Status of experimental and theoretical (n,4n) reaction cross-section data

The present status of (n,4n) reaction cross-section data for medium and heavy nuclei at the neutron energies up to 30 MeV is of the principal importance for nuclear technology applications and the nuclear theory investigation. Recently, an attempt to evaluate substantially the situation for Z=63 to 81 nuclei by the combination of experimental and theoretical (n,4n) reaction cross-section values at 26 and 28 MeV, the cross-sections dependence on the neutron excess (N-Z) and (En+Qn), (where N and Z are the target nucleus neutron and proton numbers, En and Qn are the incident neutron energy and (n,4n) reaction energy respectively) was investigated. This approach in this field is formulated. Some striking discrepancies between the existing measurements and the predicted cross-section values are identified and possibilities for the improved values are discussed