Research on the Quantum Multistep Theory for Pre-equilibrium Nuclear Reaction

The Feshbach-Kerman-Koonin(FKK) quantum multistep theory of the pre-equilibrium reaction is further improved and perfected. A unified description for the multistep compound(MSC) process of the pre-equilibrium reaction and the compound nucleus(CN) process of full equilibrium reaction can be presented. This formula can integrate MSC and CN theories with the optical model and Hauser-Feshbach formula, and can get self-consistent expression. In multistep direct(MSD) process of the pre-equilibrium reaction, the μ -step cross section can be expressed by the convolution of μ one-step cross section. And the one-step cross section for continuum can be written as the product of an averaged DWBA matrix element and the state density. For calculating the multistep direct reaction cross section, two methods, the state densities and full microscopic model, are used and compared. Some typical experiments are analyzed by using the work mentioned above. The calculated results are reasonable and in good agreement with the experimental data.