3,099 research outputs found

    In situ micro gas tungsten constricted arc welding of ultra-thin walled 2.275 mm outer diameter grade 2 commercially pure titanium tubing

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    Ultra-thin walled cooling tubes for heat exchangers and condenser units have applications in multiple high-value manufacturing industries. Grade 2 commercially pure titanium (CP-2 Ti) requires far less mass to achieve the same mass flow handling abilities as stainless steel tubing yet it is more challenging to join, particularly at wall thicknesses less than 500 μm (termed ultra-thin walled tube). This paper presents a single-pass joinery method that produces reliable welds on 2.275 mm outer diameter (OD), 160 ± 10 μm wall thickness tubing with a service life of 20 of more years. This is achieved through an automated orbital gas tungsten constricted arc welding (GTCAW) process incorporating enveloping low-mass sleeves used in tandem with a buttressing internal gas pressure to support the molten metal and maintain consistent internal diameter inside the tube. The industrial applicability is demonstrated through the production of a 1:1 scale mock-up of a fixed geometry CO2 cooling circuit for a next-generation particle detector. The tensile strengths of the joints, 403.8 ± 4.2 MPa, exceed the tensile strength of the parent CP-2 Ti

    Rate Measurement of D0K+ππ0D^{0}\to K^{+}\pi^{-}\pi^{0} and Constraints on D0D0D^{0} - \overline{D^{0}} Mixing

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    We present an observation and rate measurement of the decay D0 -> K+pi-pi0 produced in 9/fb of e+e- collisions near the Upsilon(4S) resonance. The signal is inconsistent with an upward fluctuation of the background by 4.9 standard deviations. We measured the rate of D0 -> K+pi-pi0 normalized to the rate of D0bar -> K+pi-pi0 to be 0.0043 +0.0011 -0.0010 (stat) +/- 0.0007 (syst). This decay can be produced by doubly-Cabibbo-suppressed decays or by the D0 evolving into a D0bar through mixing, followed by a Cabibbo-favored decay to K+pi-pi0. We also found the CP asymmetry A=(8 +25 -22)% to be consistent with zero.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

    First Observation of barB0 to D*0 pi+pi+pi-pi- Decays

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    We report on the observation of B0bar -> D*0 pi+ pi+ pi- pi- decays. The branching ratio is (0.30 +/- 0.07 +/- 0.06)%. Interest in this particular mode was sparked by Ligeti, Luke and Wise who propose it as a way to check the validity of factorization tests in B0bar -> D*+ pi+ pi- pi- pi0 decays.Comment: 11 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, Version to appear in Phys. Rev.

    A Search for Charmless BVVB\to VV Decays

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    We have studied two-body charmless decays of the BB meson into the final states ρ0ρ0\rho^0 \rho^0, K0ρ0K^{*0} \rho^0, K0K0K^{*0} K^{*0}, K0K0ˉK^{*0} \bar{K^{*0}}, K+ρ0K^{*+} \rho^0, K+K0ˉK^{*+} \bar{K^{*0}}, and K+KK^{*+} K^{*-} using only decay modes with charged daughter particles. Using 9.7 million BBˉB \bar{B} pairs collected with the CLEO detector, we place 90% confidence level upper limits on the branching fractions, (0.467.0)×105(0.46-7.0)\times 10^{-5}, depending on final state and polarization.Comment: 8 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

    Measurement of Inclusive B --> psi Production

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    Using the combined CLEO II and CLEO II.V data sets of 9.1 fb^{-1} at the Upsilon(4S), we measure properties of Psi mesons produced directly from decays of the B meson, where ``B'' denotes an admixture of B+, B-, B0, and B0bar, and ``Psi'' denotes either J/Psi or Psi(2S). We report first measurements of Psi polarization in B -> Psi(direct) X: alpha(J/Psi) = -0.30 {+0.07 -0.06 stat} {+-0.04 syst} and alpha(Psi(2S)) = -0.45 {+0.22 -0.19 stat} {+-0.04 syst}. We also report improved measurements of the momentum distributions of Psi produced directly from B decays, correcting for measurement smearing. Finally, we report measurements of the inclusive branching fraction for B -> Psi X and B -> Chi_c1 X.Comment: 8 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PR

    Lifetime Differences, direct CP Violation and Partial Widths in D0 Meson Decays to K+K- and pi+pi-

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    We describe several measurements using the decays D0->K+K- and pi+pi-. We find the ratio of partial widths, Gamma(D0->K+K-)/Gamma(D0->pi+pi-), to be 2.96+/-0.16+/-0.15, where the first error is statistical and the second is systematic. We observe no evidence for direct CP violation, obtaining A_CP(KK) = (0.0+/-2.2+/-0.8)% and A_CP(pipi = (1.9+/-3.2+/-0.8)%. In the limit of no CP violation we measure the mixing parameter y_CP = -0.012+/-0.025+/-0.014 by measuring the lifetime difference between D0->K+ K- or pi+pi- and the CP neutral state, D0->K-pi+. We see no evidence for mixing.Comment: 14 pages postscript, also available through http://w4.lns.cornell.edu/public/CLNS, submitted to PRD, Rapid Communicatio

    Correlated /\c-/\cbar production in e+e- annihilations at sqrt{s}~10.5 GeV

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    Using 13.6/fb of continuum two-jet e+e- -> ccbar events collected with the CLEO detector, we have searched for baryon number correlations at the primary quark level. We have measured the likelihood for a /\c+ charmed baryon to be produced in the hemisphere opposite a /\c- relative to the likelihood for a /\c+ charmed baryon to be produced opposite an anticharmed meson Dbar; in all cases, the reconstructed hadrons must have momentum greater than 2.3 GeV/c. We find that, given a /\c- (reconstructed in five different decay modes), a /\c+ is observed in the opposite hemisphere (0.72+/-0.11)% of the time (not corrected for efficiency). By contrast, given a Dbar in one hemisphere, a /\c+ is observed in the opposite hemisphere only (0.21+/-0.02)% of the time. Normalized to the total number of either /\c- or Dbar ``tags'', it is therefore 3.52+/-0.45+/-0.42 times more likely to find a /\c+ opposite a /\c- than a Dbar meson. This enhancement is not observed in the JETSET 7.3 e+e- -> ccbar Monte Carlo simulation.Comment: 19 pages, Latex, one figure separat

    A Measurement of the Decay Asymmetry Parameters in \Xi_{c}^{0}\to \X^{-}\pi^{+}

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    Using the CLEO II detector at the Cornell Electron Storage Ring we have measured the Ξc0\Xi_c^{0} decay asymmetry parameter in the decay Ξc0Ξπ+\Xi_c^{0} \to \Xi^{-} \pi^+. We find αΞc0αΞ=0.26±0.18(stat)0.04+0.05(syst)\alpha_{\Xi_c^{0}} \alpha_{\Xi} = 0.26 \pm 0.18{(stat)}^{+0.05}_{-0.04}{(syst)}, using the world average value of αΞ=0.456±0.014\alpha_{\Xi} = -0.456 \pm 0.014 we obtain αΞc0=0.56±0.39(stat)0.09+0.10(syst)\alpha_{\Xi_c^{0}} = -0.56 \pm 0.39{(stat)}^{+0.10}_{-0.09}{(syst)}. The physically allowed range of a decay asymmetry parameter is 1<α<+1-1<\alpha<+1. Our result prefers a negative value: αΞc0\alpha_{\Xi_c^{0}} is <0.1<0.1 at the 90% CL. The central value occupies the middle of the theoretically expected range but is not yet precise enough to choose between models.Comment: 10 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

    Study of Exclusive Radiative B Meson Decays

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    We have investigated exclusive, radiative B meson decays to charmless mesons (\rho, \omega, \phi, K^*(892), K^*_2(1430)) in 9.7\times 10^6 BBbar decays accumulated with the CLEO detector. The B -> K^*(892)\gamma branching fractions are determined to be Br(B^0 -> K^{*0}(892)\gamma) = (4.55 +0.72-0.68 +-0.34)\times 10^-5 and Br(B^+ -> K^{*+}(892)\gamma) = (3.76 +0.89-0.83 +-0.28)\times 10^-5. We have searched for CP asymmetry in B -> K^*(892)\gamma decays and measure Acp = +0.08 +-0.13 +-0.03. We also report the first observation of the decay B -> K^*_2(1430)\gamma with a branching fraction of (1.66 +0.59-0.53 +-0.13)\times 10^-5 and determine $Br(B -> K^*_2(1430)\gamma)/Br(B -> K^*(892)\gamma) = 0.39 +0.15-0.13 consistent with only one of two available theoretical models. No significant evidence for the decays B -> \rho\gamma and B^0 -> \omega\gamma is found and we limit Br(B -> (\rho/\omega)\gamma)/Br(B -> K^{*}(892)\gamma) < 0.32 at 90% CL. We also find no evidence for the exotic decay B^0 -> \phi\gamma.Comment: 12 pages, 3 figures, submitted to Phys. Rev. Letter

    Hadronic Structure in the Decay τππ0ντ\tau^{-}\to \pi^{-}\pi^{0}\nu_{\tau}

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    We report on a study of the invariant mass spectrum of the hadronic system in the decay tau- -> pi- pi0 nu_tau. This study was performed with data obtained with the CLEO II detector operating at the CESR e+ e- collider. We present fits to phenomenological models in which resonance parameters associated with the rho(770) and rho(1450) mesons are determined. The pi- pi0 spectral function inferred from the invariant mass spectrum is compared with data on e+ e- -> pi+ pi- as a test of the Conserved Vector Current theorem. We also discuss the implications of our data with regard to estimates of the hadronic contribution to the muon anomalous magnetic moment.Comment: 39 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN