Data on Photoneutron Reactions from Various Experiments for 133Cs, 138Ba and 209Bi Nuclei

Basic methods for determining cross sections for photoneutron partial reactions are examined. They are obtained directly in experiments with quasimonoeneregetic annihilation photons or from the cross section for the (gamma, xn) = (gamma, 1n) vertical bar 2(gamma, 2n) vertical bar 3(gamma, 3n) vertical bar... neutron-yield reaction in experiments with bremsstrahlung photons by introducing corrections based on statistical nuclear-reaction theory. The difference in the conditions of these experiments, which leads to discrepancies between their results because of sizable systematic errors, is analyzed. Physical criteria are used to study the reliability of data on the photodisintegration of Cs-133, Ba-138, and Bi-209 nuclei. The cross sections for partial and total reactions satisfying the reliability criteria are evaluated within the experimental-theoretical method (sigma(eval)(gamma, in) = F-i(theor) x sigma(expt)(gamma, xn)) on the basis of the experimental cross sections sigma(expt)(gamma, xn) and the results of the calculations within the combined model of photonuclear reactions.