Photo-neutron cross-section of nat-Gd in the bremsstrahlung end-point energies of 12 - 16 MeV and 60 - 70 MeV

The spectrum-averaged cross-sections of nat Gd(gamma,xn)159,153 Gd reactions induced by the bremsstrahlung end-point energies of 12, 14, 16. 60, 65, and 70 MeV were measured by activation and off-line gamma-ray spectrometric technique using the 20 MeV electron linac (ELBE) at HZDR, Dresden, Germany, and 100 MeV electron linac at Pohang Accelerator Laboratory, Korea. The TALYS 1.9 code was also used to calculate the theoretical nat Gd(gamma, xn)159,153 Gd reaction cross-sections as a function of photon energy. The spectrum-averaged values at various end-point energies were calculated from the literature data as well as theoretical values based on the TALYS 1.9 code, which is for mono-energetic photons. They were found to be in good agreement with
the flux-weighted values of the current experimental data. It was also observed that the experimental and theoretical cross-sections increase from the threshold values to a certain energy, at which point another reaction channel opens, indicating the role of excitation energy. Individual reaction cross-
sections decrease after a certain value as bremsstrahlung energy increases due to the opening of other reactions, indicating energy shearing among the different reaction channels.