Photoneutron Reactions on 51V Nucleus: Systematic Uncertainties in Experiments and New Evaluated Data

On the basis of objective physics criteria, it is shown that the cross sections determined for partial photoneutron reactions on V-51 nucleus by the method of photoneutronmultiplicity sorting, primarily at Livermore (USA) and Saclay (France), are not reliable because of large systematic uncertainties in them. New cross sections evaluated for such reactions by the experimental-theoretical method are found to satisfy the data reliability criteria. The discrepancies between the evaluated and experimental reaction cross sections are analyzed in detail. It is found that, in the case of the V-51 nucleus, which is relatively light, the disregard of the contribution from the (gamma, 1n1p) reaction is the main reason of sizable systematic uncertainties in the procedure used at Livermore to identify neutrons from the (gamma, 1n), (gamma, 1n1p), and (gamma, 2n) reactions.