33 research outputs found

    Performance of two Askaryan Radio Array stations and first results in the search for ultra-high energy neutrinos

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    Ultra-high energy neutrinos are interesting messenger particles since, if detected, they can transmit exclusive information about ultra-high energy processes in the Universe. These particles, with energies above 1016eV10^{16}\mathrm{eV}, interact very rarely. Therefore, detectors that instrument several gigatons of matter are needed to discover them. The ARA detector is currently being constructed at South Pole. It is designed to use the Askaryan effect, the emission of radio waves from neutrino-induced cascades in the South Pole ice, to detect neutrino interactions at very high energies. With antennas distributed among 37 widely-separated stations in the ice, such interactions can be observed in a volume of several hundred cubic kilometers. Currently 3 deep ARA stations are deployed in the ice of which two have been taking data since the beginning of the year 2013. In this publication, the ARA detector "as-built" and calibrations are described. Furthermore, the data reduction methods used to distinguish the rare radio signals from overwhelming backgrounds of thermal and anthropogenic origin are presented. Using data from only two stations over a short exposure time of 10 months, a neutrino flux limit of 3⋅10−6GeV/(cm2 s sr)3 \cdot 10^{-6} \mathrm{GeV} / (\mathrm{cm^2 \ s \ sr}) is calculated for a particle energy of 10^{18}eV, which offers promise for the full ARA detector.Comment: 21 pages, 34 figures, 1 table, includes supplementary materia

    A MEMS microphone for aeroacoustics measurements

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    This paper presents the development of a silicon-micromachined, piezoresistive microphone for aeroa-coustics measurements. The microphone consists of four dielectrically-isolated, single-crystal silicon piezore-sistors on top of a 1500 A-thick, 210 m-diameter silicon-nitride membrane. The microphone was de-signed by employing a fundamental structural model coupled with a lumped-element energy model. Prelimi-nary measurements indicate a sensitivity of 1V=V=Pa and a linear response up to 155 dB. The measured and predicted sensitivity agree to within 3 dB. 1
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