The Study of Photoproduction of Cobalt Radioisotopes from Copper Nuclei

The process of photoproduction of a series of radioisotopes from copper nuclei at the bremsstrahlung end-point energies E_γ^max = 21, 30, and 40 MeV was studied at the AANL (YerPhI) linear electron accelerator. The relative yields of 61 Co, 60 Co, 58 Co, 57 Co with respect to the 61 Cu are measured; in particular, at E_γ^max = 40 MeV they are equal to (2.6 ± 0.3) × 10 –2 , (2.67 ± 0.04) × 10 –2 , (9.3 ± 0.6) × 10 –2 , and (0.76 ± 0.04) × 10 –2 , respectively. It is shown that the predictions of the TALYS model, as well as the model inserted in the GEANT4 software package are in a contradiction (especially in the case of the GEANT4 code) with the measured relative yields. A continuously decreasing energy dependence was observed for the ratio of unfolded (weighted with the bremsstrahlung spectrum) cross-sections of reactions 65 Cu(γ,α) 61 Co and 63 Cu (γ,2n) 61 Cu, similarly to that observed earlier for the ratio of cross-sections of electronuclear reactions 65 Cu(e,e′ + α) 61 Co and 63 Cu (e, e′ + 2n) 61 Cu. The ratio of the 61 Co and 64 Cu yields is also measured, being equal to (2. 6± 0.2)×10 –3 , (3.8 ± 0.6) × 10 –3 , and (3.2 ± 0.4) × 10 –3 , respectively, at E_γ^max = 21 MeV, 30 MeV, and 40 MeV; its value (2.6 ± 0.2) × 10 –3 at E_γ^max = 21 MeV is consistent with the general trend of the dependence of this ratio on the atomic number Z , measured recently at E_γ^max = 23 MeV for heavier nuclei with the atomic numbers from Z = 47 to Z = 82.