261,636 research outputs found

    Mix-and-match compatibility in asymmetric system markets

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    This paper shows that the private incentive for mix-and-match compatibility in system markets diverges from the social planner's incentive if competing suppliers are asymmetric in production cost or product quality. There can be too much or too little compatibility when the market is served by fully integrated system suppliers. Also, the market outcome involves socially too much incompatibility in the form of exclusive technological alliances when the market is composed of independent component suppliers. These results contrast with the standard one obtained in the symmetric setup and shed new light on public policy towards compatibility, technological alliances, and bundling practices in system markets

    Pulse-shape discrimination between electron and nuclear recoils in a NaI(Tl) crystal

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    We report on the response of a high light-output NaI(Tl) crystal to nuclear recoils induced by neutrons from an Am-Be source and compare the results with the response to electron recoils produced by Compton scattered 662 keV γ\gamma-rays from a 137^{137}Cs source. The measured pulse-shape discrimination (PSD) power of the NaI(Tl) crystal is found to be significantly improved because of the high light output of the NaI(Tl) detector. We quantify the PSD power with a quality factor and estimate the sensitivity to the interaction rate for weakly interacting massive particles (WIMPs) with nucleons, and the result is compared with the annual modulation amplitude observed by the DAMA/LIBRA experiment. The sensitivity to spin-independent WIMP-nucleon interactions based on 100 kg\cdotyear of data from NaI detectors is estimated with simulated experiments, using the standard halo model.Comment: 11page

    Electronic structures of Zn1x_{1-x}Cox_xO using photoemission and x-ray absorption spectroscopy

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    Electronic structures of Zn1x_{1-x}Cox_xO have been investigated using photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). The Co 3d states are found to lie near the top of the O 2p2p valence band, with a peak around 3\sim 3 eV binding energy. The Co 2p2p XAS spectrum provides evidence that the Co ions in Zn1x_{1-x}Cox_{x}O are in the divalent Co2+^{2+} (d7d^7) states under the tetrahedral symmetry. Our finding indicates that the properly substituted Co ions for Zn sites will not produce the diluted ferromagnetic semiconductor property.Comment: 3 pages, 2 figure