Operational experience with the DIRC detector

The {\sc Dirc}, a novel type of Cherenkov ring imaging device, is the primary hadronic particle identification system for the $BABAR$ detector at the asymmetric B-factory, {\sc Pep-II} at SLAC. It is based on total internal reflection and uses long, rectangular bars made from synthetic fused silica as Cherenkov radiators and light guides. $BABAR$ began taking data with colliding beams in late spring 1999. This paper describes the performance of the {\sc Dirc} during the first 2.5 years of operation

Measurement of the CP-Violating Asymmetry Amplitude sin2β\beta

We present results on time-dependent CP-violating asymmetries in neutral B decays to several CP eigenstates. The measurements use a data sample of about 88 million Y(4S) --> B Bbar decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We study events in which one neutral B meson is fully reconstructed in a final state containing a charmonium meson and the other B meson is determined to be either a B0 or B0bar from its decay products. The amplitude of the CP-violating asymmetry, which in the Standard Model is proportional to sin2beta, is derived from the decay-time distributions in such events. We measure sin2beta = 0.741 +/- 0.067 (stat) +/- 0.033 (syst) and |lambda| = 0.948 +/- 0.051 (stat) +/- 0.017 (syst). The magnitude of lambda is consistent with unity, in agreement with the Standard Model expectation of no direct CP violation in these modes

Determination of the Form Factors for the Decay B0 --> D*-l+nu_l and of the CKM Matrix Element |Vcb|

We present a combined measurement of the Cabibbo-Kobayashi-Maskawa matrix element $|V_{cb}|$ and of the parameters $\rho^2$, $R_1$, and $R_2$, which fully characterize the form factors of the $B^0 \to D^{*-}\ell^{+}\nu_\ell$ decay in the framework of HQET, based on a sample of about 52,800 $B^0 \to D^{*-}\ell^{+}\nu_\ell$ decays recorded by the BABAR detector. The kinematical information of the fully reconstructed decay is used to extract the following values for the parameters (where the first errors are statistical and the second systematic): $\rho^2 = 1.156 \pm 0.094 \pm 0.028$, $R_1 = 1.329 \pm 0.131 \pm 0.044$, $R_2 = 0.859 \pm 0.077 \pm 0.022$, $\mathcal{F}(1)|V_{cb}| = (35.03 \pm 0.39 \pm 1.15) \times 10^{-3}$. By combining these measurements with the previous BABAR measurements of the form factors which employs a different technique on a partial sample of the data, we improve the statistical accuracy of the measurement, obtaining: $\rho^2 = 1.179 \pm 0.048 \pm 0.028, R_1 = 1.417 \pm 0.061 \pm 0.044, R_2 = 0.836 \pm 0.037 \pm 0.022,$ and $\mathcal{F}(1)|V_{cb}| = (34.68 \pm 0.32 \pm 1.15) \times 10^{-3}.$ Using the lattice calculations for the axial form factor $\mathcal{F}(1)$, we extract $|V_{cb}| =(37.74 \pm 0.35 \pm 1.25 \pm ^{1.23}_{1.44}) \times 10^{-3}$, where the third error is due to the uncertainty in $\mathcal{F}(1)$

Study of the Exclusive Initial-State Radiation Production of the DDˉD \bar D System

A study of exclusive production of the $D \bar D$ system through initial-state r adiation is performed in a search for charmonium states, where $D=D^0$ or $D^+$. The $D^0$ mesons are reconstructed in the $D^0 \to K^- \pi^+$, $D^0 \to K^- \pi^+ \pi^0$, and $D^0 \to K^- \pi^+ \pi^+ \pi^-$ decay modes. The $D^+$ is reconstructed through the $D^+ \to K^- \pi^+ \pi^+$ decay mode. The analysis makes use of an integrated luminosity of 288.5 fb$^{-1}$ collected by the BaBar experiment. The $D \bar D$ mass spectrum shows a clear $\psi(3770)$ signal. Further structures appear in the 3.9 and 4.1 GeV/$c^2$ regions. No evidence is found for Y(4260) decays to $D \bar D$, implying an up per limit \frac{\BR(Y(4260)\to D \bar D)}{\BR(Y(4260)\to J/\psi \pi^+ \pi^-)} < 7.6 (95 % confidence level)

Measurement of the electron energy spectrum and its moments in inclusive B -> Xe nu decays

We report a measurement of the inclusive electron energy spectrum for semileptonic decays of B mesons in a data sample of 52 million Y(4S)-->B(B) over bar decays collected with the BABAR detector at the PEP-II asymmetric-energy B-meson factory at SLAC. We determine the branching fraction, first, second, and third moments of the spectrum for lower cutoffs on the electron energy between 0.6 and 1.5 GeV. We measure the partial branching fraction to be B(B-->Xenu,E-e>0.6 GeV)=[10.36+/-0.06(stat.)+/-0.23(sys.)]%

Measurements of Branching Fractions, Polarizations, and Direct CP-Violation Asymmetries in B→ρK∗ and B→f0(980)K∗ Decays

We report searches for B -meson decays to the charmless final states ρ K ∗ and f 0 ( 980 ) K ∗ with a sample of 232 × 10 6 B ¯¯¯ B pairs collected with the BABAR detector at the PEP-II e + e − collider. We measure in units of 10 − 6 the following branching fractions, where the first error quoted is statistical and the second systematic, or upper limits are given at the 90% confidence level : B ( B + → ρ 0 K * + ) < 6.1 , B ( B + → ρ + K * 0 ) = 9.6 ± 1.7 ± 1.5 , B ( B 0 → ρ − K * + ) < 12.0 , B ( B 0 → ρ 0 K * 0 ) = 5.6 ± 0.9 ± 1.3 , B ( B + → f 0 ( 980 ) K * + ) = 5.2 ± 1.2 ± 0.5 , and B ( B 0 → f 0 ( 980 ) K * 0 ) < 4.3 . For the significant modes, we also measure the fraction of longitudinal polarization and the charge asymmetry: f L ( B + → ρ + K * 0 ) = 0.52 ± 0.10 ± 0.04 , f L ( B 0 → ρ 0 K * 0 ) = 0.57 ± 0.09 ± 0.08 , A C P ( B + → ρ + K * 0 ) = − 0.01 ± 0.16 ± 0.02 , A C P ( B 0 → ρ 0 K * 0 ) = 0.09 ± 0.19 ± 0.02 , and A C P ( B + → f 0 ( 980 ) K * + ) = − 0.34 ± 0.21 ± 0.03

Spin test of turbine rotor

Experimental data are presented for the tangential and radial stresses in the disks of the 36,000 horsepower, 4000 rpm turbine for the M-1 engine oxidizer turbopump. The two-stage Curtis turbine is a special light-weight design utilizing thin conical disks with hollow sheet metal blades attached by electron-beam welding techniques. The turbine was fabricated from Inconel 718, a nickel-chromium alloy. The stresses were obtained by strain-gage measurements using a slip-ring assembly to transmit the electrical signals. Measurements were made at different rotative speeds and different thermal loads. In addition to presenting test data, the report describes test equipment, design of associated hardware, test procedures, instrumentation, and tests for the selection and calibration of strain gages.NASA ORDER C-10836Approved for public release; distribution is unlimited

An investigation of secondary flow effects in curved channels of square cross section

In this study, turbulent flow in a curved channel of square cross section was investigated experimentally to determine secondary flow effects. Probe surveys were conducted to establish vortex and total pressure loss distribution in the exit plane of a 90° bend. Overall losses were determined by measuring the momentum of the flow with a force plate for different Reynolds numbers at turning angles of 0°, 45°, 90°, and 135°.http://archive.org/details/investigationofs00kennEnsign, United States NavyApproved for public release; distribution is unlimited