Resource Type

103 Matching Results

Results open in a new window/tab.

Overview of the nearby supernova factory (open access)

Overview of the nearby supernova factory

The Nearby Supernova Factory (SNfactory) is an international experiment designed to lay the foundation for the next generation of cosmology experiments (such as CFHTLS, wP, SNAP and LSST) which will measure the expansion history of the Universe using Type Ia supernovae. The SNfactory will discover and obtain frequent lightcurve spectrophotometry covering 3200-10000 {angstrom} for roughly 300 Type Ia supernovae at the low-redshift end of the smooth Hubble flow. The quantity, quality, breadth of galactic environments, and homogeneous nature of the SNfactory dataset will make it the premier source of calibration for the Type Ia supernova width-brightness relation and the intrinsic supernova colors used for K-correction and correction for extinction by host-galaxy dust. This dataset will also allow an extensive investigation of additional parameters which possibly influence the quality of Type Ia supernovae as cosmological probes. The SNfactory search capabilities and follow-up instrumentation include wide-field CCD imagers on two 1.2-m telescopes (via collaboration with the Near Earth Asteroid Tracking team at JPL and the QUEST team at Yale), and a two-channel integral-field-unit optical spectrograph/imager being fabricated for the University of Hawaii 2.2-m telescope. In addition to ground-based follow-up, UV spectra for a subsample of these supernovae will be obtained with HST. …
Date: July 29, 2002
Creator: Aldering, Greg; Adam, Gilles; Antilogus, Pierre; Astier, Pierre; Bacon, Roland; Bongard, S. et al.
System: The UNT Digital Library
Infinitely Large New Dimensions (open access)

Infinitely Large New Dimensions

We construct intersecting brane configurations in Anti-de-Sitter space localizing gravity to the intersection region, with any number n of extra dimensions. This allows us to construct two kinds of theories with infinitely large new dimensions, TeV scale quantum gravity and sub-millimeter deviations from Newton's Law. The effective 4D Planck scale M{sub Pl} is determined in terms of the fundamental Planck scale M{sub *} and the AdS radius of curvature L via the familiar relation M{sub Pl}{sup 2} {approx} M{sub *}{sup 2+n} L{sup n}; L acts as an effective radius of compactification for gravity on the intersection. Taking M{sub *} {approx} TeV and L {approx} sub-mm reproduces the phenomenology of theories with large extra dimensions. Alternately, taking M{sub *} {approx} L{sup -1} {approx} M{sub Pl}, and placing our 3-brane a distance {approx} 100M{sub Pl}{sup -1} away from the intersection gives us a theory with an exponential determination of the Weak/Planck hierarchy.
Date: July 29, 1999
Creator: Arkani-Hamed, Nima; Dimopoulos, Savas; Dvali, Gia & Kaloper, Nemanja
System: The UNT Digital Library
High Level Waste Tank Closure Modeling with Geographic Information Systems (GIS) (open access)

High Level Waste Tank Closure Modeling with Geographic Information Systems (GIS)

Waste removal from 49 underground storage tanks located in two tank farms involves three steps: bulk waste removal, water washing to remove residual waste, and in some cases chemical cleaning to remove additional residual waste. Not all waste can be completely removed by these processes-resulting in some residual waste loading following cleaning. Completely removing this residual waste would be prohibitively expensive; therefore, it will be stabilized by filling the tanks with grout. Acceptable residual waste loading inventories were determined using one-dimensional groundwater transport modeling to predict future human exposure based on several scenarios. These modeling results have been incorporated into a geographic information systems (GIS) application for rapid evaluation of various tank closure options.
Date: July 29, 2004
Creator: BOLLINGER, JAMES
System: The UNT Digital Library
Vibratory response of a precision double-multi-layer monochromator positioning system using a generic modeling program with experimental verification. (open access)

Vibratory response of a precision double-multi-layer monochromator positioning system using a generic modeling program with experimental verification.

A generic vibratory response-modeling program has been developed as a tool for designing high-precision optical positioning systems. The systems are modeled as rigid-body structures connected by linear non-rigid elements such as complex actuators and bearings. The full dynamic properties of each non-rigid element are determined experimentally or theoretically, then integrated into the program as inertial and stiffness matrices. Thus, it is possible to have a suite of standardize structural elements for modeling many different positioning systems that use standardized components. This paper will present the application of this program to a double-multi-layer monochromator positioning system that utilizes standardized components. Calculated results are compared to experimental modal analysis results.
Date: July 29, 1998
Creator: Barraza, J.
System: The UNT Digital Library
Rh(I)-Catalyzed Direct Arylation of Pyridines and Quinolines (open access)

Rh(I)-Catalyzed Direct Arylation of Pyridines and Quinolines

The pyridine and quinoline nuclei are privileged scaffolds that occupy a central role in many medicinally relevant compounds. Consequently, methods for their expeditious functionalization are of immediate interest. However, despite the immense importance of transition-metal catalyzed cross-coupling for the functionalization of aromatic scaffolds, general solutions for coupling 2-pyridyl organometallics with aryl halides have only recently been presented. Direct arylation at the ortho position of pyridine would constitute an even more efficient approach because it eliminates the need for the stoichiometric preparation and isolation of 2-pyridyl organometallics. Progress towards this goal has been achieved by activation of the pyridine nucleus for arylation via conversion to the corresponding pyridine N-oxide or N-iminopyridinium ylide. However, this approach necessitates two additional steps: activation of the pyridine or quinoline starting material, and then unmasking the arylated product. The use of pyridines directly would clearly represent the ideal situation both in terms of cost and simplicity. We now wish to document our efforts in this vein, culminating in an operationally simple Rh(I)-catalyzed direct arylation of pyridines and quinolines. We recently developed an electron-rich Rh(I) system for catalytic alkylation at the ortho position of pyridines and quinolines with alkenes. Therefore, we initially focused our attention on the …
Date: July 29, 2008
Creator: Berman, Ashley; Lewis, Jared; Bergman, Robert & Ellman, Jonathan
System: The UNT Digital Library
Accelerating Network Traffic Analytics Using Query-DrivenVisualization (open access)

Accelerating Network Traffic Analytics Using Query-DrivenVisualization

Realizing operational analytics solutions where large and complex data must be analyzed in a time-critical fashion entails integrating many different types of technology. This paper focuses on an interdisciplinary combination of scientific data management and visualization/analysis technologies targeted at reducing the time required for data filtering, querying, hypothesis testing and knowledge discovery in the domain of network connection data analysis. We show that use of compressed bitmap indexing can quickly answer queries in an interactive visual data analysis application, and compare its performance with two alternatives for serial and parallel filtering/querying on 2.5 billion records worth of network connection data collected over a period of 42 weeks. Our approach to visual network connection data exploration centers on two primary factors: interactive ad-hoc and multiresolution query formulation and execution over n dimensions and visual display of then-dimensional histogram results. This combination is applied in a case study to detect a distributed network scan and to then identify the set of remote hosts participating in the attack. Our approach is sufficiently general to be applied to a diverse set of data understanding problems as well as used in conjunction with a diverse set of analysis and visualization tools.
Date: July 29, 2006
Creator: Bethel, E. Wes; Campbell, Scott; Dart, Eli; Stockinger, Kurt & Wu,Kesheng
System: The UNT Digital Library
Spectroscopy of N=82,83 {sup 136,137}Xe isotopes from {sup 248}Cm fission. (open access)

Spectroscopy of N=82,83 {sup 136,137}Xe isotopes from {sup 248}Cm fission.

Prompt {gamma}-ray cascades in neutron-rich nuclei around doubly magic {sup 132}Sn have been studied at Eurogam II using a {sup 348}Cm fission source. Here they report results for the four-valence-proton N = 82 nucleus {sup 136}Xe and for its N = 83 neighbor {sup 137}Xe. For both nuclei, the yrast level spectra have been considerably extended, and empirical nucleon-nucleon interactions have been used to assign probable shell model configurations for most of the observed levels.
Date: July 29, 1998
Creator: Bhattacharyya, P.
System: The UNT Digital Library
Lattice disorder and magnetism in f-electron intermetallics (open access)

Lattice disorder and magnetism in f-electron intermetallics

Real materials can have real differences compared to ideal systems. For instance, non-Fermi liquid (NFL) behavior was initially thought to be due to chemical disorder, since the first such materials were all substituted. Although several nominally well-ordered NFL's have been discovered and extensively studied, the effect of disorder on the magnetic properties of f-electron intermetallic systems remains poorly understood. Disorder in NFL systems is reviewed from an experimental, local structure point of view, including a discussion of results on the nominally ordered U{sub 3}Ni{sub 3}Sn{sub 4} and CeCoIn{sub 5} systems, and the chemically disordered UCu{sub 4}Pd and CeRhRuSi{sub 2} systems.
Date: July 29, 2004
Creator: Booth, C.H.; Han, S.-W.; Skanthakumar, S. & Sarrao, J.L.
System: The UNT Digital Library
Fabrication and Test of 90-mm Nb3Sn Quadrupole Model Based on Dipole-type Collar (open access)

Fabrication and Test of 90-mm Nb3Sn Quadrupole Model Based on Dipole-type Collar

A series of 90-mm TQC quadrupole models with a collar-based mechanical structure has been fabricated and tested within the framework of the US-LHC Accelerator Research Program (LARP) using quadrupole-symmetric stainless steel collar laminations. This paper describes the design features, construction and test of TQC02Eb, the first TQC made with dipole-type collar and collaring techniques. Magnet test includes quench performance and field quality measurements at 4.5 and 1.9 K. Results of model performance for TQC quadrupoles based on dipole-type and quadrupole-type collars are compared and discussed.
Date: July 29, 2010
Creator: Bossert, R.; Andreev, N.; Chlachidze, G.; Kashikhin, V. S.; Kashikhin, V. V.; Lamm, M. J. et al.
System: The UNT Digital Library
Strain measurement by diffraction at LANSCE (open access)

Strain measurement by diffraction at LANSCE

Residual strains affect the structural integrity of components during both fabrication and service and consequently industrial manufacturers routinely invest considerable effort in their characterization and control. Neutron diffraction has proved to be a unique technique for non-destructive strain measurement within crystalline solids. The technique is achieving recognition but is limited by lack of beam time and compromises involved in using instruments designed for powder diffraction. This paper summarizes its importance, lists the capabilities of the Los Alamos (pulsed) neutron scattering center (LANSCE) and briefly describes a concept for a dedicated instrument.
Date: July 29, 1994
Creator: Bourke, Mark A. M.; Goldstone, Joyce A. & Robinson, R. A.
System: The UNT Digital Library
Shock Compressing Diamond to a Conducting Fluid (open access)

Shock Compressing Diamond to a Conducting Fluid

Laser generated shock reflectance data show that diamond undergoes a continuous transition from optically absorbing to reflecting between Hugoniot pressures 600<P{sub H}<1000 GPa. The data are consistent with diamond having a thermal population of carriers at P{sub H}{approx}600 GPa, undergoing band overlap metallization at P{sub H}{approx}1000 GPa and melting at 800<P{sub H}<1000 GPa. The results agree well with an equation of state model that predicts that elemental carbon remains solid throughout the interior of Neptune.
Date: July 29, 2004
Creator: Bradley, D K; Eggert, J H; Hicks, D G; Celliers, P M; Moon, S J; Cauble, R C et al.
System: The UNT Digital Library
Enantioselective Catalysis of the Aza-Cope Rearrangement by a Chiral Supramolecular Assembly (open access)

Enantioselective Catalysis of the Aza-Cope Rearrangement by a Chiral Supramolecular Assembly

The chiral supramolecular catalyst Ga{sub 4}L{sub 6} [L = 1,5-bis(2,3-dihydroxybenzoylamino)naphthalene] is a molecular tetrahedron that catalyzes the 3-aza-Cope rearrangement of allyl enammonium cations. This catalysis is accomplished by preorganizing the substrate in a reactive conformation within the host. This work demonstrates that through the use of enantiopure assembly, its chiral cavity is capable of catalyzing the 3-aza-Cope rearrangement enantioselectively, with yields of 21-74% and enantiomeric excesses from 6 to 64% at 50 C. At lower temperatures, the enantioselectivity improved, reaching 78% ee at 5 C. This is the highest enantioselectivity to date induced by the chiral cavity of a supramolecular assembly.
Date: July 29, 2009
Creator: Brown, Casey J.; Bergman, Robert G. & Raymond, Kenneth N.
System: The UNT Digital Library
Control of beam dynamics in high energy induction linacs (open access)

Control of beam dynamics in high energy induction linacs

The Advent of laser-ion-guiding in the Advanced test Accelerator along with the development of accelerator cavities optimized with respect to beam breakup coupling impedence now make it possible to consider a new class of high current, high emergy linear induction accelerators. The control of the beam breakup and other instabilities by laser guiding and by various magnetic focusing schemes will be discussed along with the scaling laws for the design of such machines to minimize the growth of the beam breakup instability. Many linacs, particularly induction linacs are limited in performance by the beam breakup (BBU) instability. The instability is found in two forms. In the first form the accelerating cavities communicate with one another through interaction with the beam and through propagation of cavity fields through the accelerator structure. In the second form which is the more virulent of the two, the cavities couple to each other only through their interactions with the beam. It is this second form of PPU that will be discussed in this paper.
Date: July 29, 1986
Creator: Caporaso, G.J.
System: The UNT Digital Library
Electrical properties of sand-clay mixtures: the effect of microstructure (open access)

Electrical properties of sand-clay mixtures: the effect of microstructure

We have performed a series of laboratory experiments on saturated sand-clay mixtures. Measurements include frequency-dependent electrical properties using the four-electrode technique (10 mHz to 1 MHz), permeability, porosity, and acoustic velocities. We mixed clean quartz sand with Na-montmorillonite in a number of different configurations containing 0 to 10% clay: as a dispersed mixture, as discrete clay clusters, and arranged in distinct layers. Solutions of CaCl{sub 2} ranging from 0.0005 N to 0.75 N (0.05 to 64 mS/cm) and deionized water were used as saturating fluids. We found the electrical properties to be dependent on clay content, fluid conductivity, and microstructure in a complex fashion. Increasing fluid conductivity and increasing clay content generally resulted in higher electrical conductivity. For an individual sample, two main regions of conduction exist: a region dominated by surface conduction and a region where the ionic strength of the saturating fluid controlled conduction. The sample geometry (dispersed, non-dispersed, or layered clay configuration) was found to greatly affect the magnitude of the surface conductance in the range of low fluid conductivity.
Date: July 29, 1999
Creator: Carlberg, E. D.; Roberts, J. J. & Wildenschild, D.
System: The UNT Digital Library
Growth phenomena in the surface layer and step generation from the edges of faceted crystals (open access)

Growth phenomena in the surface layer and step generation from the edges of faceted crystals

The mechanism of growth step generation from the edges of faceted crystals obtained from experimental results with KDP crystals is described. It shows that growth from the crystal edges is initiated by the deviation of the edges from their crystallographic orientation and formation of incomplete shapes of singular facets. The conditions for formation of the incomplete faceted shapes during dislocation growth are considered. It is shown that the process of step generation from the edges is determined by the mutual positions of the vicinal slopes on the adjacent faces.
Date: July 29, 1999
Creator: Carman, L.; Smolsky, I. & Zaitseva, N. P.
System: The UNT Digital Library
Evaluating clearance in the context of effluent release practices. (open access)

Evaluating clearance in the context of effluent release practices.

Within the next few decades, several million tons of scrap materials (such as metals or concrete) are expected to be removed from nuclear facilities across the world as a result of decontamination and decommissioning activities. Although much of the materials are expected to be free of radioactive contents, some will contain above-background concentrations of residual radioactive material. In many cases, materials containing or potentially containing above-background residual radioactive material have been disposed through burial at licensed facilities. However, some of the materials may be in the form of expensive equipment or devices that are still useful, and the incentive to recover them is high. Others may be expensive raw materials such as nickel, copper, or high-quality stainless steel that can easily be recovered by recycling. Yet another category, which includes carbon steel or concrete, is bulky and requires considerable space for burial. Although the value of these latter materials may not be significant, disposition options such as recycling present an attractive option for alleviating the limited burial capacity and the ever-increasing disposal costs at licensed burial facilities.
Date: July 29, 1999
Creator: Chen, S. Y.
System: The UNT Digital Library
FastQuery: A Parallel Indexing System for Scientific Data (open access)

FastQuery: A Parallel Indexing System for Scientific Data

Modern scientific datasets present numerous data management and analysis challenges. State-of-the- art index and query technologies such as FastBit can significantly improve accesses to these datasets by augmenting the user data with indexes and other secondary information. However, a challenge is that the indexes assume the relational data model but the scientific data generally follows the array data model. To match the two data models, we design a generic mapping mechanism and implement an efficient input and output interface for reading and writing the data and their corresponding indexes. To take advantage of the emerging many-core architectures, we also develop a parallel strategy for indexing using threading technology. This approach complements our on-going MPI-based parallelization efforts. We demonstrate the flexibility of our software by applying it to two of the most commonly used scientific data formats, HDF5 and NetCDF. We present two case studies using data from a particle accelerator model and a global climate model. We also conducted a detailed performance study using these scientific datasets. The results show that FastQuery speeds up the query time by a factor of 2.5x to 50x, and it reduces the indexing time by a factor of 16 on 24 cores.
Date: July 29, 2011
Creator: Chou, Jerry; Wu, Kesheng & Prabhat,
System: The UNT Digital Library
Status and Plans for an SRF Accelerator Test Facility at Fermilab (open access)

Status and Plans for an SRF Accelerator Test Facility at Fermilab

A superconducting RF accelerator test facility is currently under construction at Fermilab. The accelerator will consist of an electron gun, 40 MeV injector, beam acceleration section consisting of 3 TTF-type or ILC-type cryomodules, and multiple downstream beam lines for testing diagnostics and performing beam experiments. With 3 cryomodules installed this facility will initially be capable of generating an 810 MeV electron beam with ILC beam intensity. The facility can accommodate up to 6 cryomodules for a total beam energy of 1.5 GeV. This facility will be used to test SRF cryomodules under high intensity beam conditions, RF power equipment, instrumentation, and LLRF and controls systems for future SRF accelerators such as the ILC and Project-X. This paper describes the current status and overall plans for this facility.
Date: July 29, 2011
Creator: Church, M.; Leibfritz, J. & Nagaitsev, S.
System: The UNT Digital Library
Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers (open access)

Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers

This report was prepared to talk about Challenges of Investigating Fluid-Elastic Lock-In of a Shallow Cavity and a Cantilevered Beam at Low Mach Numbers
Date: July 29, 2005
Creator: Cody, K Lai-Fook; Hambric, SA & Pollack, ML
System: The UNT Digital Library
Null-plane invariance of Hamiltonian null-plane dynamics. (open access)

Null-plane invariance of Hamiltonian null-plane dynamics.

Relativistic Hamiltonian few-body dynamics [1,2] involves two unitary representations of the Poincare group on the Hilbert space H of physical states, with and without interactions. These two representations, U({Lambda}, a) and U{sub 0}({Lambda},a), coincide for a kinematic subgroup H. The ''Hamiltonians'' are the generators not in the Lie algebra of the kinematic subgroup. The kinematic subgroup of null-plane dynamics leaves the null-plane z {center_dot} x {triple_bond} x{sup 0} + x{sub 3} = 0 invariant. Few-body Hamiltonians satisfying the required commutation relations can be constructed as functions of a mass operator and kinematic quantities. For more than two particles there are nontrivial problems in satisfying cluster separability. [3] Consistency of electro-weak interactions with strong interactions also involves significant problems: Poincare covariance of current operators requires the construction of appropriate interaction currents.
Date: July 29, 1998
Creator: Coester, F.
System: The UNT Digital Library
The influence of pre-irradiation heat treatments on thermal non-equilibrium and radiation-induced segregation behavior in model austenitic stainless steel alloys. (open access)

The influence of pre-irradiation heat treatments on thermal non-equilibrium and radiation-induced segregation behavior in model austenitic stainless steel alloys.

The effect of pre-irradiation heat treatments on thermal non-equilibrium grain boundary segregation (TNES) and subsequent radiation-induced grain boundary segregation (RIS) is studied in a series of model austenitic stainless steels. The alloys used for this study are based on AISI 316 stainless steel and have the following nominal compositions: Fe-16Cr-13Ni-1.25Mn (base 316), Fe-16Cr-13Ni-1.25Mn-2.0Mo (316 + Mo) and Fe-16Cr-13Ni-1.25Mn-2.0Mo-0.07P (316 + Mo + P). Samples were heat treated at temperatures ranging from 1100 to 1300 C and cooled at 4 different rates (salt brine quench, water quench, air cool and furnace cool) to evaluate the effect of annealing temperature and quench rate on TNES. The alloys were than processed with the treatment (temperature and cooling rate) that resulted in the maximum Cr enrichment. Alloys with and without the heat treatment to enrich the grain boundaries with Cr were characterized following irradiation to 1 dpa at 400 C with high-energy protons in order to understand the influence of alloying additions and pre-irradiation grain boundary chemistry on irradiation-induced elemental enrichment and depletion profiles. Various mechanistic models will be examined to explain the observed behavior.
Date: July 29, 2002
Creator: Cole, J. I.; Allen, T. R.; Was, G. S.; Dropek, R. B. & Kenik, E. A.
System: The UNT Digital Library
The Little Randall-Sundrum Model at the LHC (open access)

The Little Randall-Sundrum Model at the LHC

We present a predictive warped model of flavor, cut off at an ultraviolet scale {Omicron}(10{sup 3}) TeV, called the 'Little Randall-Sundrum (LRS)' model. This model corresponds to a volume-truncation, by a factor y {approx} 6, of the RS scenario and is holographically dual to dynamics with number of colors larger by y. With separate gauge and flavor dynamics, several unwanted contributions to precision electroweak, Zb{bar b}, and flavor observables are suppressed in the LRS framework, compared with the corresponding RS case. The LRS truncation leads to a significant enhancement of the clean (golden) di-lepton LHC signals, by {Omicron}(y{sup 3}).
Date: July 29, 2008
Creator: Davoudiasl, H.
System: The UNT Digital Library
Historians at Work in the SLAC Archives: An Archivist's Perspective (open access)

Historians at Work in the SLAC Archives: An Archivist's Perspective

None
Date: July 29, 2013
Creator: Deken, Jean Marie
System: The UNT Digital Library
Certification of Superconducting Solenoid-Based Focusing Lenses (open access)

Certification of Superconducting Solenoid-Based Focusing Lenses

The first production focusing lens for the HINS beam line at Fermilab has been assembled into a cryostat and tested. A total of 5 devices will be tested before they are installed in the low energy section of the HINS beam line, which uses copper Crossbar-H (CH) style RF cavities. One of the tested CH-section lens assemblies includes a pair of weak orthogonal steering dipoles nested within a strong focusing solenoid, and has six vapor cooled power leads. The other device has only the strong focusing solenoid, and utilizes a single pair of HTS power leads. The production test program is designed to measure the thermal performance of the cryostat, minimum cooling requirements for the HTS leads, quench performance of all superconducting components, and precise determination of the magnetic axis and field angles. Results and future plans for the first production device tests are presented.
Date: July 29, 2010
Creator: DiMarco, E.Joseph; Hemmati, Ali M.; Orris, Darryl F.; Page, Thomas M.; Rabehl, Roger H.; Tartaglia, Michael A. et al.
System: The UNT Digital Library