1,137 research outputs found

    Compound particle swarm optimization in dynamic environments

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    Copyright @ Springer-Verlag Berlin Heidelberg 2008.Adaptation to dynamic optimization problems is currently receiving a growing interest as one of the most important applications of evolutionary algorithms. In this paper, a compound particle swarm optimization (CPSO) is proposed as a new variant of particle swarm optimization to enhance its performance in dynamic environments. Within CPSO, compound particles are constructed as a novel type of particles in the search space and their motions are integrated into the swarm. A special reflection scheme is introduced in order to explore the search space more comprehensively. Furthermore, some information preserving and anti-convergence strategies are also developed to improve the performance of CPSO in a new environment. An experimental study shows the efficiency of CPSO in dynamic environments.This work was supported by the Key Program of the National Natural Science Foundation (NNSF) of China under Grant No. 70431003 and Grant No. 70671020, the Science Fund for Creative Research Group of NNSF of China under Grant No. 60521003, the National Science and Technology Support Plan of China under Grant No. 2006BAH02A09 and the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant No. EP/E060722/1

    Review of Solar Neutrino Experiments

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    This paper reviews the constraints on the solar neutrino mixing parameters with data collected by the Homestake, SAGE, GALLEX, Kamiokande, SuperKamiokande, and SNO experiments. An emphasis will be given to the global solar neutrino analyses in terms of matter-enhanced oscillation of two active flavors. The results to-date, including both solar model dependent and independent measurements, indicate that electron neutrinos are changing to other active types on route to the Earth from the Sun. The total flux of solar neutrinos is found to be in very good agreement with solar model calculations. Future measurements will focus on greater accuracy for mixing parameters and on better sensitivity to low neutrino energies.Comment: Prepared for the XXI International Symposium on Lepton and Photon Interactions at High Energies, Fermilab, USA, 11-16 August 200

    Development of a method for measuring rare earth elements in the environment for future experiments with gadolinium-loaded detectors

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    Demand to use gadolinium (Gd) in detectors is increasing in the field of elementary particle physics, especially in neutrino measurements and dark matter searches. Large amounts of Gd are used in these experiments. To assess the impact of Gd on the environment it is becoming important to measure the baseline concentrations of Gd. Such measurement, however, is not easy due to interference by other elements. In this paper a method for measuring the concentrations of rare earth elements, including Gd, is proposed. In the method, inductively coupled plasma-mass spectrometry is utilized after collecting the dissolved elements in chelating resin. Results of the ability to detect anomalous concentrations of rare earth elements in river water samples in the Kamioka and Toyama areas are also reported

    Weak and Electromagnetic Nuclear Decay Signatures for Neutrino Reactions in SuperKamiokande

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    We suggest the study of events in the SuperKamiokande neutrino data due to charged- and neutral-current neutrino reactions followed by weak and/or electromagnetic decays of struck nuclei and fragments thereof. This study could improve the prospects of obtaining evidence for τ\tau production from νμντ\nu_\mu \to \nu_\tau oscillations and could augment the data sample used to disfavor νμνsterile\nu_\mu \to \nu_{sterile} oscillations.Comment: 7 pages, latex, to appear in Phys. Rev. Let

    Search for exotic neutrino-electron interactions using solar neutrinos in XMASS-I

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    We have searched for exotic neutrino-electron interactions that could be produced by a neutrino millicharge, by a neutrino magnetic moment, or by dark photons using solar neutrinos in the XMASS-I liquid xenon detector. We observed no significant signals in 711 days of data. We obtain an upper limit for neutrino millicharge of 5.4×\times1012e^{-12} e at 90\% confidence level assuming all three species of neutrino have common millicharge. We also set flavor dependent limits assuming the respective neutrino flavor is the only one carrying a millicharge, 7.3×1012e7.3 \times 10^{-12} e for νe\nu_e, 1.1×1011e1.1 \times 10^{-11} e for νμ\nu_{\mu}, and 1.1×1011e1.1 \times 10^{-11} e for ντ\nu_{\tau}. These limits are the most stringent yet obtained from direct measurements. We also obtain an upper limit for the neutrino magnetic moment of 1.8×\times1010^{-10} Bohr magnetons. In addition, we obtain upper limits for the coupling constant of dark photons in the U(1)BLU(1)_{B-L} model of 1.3×\times106^{-6} if the dark photon mass is 1×103\times 10^{-3} MeV/c2/c^{2}, and 8.8×\times105^{-5} if it is 10 MeV/c2/c^{2}
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