Extraction of the density of phonon states in LiH and NaH

The inelastic neutron scattering spectra of LiH and NaH have been measured at low temperature. After an accurate evaluation of multiple scattering and multiphonon contributions, the proton-projected density of phonon states has been extracted for both samples. The NaH spectrum was previously totally unknown, while, as far as LiH is concerned, the present result substantially improves old neutron measurements, showing a better agreement with the existing lattice dynamics calculations. The proton mean kinetic energy in LiH, derived from the density of phonon states, is compared to new deep inelastic neutron scattering results.