[en] One of the major environmental issues facing the world is the safe, long-term storage of large amounts of plutonium and other actinides from retired weapons and the nuclear power industry. An accelerator-driven subcritical assembly is being explored as a way to burn these wastes. Such a system would use a beam of high-energy protons impinging on a target of lead-bismuth liquid eutectic for neutron production. Proper calculation of the neutron yield from such a target is required for the design of a surrounding subcritical assembly. To gather data on the neutron production, we irradiated a thick (10 cm radius, 50 cm length) target of lead-bismuth in the Blue Room facility at the Los Alamos Neutron Science Center. The target was irradiated with a 24 nA beam of 800 MeV protons, and the neutron spectra was measured at various locations along the target using both time-of-flight spectroscopy and activation foils. In addition, activation foils were placed downstream of a tungsten target (target 4) in a well-characterised neutron environment to establish the spectral unfolding technique. The experimental configuration and some preliminary results of these experiments are presented in the current work. (authors)