In-beam background suppression shield

Issue title: 4th International Workshop on Neutron Delivery Systems, Institut Laue Langevin, Grenoble, September 28–30, 2015

Guest editors: Jérôme Beaucour

Article type: Research Article

Authors: Santoro, V.^{a; *} | Cai, X.X.^{a; b} | DiJulio, D.D.^{a; c} | Ansell, S.^a | Bentley, P.M.^{a; d}

Affiliations: [a] European Spallation Source ERIC, SE-221 00 Lund, Sweden | [b] DTU Nutech, Technical University of Denmark, Roskilde, Denmark | [c] Department of Physics, Lund University, SE-221 00 Lund, Sweden | [d] Department of Physics and Astronomy, Uppsala University, 751 05 Uppsala, Sweden

Correspondence: [*] Corresponding author. E-mail: valentina.santoro@esss.se.

Abstract: The long (3 ms) proton pulse of the European Spallation Source (ESS) gives rise to unique and potentially high backgrounds for the instrument suite. In such a source an instrument’s capabilities will be limited by its Signal to Noise (S/N) ratio. The instruments with a direct view of the moderator, which do not use a bender to help mitigate the fast neutron background, are the most challenging. For these beam lines we propose the innovative shielding of placing blocks of material directly into the guide system, which allow a minimum attenuation of the cold and thermal fluxes relative to the background suppression. This shielding configuration has been worked into a beam line model using Geant4. We study particularly the advantages of single crystal sapphire and silicon blocks.

Keywords: Instrument backgrounds, sapphire, filter, neutrons, spallation source

DOI: 10.3233/JNR-160034

Journal: Journal of Neutron Research, vol. 18, no. 4, pp. 135-144, 2015