935 research outputs found

    Alternative strategies for space station financing

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    The attributes of the proposed space station program are oriented toward research activities and technologies which generate long term benefits for mankind. Unless such technologies are deemed of national interest and thus are government funded, they must stand on their own in the market place. Therefore, the objectives of a United States space station should be based on commercial criteria; otherwise, such a project attracts no long term funding. There is encouraging evidence that some potential space station activities should generate revenues from shuttle related projects within the decade. Materials processing concepts as well as remote sensing indicate substantial potential. Futhermore, the economics and thus the commercial feasibility of such projects will be improved by the operating efficiencies available with an ongoing space station program

    Investigating nano-precipitation in a V-containing HSLA steel using small angle neutron scattering

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    Interphase precipitation (IPP) of nanoscale carbides in a vanadium-containing high-strength low-alloy steel has been investigated. Small angle neutron scattering (SANS) and transmission electron microscopy (TEM) were employed to characterize the precipitates and their size distributions in Fe-0.047C-0.2V-1.6Mn (in wt.%) alloy samples which had been austenitized, isothermally transformed at 700 °C for between 3 and 600 min and water quenched. TEM confirms that, following heat treatment, rows of vanadium-containing nanoscale interphase precipitates were present. Model-independent analysis of the nuclear SANS signal and model fitting calculations, using oblate spheroid and disc-shapes, were performed. The major axis diameter increased from 18 nm after 3 min to 35 nm after 600 min. Precipitate volume percent increased from 0.09 to 0.22 vol% over the same period and number density fell from 2 × 1021 to 5 × 1020 m−3. A limited number of measurements of precipitate maximum diameters from TEM images showed the mean value increased from 8 nm after 5 min to 28 nm after 600 min which is in reasonable agreement with the SANS data

    Observation of chi_c2 Production in B-meson Decay

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    We report the first observation of chi_c2 production in B-meson decays. We find an inclusive B -> chi_c2 X branching fraction of (1.80^{+0.23}_{-0.28}+/- 0.26) 10^-3. The data set, collected with the Belle detector at the KEKB e^+e^- collider, consists of 31.9 million B\bar B events. We also present branching fractions and momentum spectra for both chi_c1 and chi_c2 production.Comment: 5 pages with 2 figure

    Observation of Ds+ K- and evidence for Ds+ pi- final states in neutral B decays

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    We report the first observation of a B meson decay that is not accessible by a direct spectator process. The channel B0bar -> Ds+ K- is found in a sample of 85 timse 10^6 B Bbar events, collected with the Belle detector at KEKB, with a branching fraction Br(B0bar -> Ds+ K-)=(4.6^{+1.2}_{-1.1} +- 1.3) times 10^{-5}. We also obtain evidence for the B0 -> Ds+ pi- decay with branching fraction Br(B0 -> Ds+ pi-)=(2.4^{+1.0}_{-0.8} +- 0.7) times 10^{-5}. This value may be used to extract a model-dependent value of |Vub|.Comment: Accepted to publication in Phys. Rev. Let

    Observation of Mixing-induced CP Violation in the Neutral B Meson System

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    This report describes an observation of mixing-induced CP violation and a measurement of the CP violation parameter, sin(2phi_1), with the Belle detector at the KEKB asymmetric e+e- collider. Using a data sample of 29.1 fb-1 recorded on the Upsilon(4S) resonance that contains 31.3 million BBbar pairs, we reconstruct decays of neutral B mesons to the following CP eigenstates: J/psi K_S^0, psi(2S) K_S^0, chi_c1 K_S^0, eta_c K_S^0, J/psi K_L^0 and J/psi K^*0. The flavor of the accompanying B meson is identified by combining information from primary and secondary leptons, K+/- mesons, lambda baryons, slow and fast pions. The proper-time interval between the two B meson decays is determined from the distance between the two decay vertices measured with a silicon vertex detector. The result sin(2phi_1) = 0.99 +/- 0.14(stat) +/- 0.06(syst) is obtained by applying a maximum likelihood fit to the 1137 candidate events. We conclude that there is large CP violation in the neutral B meson system. A zero value for sin(2phi_1) is ruled out by more than six standard deviations.Comment: 25 pages, 16 figures, accepted for publication in Physical Review

    Measurement of Branching Fractions for BηcK()B\to \eta_c K^{(*)} Decays

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    We report measurements of branching fractions for charged and neutral BηcKB\to \eta_c K decays where the ηc\eta_c meson is reconstructed in the KS0K±π,K+Kπ0,K0Kπ+K_S^0 K^{\pm}\pi^{\mp}, K^+ K^- \pi^0, K^{*0} K^-\pi^+ and ppˉp \bar{p} decay channels. The neutral B0B^0 channel is a CP eigenstate and can be used to measure the CP violation parameter sin2ϕ1\sin 2\phi_1. We also report the first observation of the B0ηcK0B^0\to \eta_c K^{*0} mode. The results are based on an analysis of 29.1 fb1^{-1} of data collected by the Belle detector at KEKB.Comment: To appear in Physical Review Letter

    Observation of B+- -> omega K+- Decay

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    We report the first observation of the charmless two-body mode B±ωK±B^{\pm} \to \omega K^{\pm} decay, and a new measurement of the branching fraction for the B±ωπ±B^{\pm} \to \omega \pi^{\pm} decay. The measured branching fractions are B(B±ωK±)=(9.22.3+2.6±1.0)×106{\cal B} (B^{\pm} \to \omega K^{\pm}) = (9.2{}^{+2.6}_{-2.3}\pm 1.0) \times 10^{-6} and B(B±ωπ±)=(4.21.8+2.0±0.5)×106{\cal B} (B^{\pm} \to \omega \pi^{\pm}) = (4.2{}^{+2.0}_{-1.8}\pm 0.5) \times 10^{-6}. %and we set 90% confidence level upper limits of %B(Bωπ)<8.1×106{\cal B} (B^- \to \omega \pi^-) < 8.1\times 10^{-6}. We also measure the partial rate asymmetry of B±ωK±B^{\pm}\to\omega K^{\pm} decays and obtain ACP=0.21±0.28±0.03{\cal A}_{CP} = -0.21 \pm 0.28 \pm 0.03. The results are based on a data sample of 29.4 fb1^{-1} collected on the Υ(4S)\Upsilon(4S) resonance by the Belle detector at the KEKB e+ee^{+} e^{-} collider.Comment: 5 pages, 4 figures, resubmitted to Phys. Rev. Let

    Measurement of Inclusive Production of Neutral Pions from Upsilon(4S) Decays

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    Using the Belle detector operating at the KEKB e+e- storage ring, we have measured the mean multiplicity and the momentum spectrum of neutral pions from the decays of the Upsilon(4S) resonance. We measure a mean of 4.70 +/- 0.04 +/- 0.22 neutral pions per Upsilon(4S) decay.Comment: 15 pages, 4 figs. Submitted to Phys.Rev.
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