This proposal seeks to measure the poly-CINS (polycrystalline coherent inelastic neutron scattering) spectrum from magnesium deuteride (MgD2); a powder sample on the MARI spectrometer. Existing data gathered on the IN4 spectrometer at the ILL has proven to be overly noisy and lacking in sufficient resoliution to match a theoretical semi-empirical potential to the data without significant uncertainty in the resulting model. For this reason, three days is sought on the MARI spectrometer at two temperatures (4K and 350K) to gather Q dependent information on this important system, with the primary aim being the generation of a semi-empirical magnesium-hydrogen potential for the prediction of the dynamics of this system and other, more complex, magnesium-hydrogen systems.