Condensation of eigenphases and the elastic enhancement of average nuclear cross-sections

For the region of non-overlapping resonances, i.e., weak absorption the elastic enhancement is calculated in the absence of direct contributions. The non-overlap of resonances implies a situation where all eigenphases but one are condensated and a few very general assumptions concerning transformation properties of the S-matrix, ergodicity and analyticity allow an exact treatment beyond the well known enhancement of 3 for the weak absorption limit. (orig.)