Time-Dependent Phenomena in Neutron Slowing Down Theory

The analysis of the slowing down of a neutron pulse leads to a detailed analogy between the decay of a pulse in the fast regime versus the decay in the thermal energy region. It is found that the slope, α, of log N(t) versus log(t) depends on the system buckling, B². An “α versus B²” curve exists that is analogous to the “λ versus B²” curve for thermal systems. Other analogies between fast and thermal time decay are discussed. These analogies exist despite the fact that no time eigenvalue exists for this slowing down problem.