Exploration of the dynamics of condensed matter through neutron total cross-section measurements

We present a novel procedure to extract dynamical information from the inelastic incoherent part of the experimental neutron total cross section. The coherent elastic and inelastic components must be subtracted in order to isolate the incoherent inelastic part. We show how to obtain the one-phonon downscattering component from it, and use this result to evaluate its derivative with respect to the incident neutron wave vector. This provides a function, which serves as an input for the algorithm to extract the density of the states that is presented in this paper. We have applied this method in the case of three metal hydrides: zircaloy, magnesium and niobium, whose total cross sections were measured at a low-flux neutron source. Those results are in agreement with the inelastic scattering experiments performed at high-flux sources over the range from 40 to 250 meV. (C) 1999 Elsevier Science B.V. All rights reserved.