Skobeltsyn Institute of Nuclear Physics
Lomonosov Moscow State University

Abstract
For Terbium isotope $^{159}Tb$ the combined analysis was carried out for experimental data for cross sections of total $\sigma_{(\gamma,xn)}$ and partial photoneutron reactions obtained using bremsstrahlung and quasimonoenergetic annihilation photons. The systematic disagreements between the various experiments data were analyzed, the methods for their taking into account were examined, the analyzis of concrete experiment data reliability was carried out using the special transitional function of multiplicity $F_2=\sigma_{(\gamma,2n)}/\sigma_{(\gamma,xn)}$. In the frame of new experimental-theoretical threatment to evaluation of partial reaction cross sections the evaluated data for $\sigma_{(\gamma,n)}$, $\sigma_{(\gamma,2n)}$, $\sigma_{(\gamma,3n)}$ and $\sigma_{(\gamma,sn)}$reaction cross sections on $^{159}Tb$ free from shortcomings of experimental neutron multiplicity sorting methods were obtained.