*Article* **Yields of Photo-Proton Reactions on Nuclei of Nickel and Separation of Cobalt Isotopes from Irradiated Targets**

**Andrey G. Kazakov 1,\*, Julia S. Babenya <sup>1</sup> , Taisya Y. Ekatova <sup>1</sup> , Sergey S. Belyshev 2,3, Vadim V. Khankin <sup>3</sup> , Alexander A. Kuznetsov 2,3, Sergey E. Vinokurov <sup>1</sup> and Boris F. Myasoedov <sup>1</sup>**


**Abstract:** Nowadays, cobalt isotopes <sup>55</sup>Co, <sup>57</sup>Co, and 58mCo are considered to be promising radionuclides in nuclear medicine, with <sup>55</sup>Co receiving the most attention as an isotope for diagnostics by positron emission tomography. One of the current research directions is dedicated to its production using electron accelerators (via photonuclear method). In our work, the yields of nuclear reactions occurring during the irradiation of natNi and <sup>60</sup>Ni by bremsstrahlung photons with energy up to 55 MeV were determined. A method of fast and simple cobalt isotopes separation from irradiated targets using extraction chromatography was developed.

**Keywords:** photonuclear method; cobalt isotopes; cobalt-55; extraction chromatography; nuclear medicine
