23,935 research outputs found

    Charged-Current Disappearance Measurements in the NuMI Off-Axis Beam

    Get PDF
    This article studies the potential of combining charged-current disappearance measurements of \nu_{\mu} to \nu_{\tau} from MINOS and an off-axis beam. I find that the error on \Delta m^2 from a 100 kt-yr off-axis measurement is a few percent of itself. Further, I find little improvement to an off-axis measurement by combining it with MINOS.Comment: Presented at NuFact'02. Four pages, three figure

    The Detailed Chemical Abundance Patterns of M31 Globular Clusters

    Full text link
    We present detailed chemical abundances for >>20 elements in ∼\sim30 globular clusters in M31. These results have been obtained using high resolution (λ/Δλ∼\lambda/\Delta\lambda\sim24,000) spectra of their integrated light and analyzed using our original method. The globular clusters have galactocentric radii between 2.5 kpc and 117 kpc, and therefore provide abundance patterns for different phases of galaxy formation recorded in the inner and outer halo of M31. We find that the clusters in our survey have a range in metallicity of −2.2<-2.2<[Fe/H]<−0.11<-0.11. The inner halo clusters cover this full range, while the outer halo globular clusters at R>>20 kpc have a small range in abundance of [Fe/H]=−1.6±0.10=-1.6 \pm 0.10. We also measure abundances of alpha, r- and s-process elements. These results constitute the first abundance pattern constraints for old populations in M31 that are comparable to those known for the Milky Way halo.Comment: XII International Symposium on Nuclei in the Cosmos August 5-12, 2012 Cairns, Australia. To appear in Proceedings of Scienc

    Dissociation energy and long-range potential of diatomic molecules from vibrational spacings - The halogens

    Get PDF
    Dissociation energy and long-range potential of diatomic molecules from vibrational spacings, halogen

    Shape resonances and rotationally predissociating levels - The atomic collision time delay functions and quasibound level properties of H2 /Chi /1 Sigma g plus//

    Get PDF
    Atomic collision time delay functions and quasibound level properties of ground state of molecular hydroge

    Globular Cluster Abundances from High-Resolution, Integrated-Light Spectroscopy. II. Expanding the Metallicity Range for Old Clusters and Updated Analysis Techniques

    Full text link
    We present abundances of globular clusters in the Milky Way and Fornax from integrated light spectra. Our goal is to evaluate the consistency of the integrated light analysis relative to standard abundance analysis for individual stars in those same clusters. This sample includes an updated analysis of 7 clusters from our previous publications and results for 5 new clusters that expand the metallicity range over which our technique has been tested. We find that the [Fe/H] measured from integrated light spectra agrees to ∼\sim0.1 dex for globular clusters with metallicities as high as [Fe/H]=−0.3-0.3, but the abundances measured for more metal rich clusters may be underestimated. In addition we systematically evaluate the accuracy of abundance ratios, [X/Fe], for Na I, Mg I, Al I, Si I, Ca I, Ti I, Ti II, Sc II, V I, Cr I, Mn I, Co I, Ni I, Cu I, Y II, Zr I, Ba II, La II, Nd II, and Eu II. The elements for which the integrated light analysis gives results that are most similar to analysis of individual stellar spectra are Fe I, Ca I, Si I, Ni I, and Ba II. The elements that show the greatest differences include Mg I and Zr I. Some elements show good agreement only over a limited range in metallicity. More stellar abundance data in these clusters would enable more complete evaluation of the integrated light results for other important elements.Comment: Accepted for publication in ApJ, 37 pages, 13 tables, 29 figure

    The Extrema-effect in Total Elastic Molecular Beam Scattering Cross Sections for Characterization of the Potential Well

    Get PDF
    Extrema effect in total elastic molecular beam scattering cross sections for characterization of potential wel

    Deployable antenna demonstration project

    Get PDF
    Test program options are described for large lightweight deployable antennas for space communications, radar and radiometry systems

    Dynamic autonomous intelligent control of an asteroid lander

    Get PDF
    One of the future flagship missions of the European Space Agency (ESA) is the asteroid sample return mission Marco-Polo. Although there have been a number of past missions to asteroids, a sample has never been successfully returned. The return of asteroid regolith to the Earth's surface introduces new technical challenges. This paper develops attitude control algorithms for the descent phase onto an asteroid in micro-gravity conditions and draws a comparison between the algorithms considered. Two studies are also performed regarding the Fault Detection Isolation and Recovery (FDIR) of the control laws considered. The potential of using Direct Adaptive Control (DAC) as a controller for the surface sampling process is also investigated. Use of a DAC controller incorporates increased levels of robustness by allowing realtime variation of control gains. This leads to better response to uncertainties encountered during missions
    • …
    corecore