465 research outputs found

    Rare Kaon Decay From E949 At BNL: K^+ -->pi^+ nunubar

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    In the first year of physics run, the E949 experiment at Brookhaven National Laboratory has already collected 1.8×10121.8\times 10^{12} kaons stopping in the target. Additional evidence for the rare charged kaon decay K+π+ννˉK^+\to\pi^+\nu\bar{\nu} has been observed. Combined with previous results from the E787 experiment, the branching ratio is measured to be Br(K+π+ννˉK^+\to\pi^+\nu\bar{\nu})=(1.470.89+1.30)×1010(1.47^{+1.30}_{-0.89})\times10^{-10}.Comment: 4pages. Submitted to 32nd International Conference on High-Energy Physics (ICHEP04), Beijing, China, 16-22 Aug 200

    Discovery potential for supernova relic neutrinos with slow liquid scintillator detectors

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    Detection of supernova relic neutrinos could provide key support for our current understanding of stellar and cosmological evolution, and precise measurements of these neutrinos could yield novel insights into the universe. In this paper, we studied the detection potential of supernova relic neutrinos using linear alkyl benzene (LAB) as a slow liquid scintillator. The linear alkyl benzene features good separation of Cherenkov and scintillation lights, thereby providing a new route for particle identification. We further addressed key issues in current experiments, including (1) the charged current background of atmospheric neutrinos in water Cherenkov detectors and (2) the neutral current background of atmospheric neutrinos in typical liquid scintillator detectors. A kiloton-scale LAB detector at Jinping with O\mathcal{O}(10) years of data could discover supernova relic neutrinos with a sensitivity comparable to that of large-volume water Cherenkov detectors, typical liquid scintillator detectors, and liquid argon detectors.Comment: 9 pages, 6 figure

    Design, characterization, and sensitivity of the supernova trigger system at Daya Bay

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    Providing an early warning of galactic supernova explosions from neutrino signals is important in studying supernova dynamics and neutrino physics. A dedicated supernova trigger system has been designed and installed in the data acquisition system at Daya Bay and integrated into the worldwide Supernova Early Warning System (SNEWS). Daya Bay's unique feature of eight identically-designed detectors deployed in three separate experimental halls makes the trigger system naturally robust against cosmogenic backgrounds, enabling a prompt analysis of online triggers and a tight control of the false-alert rate. The trigger system is estimated to be fully sensitive to 1987A-type supernova bursts throughout most of the Milky Way. The significant gain in sensitivity of the eight-detector configuration over a mass-equivalent single detector is also estimated. The experience of this online trigger system is applicable to future projects with spatially distributed detectors.Comment: 8 pages, 6 figures, to be submitted to Astroparticle Physic

    Generalized integrated importance measure for system performance evaluation: application to a propeller plane system

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    The integrated importance measure (IIM) evaluates the rate of system performance change due to a component changing from one state to another. The IIM simply considers the scenarios where the transition rate of a component from one state to another is constant. This may contradict the assumption of the degradation, based on which system performance is degrading and therefore the transition rate may be increasing over time. The Weibull distribution describes the life of a component, which has been used in many different engineering applications to model complex data sets. This paper extends the IIM to a new importance measure that considers the scenarios where the transition rate of a component degrading from one state to another is a time-dependent function under the Weibull distribution. It considers the conditional probability distribution of a component sojourning at a state is the Weibull distribution, given the next state that component will jump to. The research on the new importance measure can identify the most important component during three different time periods of the system lifetime, which is corresponding to the characteristics of Weibull distributions. For illustration, the paper then derives some probabilistic properties and applies the extended importance measure to a real-world example (i.e., a propeller plane system)

    Multiqubit entanglement due to quantum gravity

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    Quantum gravity between masses can produce entangled states in thought experiments. We extend the experiments to tripartite case and construct states equivalent to Greenberger- Horne-Zeilinger states and W states under stochastic local operations and classical communication. The entanglement relates to the evolution phases induced by gravitational interaction. When we involve more masses in the experiments, multipartite entangled states can be constructed in a similar way. We measure the degree of multipartite entanglement by calculating the geometric measure. We describe the relationship between geometric measure and the evolution phases. It helps in searching out the states with robust entanglement.Comment: 17 pages,9 figure