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Narrow α + 28Si elastic-scattering states at high excitation in 32S

  • K.-M. Källman
  • M. Brenner
  • V.Z. Goldberg
  • T. Lönnroth
  • P. Manngård
  • A.E. Pakhomov
  • V.V. Pankratov

Abstract:

The excitation function and angular distributions of elastic α-particle scattering on 28Si have been measured in the laboratory energy range 6-28 MeV using a backscattering technique on a thick target, yielding a continuous energy distribution. More than 200 narrow states are observed, with widths in the range ∼ 30-100 keV at excitation energies E* = 13-32 MeV. Angular distributions at backward angles were measured, and angular momentum values of more than 83 states have been deduced. The analysis gives spin-parities Jπ, α-partial widths Γα and reduced widths of the narrow high-lying resonant states in 32S. The experimentally observed states display both the negative- and the positive-parity rotational-like sequences with seemingly no parity splitting, a finding which is at variance with most potential-model predictions. The deduced effective moment of inertia indicates a more extended structure than the ground-state configuration. The observed strength of each ℓ-value is analyzed in terms of an underlying split doorway state of Lorentzian form, which yields an interpretation as fragmented rotational α + 28Si states.

PACS. 21.10.Hw Spin, parity, and isobaric spin – 24.10.-i Nuclear-reaction models and methods – 24.30.-v Resonance reactions – 25.55.-e 3H-, 3He-, and 4He-induced reactions 

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Copyright information

© Società Italiana di Fisica and Springer-Verlag 2003

Authors and Affiliations

  • K.-M. Källman
    • 1
  • M. Brenner
    • 1
  • V.Z. Goldberg
    • 2
  • T. Lönnroth
    • 1
  • P. Manngård
    • 1
  • A.E. Pakhomov
    • 2
  • V.V. Pankratov
    • 2
  1. 1.Department of Physics, Åbo Akademi, FIN-20500 Turku, FinlandFI
  2. 2.Russian Scientific Center “Kurchatov Institute”, 123182 Moscow, RussiaRU

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