"m=1" coatings for neutron guides

International Workshop on Neutron Optics and Detectors

Cooper-Jensen, C.P.^1,2 ; Vorobiev, A.^2 ; Klinkby, E.^1,3 ; Kapaklis, V.^2 ; Wilkens, H.^4 ; Rats, D.^5 ; Hjörvarsson, B.^2 ; Kirstein, O.^1,2,6 ; Bentley, P.M.^1,2

European Spallation Source ESS AB, Lund, Sweden^1

Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden^2

DTU Nutech, Technical University of Denmark, Lyngby, Denmark^3

General AtomicNes, San Diego, CA, United States^4

NeoCoat SA, La Chaux de Fonds, Switzerland^5

School of Engineering, University of Newcastle, Australia^6

关键词: Absorption cross sections;    Diamond coating;    Lower energies;    Neutron guides;    Nickel titanium;    Orders of magnitude;    Reflectivity data;    Thermal neutrons;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/528/1/012005/pdf
DOI  :  10.1088/1742-6596/528/1/012005

来源: IOP

【 摘 要 】

A substantial fraction of the price for a supermirror neutron guide system is the shielding, which is needed because of the gamma radiation produced as a result of neutron absorption in the supermirror layers. Traditional coatings have been made of nickel-titanium heterostructures, but Ni and Ti also have a fairly high absorption cross section for cold and thermal neutrons. We examine a number of alternatives to Ni as part of a study to reduce the gamma radiation from neutron guides. Materials such as diamond and Be have higher neutron scattering density than Ni, smaller absorption cross section, and when a neutron is absorbed they emit gamma photons with lower energies. We present reflectivity data comparing Ni with Be and preliminary results from diamond coatings showing there use as neutron guide coatings. Calculations show that Be and diamond coatings emit two orders of magnitude fewer gamma photons compared to Ni, mainly because of the lower absorption cross section.