Interchange, Extension and Validation of R-matrix fits for gamma production

Abstract

The R-matrix method of Lane and Thomas is the standard procedure for modeling resonances at low energies, to determine widths and angular distributions needed for nuclear evaluations. Many different codes have been written with different input and output file formats, so a new code FERDINAND is available to interchange parameters. The standard procedure requires fixed boundary condition constants, so the ansatz of allowing energy-dependence for such ‘constants’ should be deprecated. The future need for larger R-matrix fits with more target excited states, to enable better prediction of gamma-rays from the decays of those states, will almost certainly be facilitated by the GPU parallel methods that are now appearing.