Neutron guide shielding for the BIFROST spectrometer at ESS

Research output: Contribution to journalArticle

Abstract

We report on the study of fast-neutron background for the BIFROST spectrometer at ESS. We investigate the effect of background radiation induced by the interaction of fast neutrons from the source with the material of the neutron guide and devise a reasonable fast, thermal/cold neutron shielding solution for the current guide geometry using McStas and MCNPX. We investigate the effectiveness of the steel shielding around the guide by running simulations with three different steel thicknesses. The same approach is used to study the efficiencies of the steel wall a flat cylinder pierced by the guide in the middle and the polyethylene layer. The final model presented here has a 3 cm thick steel shielding around the guide, 30 cm of polyethylene around the shielding, two 5 mm thick B4C layers and a steel wall at position Z = 38 m, being 1 m thick and 10 m in radius. The final model finally proves that it is sufficient to bring the background level below the cosmic neutron rate, which defines an order of magnitude of the lowest obtainable background in the instruments.

Details

Authors
  • K. Mantulnikovs
  • M. Bertelsen
  • C. P. Cooper-Jensen
  • K. Lefmann
  • E. B. Klinkby
External organisations
  • University of Copenhagen
  • Uppsala University
  • Technical University of Denmark
  • European Spallation Source ESS AB
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Accelerator Physics and Instrumentation
Original languageEnglish
Article number012027
JournalJournal of Physics: Conference Series
Volume746
Issue number1
Publication statusPublished - 2016 Oct 10
Publication categoryResearch
Peer-reviewedYes