Single-Particle Scattering from SolidHe4

An investigation of the high-energy, large-momentum-transfer neutron scattering from the low-density hcp and bcc phases of ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ has revealed scattered neutron groups with the same characteristics as those associated with single-particle scattering in liquid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$. The observed groups of this type are independent of the crystallographic phase and of direction within the accuracy of this investigation. Such neutron groups have been observed at energies as low as 1.5 times the maximum phonon energy in the bcc phase.