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mods:
  schema location: http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
  title info:
    title: Probing fission time scales and dynamics via GDR [] rays and neutron angular distributions
  title info:
    title: Probing fission time scales and dynamics via GDR Gamma rays and neutron angular distributions
  name:
    name part: Botting, Tye William
    name part: 1965-
    role:
      role term: creator
  type of resource: text
  genre: bibliography
  origin info:
    place:
      place term: xx
    date issued: 1999
    issuance: monographic
  language:
    language term: eng
  physical description:
    form: print
    extent: xv, 171 leaves : illustrations ; 28 cm.
  abstract: This dissertation presents a study of assign dynamics and time scales for the following reactions; 133 MeV ¹⁶O + ²⁰⁸Pb, 104 MeV ⁴He + ²⁰⁹Bi, 133 MeV ¹⁶O + ¹⁷⁶Yb, and 104 MeV ⁴He + ¹⁸⁸Os. Two disparate means were utilized: fission coincidence measurements of pre- and post-scission neutrons and of [] rays. These measurements were accomplished simultaneously and analyzed similarly, so as to minimize experimental differences and systematic model-dependent biases. Fission fragments were detected via large x-y position-sensitive parallel plate avalanche counters (PPAC'S) mounted in compact geometry to maximize their geometric efficiency. The fission fragment emission angles and relative velocities were used to reconstruct masses via standard kinematics. The y rays were detected by 144 BaF[] crystals from the U. S. Barium Fluoride Array (BFA). These detectors were arranged into two pods of 72 crystals placed at backward angles to minimize the neutron flux. The high granularity made it possible to reconstruct the event showers to obtain the total energy deposited by each detected y ray. The reconstructed energy spectra were then analyzed in the giant dipole resonance (GDR) region with the aid of statistical model calculations, giving the time scales for fission, []. From the []-ray data, the time scales obtained for the reactions ¹⁶O +²⁰⁸Pb, ⁴He + ²⁰⁹Bi, and ¹⁶O + ¹⁷⁶Yb were []=67 [] 10 zs, 45 [] 9 zs, respectively. Neutrons were detected by 8 liquid scintillator detectors from the DEMON Array, which were positioned around the target to ensure separation of neutrons and y rays and to obtain the multiplicities of pre- and post-scission neutrons. With the help of statistical model calculations, these multiplicities were also analyzed to extract the fission time scales, []. From the neutron data, the time scales obtained for the reactions ¹⁶O + ²⁰⁸Pb, ⁴He + ²⁰⁹Bi, ¹⁶O + ¹⁷⁶Yb, and ⁴He + ¹⁸⁸Os were []= 105 [] 10 zs, 72 []7 zs, 112 [] 12 zs, and 31 [] 4 zs, respectively.
  note: by Tye William Botting.
  note: Vita.
  note: "Major Subject: Chemistry".
  note: In title, Greek letter Gamma is a symbol.
  note: Issued also on microfiche from University Microfilm Inc.
  note: Ph. D. Texas A&M University 1999.
  note: Includes bibliographical references (leaves 159-168).
  subject:
    topic: Major chemistry
  identifier: 99-57394 UMI
  identifier: http://proxy.library.tamu.edu/login
  related item:
    location:
      url: http://proxy.library.tamu.edu/login
  record info:
    record content source: TXA
    record creation date: 010410
    record change date: 20190325101301.0
    record identifier: in00001603452