Stephen Schaffner

Publications (138) View all

• Article: The BaBar drift chamber

  G. Sciolla, A. Bajic, R. Bard, M. Beaulieu, V. Blinov, E. Borsato, A. Boucham, D. Boutigny, A. Boyarski, R. Boyce, [......], E. Torassa, J. Trischuk, C. Voci, S. Wagner, D. Warner, A. Weinstein, A. Woch, R.K. Yamamoto, V. Zacek, H. vonderLippe
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  ABSTRACT: The central drift chamber for the BaBar detector at the PEP-II B-factory at SLAC is a cylindrical chamber with a length of 280 cm and outer radius of 81 cm. It consists of 40 layers of small hexagonal cells arranged in 10 axial and stereo super layers.In order to minimize multiple scattering, light materials are used for the mechanical structure, and the gas mixture is helium based. The pulse height and timing electronics are mounted directly on the chamber rear end plate.A full-length prototype of the BaBar drift chamber has been built. The analysis of cosmic-ray events measures the spatial resolution averaged in the cell to be 130 μm and the dE/dx resolution to be 6.8%, meeting the performance goals for the BaBar central tracker.The mechanical assembly and stringing of the chamber was completed in December 1997 and the detector will be integrated into BaBar during summer 1998.
  Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 02/2013; 419(2-3):310-314. · 1.21 Impact Factor
• Article: The BaBaR drift chamber project

  A. Boucham, D. Boutigny, I.De Bonis, A. Jeremie, Y. Karyotakis, R. Lafaye, C. Goodenough, C. Hearty, J. Heise, M. Kelsey, [......], D. Nelson, M. Palrang, G. Sciolla, S. Schaffner, A. Snyder, S. Wagner, R. Henderson, N. Khan, D. Pitman, J.M. Roney
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  ABSTRACT: The BaBar Drift Chamber is now under construction. We review its design, the progress in the construction of the components, the plan for assembly and stringing and we present test results obtained with a prototype exposed at SLAC to cosmic rays. We also report on projected dE/dx performance from beam tests done with a chamber with a different cell design.
  Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 02/2013; 409(1-2):46-52. · 1.21 Impact Factor
• Article: Study of inclusive production of charmonium mesons in B decays

  B. Aubert, D. Boutigny, J.-M. Gaillard, A. Hicheur, Y. Karyotakis, J. P. Lees, P. Robbe, V. Tisserand, A. Zghiche, A. Palano, [......], F. Di Lodovico, Y. Pan, R. Prepost, I. J. Scott, S. J. Sekula, J. H. von Wimmersperg-Toeller, J. Wu, S. L. Wu, Z. Yu, H. Neal
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  ABSTRACT: The inclusive production of charmonium mesons in B meson decay has been studied in a 20.3 fb-1 data set collected by the BABAR experiment operating at the Υ(4S) resonance. Branching fractions have been measured for the inclusive production of the charmonium mesons J/ψ, ψ(2S), χc1, and χc2. The branching fractions are also presented as a function of the center-of-mass momentum of the mesons and of the helicity of the J/ψ.
  Phys. Rev. D. 02/2003; 67(3).
• Article: Measurement of the B0 Lifetime with Partially Reconstructed B0-->D*- l+νl Decays

  B. Aubert, D. Boutigny, J.-M. Gaillard, A. Hicheur, Y. Karyotakis, J. P. Lees, P. Robbe, V. Tisserand, A. Zghiche, A. Palano, [......], F. di Lodovico, Y. Pan, R. Prepost, I. J. Scott, S. J. Sekula, J. H. von Wimmersperg-Toeller, S. L. Wu, Z. Yu, T. M. Kordich, H. Neal
  Physical Review Letters 08/2002; 89(16):169903. · 7.37 Impact Factor
• Article: Family-based association study of 76 candidate genes in bipolar disorder: BDNF is a potential risk locus. Brain-derived neutrophic factor.

  P Sklar, S B Gabriel, M G McInnis, P Bennett, Y -M Lim, G Tsan, S Schaffner, G Kirov, I Jones, M Owen, N Craddock, J R DePaulo, E S Lander
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  ABSTRACT: Identification of the genetic bases for bipolar disorder remains a challenge for the understanding of this disease. Association between 76 candidate genes and bipolar disorder was tested by genotyping 90 single-nucleotide polymorphisms (SNPs) in these genes in 136 parent-proband trios. In this preliminary analysis, SNPs in two genes, brain-derived neurotrophic factor (BDNF) and the alpha subunit of the voltage-dependent calcium channel were associated with bipolar disorder at the P<0.05 level. In view of the large number of hypotheses tested, the two nominally positive associations were then tested in independent populations of bipolar patients and only BDNF remains a potential risk gene. In the replication samples, excess transmission of the valine allele of amino acid 66 of BDNF was observed in the direction of the original result in an additional sample of 334 parent-proband trios (T/U=108/87, P=0.066). Resequencing of 29 kb surrounding the BDNF gene identified 44 additional SNPs. Genotyping eight common SNPs identified three additional markers transmitted to bipolar probands at the P < 0.05 level. Strong LD was observed across this region and all adjacent pairwise haplotypes showed excess transmission to the bipolar proband. Analysis of these haplotypes using TRANSMIT revealed a global P value of 0.03. A single haplotype was identified that is shared by both the original dataset and the replication sample that is uniquely marked by both the rare A allele of the original SNP and a novel allele 11.5 kb 3'. Therefore, this study of 76 candidate genes has identified BDNF as a potential risk allele that will require additional study to confirm.
  Molecular Psychiatry 01/2002; 7(6):579-93. · 13.67 Impact Factor