Lead-gold eutectic: An alternative liquid target material candidate for high power spallation neutron sources

One of the main technical concerns of Megawatt-class spallation neutron sources is the removal of the heat deposited in the target station. A way to overcome it is to use targets consisting of flowing liquid metals, but the already tested materials - mercury and lead-bismuth eutectic (LBE) - are not unproblematic. We show here that another eutectic alloy containing lead and gold (LGE) could be a suitable alternative. Besides a chemical toxicity lower than mercury, this low melting-point alloy has the advantage of being solid at RT. Moreover, it combines a neutron production similar to mercury and LBE with smaller amounts of alpha-emitting nuclides, relieving safety and environmental requirements. Further advantages are a reduced decay heat a few weeks after stopping operation and density variations in the solid state significantly smaller than LBE. Steel corrosion appears to be more important than expected but if it remains manageable, the current research suggests that LGE could be a valuable alternative to LBE and mercury.