On wavenumber spectra for sound within subsonic jets

This paper clarifies the nature of sound spectra within subsonic jets. Three problems, of increasing complexity, are presented. Firstly, a point source is placed in a two-dimensional plug flow and the sound field is obtained analytically. Secondly, a point source is embedded in a diverging axisymmetric jet and the sound field is obtained by solving the linearised Euler equations. Finally, an analysis of the acoustic waves propagating through a turbulent jet obtained by direct numerical simulation is presented. In each problem, the pressure or density field are analysed in the frequency-wavenumber domain. It is found that acoustic waves can be classified into three main frequency-dependent groups. A physical justification is provided for this classification. The main conclusion is that, at low Strouhal numbers, acoustic waves satisfy the d'Alembertian dispersion relation.Comment: 20 pages, 9 figure

Proximity-Coupled Ti/TiN Multilayers for use in Kinetic Inductance Detectors

We apply the superconducting proximity effect in TiN/Ti multi-layer films to tune the critical temperature, Tc, to within 10 mK with high uniformity (less than 15 mK spread) across a 75 mm wafer. Reproducible Tc's are obtained from 0.8 - 2.5 K. These films had high resistivities, > 100 uOhm-cm and internal quality factors for resonators in the GHz range on the order of 100k and higher. Both trilayers of TiN/Ti/TiN and thicker superlattice films were prepared, demonstrating a highly controlled process for films over a wide thickness range. Detectors were fabricated and showed single photon resolution at 1550 nm. The high uniformity and controllability coupled with the high quality factor, kinetic inductance, and inertness of TiN make these films ideal for use in frequency multiplexed kinetic inductance detectors and other potential applications such as nanowire detectors, transition edge sensors and associated quantum information applications

A titanium-nitride near-infrared kinetic inductance photon-counting detector and its anomalous electrodynamics

We demonstrate single-photon counting at 1550 nm with titanium-nitride (TiN) microwave kinetic inductance detectors. Energy resolution of 0.4 eV and arrival-time resolution of 1.2 microseconds are achieved. 0-, 1-, 2-photon events are resolved and shown to follow Poisson statistics. We find that the temperature-dependent frequency shift deviates from the Mattis-Bardeen theory, and the dissipation response shows a shorter decay time than the frequency response at low temperatures. We suggest that the observed anomalous electrodynamics may be related to quasiparticle traps or subgap states in the disordered TiN films. Finally, the electron density-of-states is derived from the pulse response.Comment: 4 pages, 3 figure

Tests of Lorentz violation in muon antineutrino to electron antineutrino oscillations

A recently developed Standard-Model Extension (SME) formalism for neutrino oscillations that includes Lorentz and CPT violation is used to analyze the sidereal time variation of the neutrino event excess measured by the Liquid Scintillator Neutrino Detector (LSND) experiment. The LSND experiment, performed at Los Alamos National Laboratory, observed an excess, consistent with neutrino oscillations, of ${\bar\nu}_e$ in a beam of ${\bar\nu}_\mu$. It is determined that the LSND oscillation signal is consistent with no sidereal variation. However, there are several combinations of SME coefficients that describe the LSND data; both with and without sidereal variations. The scale of Lorentz and CPT violation extracted from the LSND data is of order $10^{-19}$ GeV for the SME coefficients $a_L$ and $E \times c_L$. This solution for Lorentz and CPT violating neutrino oscillations may be tested by other short baseline neutrino oscillation experiments, such as the MiniBooNE experiment.Comment: 10 pages, 10 figures, 2 tables, uses revtex4 replaced with version to be published in Physical Review D, 11 pages, 11 figures, 2 tables, uses revtex

Search for π0→νμνˉμ\pi^0 \to \nu_{\mu}\bar\nu_{\mu} Decay in LSND

We observe a net beam-excess of $8.7 \pm 6.3$ (stat) $\pm 2.4$ (syst) events, above 160 MeV, resulting from the charged-current reaction of $\nu_{\mu}$ and/or $\bar\nu_{\mu}$ on C and H in the LSND detector. No beam related muon background is expected in this energy regime. Within an analysis framework of $\pi^0 \to \nu_{\mu}\bar\nu_{\mu}$, we set a direct upper limit for this branching ratio of $\Gamma(\pi^0 \to \nu_\mu \bar\nu_\mu) / \Gamma(\pi^0 \to all) < 1.6 \times 10^{-6}$ at 90% confidence level.Comment: 4 pages, 4 figure

Butt Joint Reinforcement in Parallel-Laminated Veneer (PLV) Lumber

Parallel-laminated veneer (PLV) is a high-strength structural material consisting of thin parallel-laminated wood veneers. The use of graphite-cloth reinforcement, placed on either side of a butt joint in 1 1/2- by 3 1/2- by 32-inch Douglas-fir PLV tensile members, was assessed. The finite-element method of analysis was used to predict the behavior in different unreinforced and reinforced butt-jointed PLV tensile members. Relationships between the reinforcing parameters—length, modulus of elasticity, and thickness—and the stresses in the wood and reinforcement components were developed by regression analysis techniques. The reinforcing mechanism reduced the peak stresses at the butt joint and hence increased the ultimate strength of the member. Design of PLV material whose strength is limited by shear stresses that develop at the butt joint is facilitated by use of the proposed relationships.Experimental testing confirmed the predictions of the finite-element analysis. Failure initiated at the unreinforced joint in the specimens. Average tensile strength increased and variability decreased in reinforced specimens. Application of a small amount of reinforcement at the butt joint has been shown to enhance PLV performance

The Los Alamos Trapped Ion Quantum Computer Experiment

The development and theory of an experiment to investigate quantum computation with trapped calcium ions is described. The ion trap, laser and ion requirements are determined, and the parameters required for quantum logic operations as well as simple quantum factoring are described.Comment: 41 pages, 16 figures, submitted to Fortschritte der Physi