Multistep compound nuclear reactions with giant resonances as doorway states

The characteristics of multistep compound nuclear reactions with the giant resonances as doorway states are discussed in this Brief Report. A cross-section formula describing the above nuclear reactions is derived from the Feshbach-Kerman-Koonin theory with a proper modification of its basic assumptions. Parametrization of this formula leads to an extension of the conventional exciton model. As an application, the derived formula is used to calculate the cross sections of the photonuclear reactions exciting the giant dipole resonances in different nuclei, and the results are in good agreement with experimental data