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  • 1407.1681v1

    Accepted author manuscript, 403 KB, PDF document

  • J. Glorius
  • K. Sonnabend
  • J. Görres
  • D. Robertson
  • M. Knörzer
  • A. Kontos
  • T. Rauscher
  • R. Reifarth
  • A. Sauerwein
  • E. Stech
  • W. Tan
  • T. Thomas
  • M. Wiescher
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Original languageEnglish
Article number065808
Number of pages8
JournalPhysical Review C
Volume89
Issue6
DOIs
Publication statusPublished - 30 Jun 2014

Abstract

Background: Optical potentials are crucial ingredients for the prediction of nuclear reaction rates needed in simulations of the astrophysical γ process. Associated uncertainties are particularly large for reactions involving α particles. This includes (γ,α) reactions which are of special importance in the γ process. Purpose: The measurement of (α,n) reactions allows for an optimization of currently used α-nucleus potentials. The reactions Ho165(α,n) and Er166(α,n) probe the optical model in a mass region where γ process calculations exhibit an underproduction of p nuclei which is not yet understood. Method: To investigate the energy-dependent cross sections of the reactions Ho165(α,n) and Er166(α,n) close to the reaction threshold, self-supporting metallic foils were irradiated with α particles using the FN tandem Van de Graaff accelerator at the University of Notre Dame. The induced activity was determined afterwards by monitoring the specific β-decay channels. Results: Hauser-Feshbach predictions with a widely used global α potential describe the data well at energies where the cross sections are almost exclusively sensitive to the α widths. Increasing discrepancies appear towards the reaction threshold at lower energy. Conclusions: The tested global α potential is suitable at energies above 14 MeV, while a modification seems necessary close to the reaction threshold. Since the γ and neutron widths show non-negligible impact on the predictions, complementary data are required to judge whether or not the discrepancies found can be solely assigned to the α width. © 2014 American Physical Society.

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