A series of recent incoherent inelastic neutron scattering (INS) experiments on low-temperature D2+H2 and Ne+H2 mixtures have revealed pronounced deviations from the Gaussian approximation and, moreover, the presence of strong caging effects on the H2 dynamics, due to the rattling of the light molecules partially surrounded by the heavier ones. Given this intriguing scenario, we became convinced that coherent INS could provide a much richer picture than the one already obtained from purely single-particle investigations, but, given the strong incoherent signal from H2, we have to focus on Ne+D2 mixtures. For this reason, we are now proposing measurements on this system making use of the MARI spectrometer which has already shown to be totally suitableto investigate the D2 coherent dynamics , both in the the collective excitation regime and in the crossover with the single-particle one.