Design of the New CERN n_TOF Neutron Spallation Target: R&D; and Prototyping Activities

A new spallation target for the CERN neutron time-of-flight facility will be installed during Long Shutdown 2 (2019-2020), with the objective of improving operational reliability, avoiding water contamination of spallation products, corrosion/erosion and creep phenomena, as well as optimizing it for the 20 m distant vertical experimental area 2, whilst keeping the same physics performances of the current target at the 200 m far experimental area 1. Several solutions have been studied with FLUKA Monte Carlo simulations in order to find the optimal solution with respect to neutron fluence, photon background, resolution function, energy deposition and radiation damage. Thermo-mechanical studies (including CFD simulations) have been performed in order to evaluate and optimize the target ability to withstand the beam loads in terms of maximum temperatures reached, cooling system efficiency, maximum stresses, creep and fatigue behaviour of the target materials, leading to a preliminary mechanical design of the target. This paper also covers the further prototyping and material characterization activities carried out in order to validate the feasibility of the investigated solutions.