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At least 487 records · Page 27

Elementary Particle Physics and High Energy Phenomena: Final Report for FY2010-13

The work under this grant consists of experimental, theoretical, and phenomenological research on the fundamental properties of high energy subnuclear particles. The work is conducted at the University of Colorado, the European Organization for Nuclear Research (CERN), the Japan Proton Accelerator Research Complex (J-PARC), Fermi National Accelerator Laboratory (FNAL), SLAC National Accelerator Laboratory (SLAC), Los Alamos National Laboratory (LANL), and other facilities, employing neutrino-beam experiments, test beams of various particles, and proton-proton collider experiments. It emphasizes mass generation and symmetry-breaking, neutrino oscillations, bottom particle production and decay, detector development, supergravity, supersymmetry, superstrings, quantum chromodynamics, nonequilibrium statistical mechanics, cosmology, phase transitions, lattice gauge theory, and anomaly-free theories. The goals are to improve our understanding of the basic building blocks of matter and their interactions. Data from the Large Hadron Collider at CERN have revealed new interactions responsible for particle mass, and perhaps will lead to a more unified picture of the forces among elementary material constituents. To this end our research includes searches for manifestations of theories such as supersymmetry and new gauge bosons, as well as the production and decay of heavy-flavored quarks. Our current work at J-PARC, and future work at new facilities currently under conceptual design, investigate the specifics of how the neutrinos change flavor. The research is integrated with the training of students at all university levels, benefiting both the manpower and intellectual base for future technologies.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Reduced Fast Ion Transport Model For The Tokamak Transport Code TRANSP

Fast ion transport models presently implemented in the tokamak transport code TRANSP [R. J. Hawryluk, in Physics of Plasmas Close to Thermonuclear Conditions, CEC Brussels, 1, 19 (1980)] are not capturing important aspects of the physics associated with resonant transport caused by instabilities such as Toroidal Alfven Eigenmodes (TAEs). This work describes the implementation of a fast ion transport model consistent with the basic mechanisms of resonant mode-particle interaction. The model is formulated in terms of a probability distribution function for the particle's steps in phase space, which is consistent with the MonteCarlo approach used in TRANSP. The proposed model is based on the analysis of fast ion response to TAE modes through the ORBIT code [R. B. White et al., Phys. Fluids 27 , 2455 (1984)], but it can be generalized to higher frequency modes (e.g. Compressional and Global Alfven Eigenmodes) and to other numerical codes or theories.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Computational Modeling and Simulation for Nonproliferation: The History (and Present) of Monte Carlo and the MCNP(R) Code at Los Alamos [Slides]

The emergence of the Monte Carlo method as a research tool springs from work done at Los Alamos in the 1940s.Monte Carlo and the MCNP Code have been and continue to be developed at Los Alamos for many decades. From basic science in support of understanding nuclear interaction physics to global security applications, application uses of the code are extensive. Recent R&D projects and code modernization efforts make the MCNP code a great tool for nuclear nonproliferation applications. In collaboration with nuclear safeguards experts, new training has just recently been developed to help new practitioners learn how to use the code for nuclear safeguards applications.

97 MATHEMATICS AND COMPUTING↗

Deeply Virtual Compton Scattering at Hall A, Jefferson Lab

The Standard Model of particle physics de?nes quarks and leptons as the basic building blocks of all matter. The interaction between them are mediated by force carrying gauge bosons. Quantum Chromo Dynamics (QCD), the theory that explains the strong interaction is still not complete enough to derive the physical observables of a Quark-Gluon system from the fundamental degrees of freedom of its constituents. Experimentally observable single particle densities provide important insights into our understanding of the quark-gluon system and hence help fill in the gaps of QCD. Generalized Parton Distributions (GPDs) provide simultaneous information of both spacial and longitudinal momentum distributions of constituents of a quark-gluon system. Deeply Virtual Compton Scattering (DVCS) is understood to be the simplest and cleanest process to access GPDs. Even though the exclusive DVCS is simple to understand, the experimental process however, is complex with the Bethe-Heitler and e + p ? e + ? + N? being in the mix of the electron proton scattering e+p ? e+?+X. Over the years, 3 generations of DVCS experiments have been conducted in the Experimental Hall-A of Thomas Jefferson National Accelerator Facility (JLab). This thesis presents the extraction of DVCS cross section in 9 total kinematic points from the 3rd generation experiment (DVCS3) conducted after the 12 GeV upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) of JLab during Fall 2014 - Fall 2016.

Hashir Rashad, Mohamed Nuhman↗

Transgenic approaches to altering carbon and nitrogen partitioning in whole plants: assessing the potential to improve crop yields and nutritional quality

The principal components of plant productivity and nutritional value, from the standpoint of modern agriculture, are the acquisition and partitioning of organic carbon (C) and nitrogen (N) compounds among the various organs of the plant. The flow of essential organic nutrients among the plant organ systems is mediated by its complex vascular system, and is driven by a series of transport steps including export from sites of primary assimilation, transport into and out of the phloem and xylem, and transport into the various import-dependent organs. Manipulating C and N partitioning to enhance yield of harvested organs is evident in the earliest crop domestication events and continues to be a goal for modern plant biology. Research on the biochemistry, molecular and cellular biology, and physiology of C and N partitioning has now matured to an extent that strategic manipulation of these transport systems through biotechnology are being attempted to improve movement from source to sink tissues in general, but also to target partitioning to specific organs. These nascent efforts are demonstrating the potential of applied biomass targeting but are also identifying interactions between essential nutrients that require further basic research. In this review, we summarize the key transport steps involved in C and N partitioning, and discuss various transgenic approaches for directly manipulating key C and N transporters involved. In addition, we propose several experiments that could enhance biomass accumulation in targeted organs while simultaneously testing current partitioning models.

54 ENVIRONMENTAL SCIENCES↗

Basic Behavior and Properties of W-UO2 Cermets

Thermal cycling studies on cermets prepared from tungsten and UO2 powder mixtures and cermets prepared using tungsten coated UO2 particles are discussed. The cermets were tested in hydrogen at high temperatures to determine the effects of temperature, thermal cycling, and hydrogen pressure. Basic mechanism studies of tungsten­-UO2 interactions in thermally cycled cermets are also described.

Baker, R. J.↗

Observing quasars with the LST

The quasi-stellar objects (QSOs) are still a mystery as far as their energy source and physical nature are concerned. An understanding of them might throw light on basic problems such as the behavior and interaction of matter and radiation in very strong gravitational fields, and the cosmogony of galaxies. The LST will open up exciting new ways to study QSOs, e.g., observation of the UV in the crucial region 912-1550 A in QSOs with small redshifts. Searches for and studies of QSOs fainter than 20 magnitude and the removal of observational limits that restrict complete samples may help us to understand the nature of the redshifts.

Burbidge, E. M.↗

Evaluation of turbulence models for three primary types of shock-separated boundary layers

Zero-equation (algebraic), one-equation (kinetic energy), and two-equation (kinetic energy plus length scale) turbulence eddy viscosity models were used in computing three basic types of shock-separated boundary-layer flows. The three basic types of shock boundary-layer interaction discussed are: (1) a normal shock wave at transonic speeds, (2) a compression corner shock at supersonic speeds, and (3) an incident oblique shock at hypersonic speeds. The models tested are simple, unmodified models used extensively for incompressible, unseparated flows. A comparison of computed and measured results for the compressible, separated flows described herein indicates that model performance is dependent on flow configuration with no distinct superiority of one model over the other for all three flow configurations.

Coakley, T. J.↗

A general logic structure for custom LSI'S

Structure composed of standardized-circuit arrays reduces cost and complexity of fabricating special integrated circuits. Desired circuits are formed from basic mask, custom cuts, and contact points. Interactive computer program speeds design.

Sievers, M. W.↗

Dust in cosmic plasma environments

Cosmic dust is invariably immersed in a plasma and a radiative environment. Consequently, it is charged to some electrostatic potential which depends on the properties of the environment as well as the nature of the dust. This charging affects the physical and dynamical properties of the dust. In this paper the basic aspects of this dust-plasma interaction in several cosmic environments - including planetary magnetospheres, the heliosphere and the interstellar medium - are discussed. The physical and dynamical consequences of the interaction, as well as the pertinent observational evidence, are reviewed. Finally, the importance of the surface charge during the condensation process in plasma environments is stressed.

Mendis, D. A.↗

The role of zonally asymmetric heating in the vertical and temporal structure of the global scale flow fields during FGGE SOP-1

The global scale structure of atmospheric flow is best documented on time scales longer than a few days. Theoretical and observational studies of ultralong waves have emphasized forcing due to global scale variations of topography and surface heat flux, possibly interacting with baroclinically unstable or vertically refracting basic flows. Analyses of SOP-1 data in terms of global scale spherical harmonics is documented with emphasis upon weekly transitions.

Paegle, J.↗

Phenomenological and mechanics aspects of nondestructive evaluation and characterization by sound and ultrasound of material and fracture properties

Developments in fracture mechanics and elastic wave theory enhance the understanding of many physical phenomena in a mathematical context. Available literature in the material, and fracture characterization by NDT, and the related mathematical methods in mechanics that provide fundamental underlying principles for its interpretation and evaluation are reviewed. Information on the energy release mechanism of defects and the interaction of microstructures within the material is basic in the formulation of the mechanics problems that supply guidance for nondestructive evaluation (NDE).

Fu, L. S. W.↗

Satellite freeze forecast system. System configuration definition manual

Equipment listings, interconnection information, and a basic overview is given of the hardware interaction of the Ruskin HP-100 computer system. A block diagram is included of the SFFS system at the National Weather Service Office in Ruskin, Florida. The generation answer file used to create the RTE-IVB operating system currently resident in Ruskin HP-1000 computer system is also described.

Martsolf, J. D.↗

Fracture mechanics formulas on microcomputers

An interactive fracture mechanics program was developed in BASIC minima on a CBM 4032 microcomputer. It furnishes stress intensity factors and the critical size of a flaw.

Afzali, M.↗

Studies in geophysics: The Earth's electrical environment

The Earth is electrified. Between the surface and the outer reaches of the atmosphere, there is a global circuit that is maintained by worldwide thunderstorm activity and by upper atmospheric dynamo processes. The highest voltages approach a billion volts and are generated within thunderclouds, where lightning is a visual display of the cloud's electrical nature. The largest currents in the circuit, approaching a million amperes, are associated with the aurora. Because there have been significant advances in understanding many of the component parts of the global electric circuit (lightning, cloud electrification, electrical processes in specific atmospheric regions, and telluric currents), a principal research challenge is to understand how these components interact to shape the global circuit. Increased basic understanding in this field has many potential practical applications, including lightning protection, the design of advanced aircraft and spacecraft, and improvements in weather prediction.

Source record↗

Asymptotic modal analysis and statistical energy analysis of an acoustic cavity

A basic asymptotic theory for structural wall/acoustic cavity interaction is presented, and the analysis is illustrated with examples of the acoustic cavity response to a prescribed wall motion. Although, when spatially averaged, the classical modal analysis (CMA) response approaches the asymptotic modal analysis (AMA) response more rapidly as the number of modes increases, it is shown that information about local response intensification is lost in the averaging process. A larger bandwidth at a given center frequency is found to contain more excited modes than a smaller bandwidth; however, the AMA is slightly more accurate in the smaller bandwidth. All AMA asymptotes were shown to be approached from below by a CMA with fixed bandwidth and increasing center frequency.

Kubota, Y.↗

Development of an integrated BEM for hot fluid-structure interaction

The Boundary Element Method (BEM) is chosen as a basic analysis tool principally because the definition of quantities like fluxes, temperature, displacements, and velocities is very precise on a boundary base discretization scheme. One fundamental difficulty is, of course, that the entire analysis requires a very considerable amount of analytical work which is not present in other numerical methods. During the last 18 months all of this analytical work was completed and a two-dimensional, general purpose code was written. Some of the early results are described. It is anticipated that within the next two to three months almost all two-dimensional idealizations will be examined. It should be noted that the analytical work for the three-dimensional case has also been done and numerical implementation will begin next year.

Banerjee, P. K.↗

On the shear stabilization of capillary break-up of finite liquid bridges

In this paper we consider an isothermal finite liquid bridge under zero-gravity. A sinusoidal interfacial shear stress drives a nonparallel flow in the bridge. The linear stability of this flow to three-dimensional disturbances (which may deform the cylindrical gas-liquid interface) is determined numerically by solving an elliptic eigenvalue problem. Previous results on shear stabilization of capillary break-up of axially unbounded cylindrical interfaces containing a parallel flow are hereby extended to a nonparallel flow. The turning flow regions influence the stability significantly. However, for the particular cases considered, a small area in parameter space remains where the capillary instability is suppressed through interfacial shear. Second, non-axisymmetric oscillatory instabilities are found which originate from an interaction of the interface deformation and the basic flow. These instabilities may be the isothermal limit of the oscillatory instabilities observed in float-zone crystal growth.

Dijkstra, Henk A.↗