The various possibilities are examined how to measure the frequency distribution of solids by the inelastic scattering of thermal and subthermal neutrons. Particular attention is drawn on measuring-techniques that allow the determination of the frequency distribution even if the scattering cross section of the target material is not totally incoherent but a mixture of a coherent and an incoherent component. It is shown how the frequency distribution of solids can be measured even if the cross section is totally coherent by the use of a doping technique. Atoms as H and V, that have an almost entirely incoherent scattering cross section, are used as impurities in the solid of interest, serving as a probe of the host lattice vibrations. By studiing the difference of the two independent inelastic scattering experiments, one with the pure, the other with the impure solid, it is possible to derive the frequency distribution function of the host lattice itself. Examples are given for Vanadium and Niobium. In addition, evidence is given how the best experimental conditions are selected for this type of inelastic neutron scattering experiments.
Probing the in-medium nucleon-nucleon inelastic scattering cross section by using an energy-dependent
n/p
ratio
