Efficiency of Monte Carlo perturbation calculations

Using the Monte Carlo method for the solution of particle transport problems, statistical difficulties usually arise in the calculation of small effects caused by small modifications of the system properties. For sufficiently small perturbations, the use of special perturbation techniques is the only practicable way to estimate the effects with reasonable expense. Two Monte Carlo perturbation methods are briefly described and the efficiency is tested for a realistic example. It is shown that the computational efficiency can be increased by perturbation methods.