Excitation functions of 109Ag(n,2n)108mAg, 151Eu(n,2n)150mEu and 159Tb(n,2n)158Tb reactions from threshold to 15 MeV

Cross-sections were measured for the formation of long-lived products image in (n,2n) reactions on 109Ag, 151Eu and 159Tb, respectively, over the neutron energy range of 10.8–12.2 MeV. In the case of silver the target material consisted of 99.26% enriched 109Ag. The 109Ag(n,2n)108mAg reaction cross-section was also measured at 14.5 MeV using silver of natural isotopic composition. All measurements were done using the activation technique in combination with high resolution γ-ray spectrometry. A re-normalization of our previous results in the 8.7–10.7 MeV energy region for the 151Eu(n,2n)150mEu and 159Tb(n,2n)158Tb reactions was done. The experimental data were compared with results of nuclear model calculations based on compound-precompound theory. Except for some small deviations in the energy region below 10 MeV, the experimental and theoretical data for the 151Eu(n,2n)150mEu and 159Tb(n,2n)158Tb reactions agree. In the case of 109Ag(n,2n)108mAg reaction, good agreement is found between experiment and theory over the whole investigated energy range.