A tale of two foils: ISIS TS-1 water moderators

Abstract

Currently there are two, decoupled and poisoned, water moderators at the ISIS Target Station 1 (TS-1), located above the target, operating at room temperature and providing neutrons for the experiments in the fields of spectroscopy, diffraction, etc. In this paper, the details about neutronics model of ISIS Target Station 1, simulation results related to TS-1 water moderators and comparison with corresponding measurement results are presented. The importance of the quality neutronics calculations for planning the upgrade/changes in the target station (as in removal of the poisoning foil in upstream water moderator) and locating the operational issues (disappearance of poisoning foil in downstream water moderator) is discussed.