Deep inelastic neutron scattering from single-crystal hcpHe4

The inelastic neutron scattering from a single crystal of hcp ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ has been measured at high momentum transfer with $\mathbf{Q}$ oriented between the $c$ axis and the basal plane. The width of the scattering function, which reflects the width of the single-particle momentum distribution, is found to be independent of scattering angle within experimental uncertainties.