1,733 research outputs found

    A prototype system for detecting the radio-frequency pulse associated with cosmic ray air showers

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    The development of a system to detect the radio-frequency (RF) pulse associated with extensive air showers of cosmic rays is described. This work was performed at the CASA/MIA array in Utah, with the intention of designing equipment that can be used in conjunction with the Auger Giant Array. A small subset of data (less than 40 out of a total of 600 hours of running time), taken under low-noise conditions, permitted upper limits to be placed on the rate for pulses accompanying showers of energies around 101710^{17} eV.Comment: 53 pages, LaTeX, 19 figures, published in Nuclear Instruments and Methods. Revised version; some references update

    Detection of the RF Pulse Associated With Cosmic Ray Air Showers

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    A project to detect the radio-frequency pulse associated with extensive air showers of cosmic rays is described briefly. Prototype work is being performed at the CASA/MIA array in Utah, with the intention of designing equipment that can be used in conjunction with the Auger Giant Array proposal

    KINETIC AND KINEMATIC CHARACTERISTICS OF IMPACTS FROM VARIOUS HEIGHTS EXPERIENCED BY CHILDREN

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    In 1977, the United States Consumer Product Safety Commission reported treatment of93,000 children in emergency rooms for injuries sustained on playgrounds. By 1986, the number had risen to over 200,000 and 70 percent ofthese cases were falls from equipment onto various play surfaces (U.S. Consumer Product Safety Commission, 1986). In addition to free play activities, today's youth are also experiencing acute injuries from single impact trauma during organized sports (Micheli, 1986)

    On the Measurement of Atmospheric Density Using Dial in the O2 A-Band (770 Nm)

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    Differential Absorption Lidar (DIAL) measurements in the A-band of molecular oxygen were suggested as a means of profiling atmospheric density. Progress towards this capability is reported

    SEGMENTALCOORDINATIONAND TEMPORAL STRUCTURE OF THE VOLLEYBALL PIKE

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    In the game ofvol1eyball, the spike is one ofthe most difficult and demanding techniques to master. The athlete is expect4ed to jump and hit a ball with maximum force and accuracy at the approximate peak of the jump. Prsala (1982) identified four phases in the analysis of the spike: the approach, preparation, hitting, and landing. The approach involves t 0 or three controlled running strides, a transitional last step to prepare for the transfer ofhorizontal momentum to vertical momentum, and a two foot vertical jump. In the preparatory phase the striking arm is swung upward in an abduct d and laterally rotated position. The elbow is fle ed at approximately 90 degrees and the wrist hyperextended. During the hitting phase, the shoulder is elevated; the upper arm is inwardly rotated and a ducted; the forearm is extended at the elbow and the wrist is flexed. The athl te absorbs the downward momentum by flexing the joints of the lower extremities when landing

    emiT: an apparatus to test time reversal invariance in polarized neutron decay

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    We describe an apparatus used to measure the triple-correlation term (\D \hat{\sigma}_n\cdot p_e\times p_\nu) in the beta-decay of polarized neutrons. The \D-coefficient is sensitive to possible violations of time reversal invariance. The detector has an octagonal symmetry that optimizes electron-proton coincidence rates and reduces systematic effects. A beam of longitudinally polarized cold neutrons passes through the detector chamber, where a small fraction beta-decay. The final-state protons are accelerated and focused onto arrays of cooled semiconductor diodes, while the coincident electrons are detected using panels of plastic scintillator. Details regarding the design and performance of the proton detectors, beta detectors and the electronics used in the data collection system are presented. The neutron beam characteristics, the spin-transport magnetic fields, and polarization measurements are also described.Comment: 15 pages, 13 figure

    Molecular Genetic Insights on Cheetah (Acinonyx jubatus) Ecology and Conservation in Namibia

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    The extent and geographic patterns of molecular genetic diversity of the largest remaining free-ranging cheetah population were described in a survey of 313 individuals from throughout Namibia. Levels of relatedness, including paternity/maternity (parentage), were assessed across all individuals using 19 polymorphic microsatellite loci, and unrelated cheetahs (n = 89) from 7 regions were genotyped at 38 loci to document broad geographical patterns. There was limited differentiation among regions, evidence that this is a generally panmictic population. Measures of genetic variation were similar among all regions and were comparable with Eastern African cheetah populations. Parentage analyses confirmed several observations based on field studies, including 21 of 23 previously hypothesized family groups, 40 probable parent/offspring pairs, and 8 sibling groups. These results also verified the successful integration and reproduction of several cheetahs following natural dispersal or translocation. Animals within social groups (family groups, male coalitions, or sibling groups) were generally related. Within the main study area, radio-collared female cheetahs were more closely interrelated than similarly compared males, a pattern consistent with greater male dispersal. The long-term maintenance of current patterns of genetic variation in Namibia depends on retaining habitat characteristics that promote natural dispersal and gene flow of cheetah

    Searches for neutrinoless double beta decay

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    Neutrinoless double beta decay is a lepton number violating process whose observation would also establish that neutrinos are their own anti-particles. There are many experimental efforts with a variety of techniques. Some (EXO, Kamland-Zen, GERDA phase I and CANDLES) started take data in 2011 and EXO has reported the first measurement of the half life for the double beta decay with two neutrinos of 136^{136}Xe. The sensitivities of the different proposals are reviewed.Comment: 8 pages, prepared for TAUP 201

    Search for a T-odd, P-even Triple Correlation in Neutron Decay

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    Background: Time-reversal-invariance violation, or equivalently CP violation, may explain the observed cosmological baryon asymmetry as well as signal physics beyond the Standard Model. In the decay of polarized neutrons, the triple correlation D\cdot(p_{e}\timesp_{\nu}) is a parity-even, time-reversal- odd observable that is uniquely sensitive to the relative phase of the axial-vector amplitude with respect to the vector amplitude. The triple correlation is also sensitive to possible contributions from scalar and tensor amplitudes. Final-state effects also contribute to D at the level of 1e-5 and can be calculated with a precision of 1% or better. Purpose: We have improved the sensitivity to T-odd, P-even interactions in nuclear beta decay. Methods: We measured proton-electron coincidences from decays of longitudinally polarized neutrons with a highly symmetric detector array designed to cancel the time-reversal-even, parity-odd Standard-Model contributions to polarized neutron decay. Over 300 million proton-electron coincidence events were used to extract D and study systematic effects in a blind analysis. Results: We find D = [-0.94\pm1.89(stat)\pm0.97(sys)]e-4. Conclusions: This is the most sensitive measurement of D in nuclear beta decay. Our result can be interpreted as a measurement of the phase of the ratio of the axial-vector and vector coupling constants (CA/CV= |{\lambda}|exp(i{\phi}_AV)) with {\phi}_AV = 180.012{\deg} \pm0.028{\deg} (68% confidence level) or to constrain time-reversal violating scalar and tensor interactions that arise in certain extensions to the Standard Model such as leptoquarks. This paper presents details of the experiment, analysis, and systematic- error corrections.Comment: 21 pages, 22 figure
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