An improvement to the G.G. approximation in neutron slowing down through the method of generalized function

The neutron slowing down problem in an infinite homogeneous medium is treated within the G.G. approximation through the theory of generalized function (g.f.). As test function for defining the g.f.'s, the source importance for the slowing down is chosen. In place of the Taylor expansion of the collision term of slowing down equation in the G.G. method we expand the adjoint collision term of the importance equation. Solutions obtained with this method clearly reproduce the Placzek wiggles, which do not appear in corresponding solutions by the orthodox G.G. method using the same order of approximation, and our solutions are in very good agreement with the exact Placzek function.