Determination of the effective sample thickness via radiative capture

A. M. Hurst, N. C. Summers, L. Szentmiklósi, R. B. Firestone, M. S. Basunia, J. E. Escher, B. W. Sleaford

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

A procedure for determining the effective thickness of non-uniform irregular-shaped samples via radiative capture is described. In this technique, partial γ-ray production cross sections of a compound nucleus produced in a neutron-capture reaction are measured using Prompt Gamma Activation Analysis and compared to their corresponding standardized absolute values. For the low-energy transitions, the measured cross sections are lower than their standard values due to significant photoelectric absorption of the γ rays within the bulk-sample volume itself. Using standard theoretical techniques, the amount of γ-ray self absorption and neutron self shielding can then be calculated by iteratively varying the sample thickness until the observed cross sections converge with the known standards. The overall attenuation, thus, provides a measure of the effective sample thickness illuminated by the neutron beam. This procedure is illustrated through radiative neutron capture using powdered oxide samples comprising enriched 186W and 182W from which their tungsten-equivalent effective thicknesses are deduced to be 0.077(3) mm and 0.042(8) mm, respectively.

Original languageEnglish
Pages (from-to)38-44
Number of pages7
JournalNuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
Volume362
DOIs
Publication statusPublished - Nov 1 2015

Keywords

  • (n, γ) radiative capture
  • Neutron attenuation
  • Partial γ-ray production cross sections
  • Prompt Gamma Activation Analysis (PGAA)
  • γ-Ray absorption

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation

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