Scattering FunctionS(Q,ω)for Solid Helium

Abstract

The scattering function $S(Q,\omega )$ for inelastic neutron scattering from solid bcc ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ has been calculated including one- and two-phonon processes and their interference contributions. The intensity of the one-phonon line shows the anomalies found in recent experiments on solid and liquid helium. Indications for free-particle scattering are found at larger $Q$ values. Similarities between $S(Q,\omega )$ for the solid and the liquid are further explored and discussed.