The Influence of Source Geometry on Fission-Fragment Escape Properties

A formalism based on the Dirac chord method is extended from a previous paper to provide an analytical method for determining the properties of small fission-fragment sources of arbitrary convex geometry. The fragment escape probabilities, energy spectra, and energy deposition fractions are determined for spherical, slab, and cylindrical uranium-dioxide sources, using an energy-loss model that contains initial-energy spectra and range-energy relations for 42 fragment species. For comparison, calculations are also made, using two simplified energy-loss models. Finally, a method is given for generalizing the results to sources containing materials other than uranium dioxide.