Some results of 209Bi photoactivation experiment

Photoactivation of a natural bismuth target was performed in bremsstrahlung beams with maximum energies of 40 MeV, 50 MeV and 60 MeV. Several products of (γ,xn) reactions were identified in the gamma spectra and saturation activities and flux averaged sections were calculated for them. The obtained values were compared with the results based on TALYS estimates of the cross sections of the observed reactions. TALYS estimates were calculated for all combinations of photon strength function and level density (a total of 54 of them) with the intention of evaluating which of them shows the best agreement with the experimental results. The minimum and maximum estimates of the saturation activity obtained from the 54 photon SF and LD model combinations differ in most cases by an order of magnitude. The experimental values fall within this range. At 60 MeV, the experimental values of the saturation activity are lower than most TALYS estimates. A similar result is observed at 50 MeV, but to a somewhat lesser extent, while at 40 MeV, approximately the same number of saturation activities obtained from the TALYS cross-sections give both higher and lower estimates compared to the experiment. The flux averaged cross sections calculated using the TENDL estimates are two to three times larger than the experimental ones. By comparing experimental and theoretical values of flux-averaged cross sections for the formation of ²⁰⁶Bi, it was observed that good agreement was shown by those combinations of SF and LD models that are phenomenological in their formulation. No such trend was observed for other bismuth isotopes. There is a significant need to measure the cross sections of nuclear reactions with a higher multiplicity of emitted particles to provide experimental material for further development of models for calculating reaction cross sections.