12,128 research outputs found

    Drift Chamber Alignment using Cosmic Rays

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    The Collider Detector at Fermilab (CDF) is a general-purpose experimental apparatus with an inner tracking detector for measuring charged particles, surrounded by a calorimeter for measurements of electromagnetic and hadronic showers, and a muon detector system. We present a technique for, and results of, a precise relative alignment of the drift chamber wires of the CDF tracker. This alignment has been an important component of the track momentum calibration, which is the basis for the charged-lepton calibration for the measurement of the W boson mass at CDF

    Microstructure Controlled Shear Band Pattern Formation and Enhanced Plasticity of Bulk Metallic Glasses Containing in situ Formed Ductile Phase Dendrite Dispersions

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    Results are presented for a ductile metal reinforced bulk metallic glass matrix composite based on glass forming compositions in the Zr-Ti-Cu-Ni-Be system. Primary dendrite growth and solute partitioning in the molten state yields a microstructure consisting of a ductile crystalline Ti-Zr-Nb β phase, with bcc structure, in a Zr-Ti-Nb-Cu-Ni-Be bulk metallic glass matrix. Under unconstrained mechanical loading organized shear band patterns develop throughout the sample. This results in a dramatic increase in the plastic strain to failure, impact resistance, and toughness of the metallic glass

    Large supercooled liquid region and phase separation in the Zr–Ti–Ni–Cu–Be bulk metallic glasses

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    Results of calorimetric, differential thermal analysis, and structural measurements are presented for a series of bulk metallic glass forming compositions in the Zr-Ti-Cu-Ni-Be alloy system. The calorimetric data for five alloys, prepared along the tie line between phase separating and nonphase separating compositions, show that the transition from phase separating to nonphase separating behavior is smooth. The bulk glasses near the center of the tie line exhibit large supercooled liquid regions: Delta T approximate to 135 K, the largest known for a bulk metallic glass

    Testing milk and cream

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    Caption title.Digitized 2006 AES MoU

    Evaluation of AIS Data for Agronomic and Rangeland Vegetation: Preliminary Results for August 1984 Flight over Nebraska Sandhills Agricultural Laboratory

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    Since 1978 scientists from the Center for Agricultural Meteorology and Climatology at the University of Nebraska have been conducting research at the Sandhills Agricultural Laboratory on the effects of water stress on crop growth, development and yield using remote sensing techniques. We have been working to develop techniques, both remote and ground-based, to monitor water stress, phenological development, leaf area, phytomass production and grain yields of corn, soybeans and sorghum. Because of the sandy soils and relatively low rainfall at the site it is an excellent location to study water stress without the necessity of installing expensive rainout shelters. The primary objectives of research with the airborne imaging spectrometer (AIS) data collected during an August 1984 flight over the Sandhills Agricultural Laboratory are to evaluate the potential of using AIS to: (1) discriminate crop type; (2) to detect subtle architectural differences that exist among different cultivars or hybrids of agronomic crops; (3) to detect and quantify, if possible, the level of water stress imposed on the crops; and (4) to evaluate leaf area and biomass differences for different crops

    Solid state photomultiplier for astronomy, phase 2

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    Epitaxial layers with varying donor concentration profiles were grown on silicon substrate wafers using chemical vapor deposition (CVD) techniques, and solid state photomultiplier (SSPM) devices were fabricated from the wafers. Representative detectors were tested in a low background photon flux, low temperature environment to determine the device characteristics for comparison to NASA goals for astronomical applications. The SSPM temperatures varied between 6 and 11 K with background fluxes in the range from less than 5 x 10 to the 6th power to 10 to the 13th power photons/square cm per second at wavelengths of 3.2 and 20 cm. Measured parameters included quantum efficiency, dark count rate and bias current. Temperature for optimal performance is 10 K, the highest ever obtained for SSPMs. The devices exhibit a combination of the lowest dark current and highest quantum efficiency yet achieved. Experimental data were reduced, analyzed and used to generate recommendations for future studies. The background and present status of the microscopic theory of SSPM operation were reviewed and summarized. Present emphasis is on modeling of the avalanche process which is the basis for SSPM operation. Approaches to the solution of the Boltzmann transport equation are described and the treatment of electron scattering mechanisms is presented. The microscopic single-electron transport theory is ready to be implemented for large-scale computations

    Environmental Litigation in Historical Perspective

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    During the past several decades, litigation has played a major role in the attempt by citizens to realize environmental objectives. Its impact has been elaborated extensively in the vast array of writing in law journals as well as in the cases themselves. Most analyses have focused on specialized subjects of either substantive policy or legal procedure. In this brief Essay I attempt a more comprehensive overview involving two background factors- the growth of environmental values since World War II and the response of governmental institutions to the resulting demands placed upon them. Among these institutions were the courts. Their role cannot be understood simply in terms of the evolution of judicial opinion, but more in terms of the response of judges and the legal profession to changing public attitudes, legislative policies, scientific knowledge, and technical capabilities

    UA68/6/2 Dreamer, Designer & Builder

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    Part of presentation given by the Congress Debating Club in chapel regarding the history of WKU. This portion is about Henry Hardin Cherry, founder of WKU. Frank Hays was a member of the Class of 1930

    For many rural participants, Drug Court can be a positive experience, but more treatment options and support are needed.

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    Drug Courts are an increasingly popular policy intervention which can divert those convicted of drug-related offenses to treatment services rather than prison. In new research, Susan Witkin and Scott P. Hays spoke to a number of rural-based Drug Court participants about their experiences. While many participants were generally positive about the impact of Drug Court on their lives, they also ..

    Study of the technique of stellar occultation

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    The results are reported of a study of the stellar occultation technique for measuring the composition of the atmosphere. The intensity of starlight was monitored during the occultation using the Wisconsin stellar ultraviolet photometers aboard the Orbiting Astronomical Observatory (OAO-A2). A schematic diagram of an occultation is shown where the change in intensity at a given wavelength is illustrated. The vertical projection of the attenuation region is typically 60 km deep for molecular oxygen and 30 km deep for ozone. Intensity profiles obtained during various occultations were analyzed by first determining the tangential columm density of the absorbing gases, and then Abel inverting the column densities to obtain the number density profile. Errors are associated with each step in the inversion scheme and have been considered as an integral part of this study
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