Extraction of nuclear level densities from neutron spectra emitted in proton-induced reactions on lead isotopes and Bi

Neutron-production spectra from (p,n) reactions on ^{204,206,207,208}Pb and ²⁰⁹Bi measured previously by a Russian group were analyzed to extract numerical values for the level densities of the residual nuclei up to excitation energies of 5–6 MeV with uncertainties of 20–50%. Comparisons with the Gilbert-Cameron form and various parametrizations of the Ignatyuk formulation indicate that the Ignatyuk model with original parameters describes the results well whereas the other forms yield lower level densities. The agreement with the results of the first analysis by the experimenters themselves varies over the range of nuclei considered, being poorest for ^204,206Bi.