An improved coupling method for time-dependent neutron slowing down in heavy media

In this study a time dependent neutron transport equation in which an isotropic neutron source emits a pulse of neutrons into a finite (Lead, iron) sphere has been solved by different techniques. In lead, the energy range of elastic events (10 KeV- 20 eV) corresponding to microsecond range of time is considered, while in iron the inelastic effect (nano-second range of time) is examined. Time moments technique and a least square fitting procedure for laplace transformed flux have been compared. Both techniques gave good results only in a certain range of time. A coupling method, where the constants of an estimated function are chosen by the time moments technique and then modified by least square fitting procedure is suggested. This gave a simple and accurate technique in evaluating time dependent neutron slowing down