[en] The concept of using high-energy particle accelerators to produce neutrons for converting fertile material to fissile is over 25 years old. It is only relatively recently that accelerator design has progressed to a point where the operation approaches commercial viability. Critical unknowns in the concept were identified in a detailed study of specic configurations. Experiments to elucidate these unknowns in a timely manner using existing material and facilities are defined and identified. Basic measurements are described to evaluate effects of the primary particle beam and resulting secondary particles in massive assemblies of most materials of interest