Radio Astronomy

Contains reports on three research projects.National Aeronautics and Space Administration (Grant NsG-419)National Aeronautics and Space Administration (Contract NSR-22-009-120)Lincoln Laboratory Purchase Order No. 74

Economies of Size in Municipal Water-Treatment Technologies: A Texas Lower Rio Grande Valley Case Study

As the U.S. population continues to increase, the priority on planning for future water quantity and quality becomes more important. Historically, many municipalities have primarily relied upon surface water as their major source of drinking water. In recent years, however, technological advancements have improved the economic viability of reverse-osmosis (RO) desalination of brackish-groundwater as a potable water source. By including brackishgroundwater, there may be an alternative water source that provides municipalities an opportunity to hedge against droughts, political shortfalls, and protection from potential surfacewater contamination. In addition to selecting a water-treatment technology, municipalities and their associated water planners must determine the appropriate facility size, location, etc. To assist in these issues, this research investigates and reports on economies of size for both conventional surface-water treatment and brackish-groundwater desalination by using results from four water-treatment facilities in the Texas Lower Rio Grande Valley (LRGV). The methodology and associated results herein may have direct implications on future water planning as highlighting the most economically-efficient alternative(s) is a key objective. In this study, economic and financial life-cycle costs are calculated for a “small” conventional surface-water facility (i.e., 2.0 million gallons per day (mgd) Olmito facility) and a “small” brackish-groundwater desalination facility (i.e., 1.13 mgd La Sara facility). Thereafter, these results are merged with other, prior life-cycle cost analyses’ results for a “medium” conventional surface-water facility (i.e., 8.25 mgd McAllen Northwest facility) and a “medium” brackish-groundwater desalination facility (i.e., 7.5 mgd Southmost facility). The combined data allow for examination of any apparent economies of size amongst the conventional surface-water facilities and the brackish-groundwater desalination facilities. This research utilized the CITY H20 ECONOMICS and the DESAL ECONOMICS © © Excel® spreadsheet models developed by agricultural economists with Texas AgriLife Research and Texas AgriLife Extension Service. The life-cycle costs calculated within these spreadsheet models provide input for work which subsequently provides the estimations of economies of size. Although the economies of size results are only based on four facilities and are only applicable to the Texas LRGV, the results are nonetheless useful. In short, it is determined that economies of size are apparent in conventional surface-water treatment and constant economies of size are apparent in brackish-groundwater desalination. Further, based on modified life-cycle costs (which seek to more-precisely compare across water-treatment technologies and/or facilities), this research also concludes that reverse-osmosis (RO) desalination of brackish-groundwater is economically competitive with conventional surface-water treatment in this region

Two Earth-sized planets orbiting Kepler-20

Since the discovery of the first extrasolar giant planets around Sun-like stars, evolving observational capabilities have brought us closer to the detection of true Earth analogues. The size of an exoplanet can be determined when it periodically passes in front of (transits) its parent star, causing a decrease in starlight proportional to its radius. The smallest exoplanet hitherto discovered has a radius 1.42 times that of the Earth's radius (R Earth), and hence has 2.9 times its volume. Here we report the discovery of two planets, one Earth-sized (1.03R Earth) and the other smaller than the Earth (0.87R Earth), orbiting the star Kepler-20, which is already known to host three other, larger, transiting planets. The gravitational pull of the new planets on the parent star is too small to measure with current instrumentation. We apply a statistical method to show that the likelihood of the planetary interpretation of the transit signals is more than three orders of magnitude larger than that of the alternative hypothesis that the signals result from an eclipsing binary star. Theoretical considerations imply that these planets are rocky, with a composition of iron and silicate. The outer planet could have developed a thick water vapour atmosphere.Comment: Letter to Nature; Received 8 November; accepted 13 December 2011; Published online 20 December 201

Polarizations of J/psi and psi(2S) Mesons Produced in ppbar Collisions at 1.96 TeV

We have measured the polarizations of \jpsi and \psiprime mesons as functions of their transverse momentum \pt when they are produced promptly in the rapidity range $|y|<0.6$ with \pt \geq 5 \pgev. The analysis is performed using a data sample with an integrated luminosity of about 800 \ipb collected by the CDF II detector. For both vector mesons, we find that the polarizations become increasingly longitudinal as \pt increases from 5 to 30 \pgev. These results are compared to the predictions of nonrelativistic quantum chromodynamics and other contemporary models. The effective polarizations of \jpsi and \psiprime mesons from $B$-hadron decays are also reported.Comment: 8 pages, 7 figures, published in Physical Review Letter

Observation and Mass Measurement of the Baryon Ξb−\Xi^-_b

We report the observation and measurement of the mass of the bottom, strange baryon $\Xi^-_b$ through the decay chain $\Xi^-_b \to J/\psi \Xi^-$, where $J/\psi \to \mu^+ \mu^-$, $\Xi^- \to \Lambda \pi^-$, and $\Lambda \to p \pi^-$. Evidence for observation is based on a signal whose probability of arising from the estimated background is 6.6 x 10^{-15}, or 7.7 Gaussian standard deviations. The $\Xi^-_b$ mass is measured to be $5792.9\pm 2.5$ (stat.) $\pm 1.7$ (syst.) MeV/$c^2$.Comment: Minor text changes for the second version. Accepted by Phys. Rev. Let

Search for Third Generation Vector Leptoquarks in p anti-p Collisions at sqrt(s) = 1.96 TeV

We describe a search for a third generation vector leptoquark (VLQ3) that decays to a b quark and tau lepton using the CDF II detector and 322 pb^(-1) of integrated luminosity from the Fermilab Tevatron. Vector leptoquarks have been proposed in many extensions of the standard model (SM). Observing a number of events in agreement with SM expectations, assuming Yang-Mills (minimal) couplings, we obtain the most stringent upper limit on the VLQ3 pair production cross section of 344 fb (493 fb) and lower limit on the VLQ3 mass of 317 GeV/c^2 (251 GeV/c^2) at 95% C.L.Comment: 7 pages, 2 figures, submitted to PR