1,573 research outputs found

    The role of ν\nu-induced reactions on lead and iron in neutrino detectors

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    We have calculated cross sections and branching ratios for neutrino induced reactions on ^{208}Pb and ^{56}Fe for various supernova and accelerator-relevant neutrino spectra. This was motivated by the facts that lead and iron will be used on one hand as target materials in future neutrino detectors, on the other hand have been and are still used as shielding materials in accelerator-based experiments. In particular we study the inclusive ^{56}Fe(νe,e)Fe(\nu_e,e^-)^{56}Co and ^{208}Pb(νe,e)Pb(\nu_e,e^-)^{208}Bi cross sections and calculate the neutron energy spectra following the decay of the daughter nuclei. These reactions give a potential background signal in the KARMEN and LSND experiment and are discussed as a detection scheme for supernova neutrinos in the proposed OMNIS and LAND detectors. We also study the neutron-emission following the neutrino-induced neutral-current excitation of ^{56}Fe and ^{208}Pb.Comment: 23 pages (including 7 figures

    Muon capture on nuclei with N > Z, random phase approximation, and in-medium renormalization of the axial-vector coupling constant

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    We use the random phase approximation to describe the muon capture rate on 44{}^{44}Ca,48{}^{48}Ca, 56{}^{56}Fe, 90{}^{90}Zr, and 208{}^{208}Pb. With 40{}^{40}Ca as a test case, we show that the Continuum Random Phase Approximation (CRPA) and the standard RPA give essentially equivalent descriptions of the muon capture process. Using the standard RPA with the free nucleon weak form factors we reproduce the experimental total capture rates on these nuclei quite well. Confirming our previous CRPA result for the N=ZN = Z nuclei, we find that the calculated rates would be significantly lower than the data if the in-medium quenching of the axial-vector coupling constant were employed.Comment: submitted to Phys. Rev.

    The role of market orientation and innovation capability in export performance of small-and medium-sized enterprises: a Latin American perspective

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    Purpose - This study aims to extend the existing base of knowledge of proactive and reactive market orientation and innovation capability by testing their impact on the export performance of emerging-market small- and medium-sized enterprises (SMEs) in a Latin American context. Design/methodology/approach - This paper is a replication study, and its data were collected through a survey answered by general, marketing, sales or export managers at 155 Mexican SMEs. The research model was tested using partial least squares. Findings - The study results indicate that innovation capability and reactive market orientation are drivers of export performance in Latin American SMEs. Moreover, proactive market orientation has been found to have an indirect effect on export results. Practical implications - This study highlights to managers of Latin American SMEs the importance of capability development and deployment to improve export performance. Social implications - SMEs enabled by strategic and technological innovation based on current and latent customer needs can advantageously perform in foreign markets and can drive economic growth and social and human development in Latin America. Originality/value - Recent studies have focused on emerging-market enterprises and the necessity of developing dynamic capabilities to achieve internationalisation. This study extends previous research by assessing the robustness and generalizability of drivers in export performance for manufacturing SMEs in Latin America. In particular, it provides empirical insights on the capabilities to develop by Latin American SMEs to achieve better export performance

    Signal for supernova νμ\nu_\mu and ντ\nu_\tau neutrinos in water \v{C}erenkov detectors

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    We suggest that photons with energies between 5 and 10 MeV, generated by the (ν,νpγ\nu,\nu'p\gamma) and (ν,νnγ\nu,\nu'n\gamma) reactions on 16^{16}O, constitute a signal which allows a unique identification of supernova νμ\nu_\mu and ντ\nu_\tau neutrinos in water \v{C}erenkov detectors. We calculate the yield of such γ\gamma events and estimate that a few hundred of them would be detected in Superkamiokande for a supernova at 10 kpc distance.Comment: 8 pages, RevTex 3.0, figures and text available at http://www.krl.caltech.edu/preprints/MAP.htm

    Neutrino induced transitions between the ground states of the A=12 triad

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    Neutrino induced reactions on 12^{12}C, an ingredient of liquid scintillators, have been studied in several experiments. We show that for currently available neutrino energies, EνE_{\nu} \le 300 MeV, calculated exclusive cross sections 12^{12}Cgs(ν,l)_{gs}(\nu,l)12^{12}Ngs_{gs} for both muon and electron neutrinos are essentially model independent, provided the calculations simultaneously describe the rates of several other reactions involving the same states or their isobar analogs. The calculations agree well with the measured cross sections, which can be therefore used to check the normalization of the incident neutrino spectrum and the efficiency of the detector.Comment: 9 pages REVTEX, 2 postscript figures, text and figures available at http://www.krl.caltech.edu/preprints/MAP.htm

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    Monitoring surface resonances on Co2MnSi(100) by spin-resolved photoelectron spectroscopy

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    The magnitude of the spin polarization at the Fermi level of ferromagnetic materials at room temperature is a key property for spintronics. Investigating the Heusler compound Co2_2MnSi a value of 93%\% for the spin polarization has been observed at room temperature, where the high spin polarization is related to a stable surface resonance in the majority band extending deep into the bulk. In particular, we identified in our spectroscopical analysis that this surface resonance is embedded in the bulk continuum with a strong coupling to the majority bulk states. The resonance behaves very bulk-like, as it extends over the first six atomic layers of the corresponding (001)-surface. Our study includes experimental investigations, where the bulk electronic structure as well as surface-related features have been investigated using spin-resolved photoelectron spectroscopy (SR-UPS) and for a larger probing depth spin-integrated high energy x-ray photoemission spectroscopy (HAXPES). The results are interpreted in comparison with first-principles band structure and photoemission calculations which consider all relativistic, surface and high-energy effects properly.Comment: 9 pages, 8 figures, Heusler alloy, electronic structure and photoemissio

    Meta‐analytic structural equation modeling made easy: A tutorial and web application for one‐stage MASEM

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    Meta‐analytic structural equation modeling (MASEM) refers to fitting structural equation models (SEMs) (such as path models or factor models) to meta‐analytic data. Currently, fitting MASEMs may be challenging for researchers that are not accustomed to working with R software and packages. Therefore, we developed webMASEM; a web application for MASEM. This app implements the one‐stage MASEM approach, and allows users to apply MASEM in a user‐friendly way. The aim of this article is to provide a tutorial on one‐stage MASEM and a practical guide to webMASEM. We will pay specific attention to how the data should be structured and prepared for webMASEM, because mistakes in this step may lead to faulty results without receiving an error message. The use of webMASEM is illustrated with an analysis of a meta‐analytic path model in which the path coefficients are moderated by a study‐level variable, a meta‐analytic factor model in which the factor loadings are moderated by a study‐level variable, and a meta‐analytic panel model in which the effects are moderated by a study‐level variable. All used datafiles and R scripts are available online

    Political Reality: Attack Ads are Here to Stay

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    The primary research questions of this study center on two largely overlooked areas in negative political advertising: (1) Would the sponsor of the attack ad message be better off with a positive message? (2) When one is targeted by an attack ad, how should the attacked candidate respond? M-Turk subjects (n = 1,380) were used to conduct a multi-stage experimental design to capture the dynamic aspects of how subjects react to the use of attack ads in a hypothetical political campaign. In general, subjects did not respond favorably to attack ads, as these negative political messages caused damage to the image of both the attacker and the attacked. However, it was found that attack ads did cause greater harm to the evaluations of the attacked candidate than to the attacker. Positive ads offered in response to an attack ad helped the attacked candidate recover, whereas negative counter ads, when executed in response to an attack ad, inflicted greater damage to the attacked than the attacker. Suggestions for future research are offered in this highly relevant area of political campaigning
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