ИСТИНА

Photonuclear reactions cross sections important for many fields of science and technology and data files (EXFOR, RIPL, ENDF, etc.) supported by the IAEA were obtained in various experiments primarily using quasimonoenergetic annihilation photons and bremsstrahlung. There are well–known systematic discrepancies between the results, first of all cross sections of partial reactions (g, 1n), (g, 2n), (g, 3n) + .... That was a reason for generating the IAEA Photonuclear Data Library [3]. For analysis of data reliability the objective physical criteria were proposed – ratios Fi(g, in) = sigma(g, in)/sigma(g, Sn), where (g, Sn) = (g, 1n) + 2(g, 2n) + 3(g, 3n) + ... is photoneutron yield reaction. Follow definitions Fi could not have values higher than 1.00, 0.50, 0.33, ..., correspondingly for i = 1, 2, 3, ….. Higher values mean definite incorrectness of neutron multiplicity sorting and therefore non–reliability of data. Systematic analysis of experimental data revealed that for many nuclei partial photoneutron reaction cross sections as a rule are not reliable because of large systematic uncertainties of the method for determination of neutron multiplicity. The experimentally–theoretical method was proposed for evaluation of reaction cross sections satisfied physical data reliability criteria. It is based on using only (g, Sn) reaction experimental data in combination with the results of calculations in the frame of well–tested combined model [6] of photonuclear reactions: sigma-eval(g, in) = Ftheor-i(g, in) x SIGMA-exp(g, Sn). Evaluated partial and total reactions cross sections for nuclei 63,65Cu, 80Se, 90–94Zr, 115In, 112–124Sn, 133Cs, 138Ba, 159Tb, 165Ho, 181Ta, 186–192Os, 181W, 197Au, 207,208Pb, 209Bi satisfy proposed criteria and in many cases differ noticeably from experimental data and data evaluated before [3]. Therefore it became evident that IAEA Library needs to be revised and updated. Correspondent researches were partially supported by the Russia RFBR project 13–02–00124 and are supported by the upcoming IAEA CRP F41032.