A study of the effect of inelastic absorption on the validity of trajectory simulation of elastic scattering

The effect of inelastic events on the elastic scattering of particles in a scattering medium may be described in terms of inelastic absorption (depletion of the elastic scattering channel), which may be implemented either by means of a complex phaseshift or by means of an optical potential. Using both methods, inelastic absorption is introduced in the exact quantum calculation of multiple elastic s-wave scattering of a particle in a cluster of point scatterers. The average solution of the quantum calculation for a large number of simulated clusters with identical boundaries but with scatterers in randomly varying positions is compared with the result of a corresponding trajectory simulation, where an inelastic mean free path has been introduced. In the trajectory simulation an inelastic event results in the absorption of the particle, i.e. termination of the trajectory. It has previously been shown that trajectory simulation of purely elastic scattering is a valid approximation of the average quantum solution if the incident particle wavelength is at most about equal to the average distance between neighbour scatterers. It is found that this condition still holds in the presence of inelastic absorption, although quantum and trajectory calculations of the scattering event distribution inside the cluster give increasingly similar results for decreasing inelastic mean free path.