Time Reversal Violation (open access)

Time Reversal Violation

This talk briefly reviews three types of time-asymmetry in physics, which I classify as universal, macroscopic and microscopic. Most of the talk is focused on the latter, namely the violation of T-reversal invariance in particle physics theories. In sum tests of microscopic T-invariance, or observations of its violation, are limited by the fact that, while we can measure many processes, only in very few cases can we construct a matched pair of process and inverse process and observe it with sufficient sensitivity to make a test. In both the cases discussed here we can achieve an observable T violation making use of flavor tagging, and in the second case also using the quantum properties of an antisymmetric coherent state of two B mesons to construct a CP-tag. Both these tagging properties depend only on very general properties of the flavor and/or CP quantum numbers and so provide model independent tests for T-invariance violations. The microscopic laws of physics are very close to T-symmetric. There are small effects that give CP- and T-violating processes in three-generation-probing weak decays. Where a T-violating observable can be constructed we see the relationships between T-violation and CP-violation expected in a CPT conserving theory. These microscopic …
Date: January 27, 2009
Creator: Quinn, H.
System: The UNT Digital Library
Proton Fast Ignition (open access)

Proton Fast Ignition

None
Date: January 27, 2005
Creator: Key, M. H.; Freeman, R. R.; Hatchett, S. P.; MacKinnon, A. J.; Patel, P. K.; Snavely, R. A. et al.
System: The UNT Digital Library
Surface structure of CdSe Nanorods revealed by combined X-rayabsorption fine structure measurements and ab-initio calculations (open access)

Surface structure of CdSe Nanorods revealed by combined X-rayabsorption fine structure measurements and ab-initio calculations

We report orientation-specific, surface-sensitive structural characterization of colloidal CdSe nanorods with extended X-ray absorption fine structure spectroscopy and ab-initio density functional theory calculations. Our measurements of crystallographically-aligned CdSe nanorods show that they have reconstructed Cd-rich surfaces. They exhibit orientation-dependent changes in interatomic distances which are qualitatively reproduced by our calculations. These calculations reveal that the measured interatomic distance anisotropy originates from the nanorod surface.
Date: January 27, 2006
Creator: Aruguete, Deborah A.; Marcus, Matthew A.; Li, Liang-shi; Williamson, Andrew; Fakra, Sirine; Gygi, Francois et al.
System: The UNT Digital Library
Gauge Mediation Simplified (open access)

Gauge Mediation Simplified

None
Date: January 27, 2007
Creator: Murayama, Hitoshi & Nomura, Yasunori
System: The UNT Digital Library
Microbunching Instability in a Chicane: Two-Dimensional Mean Field Treatment (open access)

Microbunching Instability in a Chicane: Two-Dimensional Mean Field Treatment

We study the microbunching instability in a bunch compressor by a parallel code with some improved numerical algorithms. The two-dimensional charge/current distribution is represented by a Fourier series, with coefficients determined through Monte Carlo sampling over an ensemble of tracked points. This gives a globally smooth distribution with low noise. The field equations are solved accurately in the lab frame using retarded potentials and a novel choice of integration variables that eliminates singularities. We apply the scheme with parameters for the first bunch compressor system of FERMI{at}Elettra, with emphasis on the amplification of a perturbation at a particular wavelength. Gain curves agree with those of the linearized Vlasov model at long wavelengths, but show some deviation at the smallest wavelengths treated.
Date: January 27, 2009
Creator: Bassi, G.; Ellison, James A.; Heinemann, Klaus & Warnock, Robert
System: The UNT Digital Library
The National Ignition Facility: the World's Largest Optics and Laser System (open access)

The National Ignition Facility: the World's Largest Optics and Laser System

The National Ignition Facility, a center for the study of high energy density plasma physics and fusion energy ignition, is currently under construction at the Lawrence Livermore National Laboratory. The heart of the NIF is a frequency tripled, flashlamp-pumped Nd:glass laser system comprised of 192 independent laser beams. The laser system is capable of generating output energies of 1.8MJ at 351nm and at peak powers of 500 TW in a flexible temporal pulse format. A description of the NIF laser system and its major components is presented. We also discuss the manufacture of nearly 7500 precision large optics required by the NIF including data on the manufactured optical quality vs. specification. In addition, we present results from an on-going program to improve the operational lifetime of optics exposed to high fluence in the 351-nm section of the laser.
Date: January 27, 2003
Creator: Moses, E I; Campbell, J H; Stolz, C J & Wuest, C R
System: The UNT Digital Library
High-resolution NMR spectroscopy of biological tissues using projected Magic Angle Spinning (open access)

High-resolution NMR spectroscopy of biological tissues using projected Magic Angle Spinning

High-resolution NMR spectra of materials subject toanisotropic broadening are usually obtained by rotating the sample aboutthe magic angle, which is 54.7 degrees to the static magnetic field. Inprojected Magic Angle Spinning (p-MAS), the sample is spun about twoangles, neither of which is the magic angle. This provides a method ofobtaining isotropic spectra while spinning at shallow angles. The p-MASexperiment may be used in situations where spinning the sample at themagic angle is not possible due to geometric or other constraints,allowing the choice of spinning angle to be determined by factors such asthe shape of the sample, rather than by the spin physics. The applicationof this technique to bovine tissue samples is demonstrated as a proof ofprinciple for future biological or medical applications.
Date: January 27, 2005
Creator: Martin, Rachel W.; Jachmann, Rebecca C.; Sakellariou, Dimitris; Nielsen, Ulla Gro & Pines, Alexander
System: The UNT Digital Library
QLC relation and neutrino mass hierarchy (open access)

QLC relation and neutrino mass hierarchy

Latest measurements have revealed that the deviation from a maximal solar mixing angle is approximately the Cabibbo angle, i.e., QLC relation. We argue that it is not plausible that this deviation from maximality, be it a coincidence or not, comes from the charged lepton mixing. Consequently we have calculated the required corrections to the exactly bimaximal neutrino mass matrix ansatz necessary to account for the solar mass difference and the solar mixing angle. We point out that the relative size of these two corrections depends strongly on the hierarchy case under consideration. We find that the inverted hierarchy case with opposite CP parities, which is known to guarantee the RGE stability of the solar mixing angle, offers the most plausible scenario for a high energy origin of a QLC-corrected bimaximal neutrino mass matrix. This possibility may allow us to explain the QLC relation in connection with the origin of the charged fermion mass matrices.
Date: January 27, 2005
Creator: Ferrandis, Javier & Pakvasa, Sandip
System: The UNT Digital Library
Massless Flavor in Geometry and Matrix Models (open access)

Massless Flavor in Geometry and Matrix Models

The proper inclusion of flavor in the Dijkgraaf-Vafa proposal for the solution of N=1 gauge theories through matrix models has been subject of debate in the recent literature. We here reexamine this issue by geometrically engineering fundamental matter with type IIB branes wrapped on non-compact cycles in the resolved geometry, and following them through the geometric transition. Our approach treats massive and massless flavor fields on equal footing, including the mesons. We also study the geometric transitions and superpotentials for finite mass of the adjoint field. All superpotentials we compute reproduce the field theory results. Crucial insights come from T-dual brane constructions in type IIA.
Date: January 27, 2003
Creator: Roiban, Radu; Tatar, Radu & Walcher, Johannes
System: The UNT Digital Library
Speeding Up Simulations of Relativistic Systems using an Optimal Boosted Frame (open access)

Speeding Up Simulations of Relativistic Systems using an Optimal Boosted Frame

It can be computationally advantageous to perform computer simulations in a Lorentz boosted frame for a certain class of systems. However, even if the computer model relies on a covariant set of equations, it has been pointed out that algorithmic difficulties related to discretization errors may have to be overcome in order to take full advantage of the potential speedup. We summarize the findings, the difficulties and their solutions, and show that the technique enables simulations important to several areas of accelerator physics that are otherwise problematic, including self-consistent modeling in three-dimensions of laser wokefield accelerator stages at energies of 10 GeV and above.
Date: January 27, 2009
Creator: Vay, J. L.; Fawley, W. M.; Geddes, C. G. R.; Cormier-Michel, E. & Grote, D. P.
System: The UNT Digital Library
High Temperature Strain Gages for SOFC Application (open access)

High Temperature Strain Gages for SOFC Application

This presentation discusses the investigation/extension of high temperature strain gage applications sensors to SOFC applications.
Date: January 27, 2005
Creator: Pineault, R. L.; Johnson, C.; Gemmen, R. S.; Gregory, O. & You, T.
System: The UNT Digital Library
The Modular Point Design for Heavy Ion Fusion (open access)

The Modular Point Design for Heavy Ion Fusion

We report on an ongoing study on modular Heavy Ion Fusion drivers. The modular driver is characterized by tens ({approx} 20) nearly identical induction linacs, each carrying a single high current beam. In this scheme, the Integrated Research Experiment (IRE) can be one of the full size induction linacs. Hence, this approach offers significant advantages in terms of driver development path. For beam transport, these modules use solenoids which are capable of carrying high line charge densities, even at low energies. A new injector concept allows compression of the beam to high line densities right at the source. The final drift compression is performed in a plasma, in which the large repulsive space charge effects are neutralized. Finally, the beam is transversely compressed onto the target, using either external solenoids or current-carrying channels (in the Assisted Pinch Mode of beam propagation). We will report on progress towards a self-consistent point design from injector to target. Considerations of driver architecture, chamber environment as well as the methodology for meeting target requirements of spot size, pulse shape and symmetry will also be described. Finally, some near-term experiments to address the key scientific issues will be discussed.
Date: January 27, 2005
Creator: Yu, S. S.; Barnard, J. J.; Briggs, R. J.; Callahan-Miller, D.; Celata, C. M.; Chao, L. et al.
System: The UNT Digital Library
Transport & Disposal of TPBARs at the Tritium Extraction Facility (open access)

Transport & Disposal of TPBARs at the Tritium Extraction Facility

As a part of the Department of Energy Tritium Readiness Program, the Tritium Extraction Facility (TEF) at the Savannah River Site (SRS) is preparing to receive the first shipment of irradiated Tritium Producing Burnable Absorber Rods (TPBARs) from the Tennessee Valley Authority's Watts Bar Nuclear Plant. Tritium will be extracted from the TPBARs at the TEF. The spent TPBARs will be transported and disposed on site using the TEF Waste Container, designed and fabricated by Packaging Technology, Inc. This paper describes the TPBAR waste form, the TEF Waste Container to be used to store the waste, the operational sequence associated with management of the TBPAR waste form and the disposal facility at the SRS.
Date: January 27, 2005
Creator: BENJAMIN, SNIDER
System: The UNT Digital Library
Electrochemical in-situ reaction cell for X-ray scattering, diffraction and spectroscopy (open access)

Electrochemical in-situ reaction cell for X-ray scattering, diffraction and spectroscopy

An electrochemical in-situ reaction cell for hard X-ray experiments with battery electrodes is described. Applications include the small angle scattering, diffraction, and near-edge spectroscopy of lithium manganese oxide electrodes.
Date: January 27, 2003
Creator: Braun, Artur; Granlund, Eric & Cairns, Elton J.
System: The UNT Digital Library
Hadron calorimeters for future hadron colliders (open access)

Hadron calorimeters for future hadron colliders

Hadron calorimeters are essential for jet and neutrino physics at collider experiments. Current hadron calorimeters for the ATLAS and CMS detectors are described. Increased energy and luminosity of future hadron colliders place constraints on detector technology. Difficulties for operation of the current detectors in future hadron collider environments are discussed. New experiments for future colliders should take notice of physics processes during jet evolution that place fundamental limits on performance of the calorimeter to reconstruct jets. A technique of incorporating tracking information to improve jet resolution is described. Future detectors should be designed with these constraints in mind. Possible avenues of exploration for future technology are described.
Date: January 27, 2004
Creator: Freeman, Jim
System: The UNT Digital Library
Experimental Characterization of an Ultra-Fast Thomson Scattering X-Ray Source With Three-Dimensional Time and Frequency-Domain Analysis (open access)

Experimental Characterization of an Ultra-Fast Thomson Scattering X-Ray Source With Three-Dimensional Time and Frequency-Domain Analysis

We present a detailed comparison of the measured characteristics of Thomson backscattered x-rays produced at the PLEIADES (Picosecond Laser-Electron Interaction for the Dynamic Evaluation of Structures) facility at Lawrence Livermore National Laboratory to predicted results from a newly developed, fully three-dimensional time and frequency-domain code. Based on the relativistic differential cross section, this code has the capability to calculate time and space dependent spectra of the x-ray photons produced from linear Thomson scattering for both bandwidth-limited and chirped incident laser pulses. Spectral broadening of the scattered x-ray pulse resulting from the incident laser bandwidth, perpendicular wave vector components in the laser focus, and the transverse and longitudinal phase space of the electron beam are included. Electron beam energy, energy spread, and transverse phase space measurements of the electron beam at the interaction point are presented, and the corresponding predicted x-ray characteristics are determined. In addition, time-integrated measurements of the x-rays produced from the interaction are presented, and shown to agree well with the simulations.
Date: January 27, 2004
Creator: Kuba, J; Slaughter, D R; Fittinghoff, D N; Barty, C J; Hartouni, E P; Anderson, S G et al.
System: The UNT Digital Library
Polymeric Species of Pu in Low Ionic Strength Media (open access)

Polymeric Species of Pu in Low Ionic Strength Media

The US Government has declared that approximately 50 tons of plutonium is surplus to US needs and should be set aside for eventual disposition. The US is currently following a dual path for the disposition of this plutonium: immobilization and irradiation of mixed-oxide fuel. Some fraction of this plutonium material that is undesirable for use in mixed-oxide fuel will be immobilized in a titanate ceramic and disposed of in a geologic repository for high level waste. The reminder of Pu will be fabricated into mixed-oxide fuel and irradiated in domestic light-water reactors. The resulting spent fuel would also be disposed of in a geologic repository for high level waste. The proposed US repository would be at the Yucca Mountain site in Nevada. Plutonium present in the disposal forms, either ceramics or spent fuel, must remain isolated from the biosphere over the geologic repository regulatory performance period, which is currently 10,000 years. Contamination of the biosphere could result from slow dissolution of the disposal forms followed by transport of the dissolution products into the biosphere by flowing ground water. Measurable amounts of apparently soluble plutonium can be released if plutonium dioxide is exposed to water under some conditions. Furthermore, recent studies …
Date: January 27, 2000
Creator: Romanovski, V. V.; Palmer, C. E.; Shaw, H. F.; Bourcier, W. L. & Jardine, L. J.
System: The UNT Digital Library
Advanced Transmission Electron Microscopy of Pu Alloys (open access)

Advanced Transmission Electron Microscopy of Pu Alloys

The characterization of microstructural changes in Pu-Ga alloys resulting from storage and aging phenomena is an important technical challenge to the nuclear Stockpile Stewardship program. We have identified at least two age-related phenomena that may occur in Pu alloys, dimensional changes due to the initial transient, helium accumulation, and void swelling, and phase instability. The initial transient is a well-known effect that results from the initial cascade damage. This form of dimensional change tends to saturate within approximately two years. A second contributor to dimensional change is the build-up of helium as a result of the alpha decay. Helium is generated at a rate of approximately 40 parts per million per year. Positron annihilation results by Howell indicate that the helium atoms will quickly fill a nearby vacancy and diffuse through the lattice as a helium filled vacancy. Void swelling is potentially the most severe mechanism of dimensional change in Pu alloys. It has been observed in all-materials exposed to irradiation, but has yet to be seen in naturally aged Pu. Phase instability is a potential concern due to the fact that the {delta}-phase is thermodynamically metastable at room temperature. Timofeeva has shown that the {delta}-phase will decompose to {delta}-phase …
Date: January 27, 2003
Creator: Schwartz, A J; Wall, M A; Wolfer, W G & Moore, K T
System: The UNT Digital Library
Material Interface Reconstruction in VisIt (open access)

Material Interface Reconstruction in VisIt

In this paper, we first survey a variety of approaches to material interface reconstruction and their applicability to visualization, and we investigate the details of the current reconstruction algorithm in the VisIt scientific analysis and visualization tool. We then provide a novel implementation of the original VisIt algorithm that makes use of a wide range of the finite element zoo during reconstruction. This approach results in dramatic improvements in quality and performance without sacrificing the strengths of the VisIt algorithm as it relates to visualization.
Date: January 27, 2005
Creator: Meredith, J S
System: The UNT Digital Library
Three-dimensional time and frequency-domain theory of femtosecond x-ray pulse generation through Thomson Scattering (open access)

Three-dimensional time and frequency-domain theory of femtosecond x-ray pulse generation through Thomson Scattering

The generation of high intensity, ultra-short x-ray pulses enables exciting new experimental capabilities, such as femtosecond pump-probe experiments used to temporally resolve material structural dynamics on atomic time scales. Thomson backscattering of a high intensity laser pulse with a bright relativistic electron bunch is a promising method for producing such high brightness x-ray pulses in the 10-100 keV range within a compact facility. While a variety of methods for producing sub-picosecond x-ray bursts by Thomson scattering exist, including compression of the electron bunch to sub-picosecond bunch lengths and/or colliding a sub-picosecond laser pulse in a side-on geometry to minimize the interaction time, a promising alternative approach to achieving this goal while maintaining ultra-high brightness is the production of a time correlated (or chirped) x-ray pulse in conjunction with pulse slicing or compression. We present the results of a complete analysis of this process using a recently developed 3-D time and frequency-domain code for analyzing the spatial, temporal, and spectral properties an x-ray beam produced by relativistic Thomson scattering. Based on the relativistic differential cross section, this code has the capability to calculate time and space dependent spectra of the x-ray photons produced from linear Thomson scattering for both bandwidth-limited and …
Date: January 27, 2004
Creator: Brown, W J & Hartemann, F V
System: The UNT Digital Library
Conductivity maximum in a charged colloidal suspension (open access)

Conductivity maximum in a charged colloidal suspension

Molecular dynamics simulations of a charged colloidal suspension in the salt-free regime show that the system exhibits an electrical conductivity maximum as a function of colloid charge. We attribute this behavior to two main competing effects: colloid effective charge saturation due to counterion 'condensation' and diffusion slowdown due to the relaxation effect. In agreement with previous observations, we also find that the effective transported charge is larger than the one determined by the Stern layer and suggest that it corresponds to the boundary fluid layer at the surface of the colloidal particles.
Date: January 27, 2009
Creator: Bastea, S
System: The UNT Digital Library
Niobium Oxide Film Deposition Using a High-Density Plasma Source (open access)

Niobium Oxide Film Deposition Using a High-Density Plasma Source

Niobium oxide was deposited reactively using a new type of high-density plasma sputter source. The plasma beam used for sputtering is generated remotely and its path to the target defined by the orthogonal locations of two electromagnets: one at the orifice of the plasma tube and the other just beneath the target plane. To accommodate very large batches of substrates, the trade-off between load capacity and deposition rates was evaluated. The effect on deposition rate was determined by moving the plasma source away from the target in one direction and by moving the target assembly away in an orthogonal direction. A simple methodology was used to reestablish the reactive deposition rate and oxide quality even when large changes were made to the chamber geometry. Deposition parameters were established to produce nonabsorbing niobium oxide films of about 100- and 350-nm thicknesses. The quality of the niobium oxide films was studied spectroscopically, ellipsometrically, and stoichiometrically.
Date: January 27, 2006
Creator: Chow, R.; Schmidt, M. A.; Coombs, A. W.; Anguita, J. & Thwaites, M. J.
System: The UNT Digital Library
High Biomass Low Export Regimes in the Southern Ocean (open access)

High Biomass Low Export Regimes in the Southern Ocean

This paper investigates ballasting and remineralization controls of carbon sedimentation in the twilight zone (100-1000 m) of the Southern Ocean. Size-fractionated (<1 {micro}m, 1-51 {micro}m, >51 {micro}m) suspended particulate matter was collected by large volume in-situ filtration from the upper 1000 m in the Subantarctic (55 S, 172 W) and Antarctic (66 S, 172 W) zones of the Southern Ocean during the Southern Ocean Iron Experiment (SOFeX) in January-February 2002. Particles were analyzed for major chemical constituents (POC, P, biogenic Si, CaCO3), and digital and SEM image analyses of particles were used to aid in the interpretation of the chemical profiles. Twilight zone waters at 66 S in the Antarctic had a steeper decrease in POC with depth than at 55 S in the Subantarctic, with lower POC concentrations in all size fractions at 66 S than at 55 S, despite up to an order of magnitude higher POC in surface waters at 66 S. The decay length scale of >51 {micro}m POC was significantly shorter in the upper twilight zone at 66 S ({delta}{sub e}=26 m) compared to 55 S ({delta}{sub e}=81 m). Particles in the carbonate-producing 55 S did not have higher excess densities than particles from the …
Date: January 27, 2006
Creator: Lam, Phoebe J. & Bishop, James K.B.
System: The UNT Digital Library
SECA Core Program - Recent Development of Modeling Activities at PNNL (open access)

SECA Core Program - Recent Development of Modeling Activities at PNNL

This presentation discusses recent modeling activities at the Pacific Northwest National Laboratory.
Date: January 27, 2005
Creator: Khaleel, M. A.; Recknagle, K. P.; Koeppel, B.; Vetrano, J.; Sun, X.; Korolev, V. et al.
System: The UNT Digital Library