Photo-neutron reaction cross-section for 93Nb in the end-point bremsstrahlung energies of 12–16 and 45–70 MeV

The photo-neutron cross-sections of 93Nb at the end-point bremsstrahlung energies of 12, 14 and 16 MeV as well as 45, 50, 55, 60 and 70 MeV have been determined by the activation and the off-line γ-ray spectrometric techniques using the 20 MeV electron linac (ELBE) at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany, and 100 MeV electron linac at Pohang Accelerator Laboratory (PAL), Pohang, Korea. The 93Nb(γ, xn, image) reaction cross-sections as a function of photon energy were also calculated using computer code TALYS 1.4. The flux-weighted average values were obtained from the experimental and the theoretical (TALYS) values based on mono-energetic photons. The experimental values of present work are in good agreement with the flux-weighted theoretical values of TALYS 1.4 but are slightly higher than the flux-weighted experimental data of mono-energetic photons. It was also found that the theoretical and the experimental values of present work and literature data for the 93Nb(γ, xn) reaction cross-sections increase from the threshold values to a certain energy, where other reaction channels opens. However, the increase of 93Nb(γ, n) and 93Nb(γ, 2n) reaction cross-sections are sharper compared to 93Nb(γ, 3n) and 93Nb(γ, 4n) reaction cross-sections. The sharp increase of 93Nb(γ, n) and 93Nb(γ, 2n) reaction cross-sections from the threshold value up to 17–22 MeV is due to the Giant Dipole Resonance (GDR) effect besides the role of excitation energy. After a certain values, the individual 93Nb(γ, xn) reaction cross-sections decrease with increase of bremsstrahlung energy due to opening of other reaction channels.