A Novel Method for 57Ni and 57Co Production using Cyclotron-Generated Secondary Neutrons

Abstract

⁵⁷Ni and ⁵⁷Co radioisotpes are used in the synthesis of radiopharmaceuticals, for research purposes, as well as radiotherapy in nuclear medicine due to its decay characteristics. In this research, ⁵⁷Ni and ⁵⁷Co were produced using secondary neutrons. The secondary neutrons employed in this investigationwere generated by bombarding 11 MeV protons intoa target system consisting of Havar^Ò foil as a vacuum window, aluminum foil as an energy degrader, aluminum tube as a target holder and nickel foil as a target via (p,n), (n,n) and (n,2n) nuclear reactions. The TALYS-calculated data were used to understand the origin of the secondary neutrons.  In this experiment, variable Ni target thicknesses of 75, 150 and 225 mm were irradiated with a fixed proton beam dose of 0.67 mAhr in order to study the dependence of the radioisotope yields on the target thickness. For the first time, ⁵⁷Ni and ⁵⁷Co radioisotopes wereproduced and observed experimentally following ⁵⁸Ni(n,2n)⁵⁷Ni → ⁵⁷Co nuclear reaction. Experimental results indicated that for 225-mm thick Ni target, the ⁵⁷Ni yield of 10.85 ± 3.29 mCi/mAhr and ⁵⁷Co yield of 6.04 ± 2.45mCi/mAhr were recorded after an hour cooling period. The resulted yieldsdid not strongly depend on the target thickness. This proposed novel method is a promising method to obtain higher radioactivity yield in the production of ⁵⁷Ni and ⁵⁷Co radioisotopes.