Variational method in the theory of neutron transport from a pulsed source

Variation methods based on the heavy Debye crystal model are used for the calculation of several first time-dependent eigenvalues for the equation of neutron transport in lead. The lead diffusive parameters are determined which account for the atom chemical bonding and crystal effects. The analysis of the data obtained shows that the interference effects, although weakly influencing the diffusion coefficient, are capable of changing markedly the diffusion cooling-down coefficient. It is concluded that the interference of neutron waves scattered by various atoms results in a stepwise energy depenedence of the neutron elastic scattering cross section and, consequently, on the neutron fluence