1,431 research outputs found

    Universal scaling for the spin-electricity conversion on surface states of topological insulators

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    We have investigated spin-electricity conversion on surface states of bulk-insulating topological insulator (TI) materials using a spin pumping technique. The sample structure is Ni-Fe|Cu|TI trilayers, in which magnetic proximity effects on the TI surfaces are negligibly small owing to the inserted Cu layer. Voltage signals produced by the spin-electricity conversion are clearly observed, and enhanced with decreasing temperature in line with the dominated surface transport at lower temperatures. The efficiency of the spin-electricity conversion is greater for TI samples with higher resistivity of bulk states and longer mean free path of surface states, consistent with the surface spin-electricity conversion

    Decay and expansion of the early aftershock activity following the 2011, M_w9.0 Tohoku earthquake

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    The 2011, M_w9.0 Tohoku earthquake was followed by an abundant amount of seismicity providing a unique opportunity to analyze the triggering mechanism of great earthquakes. Although the Tohoku earthquake occurred close to a dense seismic network, many aftershocks that occurred in the first few hours after the mainshock are not recorded in the earthquake catalogs. Here we use a template waveform approach to recover as many as possible missing events in the first 12 hours following the Tohoku mainshock. Our analysis is able to detect about 1.4 times more events than those listed in the High Sensitivity Seismograph (Hi-net) earthquake catalog. Combining our new dataset with earthquakes that occurred at latter times, we are able to observe a continuous decay of the aftershock rate and along strike expansion of aftershock area. We relate the latter observation to the occurrence of post-seismic slip over the deep interface

    Symmetry Breaking for Rho Meson in Neutron Matter

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    Qualitative changes in the collective excitation spectra of the ρ\rho-meson triplet in neutron matter is studied, with particular emphasis on the breaking of the discrete pnp\leftrightarrow n symmetry. The appearance of additional branches in the dispersion characteristics, the mass splitting among the charge states, the splitting between longitudinal and transverse modes of the ρ±\rho^{\pm} mesons and the appearance of `island' modes (or loops) in the time-like region are some of the features that are exposed.Comment: Plain LaTeX fil

    Development of a low-mass and high-efficiency charged particle detector

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    We developed a low-mass and high-efficiency charged particle detector for an experimental study of the rare decay KLπ0ννˉK_L \rightarrow \pi^0 \nu \bar{\nu}. The detector is important to suppress the background with charged particles to the level below the signal branching ratio predicted by the Standard Model (O(1011^{-11})). The detector consists of two layers of 3-mm-thick plastic scintillators with wavelength shifting fibers embedded and Multi Pixel Photon Counters for readout. We manufactured the counter and evaluated the performance such as light yield, timing resolution, and efficiency. With this design, we achieved the inefficiency per layer against penetrating charged particles to be less than 1.5×1051.5 \times 10^{-5}, which satisfies the requirement of the KOTO experiment determined from simulation studies.Comment: 20 pages, 18 figure
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