Interfering Compound-Nucleus Resonances

It is shown that the unitary form of the low-energy collision matrix based on $R$-matrix theory and Feshbach's unified theory of nuclear reactions can always be put into a well-known pole-resonance form for the elastic scattering, which contains only independent observable resonance parameters. The importance of the unitary resonance form of the collision matrix is discussed in connection with the statistical study of the fluctuations of the cross sections and the intermediate resonances.