Semiempirical formula for describing neutron shell effects in the resonance-level density for s-wave resonances

A simple formula for the resonance-level density for s-wave resonances is found by fitting the assumed function of the number of neutrons to numerous experimental data. To describe shell effects, demonstrated as strong decreases in experimental data at the magic numbers of neutrons, the dependence of the assumed function on the 'complexity' of a compound nucleus is introduced. The resulting function describes quite well the character of changes in the resonance-level density with the number of neutrons, including the regions of the magic numbers