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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,135 records · Page 63
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Leggett-type nonlocal realistic inequalities without any constraint on the geometrical alignment of measurement settings

Leggett-type nonlocal realistic inequalities that have been derived to date are all contingent upon suitable geometrical constraints to be strictly satisfied by the spatial arrangement of the relevant measurement settings. This undesirable restriction is removed in the present work by deriving appropriate forms of nonlocal realistic inequalities, one of which involves the fewest number of settings compared to all such inequalities derived earlier. The way such inequalities would provide a logically firmer basis for a clearer testing of a Leggett-type nonlocal realistic model vis-a-vis quantum mechanics is explained.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

Cosmic alignment of the aether

In Einstein-aether theory and Horava gravity, a timelike unit vector is coupled to the spacetime metric. It has previously been shown that in an exponentially expanding homogeneous, isotropic background, small perturbations of the vector relax back to the isotropic frame. Here we investigate large deviations from isotropy, maintaining homogeneity. We find that, for generic values of the coupling constants, the aether and metric relax to the isotropic configuration if the initial aether hyperbolic boost angle and its time derivative in units of the cosmological constant are less than something of order unity. For larger angles or angle derivatives, the behavior is strongly dependent on the values of the coupling constants. Generally, there is runaway behavior, in which the anisotropy increases with time, and/or singularities occur.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Cavity dynamics and particle alignment in the wake of a supersonic projectile penetrating a dusty plasma

The penetration of a projectile into a strongly coupled dusty plasma was studied in a radio-frequency discharge under microgravity conditions. A supersonic projectile produces an elongated dust-free cavity in its wake. The dynamics of the cavity is analyzed and compared with Langevin dynamics simulations. Besides a three-dimensional Mach cone structure, the simulation shows that the cavity dynamics can be subdivided into three phases: An opening phase with fixed time scale, a closing phase, whose duration is affected by the projectile speed and, finally, a phase of particle realignment in the target cloud, which persists for a long time after the closure of the cavity.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

ZnO-Au x Cu 1-x Alloy and ZnO-Au x Al 1-x Alloy Vertically Aligned Nanocomposites for Low-Loss Plasmonic Metamaterials

Hyperbolic metamaterials are a class of materials exhibiting anisotropic dielectric function owing to the morphology of the nanostructures. In these structures, one direction behaves as a metal, and the orthogonal direction behaves as a dielectric material. Applications include subdiffraction imaging and hyperlenses. However, key limiting factors include energy losses of noble metals and challenging fabrication methods. In this work, self-assembled plasmonic metamaterials consisting of anisotropic nanoalloy pillars embedded into the ZnO matrix are developed using a seed-layer approach. Alloys of Au x Al 1-x or Au x Cu 1-x are explored due to their lower losses and higher stability. Optical and microstructural properties were explored. The ZnO-Au x Cu 1-x system demonstrated excellent epitaxial quality and optical properties compared with the ZnO-Au x Al 1-x system. Both nanocomposite systems demonstrate plasmonic resonance, hyperbolic dispersion, low losses, and epsilon-near-zero permittivity, making them promising candidates towards direct photonic integration.

36 MATERIALS SCIENCE↗
DOE OSTI2012

New Measurements of Upsilon Spin Alignment at the Tevatron

We describe a new analysis of {Upsilon}(nS) {yields} {mu}{sup +}{mu}{sup -} decays collected in p{bar p} collisions with the CDF II detector at the Fermilab Tevatron. This analysis measures the angular distributions of the final state muons in the {Upsilon} rest frame, providing new information about {Upsilon} production polarization. We find the angular distributions to be nearly isotropic up to {Upsilon} p{sub T} of 40 GeV/c, consistent with previous measurements by CDF, but inconsistent with results obtained by the D0 experiment. The results are compared with recent NLO calculations based on color-singlet matrix elements and non-relativistic QCD with color-octet matrix elements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Soft X-ray Spectroscopy of C60/Copper Phthalocyanine/MoO3 Interfaces: Role of Reduced MoO3 on Energetic Band Alignment and Improved Performance

The interfacial electronic structure of C{sub 60}/copper phthalocyanine (CuPc)/molybdenum trioxide (MoO{sub 3}) thin films grown in situ on indium tin oxide (ITO) substrates has been studied using synchrotron radiation-excited photoelectron spectroscopy in an attempt to understand the influence of oxide interlayers on the performance of small molecule organic photovoltaic devices. The MoO{sub 3} layer on ITO is found to significantly increase the work function of the substrate and induces large interface dipoles and band bending at the CuPc/MoO{sub 3} interface. The large band bending confirms the formation of an internal potential that assists hole extraction from the CuPc layer to the electrode. The electronic structure of the MoO{sub 3} layer on ITO was also examined using various soft X-ray spectroscopies to probe the conductive nature of the MoO{sub 3} thin film.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Tuning band alignment using interface dipoles at the Pt/anatase TiO 2 interface

The Schottky barrier heights at the Pt/TiO 2 (001) junctions are modulated over 0.8 eV by inserting <1 nm of LaAlO 3 . The large electric field in the LaAlO 3 is stabilized by preserving the continuity of in-plane lattice symmetry at the oxide interface. Lastly, these results greatly expand the application of dipole engineering to versatile polycrystalline metal/binary oxide functional interfaces.

36 MATERIALS SCIENCE↗