MULTILEVEL PARAMETRIZATION OF RESONANCE NEUTRON CROSS-SECTIONS

The methodological principles of constructing various practical method s for the multilevel parametrization of resonance neutron cross sectio ns are formulated on the basis of the classical results of Wigner R-ma trix theory. The general structure of the well known code SAMMY, which has been used effectively in recent years to analyze and represent th e detailed energy structure of the cross sections in wide ranges of th e region of resolved levels, is discussed. It is shown that similar re sults can also be obtained by the combined method and the method of ri gorous pole expansion of the U matrix. The algorithms for transforming the parameters of the various methods are presented, and their advant ages in the practical use of the ENDF/B-6 parameters are discussed. (C ) 1997 American Institute of Physics.