29,520 research outputs found

    The Geant4 Hadronic Verification Suite for the Cascade Energy Range

    Full text link
    A Geant4 hadronic process verification suite has been designed to test and optimize Geant4 hadronic models in the cascade energy range. It focuses on quantities relevant to the LHC radiation environment and spallation source targets. The general structure of the suite is presented, including the user interface, stages of verification, management of experimental data, event generation, and comparison of results to data. Verification results for the newly released Binary cascade and Bertini cascade models are presented.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 5 pages, LaTeX, 3 eps figures. PSN MOMT00

    The Bleaching of Soy Bean Oil with Peat

    Get PDF
    The color in soy bean oil is removed by four or five treatments at 120°C with 10% - 20% of its weight of north Iowa peat or peat ash. The removal of the color is accomplished with fewer treatments by first mixing the oil with an equal volume of solvent naphtha which is distilled off after the bleaching treatment. Exposure of the oil to strong sunlight, or better to ultraviolet rays, assists in removing the last traces of color

    γNΔ\gamma^{*}N\Delta Form Factors from a Relativistic Dynamical Model of Pion Electroproduction

    Full text link
    We obtain the electromagnetic form factors of the γNΔ\gamma N\Delta transition by analyzing recent pion-electroproduction data using a fully relativistic dynamical model. Special care is taken to satisfy Ward-Takahashi identities for the Born term in the presence of form factors thereby allowing the use of realistic electromagnetic form factors of the nucleon and pion. We parametrize the Q2Q^2 dependence of the {\it bare} γNΔ\gamma N \Delta form factors by a three-parameter form which is consistent with the asymptotic behavior inferred from QCD. The parameters of the bare γNΔ\gamma N \Delta form factors are the only free parameters of the model and are fitted to the differential cross-section and multipole-analysis data up to Q2=4Q^2=4 (GeV/c)2^2 in the Δ(1232)\Delta(1232)-resonance region. This analysis emphasizes the significance of the pion-cloud effects in the extraction of the resonance parameters.Comment: 9 pages, 5 figures, several small corrections, to be published in Phys. Rev.

    Capture rate and neutron helicity asymmetry for ordinary muon capture on hydrogen

    Full text link
    Applying heavy-baryon chiral perturbation theory to ordinary muon capture (OMC) on a proton, we calculate the capture rate and neutron helicity asymmetry up to next-to-next-to-leading order. For the singlet hyperfine state, we obtain the capture rate Gamma_0 = 695 sec^{-1} while, for the triplet hyperfine state, we obtain the capture rate Gamma_1 = 11.9 sec^{-1} and the neutron asymmetry alpha_1 = 0.93. If the existing formalism is used to relate these atomic capture rates to Gamma_{liq}, the OMC rate in liquid hydrogen, then Gamma_{liq} corresponding to our improved values of Gamma_0 and Gamma_1 is found to be significantly larger than the experimental value, primarily due to the updated larger value of g_A. We argue that this apparent difficulity may be correlated to the specious anomaly recently reported for mu^- + p to n + nu_mu + gamma, and we suggest a possibility to remove these two "problems" simply and simultaneously by reexamining the molecular physics input that underlies the conventional analysis of Gamma_{liq}.Comment: 14 pages, 1 figur

    Numerical Estimation of the Asymptotic Behaviour of Solid Partitions of an Integer

    Full text link
    The number of solid partitions of a positive integer is an unsolved problem in combinatorial number theory. In this paper, solid partitions are studied numerically by the method of exact enumeration for integers up to 50 and by Monte Carlo simulations using Wang-Landau sampling method for integers up to 8000. It is shown that, for large n, ln[p(n)]/n^(3/4) = 1.79 \pm 0.01, where p(n) is the number of solid partitions of the integer n. This result strongly suggests that the MacMahon conjecture for solid partitions, though not exact, could still give the correct leading asymptotic behaviour.Comment: 6 pages, 4 figures, revtex

    The Preparation of Permanent Filter Mats for Gooch Crucibles

    Get PDF
    A porcelain filter mat has been made (Sweeney and Quam - J.A.C.S. 46, 958, 1924) which withstands the heat of a blast lamp, remains constant in weight after repeated washing with aqua regia, has uniform porosity, and has the advantages of a Monroe crucible. Methods of standardizing the mats are being studied. The building of silica filter mats in silica crucibles is being investigated. Preliminary results indicate that a silica mat can be made according to the plan of the porcelain mat and have the added advantages that silica affords

    Modal Ω-Logic: Automata, Neo-Logicism, and Set-Theoretic Realism

    Get PDF
    This essay examines the philosophical significance of Ω\Omega-logic in Zermelo-Fraenkel set theory with choice (ZFC). The duality between coalgebra and algebra permits Boolean-valued algebraic models of ZFC to be interpreted as coalgebras. The modal profile of Ω\Omega-logical validity can then be countenanced within a coalgebraic logic, and Ω\Omega-logical validity can be defined via deterministic automata. I argue that the philosophical significance of the foregoing is two-fold. First, because the epistemic and modal profiles of Ω\Omega-logical validity correspond to those of second-order logical consequence, Ω\Omega-logical validity is genuinely logical, and thus vindicates a neo-logicist conception of mathematical truth in the set-theoretic multiverse. Second, the foregoing provides a modal-computational account of the interpretation of mathematical vocabulary, adducing in favor of a realist conception of the cumulative hierarchy of sets

    Quark-Gluon String Model Description of Baryon Production in K^{\pm}N Interactions

    Full text link
    The process of baryon production in K p collisions at high energies is considered in the framework of the Quark-Gluon String Model. The contribution of the string-junction mechanism to the strange baryon production is analysed. The results of numerical calculations are in reasonable agreement with the data on inclusive spectra of p, Lambda, bar{Lambda}, and on the bar{Lambda}/Lambda asymmetry. The predictions for Xi and Omega baryons are presented.Comment: 19 pages, 7 figure

    Low-Temperature Physics

    Get PDF
    Contains reports on six research projects
    corecore