Thermal moderator-reflector assembly for HBS

Abstract

The thermal moderator is the key component in a research neutron source to convert the primary neutrons which typically have energies in the MeV regime into useful neutrons for investigations with energies well below 1 eV. In the case of a HiCANS as HBS, the thermal moderator has to be optimized according to the compact target size and to the proton pulse lengths at individual target stations. Here, the details of a thermal moderator design serving up to 12 instruments at a target station and its neutronic performance are presented. The thermal moderator consists of a complex aluminium vessel filled with light water as moderator material containing 12 thin-walled extraction channels arranged in 2 levels.