The Scattering of Neutrons by Systems of Heavy Nuclei

It is shown that the scattering of neutrons by a system of heavy nuclei may, for neutron energies that are large compared with the level separation of the system, be described in terms of averages of simple two-particle operators over the initial state. Expressions are derived for the total and differential cross sections and for the first few moments of the energy transfer. The expression for the cross section can be explicitly evaluated even for complicated scattering systems and leads to an accurate representation of the energy dependence of the nuclear scattering. The results are applied to the problem of the detection of small electronic contributions to the cross section.