Brief Review of the R-Matrix Theory

Resonance theory deals with the description of the nucleon-nucleus interaction and aims at the prediction of the experimental structure of cross sections. Resonance theory is basically an interaction model which treats the nucleus as a black box, whereas nuclear models are concerned with the description of the nuclear properties based on models of the nuclear forces (nuclear potential). Any theoretical method of calculating the neutron-nucleus interactions or nuclear properties cannot fully describe the nuclear effects inside the nucleus because of the complexity of the nucleus and because the nuclear forces, acting within the nucleus, are not known in detail. Quantities related to internal properties of the nucleus are taken, in this theory, as parameters which can be determined by examining the experimental results.