Photoproduction of the 55−57Co nuclei on natNi at the bremsstrahlung end-point energy of 35–94 MeV

Production of the ${}^{55-57}$Co nuclei on ${}^{\mathrm{nat}}$Ni in photonuclear reactions using bremsstrahlung gamma photon irradiation with end-point energy $E_{\gamma \max }$ between 35 and 94 MeV has been studied. The experiment was performed at the electron linear accelerator LUE-40 NSC KIPT using the methods of $\gamma$ activation and off-line $\gamma$-ray spectroscopy. The obtained experimental flux-averaged cross-sections $〈\sigma \left(E_{\gamma \max }\right)〉$ agree with the data found in the literature. The theoretical flux-averaged cross-sections ${〈\sigma \left(E_{\gamma \max }\right)〉}_{\mathrm{th}}$ for the production of ${}^{55-57}$Co and ${}^{55-57}$Ni were estimated using the cross-section values $\sigma \left(E\right)$ from the TALYS1.95 code and bremsstrahlung spectra of gamma photons calculated by GEANT4.9.2. The experimental results for ${}^{56,57}$Co agree with the cumulative ${〈\sigma \left(E_{\gamma \max }\right)〉}_{\mathrm{th}}$. For the reactions with the production of ${}^{55}$Co nuclei, the theoretical values differ from experimental ones.