198 research outputs found

    A Seasonality Study of the West Virginia Stream Condition Index

    Get PDF
    The West Virginia Stream Condition Index (WVSCI) has not been rigorously tested for the effects of seasonal data collection. Scientific literature regarding seasonal impacts on biological indices is surprisingly limited. But most literature does agree that seasonal signals are small in comparison to variation between all possible biological conditions. Recently stream data have been collected from a full range of seasons by both West Virginia Department of Environmental Protection and myself. In this study habitat, benthic macroinvertebrate data, and WVSCI values were analyzed for seasonality. For this reason multiple independent data sets were utilized. The analyses covered in this report include the use of box-and-whisker plots, correlation analysis and ANOVAs. Preliminary results indicate that seasonality does impact certain metrics under some seasonal conditions. Among the six metrics that make up the WVSCI, some seasonal signal was detected for EPT Taxa, % Chironomidae, Hilsenhoff Biotic Index, Total Taxa and the WVSCI Index scores. These signals were very inconsistent across multiple, independent data sets. Presently, there are no suggestions for any alterations of the WVSCI that would reduce seasonal signals

    Corrugated Silicon Platelet Feed Horn Array for CMB Polarimetry at 150 GHz

    Full text link
    Next generation cosmic microwave background (CMB) polarization anisotropy measurements will feature focal plane arrays with more than 600 millimeter-wave detectors. We make use of high-resolution photolithography and wafer-scale etch tools to build planar arrays of corrugated platelet feeds in silicon with highly symmetric beams, low cross-polarization and low side lobes. A compact Au-plated corrugated Si feed designed for 150 GHz operation exhibited performance equivalent to that of electroformed feeds: ~-0.2 dB insertion loss, <-20 dB return loss from 120 GHz to 170 GHz, <-25 dB side lobes and <-23 dB cross-polarization. We are currently fabricating a 50 mm diameter array with 84 horns consisting of 33 Si platelets as a prototype for the SPTpol and ACTpol telescopes. Our fabrication facilities permit arrays up to 150 mm in diameter.Comment: 12 pages; SPIE proceedings for Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V (Conference 7741, June 2010, San Diego, CA, USA

    Integrating planar circuits with superconducting 3D microwave cavities using tunable low-loss couplers

    Full text link
    We design and test a low-loss interface between superconducting 3-dimensional microwave cavities and 2-dimensional circuits, where the coupling rate is highly tunable. This interface seamlessly integrates a magnetic antenna and a Josephson junction based coupling element with a cavity, and we demonstrate that the introduced loss from this integration only limits the quality factor to 4.5 million. The cavity external coupling rate can then be tuned from negligibly small to over 3 orders of magnitude larger than the internal loss rate with a characteristic time of 3.2 ns. This switching speed does not impose additional limits on the coupling rate because it is much faster than the coupling rate. Moreover, the coupler can be controlled by baseband signals to avoid interference with microwave signals near the cavity or qubit frequencies. Finally, the coupling element introduces a 0.04 Hz/photon self-Kerr nonlinearity to the cavity, remaining linear in high photon number operations

    Photon-noise limited sensitivity in titanium nitride kinetic inductance detectors

    Get PDF
    We demonstrate photon-noise limited performance at sub-millimeter wavelengths in feedhorn-coupled, microwave kinetic inductance detectors (MKIDs) made of a TiN/Ti/TiN trilayer superconducting film, tuned to have a transition temperature of 1.4~K. Micro-machining of the silicon-on-insulator wafer backside creates a quarter-wavelength backshort optimized for efficient coupling at 250~\micron. Using frequency read out and when viewing a variable temperature blackbody source, we measure device noise consistent with photon noise when the incident optical power is >>~0.5~pW, corresponding to noise equivalent powers >>~3×10−17\times 10^{-17} W/Hz\sqrt{\mathrm{Hz}}. This sensitivity makes these devices suitable for broadband photometric applications at these wavelengths
    • …
    corecore