Physical results from 2+1 flavor domain wall QCD (open access)

Physical results from 2+1 flavor domain wall QCD

We review recent results for the chiral behavior of meson masses and decay constants and the determination of the light quark masses by the RBC and UKQCD collaborations. We find that one-loop SU(2) chiral perturbation theory represents the behavior of our lattice data better than one-loop SU(3) chiral perturbation theory in both the pion and kaon sectors. The simulations have been performed using the Iwasaki gauge action at two different lattice spacings with the physical spatial volume held approximately fixed at (2.7fm){sup 3}. The Domain Wall fermion formulation was used for the 2+1 dynamical quark flavors: two (mass degenerate) light flavors with masses as light as roughly 1/5 the mass of the physical strange quark mass and one heavier quark flavor at approximately the value of the physical strange quark mass, On the ensembles generated with the coarser lattice spacing, we obtain for the physical average up- and down-quark and strange quark masses m{sub ud}{sup {ovr MS}} (2 GeV) = 3.72(0.16){sub stat}(0.33){sub ren}(0.18){sub syst}MeV and m{sub s}{sup {ovr MS}} (2 GeV) = 107.3(4.4){sub stat}(9.7){sub ren}(4.9){sub syst} MeV, respectively, while they find for the pion and kaon decay constants f{sub {pi}} = 124.1(3.6){sub stat}(6.9){sub syst}MeV, f{sub K} = 149.6(3.6){sub stat}(6.3){sub syst} …
Date: July 14, 2008
Creator: Scholz,E.E.
System: The UNT Digital Library
Thermal and mechanical joints to cryo-cooled silicon monochromatorcrystals (open access)

Thermal and mechanical joints to cryo-cooled silicon monochromatorcrystals

We describe the performance of various materials used as thethermal interface between silicon to silicon and silicon to copper jointswhen operated at ~;120K and loaded with ~;20 watts of thermal power. Wefind that only the indium based silicon-to-silicon joint isreliable.
Date: July 14, 2006
Creator: MacDowell, A.; Fakra, S. & Morrison, G.
System: The UNT Digital Library
Adversary Modeling for Allocation of Effort Across Countermeasures (open access)

Adversary Modeling for Allocation of Effort Across Countermeasures

None
Date: July 14, 2006
Creator: Lathrop, J F
System: The UNT Digital Library
TTF HOM Data Analysis with Curve Fitting Method (open access)

TTF HOM Data Analysis with Curve Fitting Method

To investigate the possibility of using HOM signals induced in SC cavities as beam and cavity diagnostics, narrow band (20 MHz) data was recorded around the strong TE111-6(6{pi}/9-like) dipole modes (1.7 GHz) in the 40 L-band (1.3 GHz) cavities at the DESY TTF facility. The analyses of these data have so far focused on using a Singular Value Decomposition (SVD) technique to correlate the signals with each other and data from conventional BPMs to show the dipole signals provide an alternate means of measuring the beam trajectory. However, these analyses do not extract the modal information (i.e., frequencies and Q's of the nearly degenerate horizontal and vertical modes). In this paper, we described a method to fit the signal frequency spectrum to obtain this information, and then use the resulting mode amplitudes and phases together with conventional BPM data to determine the mode polarizations and relative centers and tilts. Compared with the SVD analysis, this method is more physical, and can also be used to obtain the beam position and trajectory angle.
Date: July 14, 2009
Creator: Pei, S.; Adolphsen, C.; Li, Z.; Bane, K. & Smith, J.
System: The UNT Digital Library
The evolution of Ga and As core levels in the formation of Fe/GaAs (001):A high resolution soft x-ray photoelectron spectroscopic study (open access)

The evolution of Ga and As core levels in the formation of Fe/GaAs (001):A high resolution soft x-ray photoelectron spectroscopic study

A high resolution soft x-ray photoelectron spectroscopic study of Ga and As 3d core levels has been conducted for Fe/GaAs (001) as a function of Fe thickness. This work has provided unambiguous evidence of substrate disrupting chemical reactions induced by the Fe overlayer--a quantitative analysis of the acquired spectra indicates significantly differing behavior of Ga and As during Fe growth, and our observations have been compared with existing theoretical models. Our results demonstrate that the outdiffusing Ga and As remain largely confined to the interface region, forming a thin intermixed layer. Whereas at low coverages Fe has little influence on the underlying GaAs substrate, the onset of substrate disruption when the Fe thickness reaches 3.5 Angstrom results in major changes in the energy distribution curves (EDCs) of both As and Ga 3d cores. Our quantitative analysis suggests the presence of two additional As environments of metallic character: one bound to the interfacial region and another which, as confirmed by in situ oxidation experiments, surface segregates and persists over a wide range of overlayer thickness. Analysis of the corresponding Ga 3d EDCs found not two, but three additional environments--also metallic in nature. Two of the three are interface resident whereas the …
Date: July 14, 2008
Creator: Thompson, Jamie; Neal, James; Shen, Tiehan; Morton, Simon; Tobin, James; Waddill, George Dan et al.
System: The UNT Digital Library
Performance of the upgraded LTP-II at the ALS Optical Metrology Laboratory (open access)

Performance of the upgraded LTP-II at the ALS Optical Metrology Laboratory

The next generation of synchrotrons and free electron laser facilities requires x-ray optical systems with extremely high performance, generally of diffraction limited quality. Fabrication and use of such optics requires adequate, highly accurate metrology and dedicated instrumentation. Previously, we suggested ways to improve the performance of the Long Trace Profiler (LTP), a slope measuring instrument widely used to characterize x-ray optics at long spatial wavelengths. The main way is use of a CCD detector and corresponding technique for calibration of photo-response non-uniformity [J. L. Kirschman, et al., Proceedings of SPIE 6704, 67040J (2007)]. The present work focuses on the performance and characteristics of the upgraded LTP-II at the ALS Optical Metrology Laboratory. This includes a review of the overall aspects of the design, control system, the movement and measurement regimes for the stage, and analysis of the performance by a slope measurement of a highly curved super-quality substrate with less than 0.3 microradian (rms)slope variation.
Date: July 14, 2008
Creator: Source, Advanced Light; Yashchuk, Valeriy V; Kirschman, Jonathan L.; Domning, Edward E.; McKinney, Wayne R.; Morrison, Gregory Y. et al.
System: The UNT Digital Library
Improved Measurement of B^ \to\rho^ \rho^0 and Determination of the Quark-Mixing Phase Angle~\alpha (open access)

Improved Measurement of B^ \to\rho^ \rho^0 and Determination of the Quark-Mixing Phase Angle~\alpha

The authors present improved measurements of the branching fraction {Beta}, the longitudinal polarization fraction f{sub L}, and the direct CP asymmetry A{sub CP} in the B meson decay channel B{sup +} {yields} {rho}{sup +}{rho}{sup 0}. The data sample was collected with the BABAR detector at SLAC. The results are {Beta}(B{sup +} {yields} {rho}{sup +}{rho}{sup 0}) = (23.7 {+-} 1.4 {+-} 1.4) x 10{sup -6}, f{sub L} = 0.950 {+-} 0.015 {+-} 0.006, and A{sub CP} = -0.054 {+-} 0.055 {+-} 0.010, where the uncertainties are statistical and systematic, respectively. Based on these results, they perform an isospin analysis and determine the CKM weak phase angle {alpha} to be (92.4{sub -6.5}{sup +6.0}){sup 0}.
Date: July 14, 2009
Creator: Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X. et al.
System: The UNT Digital Library
Optimization of Carbon Coatings on LiFePO4 (open access)

Optimization of Carbon Coatings on LiFePO4

The electrochemical performance of LiFePO{sub 4} in lithium cells is strongly dependent on the structure (disordered/graphene or D/G ratio) of the in situ carbon produced during synthesis from carbon-containing precursors. Addition of pyromellitic acid (PA) prior to final calcination results in lower D/G ratios, yielding a higher-rate material. Further, improvements in electrochemical performance are realized when graphitization catalysts such as ferrocene are also added during LiFePO{sub 4} preparation, although overall carbon content is still less than 2 wt.%.
Date: July 14, 2005
Creator: Doeff, Marca M.; Wilcox, James D.; Kostecki, Robert & Lau, Grace
System: The UNT Digital Library
Nondipole Effects in Xe 4d Photoemission (open access)

Nondipole Effects in Xe 4d Photoemission

We measured the nondipole parameters for the spin-orbit doublets Xe 4d{sub 5/2} and Xe 4d{sub 3/2} over a photon-energy range from 100 eV to 250 eV at beamline 8.0.1.3 of the Advanced Light Source at the Lawrence Berkeley National Laboratory. Significant nondipole effects are found at relatively low energies as a result of Cooper minima in dipole channels and interchannel coupling in quadrupole channels. Most importantly, sharp disagreement between experiment and theory, when otherwise excellent agreement was expected, has provided the first evidence of satellite two-electron quadrupole photoionization transitions, along with their crucial importance for a quantitatively accurate theory.
Date: July 14, 2004
Creator: Hemmers, O; Guillemin, R; Wolska, A; Lindle, D W; Rolles, D.; Cheng, K T et al.
System: The UNT Digital Library
Comparative Plutonium-239 Dose Assessment for Three Desert Sites: Maralinga, Australia; Palomares, Spain; and the Nevada Test Site, USA - Before and After Remedial Action (open access)

Comparative Plutonium-239 Dose Assessment for Three Desert Sites: Maralinga, Australia; Palomares, Spain; and the Nevada Test Site, USA - Before and After Remedial Action

As a result of nuclear weapons testing and accidents, plutonium has been distributed into the environment. The areas close to the sites of these tests and accidental dispersions contain plutonium deposition of such a magnitude that health authorities and responsible officials have mandated that the contaminated areas be protected, generally through isolation or removal of the contaminated areas. In recent years remedial actions have taken place at all these sites. For reasons not entirely clear, the public perceives radiation exposure risk to be much greater than the evidence would suggest [1]. This perception seems to be particularly true for plutonium, which has often been ''demonized'' in various publications as the ''most hazardous substance known to man'' [2]. As the position statement adapted by the Health Physics Society explains, ''Plutonium's demonization is an example of how the public has been misled about radiation's environmental and health threats generally, and in cases like plutonium, how it has developed a warped ''risk perception'' that does not reflect reality'' [3]. As a result of this risk perception and ongoing debate surrounding environmental plutonium contamination, remedial action criteria are difficult to establish. By examining the data available before and after remedial actions taken at the …
Date: July 14, 2000
Creator: Church, B. W.; Shinn, J.; Williams, G. A.; Martin, L. J.; O'Brien, R. S. & Adams, S. R.
System: The UNT Digital Library
Radioisotope Electric Propulsion for Deep Space Sample Return (open access)

Radioisotope Electric Propulsion for Deep Space Sample Return

The need to answer basic questions regarding the origin of the Solar System will motivate robotic sample return missions to destinations like Pluto, its satellite Charon, and objects in the Kuiper belt. To keep the mission duration short enough to be of interest, sample return from objects farther out in the Solar System requires increasingly higher return velocities. A sample return mission involves several complicated steps to reach an object and obtain a sample, but only the interplanetary return phase of the mission is addressed in this paper. Radioisotope electric propulsion is explored in this parametric study as a means to propel small, dedicated return vehicles for transferring kilogram-size samples from deep space to Earth. Return times for both Earth orbital rendezvous and faster, direct atmospheric re-entry trajectories are calculated for objects as far away as 100 AU. Chemical retro-rocket braking at Earth is compared to radioisotope electric propulsion but the limited deceleration capability of chemical rockets forces the return trajectories to be much slower.
Date: July 14, 2009
Creator: Noble, Robert J.
System: The UNT Digital Library
Hybrid MOSFET/Driver for Ultra-Fast Switching (open access)

Hybrid MOSFET/Driver for Ultra-Fast Switching

The ultra-fast switching of power MOSFETs, in about 1ns, is very challenging. This is largely due to the parasitic inductance that is intrinsic to commercial packages used for both MOSFETs and drivers. Parasitic gate and source inductance not only limit the voltage rise time on the MOSFET internal gate structure but can also cause the gate voltage to oscillate. This paper describes a hybrid approach that substantially reduces the parasitic inductance between the driver and MOSFET gate, as well as between the MOSFET source and its external connection. A flip chip assembly is used to directly attach a die-form power MOSFET and driver on a PCB. The parasitic inductances are significantly reduced by eliminating bond wires and minimizing lead length. The experimental results demonstrate ultra-fast switching of the power MOSFET with excellent control of the gate-source voltage.
Date: July 14, 2009
Creator: Tang, T
System: The UNT Digital Library
Perterbative O(asa) matching in static heavy and domain-wall light quark system (open access)

Perterbative O(asa) matching in static heavy and domain-wall light quark system

We discuss the perturbative O(a{sub s}a) matching in the static heavy and domain-wall light quark system. The gluon action is the Iwasaki action and the link smearing is performed in the static heavy action. The chiral symmetry of the light quark realized by using the domain-wall fermion formulation does not prohibit the mixing of the operators at O(a). The application of O(a) improvement to the actual data shows that the B meson decay constant f{sub B}, the matrix elements M{sub B} and the B parameter B{sub B} have non-negligible effects, while the effect on the SU(3) breaking ratio {zeta} is small.
Date: July 14, 2008
Creator: Ishikawa,T.
System: The UNT Digital Library
Probing Structure Property Relationships in Complex Engineering Silicones by 1H NMR (open access)

Probing Structure Property Relationships in Complex Engineering Silicones by 1H NMR

It is generally accepted that the properties of polymeric materials are controlled by the network structure and the reactions by which they have been constructed. These properties include the bulk moduli at creation, but also the properties as a function of age during use. In order to interpret mechanical properties and predict the time dependent changes in these properties, detailed knowledge of the effect of structural changes must be obtained. The degree and type of crosslinking, the molecular weight between crosslinks, the number of elastically ineffective chains (loops, dangling chain ends, sol-fraction) must be characterized. A number of theoretical and experimental efforts have been reported in the last few years on model networks prepared by endlinking reactions and the relationships of those structures with the ultimate mechanical properties. A range of experimental methods have been used to investigate structure including rheometric, scattering, infrared, {sup 29}Si MAS and CPMAS, {sup 1}H relaxation measurements, and recently {sup 1}H multiple quantum methods. Characterization of the growth of multiple quantum coherences have recently been shown to provide detailed insight into silicone network structure by the ability to selective probe the individual components of the polymer network, such as the polymer-filler interface or network chains. …
Date: July 14, 2006
Creator: Chinn, S. C.; Gjersing, E. L.; Maxwell, R. S.; Eastwood, E.; Bowen, D. & Stephens, T.
System: The UNT Digital Library
Detonation Reaction Zones in Condensed Explosives (open access)

Detonation Reaction Zones in Condensed Explosives

Experimental measurements using nanosecond time resolved embedded gauges and laser interferometric techniques, combined with Non-Equilibrium Zeldovich--von Neumann--Doring (NEZND) theory and Ignition and Growth reactive flow hydrodynamic modeling, have revealed the average pressure/particle velocity states attained in reaction zones of self-sustaining detonation waves in several solid and liquid explosives. The time durations of these reaction zone processes is discussed for explosives based on pentaerythritol tetranitrate (PETN), nitromethane, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), triaminitrinitrobenzene(TATB) and trinitrotoluene (TNT).
Date: July 14, 2005
Creator: Tarver, Craig M.
System: The UNT Digital Library
Microlensing Optical Depth towards the Galactic Bulge Using Clump Giants from the MACHO Survey (open access)

Microlensing Optical Depth towards the Galactic Bulge Using Clump Giants from the MACHO Survey

Using 7 years of MACHO survey data, we present a new determination of the optical depth to microlensing towards the Galactic bulge. We select the sample of 62 microlensing events (60 unique) on clump giant sources and perform a detailed efficiency analysis. We use only the clump giant sources because these are bright bulge stars and are not as strongly affected by blending as other events. Using a subsample of 42 clump events concentrated in an area of 4.5 deg{sup 2} with 739000 clump giant stars, we find {tau} = 2.17{sub -0.38}{sup +0.47} x 10{sup -6} at (l,b) = (1{sup o}.50, -2{sup o}.68), somewhat smaller than found in most previous MACHO studies, but in excellent agreement with recent theoretical predictions. We also present the optical depth in each of the 19 fields in which we detected events, and find limits on optical depth for fields with no events. The errors in optical depth in individual fields are dominated by Poisson noise. We measure optical depth gradients of (1.06 {+-} 0.71) x 10{sup -6}deg{sup -1} and (0.29 {+-} 0.43) x 10{sup -6}deg{sup -1} in the galactic latitude b and longitude l directions, respectively. Finally, we discuss the possibility of anomalous duration …
Date: July 14, 2005
Creator: Popowski, P.; Griest, K.; Thomas, C. L.; Cook, K. H.; Bennett, D. P.; Becker, A. C. et al.
System: The UNT Digital Library
Large-scale turnover of functional transcription factor bindingsites in Drosophila (open access)

Large-scale turnover of functional transcription factor bindingsites in Drosophila

The gain and loss of functional transcription-factor bindingsites has been proposed as a major source of evolutionary change incis-regulatory DNA and gene expression. We have developed an evolutionarymodel to study binding site turnover that uses multiple sequencealignments to assess the evolutionary constraint on individual bindingsites, and to map gain and loss events along a phylogenetic tree. Weapply this model to study the evolutionary dynamics of binding sites ofthe Drosophila melanogaster transcription factor Zeste, using genome-widein vivo (ChIP-chip) binding data to identify functional Zeste bindingsites, and the genome sequences of D. melanogaster, D. simulans, D.erecta and D. yakuba to study their evolution. We estimate that more than5 percent of functional Zeste binding sites in D. melanogaster weregained along the D. melanogaster lineage or lost along one of the otherlineages. We find that Zeste bound regions have a reduced rate of bindingsite loss and an increased rate of binding site gain relative to flankingsequences. Finally, we show that binding site gains and losses areasymmetrically distributed with respect to D. melanogaster, consistentwith lineage-specific acquisition and loss of Zeste-responsive regulatoryelements.
Date: July 14, 2006
Creator: Moses, Alan M.; Pollard, Daniel A.; Nix, David A.; Iyer, VenkyN.; Li, Xiao-Yong; Biggin, Mark D. et al.
System: The UNT Digital Library
An Arbitrary Lagrangian Eulerian Formulation with Adaptive Mesh Refinement for Hydrodynamics and Material Modeling (open access)
Ultrasensitive Searches for the Axion (open access)

Ultrasensitive Searches for the Axion

The axion, a hypothetical elementary particle arising from a compelling solution to the strong-CP problem, has eluded discovery for three decades. Experiments based on coherent axion-photon mixing in strong magnetic fields are just now reaching the sensitivity to detect it, either as the dark matter or as a component of the solar flux. Although of lower sensitivity, purely laboratory experiments hold potential for surprise.
Date: July 14, 2006
Creator: Van Bibber, K. A. & Rosenberg, L. J.
System: The UNT Digital Library
Supporting Dynamic Ad hoc Collaboration Capabilities (open access)

Supporting Dynamic Ad hoc Collaboration Capabilities

Modern HENP experiments such as CMS and Atlas involve as many as 2000 collaborators around the world. Collaborations this large will be unable to meet often enough to support working closely together. Many of the tools currently available for collaboration focus on heavy-weight applications such as videoconferencing tools. While these are important, there is a more basic need for tools that support connecting physicists to work together on an ad hoc or continuous basis. Tools that support the day-to-day connectivity and underlying needs of a group of collaborators are important for providing light-weight, non-intrusive, and flexible ways to work collaboratively. Some example tools include messaging, file-sharing, and shared plot viewers. An important component of the environment is a scalable underlying communication framework. In this paper we will describe our current progress on building a dynamic and ad hoc collaboration environment and our vision for its evolution into a HENP collaboration environment.
Date: July 14, 2003
Creator: Agarwal, Deborah A. & Berket, Karlo
System: The UNT Digital Library
The Near Elimination of Hysteresis in Pd/Cr2O3 Composites (open access)

The Near Elimination of Hysteresis in Pd/Cr2O3 Composites

Although its value varies with the microstructure, hysteresis always accompanies hydride formation and decomposition in Pd(pure)-H, e.g., it is present even in nano-crystalline and thin films. Internal oxidation of Pd0.93Cr0.07 alloys leads to a pure Pd matrix containing nano-crystalline chromia precipitates. The characteristic hysteresis of Pd-H almost disappears in this form of Pd. The reasons for this are discussed. Hysteresis is an almost universal feature of first order solid state transitions. Its presence means that when such a transition is reversed, it follows a different path than that taken in the forward direction leading to a loss of useful work. Hysteresis is, of course, a reflection of the irreversibility of the transition.
Date: July 14, 2004
Creator: SHANAHAN, KIRKL
System: The UNT Digital Library
Magnetic field measurements of the LHC inner triplet quadrupoles produced at Fermilab (open access)

Magnetic field measurements of the LHC inner triplet quadrupoles produced at Fermilab

Production of 18 superconducting low-beta quadrupoles (MQXB) for the LHC is well advanced. These 5.5 m long magnets are designed to operate at 1.9 K with a peak field gradient of 215 T/m in 70 mm aperture. Two MQXB cold masses with a dipole orbit corrector between them form a single cryogenic unit (LQXB) which is the Q2 optical element of the final focus triplets in the LHC interaction regions. A program of magnetic field quality and alignment measurements of the cold masses is performed at room temperature during magnet fabrication and of the LQXB assembly as well as at superfluid helium temperature. Results of these measurements are summarized in this paper.
Date: July 14, 2004
Creator: al., G. V. Velev et
System: The UNT Digital Library
Comment on ''Thermal Behavior of Polarized Pd/D Electrodes Prepared by Co-Deposition'' (open access)

Comment on ''Thermal Behavior of Polarized Pd/D Electrodes Prepared by Co-Deposition''

This paper presents the basics of this model, including what physical conditions could produce a calibration constant shift and what might cause those conditions to arise. The new evidences are discussed and it is shown that the possibility of at-the-electrode recombination cannot be eliminated, in fact prior photographic evidence is shown to be reasonable evidence of this phenomenon. Thus in the absence of definitive data, the conclusion that apparent excess heat arises from a nuclear cause is premature. If the apparent excess heat signal is not representative of a true heat source, but is instead an equipment/method malfunction, integrating the signal is of no value. This paper proposes that is the situation, and will therefore focus on examining the phenomenon of apparent excess enthalpy (sometimes called excess heat). Not addressed will be the myriad of other purported evidences of nuclear reactions. The apparent excess heat claims form the largest block of claims for a nuclear FPHE cause, and the correlation of apparent excess heat with apparent nuclear ash detection is often cited as evidence of the nuclear nature of the FPHE. But confidence in the validity of the apparent excess heat signal is of critical importance in validating a nuclear …
Date: July 14, 2004
Creator: SHANAHAN, KIRKL.
System: The UNT Digital Library
Regional Model Calibration for Improving Seismic Location (open access)

Regional Model Calibration for Improving Seismic Location

Accurate seismic event location is integral to the effective monitoring of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), as well as being a fundamental component of earthquake source characterization. To account for the effects of crustal and mantle structure on seismic travel times, and to improve seismic event location in the Middle East and North Africa (MENA), we are developing a set of radially heterogeneous and azimuthally invariant travel-time models of the crust and upper mantle for each MENA seismic station. We begin by developing an average one-dimensional velocity model that minimizes the P-phase travel-time residuals from regional through teleseismic distance at each station. To do this we (1) generate a suite of 1-D velocity models of the earth, (2) compute travel times through the 1-D models using a tau-p formulation to produce standard travel-time tables, and (3) minimize the root-mean-square (rms) residuals between the P-phase arrivals predicted by each model and a groomed set of ISC P-phase arrival times (Engdahl et al., 1991). Once we have an average one-dimensional velocity model that minimizes the P-phase travel-time residuals for all distances, we repeat steps 1 through 3, systematically perturbing the travel-time model and using a grid search procedure to optimize models within …
Date: July 14, 2000
Creator: Swenson, J. L.; Schultz, C. A. & Myers, S. C.
System: The UNT Digital Library