Browsing by Author "Robinson, AL"

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    Pittsburgh air quality study overview
    (Atmospheric Environment, 2004-06-01) Wittig, AE; Anderson, N; Khlystov, AY; Pandis, SN; Davidson, C; Robinson, AL
    Ambient sampling for the Pittsburgh Air Quality Study (PAQS) was conducted from July 2001 to September 2002. The study was designed (1) to characterize particulate matter (PM) by examination of size, surface area, and volume distribution, chemical composition as a function of size and on a single particle basis, morphology, and temporal and spatial variability in the Pittsburgh region; (2) to quantify the impact of the various sources (transportation, power plants, biogenic sources, etc.) on the aerosol concentrations in the area; and (3) to develop and evaluate the next generation of atmospheric aerosol monitoring and modeling techniques. The PAQS objectives, study design, site descriptions and routine and intensive measurements are presented. Special study days are highlighted, including those associated with elevated concentrations of daily average PM2.5 mass. Monthly average and diurnal patterns in aerosol number concentration, and aerosol nitrate, sulfate, elemental carbon, and organic carbon concentrations, light scattering as well as gas-phase ozone, nitrogen oxides, and carbon monoxide are discussed with emphasis on the processes affecting them. Preliminary findings reveal day-to-day variability in aerosol mass and composition, but consistencies in seasonal average diurnal profiles and concentrations. For example, the seasonal average variations in the diurnal PM2.5 mass were predominately driven by the sulfate component. © 2004 Elsevier Ltd. All rights reserved.
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    Positive and negative artifacts in particulate organic carbon measurements with denuded and undenuded sampler configurations
    (Aerosol Science and Technology, 2004-05-01) Subramanian, R; Khlystov, AY; Cabada, JC; Robinson, AL
    Measurement of ambient particulate organic carbon (POC) with quartz filters is prone to positive and negative sampling artifacts. One approach for estimating these artifacts is to sample with a backup quartz filter placed behind either the main quartz filter or a Teflon filter in a parallel line. Another approach is to use a denuder to reduce the positive artifact in combination with a highly adsorbent backup filter to capture any negative artifact. Results obtained using both of these approaches in parallel for over one year in Pittsburgh, PA are presented in this article. A sampler using an activated carbon monolith denuder has been developed and tested extensively. Transmission losses were found to be negligible, and the denuder is on average 94% efficient at removing gas-phase organics. Denuder breakthrough is corrected for each run using a dynamic blank in parallel with the sample line. Comparisons with the dynamic blank indicate that the denuder almost eliminates the positive artifact on the quartz filter. Negative artifact from the denuded quartz filter is quantified using a carbon-impregnated glass fiber (CIG) backup filter and was found to be small, typically less than 10% of the ambient POC. Compared to the denuded sampler POC, 24 h bare quartz samples showed an almost constant positive artifact of 0.5 μg-C/m3 for samples taken throughout the year-long study period. Sampling for shorter durations (4-6 h) resulted in a larger positive artifact. A quartz filter behind a Teflon filter (QBT) provides a consistent estimate of the positive artifact on the bare quartz filter irrespective of sample duration, though it overcorrects for the positive artifact by 16-20% (attributed to particulate matter volatilizing off the upstream Teflon filter). The quartz behind quartz (QBQ) approach provides a reasonable estimate of the positive artifact on the bare quartz filter for the 24 h samples but not for the shorter samples. A slight seasonal variation is observed in the absolute value of the positive artifact, with higher values observed during the summer months.
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    Search for Majoron-emitting modes of $^{136}$Xe double beta decay with the complete EXO-200 dataset
    Kharusi, S Al; Anton, G; Badhrees, I; Barbeau, PS; Beck, D; Belov, V; Bhatta, T; Breidenbach, M; Brunner, T; Cao, GF; Cen, WR; Chambers, C; Cleveland, B; Coon, M; Craycraft, A; Daniels, T; Darroch, L; Daugherty, SJ; Davis, J; Delaquis, S; Mesrobian-Kabakian, A Der; DeVoe, R; Dilling, J; Dolgolenko, A; Dolinski, MJ; Echevers, J; Jr, W Fairbank; Fairbank, D; Farine, J; Feyzbakhsh, S; Fierlinger, P; Fudenberg, D; Gautam, P; Gornea, R; Gratta, G; Hall, C; Hansen, EV; Hoessl, J; Hufschmidt, P; Hughes, M; Iverson, A; Jamil, A; Jessiman, C; Jewell, MJ; Johnson, A; Karelin, A; Kaufman, LJ; Koffas, T; ucken, R Kr; Kuchenkov, A; Kumar, KS; Lan, Y; Larson, A; Lenardo, BG; Leonard, DS; Li, GS; Li, S; Li, Z; Licciardi, C; Lin, YH; MacLellan, R; McElroy, T; Michel, T; Mong, B; Moore, DC; Murray, K; Njoya, O; Nusair, O; Odian, A; Ostrovskiy, I; Perna, A; Piepke, A; Pocar, A; Retiere, F; Robinson, AL; Rowson, PC; Rudde, D; Runge, J; Schmidt, S; Sinclair, D; Skarpaas, K; Soma, AK; Stekhanov, V; Tarka, M; Thibado, S; Todd, J; Tolba, T; Totev, TI; Tsang, R; Veenstra, B; Veeraraghavan, V; Vogel, P; Vuilleumier, J-L; Wagenpfeil, M; Watkins, J; Weber, M; Wen, LJ; Wichoski, U; Wrede, G; Wu, SX; Xia, Q; Yahne, DR; Yang, L; Yen, Y-R; Zeldovich, O Ya; Ziegler, T
    A search for Majoron-emitting modes of the neutrinoless double-beta decay of $^{136}$Xe is performed with the full EXO-200 dataset. This dataset consists of a total $^{136}$Xe exposure of 234.1 kg$\cdot$yr, and includes data with detector upgrades that have improved the energy threshold relative to previous searches. A lower limit of T$_{1/2}^{\rm{^{136}Xe}}>$4.3$\cdot$10$^{24}$ yr at 90\% C.L. on the half-life of the spectral index $n=1$ Majoron decay was obtained, a factor of 3.6 more stringent than the previous limit from EXO-200, corresponding to a constraint on the Majoron-neutrino coupling constant of $|\langle g_{ee}^{M}\rangle|$$<(0.4$-$0.9)\cdot10^{-5}$. The lower threshold and the additional data taken resulted in a factor 8.4 improvement for the $n=7$ mode compared to the previous EXO search. This search provides the most stringent limits to-date on the Majoron-emitting decays of $^{136}$Xe with spectral indices $n=1,2,3,$ and 7.
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    The EXO-200 detector, part II: Auxiliary Systems
    Ackerman, N; Albert, J; Auger, M; Auty, DJ; Badhrees, I; Barbeau, PS; Bartoszek, L; Baussan, E; Belov, V; Benitez-Medina, C; Bhatta, T; Breidenbach, M; Brunner, T; Cao, GF; Cen, WR; Chambers, C; Cleveland, B; Conley, R; Cook, S; Coon, M; Craddock, W; Craycraft, A; Cree, W; Daniels, T; Darroch, L; Daugherty, SJ; Daughhetee, J; Davis, CG; Davis, J; Delaquis, S; Mesrobian-Kabakian, A Der; deVoe, R; Didberidze, T; Dilling, J; Dobi, A; Dolgolenko, AG; Dolinski, MJ; Dunford, M; Echevers, J; Espic, L; Jr, W Fairbank; Fairbank, D; Farine, J; Feldmeier, W; Feyzbakhsh, S; Fierlinger, P; Fouts, K; Franco, D; Freytag, D; Fudenberg, D; Gautam, P; Giroux, G; Gornea, R; Graham, K; Gratta, G; Hagemann, C; Hall, C; Hall, K; Haller, G; Hansen, EV; Hargrove, C; Herbst, R; Herrin, S; Hodgson, J; Hughes, M; Iverson, A; Jamil, A; Jessiman, C; Jewell, MJ; Johnson, A; Johnson, TN; Johnston, S; Karelin, A; Kaufman, LJ; Killick, R; Koffas, T; Kravitz, S; Krücken, R; Kuchenkov, A; Kumar, KS; Lan, Y; Larson, A; Leonard, DS; Leonard, F; LePort, F; Li, GS; Li, S; Li, Z; Licciardi, C; Lin, YH; Mackay, D; MacLellan, R; Marino, M; Martin, J-M; Martin, Y; McElroy, T; McFarlane, K; Michel, T; Mong, B; Moore, DC; Murray, K; Neilson, R; Njoya, O; Nusair, O; O'Sullivan, K; Odian, A; Ostrovskiy, I; Ouellet, C; Piepke, A; Pocar, A; Prescott, CY; Pushkin, K; Retiere, F; Rivas, A; Robinson, AL; Rollin, E; Rowson, PC; Rozo, MP; Runge, J; Russell, JJ; Schmidt, S; Schubert, A; Sinclair, D; Skarpaas, K; Slutsky, S; Smith, E; Soma, AK; Stekhanov, V; Strickland, V; Swift, M; Tarka, M; Todd, J; Tolba, T; Tosi, D; Totev, TI; Tsang, R; Twelker, K; Veenstra, B; Veeraraghavan, V; Vuilleumier, J-L; Vuilleumier, J-M; Wagenpfeil, M; Waite, A; Walton, J; Walton, T; Wamba, K; Watkins, J; Weber, M; Wen, LJ; Wichoski, U; Wittgen, M; Wodin, J; Wood, J; Wrede, G; Wu, SX; Xia, Q; Yang, L; Yen, Y-R; Zeldovich, O Ya; Ziegler, T
    The EXO-200 experiment searched for neutrinoless double-beta decay of $^{136}$Xe with a single-phase liquid xenon detector. It used an active mass of 110 kg of 80.6%-enriched liquid xenon in an ultra-low background time projection chamber with ionization and scintillation detection and readout. This paper describes the design and performance of the various support systems necessary for detector operation, including cryogenics, xenon handling, and controls. Novel features of the system were driven by the need to protect the thin-walled detector chamber containing the liquid xenon, to achieve high chemical purity of the Xe, and to maintain thermal uniformity across the detector.