A new approach to impulsive neutron scattering

Abstract
The authors give a simple derivation of the impulse approximation for scattering of neutrons with large momentum and energy transfers from a single particle in a potential well. It does not rely on any definition of 'interaction time'. It clearly shows how the apparently free-particle nature of the final state allows the deduction of the ground-state momentum distribution from the scattered intensity and gives an unambiguous criterion for the validity of the impulse approximation.