain ground state, the magnetization is uniformly reduced after excitation by an intense 50 fs laser pulse. Using the normalized time correlation, we study the magnetization recovery on a picosecond timescale. The dynamic scattering intensity is separated into an elastic portion at length scales above 65 nm which retains memory of the initial domain magnetization, and a fluctuating portion at smaller length scales corresponding to domain boundary motion during recovery.
Date: April 5, 2012
Creator: Wu, Benny
Object Type: Article
System: The UNT Digital Library
Review of the WECC EDT phase 2 EIM benefits analysis and results report. (open access)

Review of the WECC EDT phase 2 EIM benefits analysis and results report.

A region-wide Energy Imbalance Market (EIM) was recently proposed by the Western Electricity Coordinating Council (WECC). In order for the Western Area Power Administration (Western) to make more informed decisions regarding its involvement in the EIM, Western asked Argonne National Laboratory (Argonne) to review the EIM benefits study (the October 2011 revision) performed by Energy and Environmental Economics, Inc. (E3). Key components of the E3 analysis made use of results from a study conducted by the National Renewable Energy Laboratory (NREL); therefore, we also reviewed the NREL work. This report examines E3 and NREL methods and models used in the EIM study. Estimating EIM benefits is very challenging because of the complex nature of the Western Interconnection (WI), the variability and uncertainty of renewable energy resources, and the complex decisions and potentially strategic bidding of market participants. Furthermore, methodologies used for some of the more challenging aspects of the EIM have not yet matured. This review is complimentary of several components of the EIM study. Analysts and modelers clearly took great care when conducting detailed simulations of the WI using well-established industry tools under stringent time and budget constraints. However, it is our opinion that the following aspects of the …
Date: April 5, 2012
Creator: Veselka, T.D.; Poch, L.A. & Botterud, A. (Decision and Information Sciences)
Object Type: Report
System: The UNT Digital Library
Search for a Low-Mass Higgs Boson (A0) at BaBar (open access)

Search for a Low-Mass Higgs Boson (A0) at BaBar

The BABAR Collaboration has performed three searches for a light Higgs boson, A{sup 0}, in radiative Upsilon ({Upsilon}) decays: {Upsilon}(3S) {yields} {gamma}A{sup 0}, A{sup 0} {yields} {tau}{sup +}{tau}{sup -}; {Upsilon}(nS) {yields} {gamma}A{sup 0}, A{sup 0} {yields} {mu}{sup +}{mu}{sup -} (n = 2,3); and {Upsilon}(3S) {yields} {gamma}A{sup 0}, A{sup 0} {yields} invisible. Such a Higgs boson (A{sup 0}) appears in the Next-to-Minimal Supersymmetric extensions of the Standard Model, where a light CP-odd Higgs boson couples strongly to b-quarks. The searches are based on data samples that consist of 122 x 10{sup 6} {Upsilon}(3S) and 99 x 10{sup 6} {Upsilon}(2S) decays, collected by the BABAR detector at the SLAC National Accelerator Laboratory. The searches reveal no evidence for an A{sup 0}, and product of branching fractions upper limits, at 90% C.L., of (1.5-16) x 10{sup -5}, (0.44-44) x 10{sup -6}, and (0.7-31) x 10{sup -6} were obtained for these searches, respectively. Also, we set the upper limits {Beta}({eta}{sub b} {yields} {tau}{sup +}{tau}{sup -}) < 8% and {Beta}({eta}{sub b} {yields} {mu}{sup +}{mu}{sup -}) < 0.9%.
Date: April 5, 2012
Creator: Mokhtar, Arafat Gabareen
Object Type: Article
System: The UNT Digital Library
Switchgrass Demonstration Project (open access)

Switchgrass Demonstration Project

Develop a pilot study that establishes up to 120 acres of cropland in switchgrass and 20 acres on a TN Experiment Station Farm. This subtask would assess production of switchgrass within the state of Tennessee under a variety of conditions and topography through on-farm production totaling 120 acres. Farms would be selected to participate through a bid process. Costs of establishment and maintenance of the switchgrass would be covered. In addition, allowances would be made for covering land rent and providing a yield incentive. An information and education program would be provided to producers prior to the bid process to assist producers in their bid decision. Agronomic, logistic, energy conversion and farming system issues associated with commercialization of a biomass energy industry are evaluated. Information on the opportunities for producing switchgrass as an energy feedstock are extended
Date: April 5, 2012
Creator: Ugarte, Burton C. English and Daniel De La Torre
Object Type: Report
System: The UNT Digital Library
Two- and Three-Body Charmless B Decays at BaBar (open access)

Two- and Three-Body Charmless B Decays at BaBar

We report recent measurements of rare charmless B decays performed by BaBar. The results are based on the final BaBar dataset of 424 fb{sup -1} collected at the PEP-II B-factory based at the SLAC National Accelerator Laboratory. The study of rare B decays is a key ingredient to meet two of the main goals of the B-factories: assessing the validity of the Cabibbo-Kobayashi-Maskawa (CKM) picture of CP-violation by precisely measuring the elements of the Unitarity Triangle (UT), and searching for hints of New Physics (NP), or otherwise constraining NP scenarios, in processes which are suppressed in the Standard Model (SM). In loop processes, in particular, NP at some higher energy scale may manifest itself in the low energy effective theory as new couplings, such as those introduced by new very massive virtual particles in the loop. In NP searches hadronic uncertainties can play a major role, expecially for branching fraction measurements. Many theoretical uncertainties cancel in ratios of amplitudes, and most NP probes are therefore of this kind. In the following sections we report recent measurements, performed by the BaBar Collaboration, that are relevant to NP searches in charmless hadronic B decays.
Date: April 5, 2012
Creator: Stracka, Simone
Object Type: Article
System: The UNT Digital Library
Unitarity Bounds and RG Flows in Time Dependent Quantum Field Theory (open access)

Unitarity Bounds and RG Flows in Time Dependent Quantum Field Theory

We generalize unitarity bounds on operator dimensions in conformal field theory to field theories with spacetime dependent couplings. Below the energy scale of spacetime variation of the couplings, their evolution can strongly affect the physics, effectively shifting the infrared operator scaling and unitarity bounds determined from correlation functions in the theory. We analyze this explicitly for large-N double-trace flows, and connect these to UV complete field theories. One motivating class of examples comes from our previous work on FRW holography, where this effect explains the range of flavors allowed in the dual, time dependent, field theory.
Date: April 5, 2012
Creator: Dong, Xi; Horn, Bart; Silverstein, Eva; Torroba, Gonzalo & /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC
Object Type: Report
System: The UNT Digital Library
Ab initio Guided Optimization of GaTe for Radiation Detection Applications (open access)

Ab initio Guided Optimization of GaTe for Radiation Detection Applications

None
Date: April 5, 2011
Creator: Leao, C R & Lordi, V
Object Type: Article
System: The UNT Digital Library
Case for an Improved Effective-Atomic-Number for the Electronic Baggage Scanning Program (open access)

Case for an Improved Effective-Atomic-Number for the Electronic Baggage Scanning Program

Z{sub eff}, a parameter representing an 'effective atomic number' for a material, plays an important role in the Electronic Baggage Scanning Program (EBSP) to detect threats in dual-energy computed tomography (CT) baggage-scanning systems. We believe that Z{sub eff}, as defined and used on this program, does not provide the accurate representation of a material's x-ray absorption properties that is needed by the EBSP. We present the case for a new method that defines an effective atomic number for compounds and mixtures, which we refer to as Z{sub e}. Unlike Z{sub eff}, Z{sub e} is tied by definition to the x-ray absorption properties of each specific material. Use of this alternative will provide a more accurate scale for calibrating Micro-CT and EDS systems against standard reference materials and will provide a more accurate physical characterization of the x-ray properties of materials evaluated on those systems. This document: (1) Describes the current usage of the Z{sub eff} parameter; (2) Details problems entailed in the use of the Z{sub eff} parameter; (3) Proposes a well-defined alternative - Z{sub e}; (4) Proposes and demonstrates an algorithm for optimally associating Z{sub e} with any specified compound or mixture; (5) Discusses issues that can impact the …
Date: April 5, 2011
Creator: Smith, J. A.; Martz, H. E. & Kallman, J. S.
Object Type: Report
System: The UNT Digital Library