Natural and enriched Cr target development for production of Manganese-52

Abstract

52Mn is a promising PET radiometal with a half-life of 5.6 days and an average positron energy of 242 keV. Typically, chromium of natural isotope abundance is used as a target material to produce this isotope through the nat/52Cr(p,n)52Mn reaction. While natural Cr is a suitable target material, higher purity 52Mn could be produced by transitioning to enriched 52Cr targets to prevent the co-production of long-lived 54Mn (t1/2 = 312 day). Unfortunately, 52Cr targets are not cost-effective without recycling processes in place, therefore, this work aims to explore routes to prepare Cr targets that could be recycled. Natural Cr foils, metal powder pellets, enriched chromium-52 oxide and Cr(III) electroplated targets were investigated in this work. Each of these cyclotron targets were irradiated, and the produced 52Mn was purified, when possible, using a semi-automated system. An improved purification by solid-phase anion exchange from ethanol-HCl mixtures resulted in recoveries of 94.5 ± 2.2% of 52Mn. The most promising target configuration to produce a recyclable target was electroplated Cr(III). This work presents several pathways to optimize enriched Cr targets for the production of high purity 52Mn.