A spallation target at TRIUMF for fundamental neutron physics

Ultracold neutrons (UCNs) are a powerful tool for probing the Standard Model at high precision. The TRIUMF Ultracold Advanced Neutron (TUCAN) collaboration is building a new UCN source to provide unprecedented densities of UCNs for experiments. This source will use a tantalum-clad tungsten spallation target, receiving up to 40 mu A of 480-MeV protons from TRIUMF's main cyclotron. The beamline and target were constructed from 2014 to 2016 and operated at beam currents up to 10 mu A from 2017 to 2019 as part of a prototype UCN source. We describe the design choices for the target and target-handling system, as well as our benchmarking of the target performance using UCN production measurements.