2,696 research outputs found

    The Cosmic Ray Observatory Project: A Statewide Outreach and Education Experiment in Nebraska

    Get PDF
    The Cosmic Ray Observatory Project (CROP) is a statewide education and research experiment involving Nebraska high school students, teachers and university undergraduates in the study of extensive cosmic-ray air showers. A network of high school teams construct, install, and operate school-based detectors in coordination with University of Nebraska physics professors and graduate students. The detector system at each school is an array of scintillation counters recycled from the Chicago Air Shower Array in weather-proof enclosures on the school roof, with a GPS receiver providing a time stamp for cosmic-ray events. The detectors are connected to triggering electronics and a data-acquisition PC inside the building. Students share data via the Internet to search for time coincidences with other sites. Funded by the National Science Foundation, CROP has enlisted 29 schools with the aim of expanding to the 314 high schools in the state over several years. This report highlights both the scientific and professional development achievements of the project to date.Comment: 4 pages, 4 figures, submitted to the 2007 International Cosmic Ray Conference (ICRC2007), Merida, Mexico, July 200

    Traženje Higgsa i supersimetrije tevatronom

    Get PDF
    Results are presented of searches for Standard Model and MSSM Higgs, as well as supersymmetric particles. A broad variety of signatures were explored by the CDF and DØ experiments, using approximately 2 fb−1 of reconstructed pp¯ data from collisions at 1.96 TeV at Fermilab’s Tevatron. No significant deviation from background sources has been observed in any of the searches, and new limits have been set on the production cross sections.Predstavljamo ishode traženja Higgsa i supersimetričnih čestica prema standardnom modelu i prema MSSM. Primjenjuje se široka lepeza znakova u CDF i DØ eksperimentima, rabeći oko 2 fb−1 analiziranih podataka za pp¯ sudare na 1.96 TeV u Tevatronu Fermilab-a. U tim traženjima nismo našli odstupanja od šuma, i postavili smo nove granice za udarne presjeke

    Attribute abstraction, feature-dimensionality, and the scaling of product similarities

    Get PDF
    This paper examines the attributes that consumers use when making product similarity judgments and their effect on similarity scaling. Previous research suggests that concrete brands are judged using dichotomous features while more abstract product categories are judged using continuous dimensions. This, in turn, suggests that the appropriateness of spatial scaling increases relative to tree scaling as one moves from brands to product categories. The results of two studies support an increase in the fit of spaces relative to trees from brands to categories. However, the abstractness of the judgments appears to be driving the effect, not the use of features or dimensions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30067/1/0000437.pd

    Search for a Fourth Generation tl Quark in pp̅ Collisions at √s= 1.96 TeV

    Get PDF
    We present a search for pair production of a fourth generation tl quark and its antiparticle, followed by their decays to a W boson and a jet, based on an integrated luminosity of 5.3 fb-1 of proton-antiproton collisions at √s= 1.96 TeV collected by the D0 Collaboration at the Fermilab Tevatron Collider. We set upper limits on the tlt-l production cross section that exclude at the 95% C.L. a tl quark that decays exclusively to W + jet with a mass below 285 GeV. We observe a small excess in the µ + jets channel which reduces the mass range excluded compared to the expected limit of 320 GeV in the absence of a signal

    Wy Production and Limits on Anomalous WWy Couplings in pp̅ Collisions √s = 1.96 TeV

    Get PDF
    We measure the cross section and the difference in rapidities between photons and charged leptons for inclusive W(→ lv) + y production in ey and µy final states. Using data corresponding to an integrated luminosity of 4.2 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider, the measured cross section times branching fraction for the process pp̅ → Wy + X → lvy + X and the distribution of the charge-signed photon-lepton rapidity difference are found to be in agreement with the standard model. These results provide the most stringent limits on anomalous WW[1] couplings for data from hadron colliders: -0.4 \u3c ∆ky \u3c 0.4 and -0.08 \u3c λy \u3c 0.07 at the 95% C.L

    Evidence for Simultaneous Production of J/ψ and ϒ Mesons

    Get PDF
    We report evidence for the simultaneous production of J/ψ and ϒ mesons in 8.1 fb−1 of data collected at √s = 1.96 TeV by the D0 experiment at the Fermilab p¯p Tevatron Collider. Events with these characteristics are expected to be produced predominantly by gluon-gluon interactions. In this analysis, we extract the effective cross section characterizing the initial parton spatial distribution, σeff = 2.2 ± 0.7(stat) ± 0.9(syst) mb

    Wy Production and Limits on Anomalous WWy Couplings in pp̅ Collisions √s = 1.96 TeV

    Get PDF
    We measure the cross section and the difference in rapidities between photons and charged leptons for inclusive W(→ lv) + y production in ey and µy final states. Using data corresponding to an integrated luminosity of 4.2 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider, the measured cross section times branching fraction for the process pp̅ → Wy + X → lvy + X and the distribution of the charge-signed photon-lepton rapidity difference are found to be in agreement with the standard model. These results provide the most stringent limits on anomalous WW[1] couplings for data from hadron colliders: -0.4 \u3c ∆ky \u3c 0.4 and -0.08 \u3c λy \u3c 0.07 at the 95% C.L

    <i>Trypanosoma evansi</i>: Genetic variability detected using amplified restriction fragment length polymorphism (AFLP) and random amplified polymorphic DNA (RAPD) analysis of Kenyan isolates

    Get PDF
    We compared two methods to generate polymorphic markers to investigate the population genetics of Trypanosoma evansi; random amplified polymorphic DNA (RAPD) and amplified restriction fragment length polymorphism (AFLP) analyses. AFLP accessed many more polymorphisms than RAPD. Cluster analysis of the AFLP data showed that 12 T.evansi isolates were very similar (‘type A’) whereas 2 isolates differed substantially (‘type B’). Type A isolates have been generally regarded as genetically identical but AFLP analysis was able to identify multiple differences between them and split the type A T. evansi isolates into two distinct clades

    Measurement of the top quark mass using the matrix element technique in dilepton final states

    Get PDF
    We present a measurement of the top quark mass in pp collisions at a center-of-mass energy of 1.96 TeV at the Fermilab Tevatron collider. The data were collected by the D0 experiment corresponding to an integrated luminosity of 9.7 fb−1. The matrix element technique is applied to tt events in the final state containing leptons (electrons or muons) with high transverse momenta and at least two jets. The calibration of the jet energy scale determined in the lepton + jets final state of tt decays is applied to jet energies. This correction provides a substantial reduction in systematic uncertainties. We obtain a top quark mass of mt = 173.93 ± 1.84 GeV

    [?] lifetime measurement in the \u3ci\u3eCP\u3c/i\u3e-odd decay channel [?] → J/ψ f\u3ci\u3e0\u3c/i\u3e(980)

    Get PDF
    The lifetime of the [?] meson is measured in the decay channel [?] → J/ψπ+π− with 880 ≤ Mπ+π- - ≤ 1080 MeV / c2, which is mainly a CP-odd state and dominated by the f0 (980) resonance. In 10.4 fb-1 of data collected with the D0 detector in Run II of the Tevatron, the lifetime of the [?] meson is measured to be [?] = 1.70 ± 0.14(stat) ± 0.05(syst) ps. Neglecting CP violation in [?]/[?] mixing, the measurement can be translated into the width of the heavy mass eigenstate of the [?], ΓH = 0.59 ± 0.05(stat) ± 0.02(syst) ps-1
    corecore