Photoabsorption cross sections in the isotopes of Pb, Bi, and Ta in the energy region E/sub. gamma. /< or =12 MeV

Cross sections for the (..gamma..,n) reaction have been studied experimentally by means of a bremsstrahlung technique for the nuclei /sup 206//sup ,//sup 207//sup ,//sup 208/Pb, /sup 209/Bi, and /sup 181/Ta with a small energy step in order to search for intermediate structure in the interval from the reaction threshold up to approx.12 MeV. Such structure has been observed for all nuclei investigated except /sup 181/Ta, its contribution to the cross section has been estimated, and the results are compared with data of other experiments and with calculations according to the quasiparticle-phonon model.