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Open Access Publications from the University of California

Scholarly Works (3 results)

  • Article
  • Peer Reviewed
UC Santa Barbara Previously Published Works (2006)

The BABAR Silicon Vertex Tracker (SVT) has been efficiently operated for six years since the start of data taking in 1999. Due to higher than expected background levels some unforeseen effects have appeared. We discuss: a shift in the pedestal for the channels of the AToM readout chips that are most exposed to radiation; an anomalous increase in the bias leakage current for the modules in the outer layers. Estimates of future radiation doses and occupancies are shown together with the extrapolated detector performance and lifetime, in light of the new observations. (c) 2006 Elsevier B.V. All rights reserved.

    Cover page: BABAR silicon vertex tracker: Status and prospects
    • Article
    • Peer Reviewed
    UC Berkeley Previously Published Works (2012)
    The photon spectrum in B→Xs γ decay, where X s is any strange hadronic state, is studied using a data sample of (382.8±4.2)×106 e+e-→Υ(4S)→BB events collected by the BABAR experiment at the PEP-II collider. The spectrum is used to measure the branching fraction B(B→Xsγ)=(3. 21±0.15±0.29±0.08)×10-4 and the first, second, and third moments YEγ Ÿ ;=2.267±0. 019±0.032±0.003 GeV, Y(Eγ-YEγ Ÿ) 2Ÿ=0.0484±0.0053±0.0077±0.0005 GeV2, and Y(Eγ-YEγ Ÿ) 3Ÿ=-0.0048±0. 0011±0.0011±0.0004 GeV3, for the range Eγ>1.8 GeV, where Eγ is the photon energy in the B-meson rest frame. Results are also presented for narrower Eγ ranges. In addition, the direct CP asymmetry ACP(B→Xs+dγ) is measured to be 0.057±0.063. The spectrum itself is also unfolded to the B-meson rest frame; that is the frame in which theoretical predictions for its shape are made. © 2012 American Physical Society.
      Cover page: Measurement of B (B→Xsγ), the B→Xsγ photon energy spectrum, and the direct CP asymmetry in B→Xs+dγ decaysCreative Commons 'BY' version 4.0 license
      • Article
      • Peer Reviewed
      UC Irvine Previously Published Works (2012)
      The photon spectrum in the inclusive electromagnetic radiative decays of the B meson, B → X(s)γ plus B → X(d)γ, is studied using a data sample of (382.8 ± 4.2) × 10(6)Υ(4S) → BB decays collected by the BABAR experiment at SLAC. The spectrum is used to extract the branching fraction B(B → X(s)γ) = (3.21 ± 0.33) × 10(-4) for E(γ) >1.8 GeV and the direct CP asymmetry A(CP) (B → X(s+d)γ) = 0.057 ± 0.063. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the B meson rest frame.
        Cover page: Precision Measurement of the B→Xsγ Photon Energy Spectrum, Branching Fraction, and Direct CP Asymmetry ACP(B→Xs+dγ)Creative Commons 'BY' version 4.0 license
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