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,x=1-4) reaction cross-sections as a function of photon energies were also calculated using computer code TALYS1.4. 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.