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Neutron guide shielding for the BIFROST spectrometer at ESS

Mantulnikovs, K.; Bertelsen, M.; Cooper-Jensen, C. P. LU ; Lefmann, K. LU and Klinkby, E. B. (2016) In Journal of Physics: Conference Series 746(1).
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... (More)

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.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Journal of Physics: Conference Series
volume
746
issue
1
publisher
IOP Publishing
external identifiers
  • scopus:84994314559
ISSN
1742-6588
DOI
10.1088/1742-6596/746/1/012027
language
English
LU publication?
yes
id
55505b7c-8135-4f91-9d27-281000f85fab
date added to LUP
2016-12-07 12:06:08
date last changed
2017-04-19 14:35:44
@article{55505b7c-8135-4f91-9d27-281000f85fab,
  abstract     = {<p>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 B<sub>4</sub>C 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.</p>},
  articleno    = {012027},
  author       = {Mantulnikovs, K. and Bertelsen, M. and Cooper-Jensen, C. P. and Lefmann, K. and Klinkby, E. B.},
  issn         = {1742-6588},
  language     = {eng},
  month        = {10},
  number       = {1},
  publisher    = {IOP Publishing},
  series       = {Journal of Physics: Conference Series},
  title        = {Neutron guide shielding for the BIFROST spectrometer at ESS},
  url          = {http://dx.doi.org/10.1088/1742-6596/746/1/012027},
  volume       = {746},
  year         = {2016},
}