Final-State Effects on Thermal-Neutron Scattering at High-Energy Transfer

An approximation is developed for nuclear scattering of neutrons from a target of spinless particles of a single isotope. It has the correct limit for large momentum transfer, the impulse approximation, and is calculable in practice if the single-particle momentum distribution, the off-diagonal two-particle density matrix, and the two-body interaction potential of the target atoms are known. An intended application of the theory is to neutron scattering from liquid helium in the moderately-high momentum-transfer region ($\overrightarrow{\mathrm{k}}\approx 15$ ${\mathrm{\AA }}^{-1\mathrm{}}$) presently accessible with reactor neutrons.