Slowing down of neutrons from a pulsed, point, monoenergetic source in a hydrogenous medium

Abstract We present an approximate analytic solution for the distribution of neutrons from a pulsed, point source in an infinite hydrogenous medium. The solution is obtained in the diffusion approximation but with the energy loss due to collisions with the hydrogen nuclei treated exactly. In spite of this our solution yields a result which is very close to the Age-Diffusion theory result. We then extend the method to apply to a point source surrounded by a bare spherical moderator and compare the results with those obtained from Monte Carlo (TIMOC) calculations and a steady state transport code (ANISN).